pocketpy/plugins/flutter/src/pocketpy.h

/*
 *  Copyright (c) 2023 blueloveTH
 *  Distributed Under The MIT License
 *  https://github.com/blueloveTH/pocketpy
 */

#ifndef POCKETPY_H
#define POCKETPY_H
// emhash8::HashMap for C++11/14/17
// version 1.6.3
//
// Licensed under the MIT License <http://opensource.org/licenses/MIT>.
// SPDX-License-Identifier: MIT
// Copyright (c) 2019-2022 Huang Yuanbing & bailuzhou AT 163.com
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE



#include <cstring>
#include <string>
#include <cstdlib>
#include <type_traits>
#include <cassert>
#include <utility>
#include <cstdint>
#include <functional>
#include <iterator>
#include <algorithm>

#ifdef EMH_KEY
    #undef  EMH_KEY
    #undef  EMH_VAL
    #undef  EMH_KV
    #undef  EMH_BUCKET
    #undef  EMH_NEW
    #undef  EMH_EMPTY
    #undef  EMH_PREVET
    #undef  EMH_LIKELY
    #undef  EMH_UNLIKELY
#endif

// likely/unlikely
#if defined(__GNUC__) || defined(__INTEL_COMPILER) || defined(__clang__)
#    define EMH_LIKELY(condition)   __builtin_expect(condition, 1)
#    define EMH_UNLIKELY(condition) __builtin_expect(condition, 0)
#else
#    define EMH_LIKELY(condition)   (condition)
#    define EMH_UNLIKELY(condition) (condition)
#endif

#define EMH_KEY(p, n)     p[n].first
#define EMH_VAL(p, n)     p[n].second
#define EMH_KV(p, n)      p[n]

#define EMH_INDEX(i, n)   i[n]
#define EMH_BUCKET(i, n)  i[n].bucket
#define EMH_HSLOT(i, n)   i[n].slot
#define EMH_SLOT(i, n)    (i[n].slot & _mask)
#define EMH_PREVET(i, n)  i[n].slot

#define EMH_KEYMASK(key, mask)  ((size_type)(key) & ~mask)
#define EMH_EQHASH(n, key_hash) (EMH_KEYMASK(key_hash, _mask) == (_index[n].slot & ~_mask))
#define EMH_NEW(key, val, bucket, key_hash) \
    new(_pairs + _num_filled) value_type(key, val); \
    _etail = bucket; \
    _index[bucket] = {bucket, _num_filled++ | EMH_KEYMASK(key_hash, _mask)}

#define EMH_EMPTY(i, n) (0 > (int)i[n].bucket)

namespace emhash8 {

#ifndef EMH_DEFAULT_LOAD_FACTOR
    constexpr static float EMH_DEFAULT_LOAD_FACTOR = 0.80f;
    constexpr static float EMH_MIN_LOAD_FACTOR     = 0.25f; //< 0.5
#endif
#if EMH_CACHE_LINE_SIZE < 32
    constexpr static uint32_t EMH_CACHE_LINE_SIZE  = 64;
#endif

template <typename KeyT, typename ValueT, typename HashT = std::hash<KeyT>, typename EqT = std::equal_to<KeyT>>
class HashMap
{
public:
    using htype = HashMap<KeyT, ValueT, HashT, EqT>;
    using value_type = std::pair<KeyT, ValueT>;
    using key_type = KeyT;
    using mapped_type = ValueT;

#ifdef EMH_SMALL_TYPE
    using size_type = uint16_t;
#elif EMH_SIZE_TYPE == 0
    using size_type = uint32_t;
#else
    using size_type = size_t;
#endif

    using hasher = HashT;
    using key_equal = EqT;

    constexpr static size_type INACTIVE = 0-1u;
    //constexpr uint32_t END      = 0-0x1u;
    constexpr static size_type EAD      = 2;

    struct Index
    {
        size_type bucket;
        size_type slot;
    };

    class const_iterator;
    class iterator
    {
    public:
        using iterator_category = std::bidirectional_iterator_tag;
        using difference_type = std::ptrdiff_t;
        using value_type      = typename htype::value_type;
        using pointer         = value_type*;
        using const_pointer   = const value_type* ;
        using reference       = value_type&;
        using const_reference = const value_type&;

        iterator() : kv_(nullptr) {}
        iterator(const_iterator& cit) {
            kv_ = cit.kv_;
        }

        iterator(const htype* hash_map, size_type bucket) {
            kv_ = hash_map->_pairs + (int)bucket;
        }

        iterator& operator++()
        {
            kv_ ++;
            return *this;
        }

        iterator operator++(int)
        {
            auto cur = *this; kv_ ++;
            return cur;
        }

        iterator& operator--()
        {
            kv_ --;
            return *this;
        }

        iterator operator--(int)
        {
            auto cur = *this; kv_ --;
            return cur;
        }

        reference operator*() const { return *kv_; }
        pointer operator->() const { return kv_; }

        bool operator == (const iterator& rhs) const { return kv_ == rhs.kv_; }
        bool operator != (const iterator& rhs) const { return kv_ != rhs.kv_; }
        bool operator == (const const_iterator& rhs) const { return kv_ == rhs.kv_; }
        bool operator != (const const_iterator& rhs) const { return kv_ != rhs.kv_; }

    public:
        value_type* kv_;
    };

    class const_iterator
    {
    public:
        using iterator_category = std::bidirectional_iterator_tag;
        using value_type        = typename htype::value_type;
        using difference_type   = std::ptrdiff_t;
        using pointer           = value_type*;
        using const_pointer     = const value_type*;
        using reference         = value_type&;
        using const_reference   = const value_type&;

        const_iterator(const iterator& it) {
            kv_ = it.kv_;
        }

        const_iterator (const htype* hash_map, size_type bucket) {
            kv_ = hash_map->_pairs + (int)bucket;
        }

        const_iterator& operator++()
        {
            kv_ ++;
            return *this;
        }

        const_iterator operator++(int)
        {
            auto cur = *this; kv_ ++;
            return cur;
        }

        const_iterator& operator--()
        {
            kv_ --;
            return *this;
        }

        const_iterator operator--(int)
        {
            auto cur = *this; kv_ --;
            return cur;
        }

        const_reference operator*() const { return *kv_; }
        const_pointer operator->() const { return kv_; }

        bool operator == (const iterator& rhs) const { return kv_ == rhs.kv_; }
        bool operator != (const iterator& rhs) const { return kv_ != rhs.kv_; }
        bool operator == (const const_iterator& rhs) const { return kv_ == rhs.kv_; }
        bool operator != (const const_iterator& rhs) const { return kv_ != rhs.kv_; }
    public:
        const value_type* kv_;
    };

    void init(size_type bucket, float mlf = EMH_DEFAULT_LOAD_FACTOR)
    {
        _pairs = nullptr;
        _index = nullptr;
        _mask  = _num_buckets = 0;
        _num_filled = 0;
        max_load_factor(mlf);
        rehash(bucket);
    }

    HashMap(size_type bucket = 2, float mlf = EMH_DEFAULT_LOAD_FACTOR)
    {
        init(bucket, mlf);
    }

    HashMap(const HashMap& rhs)
    {
        if (rhs.load_factor() > EMH_MIN_LOAD_FACTOR) {
            _pairs = alloc_bucket((size_type)(rhs._num_buckets * rhs.max_load_factor()) + 4);
            _index = alloc_index(rhs._num_buckets);
            clone(rhs);
        } else {
            init(rhs._num_filled + 2, EMH_DEFAULT_LOAD_FACTOR);
            for (auto it = rhs.begin(); it != rhs.end(); ++it)
                insert_unique(it->first, it->second);
        }
    }

    HashMap(HashMap&& rhs) noexcept
    {
        init(0);
        *this = std::move(rhs);
    }

    HashMap(std::initializer_list<value_type> ilist)
    {
        init((size_type)ilist.size());
        for (auto it = ilist.begin(); it != ilist.end(); ++it)
            do_insert(*it);
    }

    template<class InputIt>
    HashMap(InputIt first, InputIt last, size_type bucket_count=4)
    {
        init(std::distance(first, last) + bucket_count);
        for (; first != last; ++first)
            emplace(*first);
    }

    HashMap& operator=(const HashMap& rhs)
    {
        if (this == &rhs)
            return *this;

        if (rhs.load_factor() < EMH_MIN_LOAD_FACTOR) {
            clear(); free(_pairs); _pairs = nullptr;
            rehash(rhs._num_filled + 2);
            for (auto it = rhs.begin(); it != rhs.end(); ++it)
                insert_unique(it->first, it->second);
            return *this;
        }

        clearkv();

        if (_num_buckets != rhs._num_buckets) {
            free(_pairs); free(_index);
            _index = alloc_index(rhs._num_buckets);
            _pairs = alloc_bucket((size_type)(rhs._num_buckets * rhs.max_load_factor()) + 4);
        }

        clone(rhs);
        return *this;
    }

    HashMap& operator=(HashMap&& rhs) noexcept
    {
        if (this != &rhs) {
            swap(rhs);
            rhs.clear();
        }
        return *this;
    }

    template<typename Con>
    bool operator == (const Con& rhs) const
    {
        if (size() != rhs.size())
            return false;

        for (auto it = begin(), last = end(); it != last; ++it) {
            auto oi = rhs.find(it->first);
            if (oi == rhs.end() || it->second != oi->second)
                return false;
        }
        return true;
    }

    template<typename Con>
    bool operator != (const Con& rhs) const { return !(*this == rhs); }

    ~HashMap() noexcept
    {
        clearkv();
        free(_pairs);
        free(_index);
    }

    void clone(const HashMap& rhs)
    {
        _hasher      = rhs._hasher;
//        _eq          = rhs._eq;
        _num_buckets = rhs._num_buckets;
        _num_filled  = rhs._num_filled;
        _mlf         = rhs._mlf;
        _last        = rhs._last;
        _mask        = rhs._mask;
#if EMH_HIGH_LOAD
        _ehead       = rhs._ehead;
#endif
        _etail       = rhs._etail;

        auto opairs  = rhs._pairs;
        memcpy((char*)_index, (char*)rhs._index, (_num_buckets + EAD) * sizeof(Index));

        if (is_copy_trivially()) {
            if (opairs)
                memcpy((char*)_pairs, (char*)opairs, _num_filled * sizeof(value_type));
        } else {
            for (size_type slot = 0; slot < _num_filled; slot++)
                new(_pairs + slot) value_type(opairs[slot]);
        }
    }

    void swap(HashMap& rhs)
    {
        //      std::swap(_eq, rhs._eq);
        std::swap(_hasher, rhs._hasher);
        std::swap(_pairs, rhs._pairs);
        std::swap(_index, rhs._index);
        std::swap(_num_buckets, rhs._num_buckets);
        std::swap(_num_filled, rhs._num_filled);
        std::swap(_mask, rhs._mask);
        std::swap(_mlf, rhs._mlf);
        std::swap(_last, rhs._last);
#if EMH_HIGH_LOAD
        std::swap(_ehead, rhs._ehead);
#endif
        std::swap(_etail, rhs._etail);
    }

    // -------------------------------------------------------------
    inline iterator first() const { return {this, 0}; }
    inline iterator last() const { return {this, _num_filled - 1}; }

    inline iterator begin() { return first(); }
    inline const_iterator cbegin() const { return first(); }
    inline const_iterator begin() const { return first(); }

    inline iterator end() { return {this, _num_filled}; }
    inline const_iterator cend() const { return {this, _num_filled}; }
    inline const_iterator end() const { return cend(); }

    inline const value_type* values() const { return _pairs; }
    inline const Index* index() const { return _index; }

    inline size_type size() const { return _num_filled; }
    inline bool empty() const { return _num_filled == 0; }
    inline size_type bucket_count() const { return _num_buckets; }

    /// Returns average number of elements per bucket.
    inline float load_factor() const { return static_cast<float>(_num_filled) / (_mask + 1); }

    inline HashT& hash_function() const { return _hasher; }
    inline EqT& key_eq() const { return _eq; }

    void max_load_factor(float mlf)
    {
        if (mlf < 0.991 && mlf > EMH_MIN_LOAD_FACTOR) {
            _mlf = (uint32_t)((1 << 27) / mlf);
            if (_num_buckets > 0) rehash(_num_buckets);
        }
    }

    inline constexpr float max_load_factor() const { return (1 << 27) / (float)_mlf; }
    inline constexpr size_type max_size() const { return (1ull << (sizeof(size_type) * 8 - 1)); }
    inline constexpr size_type max_bucket_count() const { return max_size(); }

#if EMH_STATIS
    //Returns the bucket number where the element with key k is located.
    size_type bucket(const KeyT& key) const
    {
        const auto bucket = hash_bucket(key);
        const auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return 0;
        else if (bucket == next_bucket)
            return bucket + 1;

        return hash_main(bucket) + 1;
    }

    //Returns the number of elements in bucket n.
    size_type bucket_size(const size_type bucket) const
    {
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return 0;

        next_bucket = hash_main(bucket);
        size_type ibucket_size = 1;

        //iterator each item in current main bucket
        while (true) {
            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket) {
                break;
            }
            ibucket_size ++;
            next_bucket = nbucket;
        }
        return ibucket_size;
    }

    size_type get_main_bucket(const size_type bucket) const
    {
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return INACTIVE;

        return hash_main(bucket);
    }

    size_type get_diss(size_type bucket, size_type next_bucket, const size_type slots) const
    {
        auto pbucket = reinterpret_cast<uint64_t>(&_pairs[bucket]);
        auto pnext   = reinterpret_cast<uint64_t>(&_pairs[next_bucket]);
        if (pbucket / EMH_CACHE_LINE_SIZE == pnext / EMH_CACHE_LINE_SIZE)
            return 0;
        size_type diff = pbucket > pnext ? (pbucket - pnext) : (pnext - pbucket);
        if (diff / EMH_CACHE_LINE_SIZE < slots - 1)
            return diff / EMH_CACHE_LINE_SIZE + 1;
        return slots - 1;
    }

    int get_bucket_info(const size_type bucket, size_type steps[], const size_type slots) const
    {
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return -1;

        const auto main_bucket = hash_main(bucket);
        if (next_bucket == main_bucket)
            return 1;
        else if (main_bucket != bucket)
            return 0;

        steps[get_diss(bucket, next_bucket, slots)] ++;
        size_type ibucket_size = 2;
        //find a empty and linked it to tail
        while (true) {
            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket)
                break;

            steps[get_diss(nbucket, next_bucket, slots)] ++;
            ibucket_size ++;
            next_bucket = nbucket;
        }
        return (int)ibucket_size;
    }

    void dump_statics() const
    {
        const size_type slots = 128;
        size_type buckets[slots + 1] = {0};
        size_type steps[slots + 1]   = {0};
        for (size_type bucket = 0; bucket < _num_buckets; ++bucket) {
            auto bsize = get_bucket_info(bucket, steps, slots);
            if (bsize > 0)
                buckets[bsize] ++;
        }

        size_type sumb = 0, collision = 0, sumc = 0, finds = 0, sumn = 0;
        puts("============== buckets size ration =========");
        for (size_type i = 0; i < sizeof(buckets) / sizeof(buckets[0]); i++) {
            const auto bucketsi = buckets[i];
            if (bucketsi == 0)
                continue;
            sumb += bucketsi;
            sumn += bucketsi * i;
            collision += bucketsi * (i - 1);
            finds += bucketsi * i * (i + 1) / 2;
            printf("  %2u  %8u  %2.2lf|  %.2lf\n", i, bucketsi, bucketsi * 100.0 * i / _num_filled, sumn * 100.0 / _num_filled);
        }

        puts("========== collision miss ration ===========");
        for (size_type i = 0; i < sizeof(steps) / sizeof(steps[0]); i++) {
            sumc += steps[i];
            if (steps[i] <= 2)
                continue;
            printf("  %2u  %8u  %.2lf  %.2lf\n", i, steps[i], steps[i] * 100.0 / collision, sumc * 100.0 / collision);
        }

        if (sumb == 0)  return;
        printf("    _num_filled/bucket_size/packed collision/cache_miss/hit_find = %u/%.2lf/%zd/ %.2lf%%/%.2lf%%/%.2lf\n",
                _num_filled, _num_filled * 1.0 / sumb, sizeof(value_type), (collision * 100.0 / _num_filled), (collision - steps[0]) * 100.0 / _num_filled, finds * 1.0 / _num_filled);
        assert(sumn == _num_filled);
        assert(sumc == collision);
        puts("============== buckets size end =============");
    }
#endif

    // ------------------------------------------------------------
    template<typename K=KeyT>
    inline iterator find(const K& key) noexcept
    {
        return {this, find_filled_slot(key)};
    }

    template<typename K=KeyT>
    inline const_iterator find(const K& key) const noexcept
    {
        return {this, find_filled_slot(key)};
    }

    template<typename K=KeyT>
    ValueT& at(const K& key)
    {
        const auto slot = find_filled_slot(key);
        //throw
        return EMH_VAL(_pairs, slot);
    }

    template<typename K=KeyT>
    const ValueT& at(const K& key) const
    {
        const auto slot = find_filled_slot(key);
        //throw
        return EMH_VAL(_pairs, slot);
    }

    template<typename K=KeyT>
    inline bool contains(const K& key) const noexcept
    {
        return find_filled_slot(key) != _num_filled;
    }

    template<typename K=KeyT>
    inline size_type count(const K& key) const noexcept
    {
        return find_filled_slot(key) == _num_filled ? 0 : 1;
        //return find_sorted_bucket(key) == END ? 0 : 1;
        //return find_hash_bucket(key) == END ? 0 : 1;
    }

    template<typename K=KeyT>
    std::pair<iterator, iterator> equal_range(const K& key)
    {
        const auto found = find(key);
        if (found.second == _num_filled)
            return { found, found };
        else
            return { found, std::next(found) };
    }

    void merge(HashMap& rhs)
    {
        if (empty()) {
            *this = std::move(rhs);
            return;
        }

        for (auto rit = rhs.begin(); rit != rhs.end(); ) {
            auto fit = find(rit->first);
            if (fit == end()) {
                insert_unique(rit->first, std::move(rit->second));
                rit = rhs.erase(rit);
            } else {
                ++rit;
            }
        }
    }

    /// Returns the matching ValueT or nullptr if k isn't found.
    bool try_get(const KeyT& key, ValueT& val) const noexcept
    {
        const auto slot = find_filled_slot(key);
        const auto found = slot != _num_filled;
        if (found) {
            val = EMH_VAL(_pairs, slot);
        }
        return found;
    }

    /// Returns the matching ValueT or nullptr if k isn't found.
    ValueT* try_get(const KeyT& key) noexcept
    {
        const auto slot = find_filled_slot(key);
        return slot != _num_filled ? &EMH_VAL(_pairs, slot) : nullptr;
    }

    /// Const version of the above
    ValueT* try_get(const KeyT& key) const noexcept
    {
        const auto slot = find_filled_slot(key);
        return slot != _num_filled ? &EMH_VAL(_pairs, slot) : nullptr;
    }

    /// set value if key exist
    bool try_set(const KeyT& key, const ValueT& val) noexcept
    {
        const auto slot = find_filled_slot(key);
        if (slot == _num_filled)
            return false;

        EMH_VAL(_pairs, slot) = val;
        return true;
    }

    /// set value if key exist
    bool try_set(const KeyT& key, ValueT&& val) noexcept
    {
        const auto slot = find_filled_slot(key);
        if (slot == _num_filled)
            return false;

        EMH_VAL(_pairs, slot) = std::move(val);
        return true;
    }

    /// Convenience function.
    ValueT get_or_return_default(const KeyT& key) const noexcept
    {
        const auto slot = find_filled_slot(key);
        return slot == _num_filled ? ValueT() : EMH_VAL(_pairs, slot);
    }

    // -----------------------------------------------------
    std::pair<iterator, bool> do_insert(const value_type& value) noexcept
    {
        const auto key_hash = hash_key(value.first);
        const auto bucket = find_or_allocate(value.first, key_hash);
        const auto bempty  = EMH_EMPTY(_index, bucket);
        if (bempty) {
            EMH_NEW(value.first, value.second, bucket, key_hash);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return { {this, slot}, bempty };
    }

    std::pair<iterator, bool> do_insert(value_type&& value) noexcept
    {
        const auto key_hash = hash_key(value.first);
        const auto bucket = find_or_allocate(value.first, key_hash);
        const auto bempty  = EMH_EMPTY(_index, bucket);
        if (bempty) {
            EMH_NEW(std::move(value.first), std::move(value.second), bucket, key_hash);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return { {this, slot}, bempty };
    }

    template<typename K, typename V>
    std::pair<iterator, bool> do_insert(K&& key, V&& val) noexcept
    {
        const auto key_hash = hash_key(key);
        const auto bucket = find_or_allocate(key, key_hash);
        const auto bempty = EMH_EMPTY(_index, bucket);
        if (bempty) {
            EMH_NEW(std::forward<K>(key), std::forward<V>(val), bucket, key_hash);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return { {this, slot}, bempty };
    }

    template<typename K, typename V>
    std::pair<iterator, bool> do_assign(K&& key, V&& val) noexcept
    {
        check_expand_need();
        const auto key_hash = hash_key(key);
        const auto bucket = find_or_allocate(key, key_hash);
        const auto bempty = EMH_EMPTY(_index, bucket);
        if (bempty) {
            EMH_NEW(std::forward<K>(key), std::forward<V>(val), bucket, key_hash);
        } else {
            EMH_VAL(_pairs, EMH_SLOT(_index, bucket)) = std::move(val);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return { {this, slot}, bempty };
    }

    std::pair<iterator, bool> insert(const value_type& p)
    {
        check_expand_need();
        return do_insert(p);
    }

    std::pair<iterator, bool> insert(value_type && p)
    {
        check_expand_need();
        return do_insert(std::move(p));
    }

    void insert(std::initializer_list<value_type> ilist)
    {
        reserve(ilist.size() + _num_filled, false);
        for (auto it = ilist.begin(); it != ilist.end(); ++it)
            do_insert(*it);
    }

    template <typename Iter>
    void insert(Iter first, Iter last)
    {
        reserve(std::distance(first, last) + _num_filled, false);
        for (; first != last; ++first)
            do_insert(first->first, first->second);
    }

#if 0
    template <typename Iter>
    void insert_unique(Iter begin, Iter end)
    {
        reserve(std::distance(begin, end) + _num_filled, false);
        for (; begin != end; ++begin) {
            insert_unique(*begin);
        }
    }
#endif

    template<typename K, typename V>
    size_type insert_unique(K&& key, V&& val)
    {
        check_expand_need();
        const auto key_hash = hash_key(key);
        auto bucket = find_unique_bucket(key_hash);
        EMH_NEW(std::forward<K>(key), std::forward<V>(val), bucket, key_hash);
        return bucket;
    }

    size_type insert_unique(value_type&& value)
    {
        return insert_unique(std::move(value.first), std::move(value.second));
    }

    inline size_type insert_unique(const value_type& value)
    {
        return insert_unique(value.first, value.second);
    }

    template <class... Args>
    inline std::pair<iterator, bool> emplace(Args&&... args) noexcept
    {
        check_expand_need();
        return do_insert(std::forward<Args>(args)...);
    }

    //no any optimize for position
    template <class... Args>
    iterator emplace_hint(const_iterator hint, Args&&... args)
    {
        (void)hint;
        check_expand_need();
        return do_insert(std::forward<Args>(args)...).first;
    }

    template<class... Args>
    std::pair<iterator, bool> try_emplace(const KeyT& k, Args&&... args)
    {
        check_expand_need();
        return do_insert(k, std::forward<Args>(args)...);
    }

    template<class... Args>
    std::pair<iterator, bool> try_emplace(KeyT&& k, Args&&... args)
    {
        check_expand_need();
        return do_insert(std::move(k), std::forward<Args>(args)...);
    }

    template <class... Args>
    inline size_type emplace_unique(Args&&... args)
    {
        return insert_unique(std::forward<Args>(args)...);
    }

    std::pair<iterator, bool> insert_or_assign(const KeyT& key, ValueT&& val) { return do_assign(key, std::forward<ValueT>(val)); }
    std::pair<iterator, bool> insert_or_assign(KeyT&& key, ValueT&& val) { return do_assign(std::move(key), std::forward<ValueT>(val)); }

    /// Return the old value or ValueT() if it didn't exist.
    ValueT set_get(const KeyT& key, const ValueT& val)
    {
        check_expand_need();
        const auto key_hash = hash_key(key);
        const auto bucket = find_or_allocate(key, key_hash);
        if (EMH_EMPTY(_index, bucket)) {
            EMH_NEW(key, val, bucket, key_hash);
            return ValueT();
        } else {
            const auto slot = EMH_SLOT(_index, bucket);
            ValueT old_value(val);
            std::swap(EMH_VAL(_pairs, slot), old_value);
            return old_value;
        }
    }

    /// Like std::map<KeyT, ValueT>::operator[].
    ValueT& operator[](const KeyT& key) noexcept
    {
        check_expand_need();
        const auto key_hash = hash_key(key);
        const auto bucket = find_or_allocate(key, key_hash);
        if (EMH_EMPTY(_index, bucket)) {
            /* Check if inserting a value rather than overwriting an old entry */
            EMH_NEW(key, std::move(ValueT()), bucket, key_hash);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return EMH_VAL(_pairs, slot);
    }

    ValueT& operator[](KeyT&& key) noexcept
    {
        check_expand_need();
        const auto key_hash = hash_key(key);
        const auto bucket = find_or_allocate(key, key_hash);
        if (EMH_EMPTY(_index, bucket)) {
            EMH_NEW(std::move(key), std::move(ValueT()), bucket, key_hash);
        }

        const auto slot = EMH_SLOT(_index, bucket);
        return EMH_VAL(_pairs, slot);
    }

    /// Erase an element from the hash table.
    /// return 0 if element was not found
    size_type erase(const KeyT& key) noexcept
    {
        const auto key_hash = hash_key(key);
        const auto sbucket = find_filled_bucket(key, key_hash);
        if (sbucket == INACTIVE)
            return 0;

        const auto main_bucket = key_hash & _mask;
        erase_slot(sbucket, (size_type)main_bucket);
        return 1;
    }

    //iterator erase(const_iterator begin_it, const_iterator end_it)
    iterator erase(const const_iterator& cit) noexcept
    {
        const auto slot = (size_type)(cit.kv_ - _pairs);
        size_type main_bucket;
        const auto sbucket = find_slot_bucket(slot, main_bucket); //TODO
        erase_slot(sbucket, main_bucket);
        return {this, slot};
    }

    //only last >= first
    iterator erase(const_iterator first, const_iterator last) noexcept
    {
        auto esize = long(last.kv_ - first.kv_);
        auto tsize = long((_pairs + _num_filled) - last.kv_); //last to tail size
        auto next = first;
        while (tsize -- > 0) {
            if (esize-- <= 0)
                break;
            next = ++erase(next);
        }

        //fast erase from last
        next = this->last();
        while (esize -- > 0)
            next = --erase(next);

        return {this, size_type(next.kv_ - _pairs)};
    }

    template<typename Pred>
    size_type erase_if(Pred pred)
    {
        auto old_size = size();
        for (auto it = begin(); it != end();) {
            if (pred(*it))
                it = erase(it);
            else
                ++it;
        }
        return old_size - size();
    }

    static constexpr bool is_triviall_destructable()
    {
#if __cplusplus >= 201402L || _MSC_VER > 1600
        return !(std::is_trivially_destructible<KeyT>::value && std::is_trivially_destructible<ValueT>::value);
#else
        return !(std::is_pod<KeyT>::value && std::is_pod<ValueT>::value);
#endif
    }

    static constexpr bool is_copy_trivially()
    {
#if __cplusplus >= 201103L || _MSC_VER > 1600
        return (std::is_trivially_copyable<KeyT>::value && std::is_trivially_copyable<ValueT>::value);
#else
        return (std::is_pod<KeyT>::value && std::is_pod<ValueT>::value);
#endif
    }

    void clearkv()
    {
        if (is_triviall_destructable()) {
            while (_num_filled --)
                _pairs[_num_filled].~value_type();
        }
    }

    /// Remove all elements, keeping full capacity.
    void clear() noexcept
    {
        clearkv();

        if (_num_filled > 0)
            memset((char*)_index, INACTIVE, sizeof(_index[0]) * _num_buckets);

        _last = _num_filled = 0;
        _etail = INACTIVE;

#if EMH_HIGH_LOAD
        _ehead = 0;
#endif
    }

    void shrink_to_fit(const float min_factor = EMH_DEFAULT_LOAD_FACTOR / 4)
    {
        if (load_factor() < min_factor && bucket_count() > 10) //safe guard
            rehash(_num_filled + 1);
    }

#if EMH_HIGH_LOAD
    void set_empty()
    {
        auto prev = 0;
        for (int32_t bucket = 1; bucket < _num_buckets; ++bucket) {
            if (EMH_EMPTY(_index, bucket)) {
                if (prev != 0) {
                    EMH_PREVET(_index, bucket) = prev;
                    EMH_BUCKET(_index, prev) = -bucket;
                }
                else
                    _ehead = bucket;
                prev = bucket;
            }
        }

        EMH_PREVET(_index, _ehead) = prev;
        EMH_BUCKET(_index, prev) = 0-_ehead;
        _ehead = 0-EMH_BUCKET(_index, _ehead);
    }

    void clear_empty()
    {
        auto prev = EMH_PREVET(_index, _ehead);
        while (prev != _ehead) {
            EMH_BUCKET(_index, prev) = INACTIVE;
            prev = EMH_PREVET(_index, prev);
        }
        EMH_BUCKET(_index, _ehead) = INACTIVE;
        _ehead = 0;
    }

    //prev-ehead->next
    size_type pop_empty(const size_type bucket)
    {
        const auto prev_bucket = EMH_PREVET(_index, bucket);
        const int next_bucket = 0-EMH_BUCKET(_index, bucket);

        EMH_PREVET(_index, next_bucket) = prev_bucket;
        EMH_BUCKET(_index, prev_bucket) = -next_bucket;

        _ehead = next_bucket;
        return bucket;
    }

    //ehead->bucket->next
    void push_empty(const int32_t bucket)
    {
        const int next_bucket = 0-EMH_BUCKET(_index, _ehead);
        assert(next_bucket > 0);

        EMH_PREVET(_index, bucket) = _ehead;
        EMH_BUCKET(_index, bucket) = -next_bucket;

        EMH_PREVET(_index, next_bucket) = bucket;
        EMH_BUCKET(_index, _ehead) = -bucket;
        //        _ehead = bucket;
    }
#endif

    /// Make room for this many elements
    bool reserve(uint64_t num_elems, bool force)
    {
        (void)force;
#if EMH_HIGH_LOAD == 0
        const auto required_buckets = num_elems * _mlf >> 27;
        if (EMH_LIKELY(required_buckets < _mask)) // && !force
            return false;

#elif EMH_HIGH_LOAD
        const auto required_buckets = num_elems + num_elems * 1 / 9;
        if (EMH_LIKELY(required_buckets < _mask))
            return false;

        else if (_num_buckets < 16 && _num_filled < _num_buckets)
            return false;

        else if (_num_buckets > EMH_HIGH_LOAD) {
            if (_ehead == 0) {
                set_empty();
                return false;
            } else if (/*_num_filled + 100 < _num_buckets && */EMH_BUCKET(_index, _ehead) != 0-_ehead) {
                return false;
            }
        }
#endif
#if EMH_STATIS
        if (_num_filled > EMH_STATIS) dump_statics();
#endif

        //assert(required_buckets < max_size());
        rehash(required_buckets + 2);
        return true;
    }

    static value_type* alloc_bucket(size_type num_buckets)
    {
        auto new_pairs = (char*)malloc((uint64_t)num_buckets * sizeof(value_type));
        return (value_type *)(new_pairs);
    }

    static Index* alloc_index(size_type num_buckets)
    {
        auto new_index = (char*)malloc((uint64_t)(EAD + num_buckets) * sizeof(Index));
        return (Index *)(new_index);
    }

    bool reserve(size_type required_buckets) noexcept
    {
        if (_num_filled != required_buckets)
            return reserve(required_buckets, true);

        _last = 0;
#if EMH_HIGH_LOAD
        _ehead = 0;
#endif

#if EMH_SORT
        std::sort(_pairs, _pairs + _num_filled, [this](const value_type & l, const value_type & r) {
            const auto hashl = (size_type)hash_key(l.first) & _mask, hashr = (size_type)hash_key(r.first) & _mask;
            return hashl < hashr;
            //return l.first < r.first;
        });
#endif

        memset((char*)_index, INACTIVE, sizeof(_index[0]) * _num_buckets);
        for (size_type slot = 0; slot < _num_filled; slot++) {
            const auto& key = EMH_KEY(_pairs, slot);
            const auto key_hash = hash_key(key);
            const auto bucket = size_type(key_hash & _mask);
            auto& next_bucket = EMH_BUCKET(_index, bucket);
            if ((int)next_bucket < 0)
                EMH_INDEX(_index, bucket) = {1, slot | EMH_KEYMASK(key_hash, _mask)};
            else {
                EMH_HSLOT(_index, bucket) |= EMH_KEYMASK(key_hash, _mask);
                next_bucket ++;
            }
        }
        return true;
    }

    void rebuild(size_type num_buckets) noexcept
    {
        free(_index);
        auto new_pairs = (value_type*)alloc_bucket((size_type)(num_buckets * max_load_factor()) + 4);
        if (is_copy_trivially()) {
            memcpy((char*)new_pairs, (char*)_pairs, _num_filled * sizeof(value_type));
        } else {
            for (size_type slot = 0; slot < _num_filled; slot++) {
                new(new_pairs + slot) value_type(std::move(_pairs[slot]));
                if (is_triviall_destructable())
                    _pairs[slot].~value_type();
            }
        }
        free(_pairs);
        _pairs = new_pairs;
        _index = (Index*)alloc_index (num_buckets);

        memset((char*)_index, INACTIVE, sizeof(_index[0]) * num_buckets);
        memset((char*)(_index + num_buckets), 0, sizeof(_index[0]) * EAD);
    }

    void rehash(uint64_t required_buckets)
    {
        if (required_buckets < _num_filled)
            return;

        assert(required_buckets < max_size());
        auto num_buckets = _num_filled > (1u << 16) ? (1u << 16) : 4u;
        while (num_buckets < required_buckets) { num_buckets *= 2; }

#if EMH_REHASH_LOG
        auto last = _last;
        size_type collision = 0;
#endif

#if EMH_HIGH_LOAD
        _ehead = 0;
#endif
        _last = _mask / 4;

        _mask        = num_buckets - 1;
#if EMH_PACK_TAIL > 1
        _last = _mask;
        num_buckets += num_buckets * EMH_PACK_TAIL / 100; //add more 5-10%
#endif
        _num_buckets = num_buckets;

        rebuild(num_buckets);

#ifdef EMH_SORT
        std::sort(_pairs, _pairs + _num_filled, [this](const value_type & l, const value_type & r) {
            const auto hashl = hash_key(l.first), hashr = hash_key(r.first);
            auto diff = int64_t((hashl & _mask) - (hashr & _mask));
            if (diff != 0)
                return diff < 0;
            return hashl < hashr;
//          return l.first < r.first;
        });
#endif

        _etail = INACTIVE;
        for (size_type slot = 0; slot < _num_filled; ++slot) {
            const auto& key = EMH_KEY(_pairs, slot);
            const auto key_hash = hash_key(key);
            const auto bucket = find_unique_bucket(key_hash);
            EMH_INDEX(_index, bucket) = {bucket, slot | EMH_KEYMASK(key_hash, _mask)};

#if EMH_REHASH_LOG
            if (bucket != hash_main(bucket))
                collision ++;
#endif
        }

#if EMH_REHASH_LOG
        if (_num_filled > EMH_REHASH_LOG) {
            auto mbucket = _num_filled - collision;
            char buff[255] = {0};
            sprintf(buff, "    _num_filled/aver_size/K.V/pack/collision|last = %u/%.2lf/%s.%s/%zd|%.2lf%%,%.2lf%%",
                    _num_filled, double (_num_filled) / mbucket, typeid(KeyT).name(), typeid(ValueT).name(), sizeof(_pairs[0]), collision * 100.0 / _num_filled, last * 100.0 / _num_buckets);
#ifdef EMH_LOG
            static uint32_t ihashs = 0; EMH_LOG() << "hash_nums = " << ihashs ++ << "|" <<__FUNCTION__ << "|" << buff << endl;
#else
            puts(buff);
#endif
        }
#endif
    }

private:
    // Can we fit another element?
    inline bool check_expand_need()
    {
        return reserve(_num_filled, false);
    }

    size_type slot_to_bucket(const size_type slot) const noexcept
    {
        size_type main_bucket;
        return find_slot_bucket(slot, main_bucket); //TODO
    }

    //very slow
    void erase_slot(const size_type sbucket, const size_type main_bucket) noexcept
    {
        const auto slot = EMH_SLOT(_index, sbucket);
        const auto ebucket = erase_bucket(sbucket, main_bucket);
        const auto last_slot = --_num_filled;
        if (EMH_LIKELY(slot != last_slot)) {
            const auto last_bucket = (_etail == INACTIVE || ebucket == _etail)
                ? slot_to_bucket(last_slot) : _etail;

            EMH_KV(_pairs, slot) = std::move(EMH_KV(_pairs, last_slot));
            EMH_HSLOT(_index, last_bucket) = slot | (EMH_HSLOT(_index, last_bucket) & ~_mask);
        }

        if (is_triviall_destructable())
            _pairs[last_slot].~value_type();

        _etail = INACTIVE;
        EMH_INDEX(_index, ebucket) = {INACTIVE, 0};
#if EMH_HIGH_LOAD
        if (_ehead) {
            if (10 * _num_filled < 8 * _num_buckets)
                clear_empty();
            else if (ebucket)
                push_empty(ebucket);
        }
#endif
    }

    size_type erase_bucket(const size_type bucket, const size_type main_bucket) noexcept
    {
        const auto next_bucket = EMH_BUCKET(_index, bucket);
        if (bucket == main_bucket) {
            if (main_bucket != next_bucket) {
                const auto nbucket = EMH_BUCKET(_index, next_bucket);
                EMH_INDEX(_index, main_bucket) = {
                    (nbucket == next_bucket) ? main_bucket : nbucket,
                    EMH_HSLOT(_index, next_bucket)
                };
            }
            return next_bucket;
        }

        const auto prev_bucket = find_prev_bucket(main_bucket, bucket);
        EMH_BUCKET(_index, prev_bucket) = (bucket == next_bucket) ? prev_bucket : next_bucket;
        return bucket;
    }

    // Find the slot with this key, or return bucket size
    size_type find_slot_bucket(const size_type slot, size_type& main_bucket) const
    {
        const auto key_hash = hash_key(EMH_KEY(_pairs, slot));
        const auto bucket = main_bucket = size_type(key_hash & _mask);
        if (slot == EMH_SLOT(_index, bucket))
            return bucket;

        auto next_bucket = EMH_BUCKET(_index, bucket);
        while (true) {
            if (EMH_LIKELY(slot == EMH_SLOT(_index, next_bucket)))
                return next_bucket;
            next_bucket = EMH_BUCKET(_index, next_bucket);
        }

        return INACTIVE;
    }

    // Find the slot with this key, or return bucket size
    size_type find_filled_bucket(const KeyT& key, uint64_t key_hash) const noexcept
    {
        const auto bucket = size_type(key_hash & _mask);
        auto next_bucket  = EMH_BUCKET(_index, bucket);
        if (EMH_UNLIKELY((int)next_bucket < 0))
            return INACTIVE;

        if (EMH_EQHASH(bucket, key_hash)) {
            const auto slot = EMH_SLOT(_index, bucket);
            if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, slot))))
                return bucket;
        }
        if (next_bucket == bucket)
            return INACTIVE;

        while (true) {
            if (EMH_EQHASH(next_bucket, key_hash)) {
                const auto slot = EMH_SLOT(_index, next_bucket);
                if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, slot))))
                    return next_bucket;
            }

            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket)
                return INACTIVE;
            next_bucket = nbucket;
        }

        return INACTIVE;
    }

    // Find the slot with this key, or return bucket size
    template<typename K=KeyT>
    size_type find_filled_slot(const K& key) const noexcept
    {
        const auto key_hash = hash_key(key);
        const auto bucket = size_type(key_hash & _mask);
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return _num_filled;

        if (EMH_EQHASH(bucket, key_hash)) {
            const auto slot = EMH_SLOT(_index, bucket);
            if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, slot))))
                return slot;
        }
        if (next_bucket == bucket)
            return _num_filled;

        while (true) {
            if (EMH_EQHASH(next_bucket, key_hash)) {
                const auto slot = EMH_SLOT(_index, next_bucket);
                if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, slot))))
                    return slot;
            }

            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket)
                return _num_filled;
            next_bucket = nbucket;
        }

        return _num_filled;
    }

#if EMH_SORT
    size_type find_hash_bucket(const KeyT& key) const noexcept
    {
        const auto key_hash = hash_key(key);
        const auto bucket = size_type(key_hash & _mask);
        const auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0)
            return END;

        auto slot = EMH_SLOT(_index, bucket);
        if (_eq(key, EMH_KEY(_pairs, slot++)))
            return slot;
        else if (next_bucket == bucket)
            return END;

        while (true) {
            const auto& okey = EMH_KEY(_pairs, slot++);
            if (_eq(key, okey))
                return slot;

            const auto hasho = hash_key(okey);
            if ((hasho & _mask) != bucket)
                break;
            else if (hasho > key_hash)
                break;
            else if (EMH_UNLIKELY(slot >= _num_filled))
                break;
        }

        return END;
    }

    //only for find/can not insert
    size_type find_sorted_bucket(const KeyT& key) const noexcept
    {
        const auto key_hash = hash_key(key);
        const auto bucket = size_type(key_hash & _mask);
        const auto slots = (int)(EMH_BUCKET(_index, bucket)); //TODO
        if (slots < 0 /**|| key < EMH_KEY(_pairs, slot)*/)
            return END;

        const auto slot = EMH_SLOT(_index, bucket);
        auto ormask = _index[bucket].slot & ~_mask;
        auto hmask  = EMH_KEYMASK(key_hash, _mask);
        if ((hmask | ormask) != ormask)
            return END;

        if (_eq(key, EMH_KEY(_pairs, slot)))
            return slot;
        else if (slots == 1 || key < EMH_KEY(_pairs, slot))
            return END;

#if EMH_SORT
        if (key < EMH_KEY(_pairs, slot) || key > EMH_KEY(_pairs, slots + slot - 1))
            return END;
#endif

        for (size_type i = 1; i < slots; ++i) {
            const auto& okey = EMH_KEY(_pairs, slot + i);
            if (_eq(key, okey))
                return slot + i;
//            else if (okey > key)
//                return END;
        }

        return END;
    }
#endif

    //kick out bucket and find empty to occpuy
    //it will break the orgin link and relnik again.
    //before: main_bucket-->prev_bucket --> bucket   --> next_bucket
    //atfer : main_bucket-->prev_bucket --> (removed)--> new_bucket--> next_bucket
    size_type kickout_bucket(const size_type kmain, const size_type bucket) noexcept
    {
        const auto next_bucket = EMH_BUCKET(_index, bucket);
        const auto new_bucket  = find_empty_bucket(next_bucket, 2);
        const auto prev_bucket = find_prev_bucket(kmain, bucket);

        const auto last = next_bucket == bucket ? new_bucket : next_bucket;
        EMH_INDEX(_index, new_bucket) = {last, EMH_HSLOT(_index, bucket)};

        EMH_BUCKET(_index, prev_bucket) = new_bucket;
        EMH_BUCKET(_index, bucket) = INACTIVE;

        return bucket;
    }

/*
** inserts a new key into a hash table; first, check whether key's main
** bucket/position is free. If not, check whether colliding node/bucket is in its main
** position or not: if it is not, move colliding bucket to an empty place and
** put new key in its main position; otherwise (colliding bucket is in its main
** position), new key goes to an empty position.
*/
    template<typename K=KeyT>
    size_type find_or_allocate(const K& key, uint64_t key_hash) noexcept
    {
        const auto bucket = size_type(key_hash & _mask);
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0) {
#if EMH_HIGH_LOAD
            if (next_bucket != INACTIVE)
                pop_empty(bucket);
#endif
            return bucket;
        }

        const auto slot = EMH_SLOT(_index, bucket);
        if (EMH_EQHASH(bucket, key_hash))
            if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, slot))))
            return bucket;

        //check current bucket_key is in main bucket or not
        const auto kmain = hash_bucket(EMH_KEY(_pairs, slot));
        if (kmain != bucket)
            return kickout_bucket(kmain, bucket);
        else if (next_bucket == bucket)
            return EMH_BUCKET(_index, next_bucket) = find_empty_bucket(next_bucket, 1);

        uint32_t csize = 1;
        //find next linked bucket and check key
        while (true) {
            const auto eslot = EMH_SLOT(_index, next_bucket);
            if (EMH_EQHASH(next_bucket, key_hash)) {
                if (EMH_LIKELY(_eq(key, EMH_KEY(_pairs, eslot))))
                return next_bucket;
            }

            csize += 1;
            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket)
                break;
            next_bucket = nbucket;
        }

        //find a empty and link it to tail
        const auto new_bucket = find_empty_bucket(next_bucket, csize);
        return EMH_BUCKET(_index, next_bucket) = new_bucket;
    }

    size_type find_unique_bucket(uint64_t key_hash) noexcept
    {
        const auto bucket = size_type(key_hash & _mask);
        auto next_bucket = EMH_BUCKET(_index, bucket);
        if ((int)next_bucket < 0) {
#if EMH_HIGH_LOAD
            if (next_bucket != INACTIVE)
                pop_empty(bucket);
#endif
            return bucket;
        }

        //check current bucket_key is in main bucket or not
        const auto kmain = hash_main(bucket);
        if (EMH_UNLIKELY(kmain != bucket))
            return kickout_bucket(kmain, bucket);
        else if (EMH_UNLIKELY(next_bucket != bucket))
            next_bucket = find_last_bucket(next_bucket);

        return EMH_BUCKET(_index, next_bucket) = find_empty_bucket(next_bucket, 2);
    }

/***
  Different probing techniques usually provide a trade-off between memory locality and avoidance of clustering.
Since Robin Hood hashing is relatively resilient to clustering (both primary and secondary), linear probing is the most cache friendly alternativeis typically used.

    It's the core algorithm of this hash map with highly optimization/benchmark.
normaly linear probing is inefficient with high load factor, it use a new 3-way linear
probing strategy to search empty slot. from benchmark even the load factor > 0.9, it's more 2-3 timer fast than
one-way search strategy.

1. linear or quadratic probing a few cache line for less cache miss from input slot "bucket_from".
2. the first  search  slot from member variant "_last", init with 0
3. the second search slot from calculated pos "(_num_filled + _last) & _mask", it's like a rand value
*/
    // key is not in this mavalue. Find a place to put it.
    size_type find_empty_bucket(const size_type bucket_from, uint32_t csize) noexcept
    {
#if EMH_HIGH_LOAD
        if (_ehead)
            return pop_empty(_ehead);
#endif

        auto bucket = bucket_from;
        if (EMH_EMPTY(_index, ++bucket) || EMH_EMPTY(_index, ++bucket))
            return bucket;

#ifdef EMH_QUADRATIC
        constexpr size_type linear_probe_length = 2 * EMH_CACHE_LINE_SIZE / sizeof(Index);//16
        for (size_type offset = csize + 2, step = 4; offset <= linear_probe_length; ) {
            bucket = (bucket_from + offset) & _mask;
            if (EMH_EMPTY(_index, bucket) || EMH_EMPTY(_index, ++bucket))
                return bucket;
            offset += step; //7/8. 12. 16
        }
#else
        constexpr size_type quadratic_probe_length = 6u;
        for (size_type offset = 4u, step = 3u; step < quadratic_probe_length; ) {
            bucket = (bucket_from + offset) & _mask;
            if (EMH_EMPTY(_index, bucket) || EMH_EMPTY(_index, ++bucket))
                return bucket;
            offset += step++;//3.4.5
        }
#endif

#if EMH_PREFETCH
        __builtin_prefetch(static_cast<const void*>(_index + _last + 1), 0, EMH_PREFETCH);
#endif

        for (;;) {
#if EMH_PACK_TAIL
            //find empty bucket and skip next
            if (EMH_EMPTY(_index, _last++))// || EMH_EMPTY(_index, _last++))
                return _last++ - 1;

            if (EMH_UNLIKELY(_last >= _num_buckets))
                _last = 0;

            auto medium = (_mask / 4 + _last++) & _mask;
            if (EMH_EMPTY(_index, medium))
                return medium;
#else
            if (EMH_EMPTY(_index, ++_last))// || EMH_EMPTY(_index, ++_last))
                return _last++;

            _last &= _mask;
            auto medium = (_num_buckets / 2 + _last) & _mask;
            if (EMH_EMPTY(_index, medium))// || EMH_EMPTY(_index, ++medium))
                return _last = medium;
#endif
        }

        return 0;
    }

    size_type find_last_bucket(size_type main_bucket) const
    {
        auto next_bucket = EMH_BUCKET(_index, main_bucket);
        if (next_bucket == main_bucket)
            return main_bucket;

        while (true) {
            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == next_bucket)
                return next_bucket;
            next_bucket = nbucket;
        }
    }

    size_type find_prev_bucket(const size_type main_bucket, const size_type bucket) const
    {
        auto next_bucket = EMH_BUCKET(_index, main_bucket);
        if (next_bucket == bucket)
            return main_bucket;

        while (true) {
            const auto nbucket = EMH_BUCKET(_index, next_bucket);
            if (nbucket == bucket)
                return next_bucket;
            next_bucket = nbucket;
        }
    }

    inline size_type hash_bucket(const KeyT& key) const noexcept
    {
        return (size_type)hash_key(key) & _mask;
    }

    inline size_type hash_main(const size_type bucket) const noexcept
    {
        const auto slot = EMH_SLOT(_index, bucket);
        return (size_type)hash_key(EMH_KEY(_pairs, slot)) & _mask;
    }

#if EMH_INT_HASH
    static constexpr uint64_t KC = UINT64_C(11400714819323198485);
    static uint64_t hash64(uint64_t key)
    {
#if __SIZEOF_INT128__ && EMH_INT_HASH == 1
        __uint128_t r = key; r *= KC;
        return (uint64_t)(r >> 64) + (uint64_t)r;
#elif EMH_INT_HASH == 2
        //MurmurHash3Mixer
        uint64_t h = key;
        h ^= h >> 33;
        h *= 0xff51afd7ed558ccd;
        h ^= h >> 33;
        h *= 0xc4ceb9fe1a85ec53;
        h ^= h >> 33;
        return h;
#elif _WIN64 && EMH_INT_HASH == 1
        uint64_t high;
        return _umul128(key, KC, &high) + high;
#elif EMH_INT_HASH == 3
        auto ror  = (key >> 32) | (key << 32);
        auto low  = key * 0xA24BAED4963EE407ull;
        auto high = ror * 0x9FB21C651E98DF25ull;
        auto mix  = low + high;
        return mix;
#elif EMH_INT_HASH == 1
        uint64_t r = key * UINT64_C(0xca4bcaa75ec3f625);
        return (r >> 32) + r;
#elif EMH_WYHASH64
        return wyhash64(key, KC);
#else
        uint64_t x = key;
        x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
        x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
        x = x ^ (x >> 31);
        return x;
#endif
    }
#endif

#if EMH_WYHASH_HASH
    //#define WYHASH_CONDOM 1
    inline uint64_t wymix(uint64_t A, uint64_t B)
    {
#if defined(__SIZEOF_INT128__)
        __uint128_t r = A; r *= B;
#if WYHASH_CONDOM2
        A ^= (uint64_t)r; B ^= (uint64_t)(r >> 64);
#else
        A = (uint64_t)r; B = (uint64_t)(r >> 64);
#endif

#elif defined(_MSC_VER) && defined(_M_X64)
#if WYHASH_CONDOM2
        uint64_t a, b;
        a = _umul128(A, B, &b);
        A ^= a; B ^= b;
#else
        A = _umul128(A, B, &B);
#endif
#else
        uint64_t ha = A >> 32, hb = B >> 32, la = (uint32_t)A, lb = (uint32_t)B, hi, lo;
        uint64_t rh = ha * hb, rm0 = ha * lb, rm1 = hb * la, rl = la * lb, t = rl + (rm0 << 32), c = t < rl;
        lo = t + (rm1 << 32); c += lo < t; hi = rh + (rm0 >> 32) + (rm1 >> 32) + c;
#if WYHASH_CONDOM2
        A ^= lo; B ^= hi;
#else
        A = lo; B = hi;
#endif
#endif
        return A ^ B;
    }

    //multiply and xor mix function, aka MUM
    static inline uint64_t wyr8(const uint8_t *p) { uint64_t v; memcpy(&v, p, 8); return v; }
    static inline uint64_t wyr4(const uint8_t *p) { uint32_t v; memcpy(&v, p, 4); return v; }
    static inline uint64_t wyr3(const uint8_t *p, size_t k) {
        return (((uint64_t)p[0]) << 16) | (((uint64_t)p[k >> 1]) << 8) | p[k - 1];
    }

    static constexpr uint64_t secret[4] = {
        0xa0761d6478bd642full, 0xe7037ed1a0b428dbull,
        0x8ebc6af09c88c6e3ull, 0x589965cc75374cc3ull};

public:
    //wyhash main function https://github.com/wangyi-fudan/wyhash
    static uint64_t wyhashstr(const char *key, const size_t len)
    {
        uint64_t a = 0, b = 0, seed = secret[0];
        const uint8_t *p = (const uint8_t*)key;
        if (EMH_LIKELY(len <= 16)) {
            if (EMH_LIKELY(len >= 4)) {
                const auto half = (len >> 3) << 2;
                a = (wyr4(p) << 32U) | wyr4(p + half); p += len - 4;
                b = (wyr4(p) << 32U) | wyr4(p - half);
            } else if (len) {
                a = wyr3(p, len);
            }
        } else {
            size_t i = len;
            if (EMH_UNLIKELY(i > 48)) {
                uint64_t see1 = seed, see2 = seed;
                do {
                    seed = wymix(wyr8(p +  0) ^ secret[1], wyr8(p +  8) ^ seed);
                    see1 = wymix(wyr8(p + 16) ^ secret[2], wyr8(p + 24) ^ see1);
                    see2 = wymix(wyr8(p + 32) ^ secret[3], wyr8(p + 40) ^ see2);
                    p += 48; i -= 48;
                } while (EMH_LIKELY(i > 48));
                seed ^= see1 ^ see2;
            }
            while (i > 16) {
                seed = wymix(wyr8(p) ^ secret[1], wyr8(p + 8) ^ seed);
                i -= 16; p += 16;
            }
            a = wyr8(p + i - 16);
            b = wyr8(p + i - 8);
        }

        return wymix(secret[1] ^ len, wymix(a ^ secret[1], b ^ seed));
    }
#endif

private:
    template<typename UType, typename std::enable_if<std::is_integral<UType>::value, uint32_t>::type = 0>
    inline uint64_t hash_key(const UType key) const
    {
#if EMH_INT_HASH
        return hash64(key);
#elif EMH_IDENTITY_HASH
        return key + (key >> 24);
#else
        return _hasher(key);
#endif
    }

    template<typename UType, typename std::enable_if<std::is_same<UType, std::string>::value, uint32_t>::type = 0>
    inline uint64_t hash_key(const UType& key) const
    {
#if EMH_WYHASH_HASH
        return wyhashstr(key.data(), key.size());
#else
        return _hasher(key);
#endif
    }

    template<typename UType, typename std::enable_if<!std::is_integral<UType>::value && !std::is_same<UType, std::string>::value, uint32_t>::type = 0>
    inline uint64_t hash_key(const UType& key) const
    {
        return _hasher(key);
    }

private:
    Index*    _index;
    value_type*_pairs;

    HashT     _hasher;
    EqT       _eq;
    uint32_t  _mlf;
    size_type _mask;
    size_type _num_buckets;
    size_type _num_filled;
    size_type _last;
#if EMH_HIGH_LOAD
    size_type _ehead;
#endif
    size_type _etail;
};
} // namespace emhash



#ifdef _MSC_VER
#pragma warning (disable:4267)
#pragma warning (disable:4101)
#define _CRT_NONSTDC_NO_DEPRECATE
#define strdup _strdup
#endif

#include <sstream>
#include <regex>
#include <stack>
#include <cmath>
#include <stdexcept>
#include <vector>
#include <string>
#include <cstring>
#include <chrono>
#include <string_view>
#include <queue>
#include <iomanip>
#include <memory>
#include <functional>
#include <iostream>

#ifdef POCKETPY_H
#define UNREACHABLE() throw std::runtime_error( "L" + std::to_string(__LINE__) + " UNREACHABLE()! This should be a bug, please report it");
#else
#define UNREACHABLE() throw std::runtime_error( __FILE__ + std::string(":") + std::to_string(__LINE__) + " UNREACHABLE()!");
#endif

#ifdef __EMSCRIPTEN__
#include <emscripten.h>
#endif

#define PK_VERSION "0.8.1"

typedef int64_t i64;
typedef double f64;
#define DUMMY_VAL (i64)0

#define CPP_LAMBDA(x) ([](VM* vm, const pkpy::Args& args) { return x; })


namespace pkpy{
    template <typename T>
    class shared_ptr {
        int* counter = nullptr;

#define _t() ((T*)(counter + 1))
#define _inc_counter() if(counter) ++(*counter)
#define _dec_counter() if(counter && --(*counter) == 0){ _t()->~T(); free(counter); }

    public:
        shared_ptr() {}
        shared_ptr(int* block) : counter(block) {}
        shared_ptr(const shared_ptr& other) : counter(other.counter) {
            _inc_counter();
        }
        shared_ptr(shared_ptr&& other) noexcept : counter(other.counter) {
            other.counter = nullptr;
        }
        ~shared_ptr() { _dec_counter(); }

        bool operator==(const shared_ptr& other) const {
            return counter == other.counter;
        }

        bool operator!=(const shared_ptr& other) const {
            return counter != other.counter;
        }

        bool operator==(std::nullptr_t) const {
            return counter == nullptr;
        }

        bool operator!=(std::nullptr_t) const {
            return counter != nullptr;
        }

        shared_ptr& operator=(const shared_ptr& other) {
            _dec_counter();
            counter = other.counter;
            _inc_counter();
            return *this;
        }

        shared_ptr& operator=(shared_ptr&& other) noexcept {
            _dec_counter();
            counter = other.counter;
            other.counter = nullptr;
            return *this;
        }

        T& operator*() const { return *_t(); }
        T* operator->() const { return _t(); }
        T* get() const { return _t(); }
        int use_count() const { return counter ? *counter : 0; }

        void reset(){
            _dec_counter();
            counter = nullptr;
        }
    };

#undef _t
#undef _inc_counter
#undef _dec_counter

    template <typename T, typename U, typename... Args>
    shared_ptr<T> make_shared(Args&&... args) {
        static_assert(std::is_base_of_v<T, U>, "U must be derived from T");
        static_assert(std::has_virtual_destructor_v<T>, "T must have virtual destructor");
        int* p = (int*)malloc(sizeof(int) + sizeof(U));
        *p = 1;
        new(p+1) U(std::forward<Args>(args)...);
        return shared_ptr<T>(p);
    }

    template <typename T, typename... Args>
    shared_ptr<T> make_shared(Args&&... args) {
        int* p = (int*)malloc(sizeof(int) + sizeof(T));
        *p = 1;
        new(p+1) T(std::forward<Args>(args)...);
        return shared_ptr<T>(p);
    }
};


typedef std::stringstream _StrStream;

class _Str : public std::string {
    mutable std::vector<uint16_t>* _u8_index = nullptr;
    mutable bool hash_initialized = false;
    mutable size_t _hash;

    void utf8_lazy_init() const{
        if(_u8_index != nullptr) return;
        _u8_index = new std::vector<uint16_t>();
        _u8_index->reserve(size());
        if(size() > 65535) throw std::runtime_error("String has more than 65535 bytes.");
        for(uint16_t i = 0; i < size(); i++){
            // https://stackoverflow.com/questions/3911536/utf-8-unicode-whats-with-0xc0-and-0x80
            if((at(i) & 0xC0) != 0x80)
                _u8_index->push_back(i);
        }
    }
public:
    _Str() : std::string() {}
    _Str(const char* s) : std::string(s) {}
    _Str(const char* s, size_t n) : std::string(s, n) {}
    _Str(const std::string& s) : std::string(s) {}
    _Str(const _Str& s) : std::string(s) {
        if(s._u8_index != nullptr){
            _u8_index = new std::vector<uint16_t>(*s._u8_index);
        }
        if(s.hash_initialized){
            _hash = s._hash;
            hash_initialized = true;
        }
    }
    _Str(_Str&& s) : std::string(std::move(s)) {
        if(_u8_index != nullptr) delete _u8_index;
        _u8_index = s._u8_index;
        s._u8_index = nullptr;
        if(s.hash_initialized){
            _hash = s._hash;
            hash_initialized = true;
        }
    }

    inline size_t hash() const{
        if(!hash_initialized){
            _hash = std::hash<std::string>()(*this);
            hash_initialized = true;
        }
        return _hash;
    }

    i64 __to_u8_index(i64 index) const{
        utf8_lazy_init();
        auto p = std::lower_bound(_u8_index->begin(), _u8_index->end(), index);
        if(p != _u8_index->end() && *p != index) UNREACHABLE();
        return p - _u8_index->begin();
    }

    int u8_length() const {
        utf8_lazy_init();
        return _u8_index->size();
    }

    _Str u8_getitem(int i) const{
        return u8_substr(i, i+1);
    }

    _Str u8_substr(int start, int end) const{
        utf8_lazy_init();
        if(start >= end) return _Str();
        int c_end = end >= _u8_index->size() ? size() : _u8_index->at(end);
        return substr(_u8_index->at(start), c_end - _u8_index->at(start));
    }

    _Str __lstrip() const {
        _Str copy(*this);
        copy.erase(copy.begin(), std::find_if(copy.begin(), copy.end(), [](char c) {
            // std::isspace(c) does not working on windows (Debug)
            return c != ' ' && c != '\t' && c != '\r' && c != '\n';
        }));
        return _Str(copy);
    }

    _Str __escape(bool single_quote) const {
        _StrStream ss;
        ss << (single_quote ? '\'' : '"');
        for (int i=0; i<length(); i++) {
            char c = this->operator[](i);
            switch (c) {
                case '"':
                    if(!single_quote) ss << '\\';
                    ss << '"';
                    break;
                case '\'':
                    if(single_quote) ss << '\\';
                    ss << '\'';
                    break;
                case '\\': ss << '\\' << '\\'; break;
                case '\n': ss << "\\n"; break;
                case '\r': ss << "\\r"; break;
                case '\t': ss << "\\t"; break;
                default:
                    if ('\x00' <= c && c <= '\x1f') {
                        ss << "\\u"
                        << std::hex << std::setw(4) << std::setfill('0') << static_cast<int>(c);
                    } else {
                        ss << c;
                    }
            }
        }
        ss << (single_quote ? '\'' : '"');
        return ss.str();
    }

    _Str& operator=(const _Str& s){
        this->std::string::operator=(s);
        if(_u8_index != nullptr) delete _u8_index;
        this->_u8_index = s._u8_index;
        this->hash_initialized = s.hash_initialized;
        this->_hash = s._hash;
        return *this;
    }

    _Str& operator=(_Str&& s){
        this->std::string::operator=(std::move(s));
        if(_u8_index != nullptr) delete _u8_index;
        this->_u8_index = s._u8_index;
        this->hash_initialized = s.hash_initialized;
        this->_hash = s._hash;
        return *this;
    }

    ~_Str(){
        if(_u8_index != nullptr) delete _u8_index;
    }
};

namespace std {
    template<>
    struct hash<_Str> {
        inline std::size_t operator()(const _Str& s) const {
            return s.hash();
        }
    };
}

const _Str& __class__ = _Str("__class__");
const _Str& __base__ = _Str("__base__");
const _Str& __new__ = _Str("__new__");
const _Str& __iter__ = _Str("__iter__");
const _Str& __str__ = _Str("__str__");
const _Str& __repr__ = _Str("__repr__");
const _Str& __module__ = _Str("__module__");
const _Str& __getitem__ = _Str("__getitem__");
const _Str& __setitem__ = _Str("__setitem__");
const _Str& __delitem__ = _Str("__delitem__");
const _Str& __contains__ = _Str("__contains__");
const _Str& __init__ = _Str("__init__");
const _Str& __json__ = _Str("__json__");
const _Str& __name__ = _Str("__name__");
const _Str& __len__ = _Str("__len__");

const _Str& m_append = _Str("append");
const _Str& m_eval = _Str("eval");
const _Str& m_self = _Str("self");
const _Str& __enter__ = _Str("__enter__");
const _Str& __exit__ = _Str("__exit__");

const _Str CMP_SPECIAL_METHODS[] = {
    "__lt__", "__le__", "__eq__", "__ne__", "__gt__", "__ge__"
};

const _Str BINARY_SPECIAL_METHODS[] = {
    "__add__", "__sub__", "__mul__", "__truediv__", "__floordiv__", "__mod__", "__pow__"
};

const _Str BITWISE_SPECIAL_METHODS[] = {
    "__lshift__", "__rshift__", "__and__", "__or__", "__xor__"
};

const uint32_t __LoRangeA[] = {170,186,443,448,660,1488,1519,1568,1601,1646,1649,1749,1774,1786,1791,1808,1810,1869,1969,1994,2048,2112,2144,2208,2230,2308,2365,2384,2392,2418,2437,2447,2451,2474,2482,2486,2493,2510,2524,2527,2544,2556,2565,2575,2579,2602,2610,2613,2616,2649,2654,2674,2693,2703,2707,2730,2738,2741,2749,2768,2784,2809,2821,2831,2835,2858,2866,2869,2877,2908,2911,2929,2947,2949,2958,2962,2969,2972,2974,2979,2984,2990,3024,3077,3086,3090,3114,3133,3160,3168,3200,3205,3214,3218,3242,3253,3261,3294,3296,3313,3333,3342,3346,3389,3406,3412,3423,3450,3461,3482,3507,3517,3520,3585,3634,3648,3713,3716,3718,3724,3749,3751,3762,3773,3776,3804,3840,3904,3913,3976,4096,4159,4176,4186,4193,4197,4206,4213,4238,4352,4682,4688,4696,4698,4704,4746,4752,4786,4792,4800,4802,4808,4824,4882,4888,4992,5121,5743,5761,5792,5873,5888,5902,5920,5952,5984,5998,6016,6108,6176,6212,6272,6279,6314,6320,6400,6480,6512,6528,6576,6656,6688,6917,6981,7043,7086,7098,7168,7245,7258,7401,7406,7413,7418,8501,11568,11648,11680,11688,11696,11704,11712,11720,11728,11736,12294,12348,12353,12447,12449,12543,12549,12593,12704,12784,13312,19968,40960,40982,42192,42240,42512,42538,42606,42656,42895,42999,43003,43011,43015,43020,43072,43138,43250,43259,43261,43274,43312,43360,43396,43488,43495,43514,43520,43584,43588,43616,43633,43642,43646,43697,43701,43705,43712,43714,43739,43744,43762,43777,43785,43793,43808,43816,43968,44032,55216,55243,63744,64112,64285,64287,64298,64312,64318,64320,64323,64326,64467,64848,64914,65008,65136,65142,65382,65393,65440,65474,65482,65490,65498,65536,65549,65576,65596,65599,65616,65664,66176,66208,66304,66349,66370,66384,66432,66464,66504,66640,66816,66864,67072,67392,67424,67584,67592,67594,67639,67644,67647,67680,67712,67808,67828,67840,67872,67968,68030,68096,68112,68117,68121,68192,68224,68288,68297,68352,68416,68448,68480,68608,68864,69376,69415,69424,69600,69635,69763,69840,69891,69956,69968,70006,70019,70081,70106,70108,70144,70163,70272,70280,70282,70287,70303,70320,70405,70415,70419,70442,70450,70453,70461,70480,70493,70656,70727,70751,70784,70852,70855,71040,71128,71168,71236,71296,71352,71424,71680,71935,72096,72106,72161,72163,72192,72203,72250,72272,72284,72349,72384,72704,72714,72768,72818,72960,72968,72971,73030,73056,73063,73066,73112,73440,73728,74880,77824,82944,92160,92736,92880,92928,93027,93053,93952,94032,94208,100352,110592,110928,110948,110960,113664,113776,113792,113808,123136,123214,123584,124928,126464,126469,126497,126500,126503,126505,126516,126521,126523,126530,126535,126537,126539,126541,126545,126548,126551,126553,126555,126557,126559,126561,126564,126567,126572,126580,126585,126590,126592,126603,126625,126629,126635,131072,173824,177984,178208,183984,194560};
const uint32_t __LoRangeB[] = {170,186,443,451,660,1514,1522,1599,1610,1647,1747,1749,1775,1788,1791,1808,1839,1957,1969,2026,2069,2136,2154,2228,2237,2361,2365,2384,2401,2432,2444,2448,2472,2480,2482,2489,2493,2510,2525,2529,2545,2556,2570,2576,2600,2608,2611,2614,2617,2652,2654,2676,2701,2705,2728,2736,2739,2745,2749,2768,2785,2809,2828,2832,2856,2864,2867,2873,2877,2909,2913,2929,2947,2954,2960,2965,2970,2972,2975,2980,2986,3001,3024,3084,3088,3112,3129,3133,3162,3169,3200,3212,3216,3240,3251,3257,3261,3294,3297,3314,3340,3344,3386,3389,3406,3414,3425,3455,3478,3505,3515,3517,3526,3632,3635,3653,3714,3716,3722,3747,3749,3760,3763,3773,3780,3807,3840,3911,3948,3980,4138,4159,4181,4189,4193,4198,4208,4225,4238,4680,4685,4694,4696,4701,4744,4749,4784,4789,4798,4800,4805,4822,4880,4885,4954,5007,5740,5759,5786,5866,5880,5900,5905,5937,5969,5996,6000,6067,6108,6210,6264,6276,6312,6314,6389,6430,6509,6516,6571,6601,6678,6740,6963,6987,7072,7087,7141,7203,7247,7287,7404,7411,7414,7418,8504,11623,11670,11686,11694,11702,11710,11718,11726,11734,11742,12294,12348,12438,12447,12538,12543,12591,12686,12730,12799,19893,40943,40980,42124,42231,42507,42527,42539,42606,42725,42895,42999,43009,43013,43018,43042,43123,43187,43255,43259,43262,43301,43334,43388,43442,43492,43503,43518,43560,43586,43595,43631,43638,43642,43695,43697,43702,43709,43712,43714,43740,43754,43762,43782,43790,43798,43814,43822,44002,55203,55238,55291,64109,64217,64285,64296,64310,64316,64318,64321,64324,64433,64829,64911,64967,65019,65140,65276,65391,65437,65470,65479,65487,65495,65500,65547,65574,65594,65597,65613,65629,65786,66204,66256,66335,66368,66377,66421,66461,66499,66511,66717,66855,66915,67382,67413,67431,67589,67592,67637,67640,67644,67669,67702,67742,67826,67829,67861,67897,68023,68031,68096,68115,68119,68149,68220,68252,68295,68324,68405,68437,68466,68497,68680,68899,69404,69415,69445,69622,69687,69807,69864,69926,69956,70002,70006,70066,70084,70106,70108,70161,70187,70278,70280,70285,70301,70312,70366,70412,70416,70440,70448,70451,70457,70461,70480,70497,70708,70730,70751,70831,70853,70855,71086,71131,71215,71236,71338,71352,71450,71723,71935,72103,72144,72161,72163,72192,72242,72250,72272,72329,72349,72440,72712,72750,72768,72847,72966,72969,73008,73030,73061,73064,73097,73112,73458,74649,75075,78894,83526,92728,92766,92909,92975,93047,93071,94026,94032,100343,101106,110878,110930,110951,111355,113770,113788,113800,113817,123180,123214,123627,125124,126467,126495,126498,126500,126503,126514,126519,126521,126523,126530,126535,126537,126539,126543,126546,126548,126551,126553,126555,126557,126559,126562,126564,126570,126578,126583,126588,126590,126601,126619,126627,126633,126651,173782,177972,178205,183969,191456,195101};

bool __isLoChar(uint32_t c) {
    auto index = std::lower_bound(__LoRangeA, __LoRangeA + 476, c) - __LoRangeA;
    if(c == __LoRangeA[index]) return true;
    index -= 1;
    if(index < 0) return false;
    return c >= __LoRangeA[index] && c <= __LoRangeB[index];
}



struct PyObject;
typedef pkpy::shared_ptr<PyObject> PyVar;
typedef PyVar PyVarOrNull;
typedef PyVar PyVarRef;

class PyVarList: public std::vector<PyVar> {
    PyVar& at(size_t) = delete;

    inline void __checkIndex(size_t i) const {
        if (i >= size()){
            auto msg = "std::vector index out of range, " + std::to_string(i) + " not in [0, " + std::to_string(size()) + ")";
            throw std::out_of_range(msg);
        }
    }
public:
    PyVar& operator[](size_t i) {
        __checkIndex(i);
        return std::vector<PyVar>::operator[](i);
    }

    const PyVar& operator[](size_t i) const {
        __checkIndex(i);
        return std::vector<PyVar>::operator[](i);
    }

    using std::vector<PyVar>::vector;
};

typedef emhash8::HashMap<_Str, PyVar> PyVarDict;

namespace pkpy {
    const int kMaxPoolSize = 10;
    static thread_local std::vector<PyVar*>* _poolArgs = new std::vector<PyVar*>[kMaxPoolSize];

    class Args {
        PyVar* _args;
        int _size;

        void __tryAlloc(size_t n){
            if(n == 0){
                this->_args = nullptr;
                this->_size = 0;
                return;
            }
            if(n >= kMaxPoolSize || _poolArgs[n].empty()){
                this->_args = new PyVar[n];
                this->_size = n;
            }else{
                this->_args = _poolArgs[n].back();
                this->_size = n;
                _poolArgs[n].pop_back();
            }
        }

        void __tryRelease(){
            if(_size == 0 || _args == nullptr) return;
            if(_size >= kMaxPoolSize || _poolArgs[_size].size() > 32){
                delete[] _args;
            }else{
                for(int i = 0; i < _size; i++) _args[i].reset();
                _poolArgs[_size].push_back(_args);
            }
        }

    public:
        Args(size_t n){ __tryAlloc(n); }

        Args(const Args& other){
            __tryAlloc(other._size);
            for(int i=0; i<_size; i++) _args[i] = other._args[i];
        }

        Args(Args&& other) noexcept {
            this->_args = other._args;
            this->_size = other._size;
            other._args = nullptr;
            other._size = 0;
        }

        Args(PyVarList&& other) noexcept {
            __tryAlloc(other.size());
            for(int i=0; i<_size; i++) _args[i] = std::move(other[i]);
            other.clear();
        }

        PyVar& operator[](int i){ return _args[i]; }
        const PyVar& operator[](int i) const { return _args[i]; }

        Args& operator=(Args&& other) noexcept {
            __tryRelease();
            this->_args = other._args;
            this->_size = other._size;
            other._args = nullptr;
            other._size = 0;
            return *this;
        }

        inline int size() const { return _size; }

        PyVarList toList() const {
            PyVarList ret(_size);
            for(int i=0; i<_size; i++) ret[i] = _args[i];
            return ret;
        }

        void extend_self(const PyVar& self){
            static_assert(std::is_standard_layout_v<PyVar>);
            PyVar* old_args = _args;
            int old_size = _size;
            __tryAlloc(old_size+1);
            _args[0] = self;
            if(old_size == 0) return;

            memcpy((void*)(_args+1), (void*)old_args, sizeof(PyVar)*old_size);
            memset((void*)old_args, 0, sizeof(PyVar)*old_size);
            if(old_size >= kMaxPoolSize || _poolArgs[old_size].size() > 32){
                delete[] old_args;
            }else{
                _poolArgs[old_size].push_back(old_args);
            }
        }

        ~Args(){ __tryRelease(); }
    };

    const Args& noArg(){
        static const Args ret(0);
        return ret;
    }

    template<typename T>
    Args oneArg(T&& a) {
        Args ret(1);
        ret[0] = std::forward<T>(a);
        return ret;
    }

    template<typename T1, typename T2>
    Args twoArgs(T1&& a, T2&& b) {
        Args ret(2);
        ret[0] = std::forward<T1>(a);
        ret[1] = std::forward<T2>(b);
        return ret;
    }
}


const char* __BUILTINS_CODE = R"(
def print(*args, sep=' ', end='\n'):
    s = sep.join([str(i) for i in args])
    __sys_stdout_write(s + end)

def round(x, ndigits=0):
    assert ndigits >= 0
    if ndigits == 0:
        return x >= 0 ? int(x + 0.5) : int(x - 0.5)
    if x >= 0:
        return int(x * 10**ndigits + 0.5) / 10**ndigits
    else:
        return int(x * 10**ndigits - 0.5) / 10**ndigits

def isinstance(obj, cls):
    assert type(cls) is type
    obj_t = type(obj)
    while obj_t is not None:
        if obj_t is cls:
            return True
        obj_t = obj_t.__base__
    return False

def abs(x):
    return x < 0 ? -x : x

def max(a, b):
    return a > b ? a : b

def min(a, b):
    return a < b ? a : b

def sum(iterable):
    res = 0
    for i in iterable:
        res += i
    return res

def map(f, iterable):
    return [f(i) for i in iterable]

def zip(a, b):
    return [(a[i], b[i]) for i in range(min(len(a), len(b)))]

def reversed(iterable):
    a = list(iterable)
    return [a[i] for i in range(len(a)-1, -1, -1)]

def sorted(iterable, key=None, reverse=False):
    if key is None:
        key = lambda x: x
    a = [key(i) for i in iterable]
    b = list(iterable)
    for i in range(len(a)):
        for j in range(i+1, len(a)):
            if (a[i] > a[j]) ^ reverse:
                a[i], a[j] = a[j], a[i]
                b[i], b[j] = b[j], b[i]
    return b

##### str #####

str.__mul__ = lambda self, n: ''.join([self for _ in range(n)])

def __str4split(self, sep):
    if sep == "":
        return list(self)
    res = []
    i = 0
    while i < len(self):
        if self[i:i+len(sep)] == sep:
            res.append(self[:i])
            self = self[i+len(sep):]
            i = 0
        else:
            i += 1
    res.append(self)
    return res
str.split = __str4split
del __str4split

def __str4index(self, sub):
    for i in range(len(self)):
        if self[i:i+len(sub)] == sub:
            return i
    return -1
str.index = __str4index
del __str4index

def __str4strip(self, chars=None):
    chars = chars or ' \t\n\r'
    i = 0
    while i < len(self) and self[i] in chars:
        i += 1
    j = len(self) - 1
    while j >= 0 and self[j] in chars:
        j -= 1
    return self[i:j+1]
str.strip = __str4strip
del __str4strip

##### list #####

list.__repr__ = lambda self: '[' + ', '.join([repr(i) for i in self]) + ']'
tuple.__repr__ = lambda self: '(' + ', '.join([repr(i) for i in self]) + ')'
list.__json__ = lambda self: '[' + ', '.join([i.__json__() for i in self]) + ']'
tuple.__json__ = lambda self: '[' + ', '.join([i.__json__() for i in self]) + ']'

def __list4extend(self, other):
    for i in other:
        self.append(i)
list.extend = __list4extend
del __list4extend

def __list4remove(self, value):
    for i in range(len(self)):
        if self[i] == value:
            del self[i]
            return True
    return False
list.remove = __list4remove
del __list4remove

def __list4index(self, value):
    for i in range(len(self)):
        if self[i] == value:
            return i
    return -1
list.index = __list4index
del __list4index

def __list4pop(self, i=-1):
    res = self[i]
    del self[i]
    return res
list.pop = __list4pop
del __list4pop

def __list4__mul__(self, n):
    a = []
    for i in range(n):
        a.extend(self)
    return a
list.__mul__ = __list4__mul__
del __list4__mul__

def __iterable4__eq__(self, other):
    if len(self) != len(other):
        return False
    for i in range(len(self)):
        if self[i] != other[i]:
            return False
    return True
list.__eq__ = __iterable4__eq__
tuple.__eq__ = __iterable4__eq__
list.__ne__ = lambda self, other: not self.__eq__(other)
tuple.__ne__ = lambda self, other: not self.__eq__(other)
del __iterable4__eq__

def __iterable4count(self, x):
    res = 0
    for i in self:
        if i == x:
            res += 1
    return res
list.count = __iterable4count
tuple.count = __iterable4count
del __iterable4count

def __iterable4__contains__(self, item):
    for i in self:
        if i == item:
            return True
    return False
list.__contains__ = __iterable4__contains__
tuple.__contains__ = __iterable4__contains__
del __iterable4__contains__

list.__new__ = lambda obj: [i for i in obj]

# https://github.com/python/cpython/blob/main/Objects/dictobject.c
class dict:
    def __init__(self, capacity=16):
        self._capacity = capacity
        self._a = [None] * self._capacity
        self._len = 0
        
    def __len__(self):
        return self._len

    def __probe(self, key):
        i = hash(key) % self._capacity
        while self._a[i] is not None:
            if self._a[i][0] == key:
                return True, i
            i = (i + 1) % self._capacity
        return False, i

    def __getitem__(self, key):
        ok, i = self.__probe(key)
        if not ok:
            raise KeyError(repr(key))
        return self._a[i][1]

    def __contains__(self, key):
        ok, i = self.__probe(key)
        return ok

    def __setitem__(self, key, value):
        ok, i = self.__probe(key)
        if ok:
            self._a[i][1] = value
        else:
            self._a[i] = [key, value]
            self._len += 1
            if self._len > self._capacity * 0.8:
                self._capacity *= 2
                self.__rehash()

    def __delitem__(self, key):
        ok, i = self.__probe(key)
        if not ok:
            raise KeyError(repr(key))
        self._a[i] = None
        self._len -= 1

    def __rehash(self):
        old_a = self._a
        self._a = [None] * self._capacity
        self._len = 0
        for kv in old_a:
            if kv is not None:
                self[kv[0]] = kv[1]

    def keys(self):
        return [kv[0] for kv in self._a if kv is not None]

    def values(self):
        return [kv[1] for kv in self._a if kv is not None]

    def items(self):
        return [kv for kv in self._a if kv is not None]

    def clear(self):
        self._a = [None] * self._capacity
        self._len = 0

    def update(self, other):
        for k, v in other.items():
            self[k] = v

    def copy(self):
        d = dict()
        for kv in self._a:
            if kv is not None:
                d[kv[0]] = kv[1]
        return d

    def __repr__(self):
        a = [repr(k)+': '+repr(v) for k,v in self.items()]
        return '{'+ ', '.join(a) + '}'

    def __json__(self):
        a = []
        for k,v in self.items():
            if type(k) is not str:
                raise TypeError('json keys must be strings, got ' + repr(k) )
            a.append(k.__json__()+': '+v.__json__())
        return '{'+ ', '.join(a) + '}'

class set:
    def __init__(self, iterable=None):
        iterable = iterable or []
        self._a = dict()
        for item in iterable:
            self.add(item)

    def add(self, elem):
        self._a[elem] = None
        
    def discard(self, elem):
        if elem in self._a:
            del self._a[elem]

    def remove(self, elem):
        del self._a[elem]
        
    def clear(self):
        self._a.clear()

    def update(self,other):
        for elem in other:
            self.add(elem)
        return self

    def __len__(self):
        return len(self._a)
    
    def copy(self):
        return set(self._a.keys())
    
    def __and__(self, other):
        ret = set()
        for elem in self:
            if elem in other:
                ret.add(elem)
        return ret
    
    def __or__(self, other):
        ret = self.copy()
        for elem in other:
            ret.add(elem)
        return ret

    def __sub__(self, other):
        ret = set() 
        for elem in self:
            if elem not in other: 
                ret.add(elem) 
        return ret
    
    def __xor__(self, other): 
        ret = set() 
        for elem in self: 
            if elem not in other: 
                ret.add(elem) 
        for elem in other: 
            if elem not in self: 
                ret.add(elem) 
        return ret

    def union(self, other):
        return self | other

    def intersection(self, other):
        return self & other

    def difference(self, other):
        return self - other

    def symmetric_difference(self, other):      
        return self ^ other
    
    def __eq__(self, other):
        return self.__xor__(other).__len__() == 0

    def __ne__(self, other):
        return self.__xor__(other).__len__() != 0
    
    def isdisjoint(self, other):
        return self.__and__(other).__len__() == 0
    
    def issubset(self, other):
        return self.__sub__(other).__len__() == 0
    
    def issuperset(self, other):
        return other.__sub__(self).__len__() == 0

    def __contains__(self, elem):
        return elem in self._a
    
    def __repr__(self):
        if len(self) == 0:
            return 'set()'
        return '{'+ ', '.join(self._a.keys()) + '}'
    
    def __iter__(self):
        return self._a.keys().__iter__()
)";

const char* __RANDOM_CODE = R"(
import time as _time

__all__ = ['Random', 'seed', 'random', 'randint', 'uniform']

def _int32(x):
	return int(0xffffffff & x)

class Random:
	def __init__(self, seed=None):
		if seed is None:
			seed = int(_time.time() * 1000000)
		seed = _int32(seed)
		self.mt = [0] * 624
		self.mt[0] = seed
		self.mti = 0
		for i in range(1, 624):
			self.mt[i] = _int32(1812433253 * (self.mt[i - 1] ^ self.mt[i - 1] >> 30) + i)
	
	def extract_number(self):
		if self.mti == 0:
			self.twist()
		y = self.mt[self.mti]
		y = y ^ y >> 11
		y = y ^ y << 7 & 2636928640
		y = y ^ y << 15 & 4022730752
		y = y ^ y >> 18
		self.mti = (self.mti + 1) % 624
		return _int32(y)
	
	def twist(self):
		for i in range(0, 624):
			y = _int32((self.mt[i] & 0x80000000) + (self.mt[(i + 1) % 624] & 0x7fffffff))
			self.mt[i] = (y >> 1) ^ self.mt[(i + 397) % 624]
			
			if y % 2 != 0:
				self.mt[i] = self.mt[i] ^ 0x9908b0df
				
	def seed(self, x):
		assert type(x) is int
		self.mt = [0] * 624
		self.mt[0] = _int32(x)
		self.mti = 0
		for i in range(1, 624):
			self.mt[i] = _int32(1812433253 * (self.mt[i - 1] ^ self.mt[i - 1] >> 30) + i)
			
	def random(self):
		return self.extract_number() / 2 ** 32
		
	def randint(self, a, b):
		assert a <= b
		return int(self.random() * (b - a + 1)) + a
		
	def uniform(self, a, b):
		if a > b:
			a, b = b, a
		return self.random() * (b - a) + a

    def shuffle(self, L):
        for i in range(len(L)):
            j = self.randint(i, len(L) - 1)
            L[i], L[j] = L[j], L[i]

    def choice(self, L):
        return L[self.randint(0, len(L) - 1)]
		
_inst = Random()
seed = _inst.seed
random = _inst.random
randint = _inst.randint
uniform = _inst.uniform
shuffle = _inst.shuffle
choice = _inst.choice

)";


struct NeedMoreLines {
    NeedMoreLines(bool isClassDef) : isClassDef(isClassDef) {}
    bool isClassDef;
};

struct HandledException {};
struct UnhandledException {};
struct ToBeRaisedException {};

enum CompileMode {
    EXEC_MODE,
    EVAL_MODE,
    SINGLE_MODE,     // for REPL
    JSON_MODE,
};

struct SourceData {
    const char* source;
    _Str filename;
    std::vector<const char*> lineStarts;
    CompileMode mode;

    std::pair<const char*,const char*> getLine(int lineno) const {
        if(lineno == -1) return {nullptr, nullptr};
        lineno -= 1;
        if(lineno < 0) lineno = 0;
        const char* _start = lineStarts.at(lineno);
        const char* i = _start;
        while(*i != '\n' && *i != '\0') i++;
        return {_start, i};
    }

    SourceData(const char* source, _Str filename, CompileMode mode) {
        source = strdup(source);
        // Skip utf8 BOM if there is any.
        if (strncmp(source, "\xEF\xBB\xBF", 3) == 0) source += 3;
        this->filename = filename;
        this->source = source;
        lineStarts.push_back(source);
        this->mode = mode;
    }

    _Str snapshot(int lineno, const char* cursor=nullptr){
        _StrStream ss;
        ss << "  " << "File \"" << filename << "\", line " << lineno << '\n';
        std::pair<const char*,const char*> pair = getLine(lineno);
        _Str line = "<?>";
        int removedSpaces = 0;
        if(pair.first && pair.second){
            line = _Str(pair.first, pair.second-pair.first).__lstrip();
            removedSpaces = pair.second - pair.first - line.size();
            if(line.empty()) line = "<?>";
        }
        ss << "    " << line;
        if(cursor && line != "<?>" && cursor >= pair.first && cursor <= pair.second){
            auto column = cursor - pair.first - removedSpaces;
            if(column >= 0) ss << "\n    " << std::string(column, ' ') << "^";
        }
        return ss.str();
    }

    ~SourceData(){
        free((void*)source);
    }
};

class _Exception {
    _Str type;
    _Str msg;
    std::stack<_Str> stacktrace;
public:
    _Exception(_Str type, _Str msg): type(type), msg(msg) {}
    bool match_type(const _Str& type) const { return this->type == type;}
    bool is_re = true;

    void st_push(_Str snapshot){
        if(stacktrace.size() >= 8) return;
        stacktrace.push(snapshot);
    }

    _Str summary() const {
        std::stack<_Str> st(stacktrace);
        _StrStream ss;
        if(is_re) ss << "Traceback (most recent call last):\n";
        while(!st.empty()) { ss << st.top() << '\n'; st.pop(); }
        ss << type << ": " << msg;
        return ss.str();
    }
};


struct CodeObject;
struct Frame;
struct BaseRef;
class VM;

//typedef PyVar (*_CppFuncRaw)(VM*, const pkpy::Args&);
typedef std::function<PyVar(VM*, const pkpy::Args&)> _CppFuncRaw;
typedef pkpy::shared_ptr<CodeObject> _Code;

struct _CppFunc {
    _CppFuncRaw f;
    int argc;       // DONOT include self
    bool method;
    
    _CppFunc(_CppFuncRaw f, int argc, bool method) : f(f), argc(argc), method(method) {}
    inline PyVar operator()(VM* vm, const pkpy::Args& args) const;
};

struct Function {
    _Str name;
    _Code code;
    std::vector<_Str> args;
    _Str starredArg;        // empty if no *arg
    PyVarDict kwArgs;       // empty if no k=v
    std::vector<_Str> kwArgsOrder;

    bool hasName(const _Str& val) const {
        bool _0 = std::find(args.begin(), args.end(), val) != args.end();
        bool _1 = starredArg == val;
        bool _2 = kwArgs.find(val) != kwArgs.end();
        return _0 || _1 || _2;
    }
};

struct _BoundMethod {
    PyVar obj;
    PyVar method;
};

struct _Range {
    i64 start = 0;
    i64 stop = -1;
    i64 step = 1;
};

struct _Slice {
    int start = 0;
    int stop = 0x7fffffff; 

    void normalize(int len){
        if(start < 0) start += len;
        if(stop < 0) stop += len;
        if(start < 0) start = 0;
        if(stop > len) stop = len;
    }
};

class BaseIterator {
protected:
    VM* vm;
    PyVar _ref;     // keep a reference to the object so it will not be deleted while iterating
public:
    virtual PyVar next() = 0;
    virtual bool hasNext() = 0;
    PyVarRef var;
    BaseIterator(VM* vm, PyVar _ref) : vm(vm), _ref(_ref) {}
    virtual ~BaseIterator() = default;
};

typedef pkpy::shared_ptr<Function> _Func;
typedef pkpy::shared_ptr<BaseIterator> _Iterator;

struct PyObject {
    PyVar type;
    PyVarDict attribs;

    inline bool is_type(const PyVar& type) const noexcept{ return this->type == type; }
    inline virtual void* value() = 0;

    PyObject(const PyVar& type) : type(type) {}
    virtual ~PyObject() = default;
};

template <typename T>
struct Py_ : PyObject {
    T _value;

    Py_(const PyVar& type, T val) : PyObject(type), _value(val) {}
    virtual void* value() override { return &_value; }
};

//#define OBJ_GET(T, obj) (((Py_<T>*)((obj).get()))->_value)
#define OBJ_GET(T, obj) (*static_cast<T*>((obj)->value()))
#define OBJ_NAME(obj) OBJ_GET(_Str, (obj)->attribs[__name__])
#define OBJ_TP_NAME(obj) OBJ_GET(_Str, (obj)->type->attribs[__name__])


class RangeIterator : public BaseIterator {
private:
    i64 current;
    _Range r;
public:
    RangeIterator(VM* vm, PyVar _ref) : BaseIterator(vm, _ref) {
        this->r = OBJ_GET(_Range, _ref);
        this->current = r.start;
    }

    bool hasNext() override {
        if(r.step > 0){
            return current < r.stop;
        }else{
            return current > r.stop;
        }
    }

    PyVar next() override;
};

class VectorIterator : public BaseIterator {
private:
    size_t index = 0;
    const PyVarList* vec;
public:
    VectorIterator(VM* vm, PyVar _ref) : BaseIterator(vm, _ref) {
        vec = &OBJ_GET(PyVarList, _ref);
    }

    bool hasNext(){
        return index < vec->size();
    }

    PyVar next(){
        return vec->operator[](index++);
    }
};

class StringIterator : public BaseIterator {
private:
    int index = 0;
    _Str str;
public:
    StringIterator(VM* vm, PyVar _ref) : BaseIterator(vm, _ref) {
        str = OBJ_GET(_Str, _ref);
    }

    bool hasNext(){
        return index < str.u8_length();
    }

    PyVar next();
};



typedef uint8_t _TokenType;

constexpr const char* __TOKENS[] = {
    "@error", "@eof", "@eol", "@sof",
    ".", ",", ":", ";", "#", "(", ")", "[", "]", "{", "}", "%",
    "+", "-", "*", "/", "//", "**", "=", ">", "<", "...", "->",
    "<<", ">>", "&", "|", "^", "?",
    "==", "!=", ">=", "<=",
    "+=", "-=", "*=", "/=", "//=", "%=", "&=", "|=", "^=",
    /** KW_BEGIN **/
    "class", "import", "as", "def", "lambda", "pass", "del", "from", "with",
    "None", "in", "is", "and", "or", "not", "True", "False", "global", "try", "except", "finally",
    "goto", "label",      // extended keywords, not available in cpython
    "while", "for", "if", "elif", "else", "break", "continue", "return", "assert", "raise",
    /** KW_END **/
    "is not", "not in",
    "@id", "@num", "@str", "@fstr",
    "@indent", "@dedent"
};

const _TokenType __TOKENS_LEN = sizeof(__TOKENS) / sizeof(__TOKENS[0]);

constexpr _TokenType TK(const char* const token) {
    for(int k=0; k<__TOKENS_LEN; k++){
        const char* i = __TOKENS[k];
        const char* j = token;
        while(*i && *j && *i == *j) { i++; j++;}
        if(*i == *j) return k;
    }
    return 0;
}

#define TK_STR(t) __TOKENS[t]
const _TokenType __KW_BEGIN = TK("class");
const _TokenType __KW_END = TK("raise");

const emhash8::HashMap<std::string_view, _TokenType> __KW_MAP = [](){
    emhash8::HashMap<std::string_view, _TokenType> map;
    for(int k=__KW_BEGIN; k<=__KW_END; k++) map[__TOKENS[k]] = k;
    return map;
}();


struct Token{
  _TokenType type;

  const char* start; //< Begining of the token in the source.
  int length;        //< Number of chars of the token.
  int line;          //< Line number of the token (1 based).
  PyVar value;       //< Literal value of the token.

  const _Str str() const { return _Str(start, length);}

  const _Str info() const {
    _StrStream ss;
    _Str raw = str();
    if (raw == _Str("\n")) raw = "\\n";
    ss << line << ": " << TK_STR(type) << " '" << raw << "'";
    return ss.str();
  }
};

enum Precedence {
  PREC_NONE,
  PREC_ASSIGNMENT,    // =
  PREC_COMMA,         // ,
  PREC_TERNARY,       // ?:
  PREC_LOGICAL_OR,    // or
  PREC_LOGICAL_AND,   // and
  PREC_EQUALITY,      // == !=
  PREC_TEST,          // in is
  PREC_COMPARISION,   // < > <= >=
  PREC_BITWISE_OR,    // |
  PREC_BITWISE_XOR,   // ^
  PREC_BITWISE_AND,   // &
  PREC_BITWISE_SHIFT, // << >>
  PREC_TERM,          // + -
  PREC_FACTOR,        // * / % //
  PREC_UNARY,         // - not
  PREC_EXPONENT,      // **
  PREC_CALL,          // ()
  PREC_SUBSCRIPT,     // []
  PREC_ATTRIB,        // .index
  PREC_PRIMARY,
};

// The context of the parsing phase for the compiler.
struct Parser {
    pkpy::shared_ptr<SourceData> src;

    const char* token_start;
    const char* curr_char;
    int current_line = 1;
    Token prev, curr;
    std::queue<Token> nexts;
    std::stack<int> indents;

    int brackets_level = 0;

    Token next_token(){
        if(nexts.empty()){
            return Token{TK("@error"), token_start, (int)(curr_char - token_start), current_line};
        }
        Token t = nexts.front();
        if(t.type == TK("@eof") && indents.size()>1){
            nexts.pop();
            indents.pop();
            return Token{TK("@dedent"), token_start, 0, current_line};
        }
        nexts.pop();
        return t;
    }

    inline char peekchar() const{ return *curr_char; }

    bool match_n_chars(int n, char c0){
        const char* c = curr_char;
        for(int i=0; i<n; i++){
            if(*c == '\0') return false;
            if(*c != c0) return false;
            c++;
        }
        for(int i=0; i<n; i++) eatchar_include_newline();
        return true;
    }

    int eat_spaces(){
        int count = 0;
        while (true) {
            switch (peekchar()) {
                case ' ' : count+=1; break;
                case '\t': count+=4; break;
                default: return count;
            }
            eatchar();
        }
    }

    bool eat_indentation(){
        if(brackets_level > 0) return true;
        int spaces = eat_spaces();
        if(peekchar() == '#') skip_line_comment();
        if(peekchar() == '\0' || peekchar() == '\n') return true;
        // https://docs.python.org/3/reference/lexical_analysis.html#indentation
        if(spaces > indents.top()){
            indents.push(spaces);
            nexts.push(Token{TK("@indent"), token_start, 0, current_line});
        } else if(spaces < indents.top()){
            while(spaces < indents.top()){
                indents.pop();
                nexts.push(Token{TK("@dedent"), token_start, 0, current_line});
            }
            if(spaces != indents.top()){
                return false;
            }
        }
        return true;
    }

    char eatchar() {
        char c = peekchar();
        if(c == '\n') throw std::runtime_error("eatchar() cannot consume a newline");
        curr_char++;
        return c;
    }

    char eatchar_include_newline() {
        char c = peekchar();
        curr_char++;
        if (c == '\n'){
            current_line++;
            src->lineStarts.push_back(curr_char);
        }
        return c;
    }

    int eat_name() {
        curr_char--;
        while(true){
            uint8_t c = peekchar();
            int u8bytes = 0;
            if((c & 0b10000000) == 0b00000000) u8bytes = 1;
            else if((c & 0b11100000) == 0b11000000) u8bytes = 2;
            else if((c & 0b11110000) == 0b11100000) u8bytes = 3;
            else if((c & 0b11111000) == 0b11110000) u8bytes = 4;
            else return 1;
            if(u8bytes == 1){
                if(isalpha(c) || c=='_' || isdigit(c)) {
                    curr_char++;
                    continue;
                }else{
                    break;
                }
            }
            // handle multibyte char
            std::string u8str(curr_char, u8bytes);
            if(u8str.size() != u8bytes) return 2;
            uint32_t value = 0;
            for(int k=0; k < u8bytes; k++){
                uint8_t b = u8str[k];
                if(k==0){
                    if(u8bytes == 2) value = (b & 0b00011111) << 6;
                    else if(u8bytes == 3) value = (b & 0b00001111) << 12;
                    else if(u8bytes == 4) value = (b & 0b00000111) << 18;
                }else{
                    value |= (b & 0b00111111) << (6*(u8bytes-k-1));
                }
            }
            if(__isLoChar(value)) curr_char += u8bytes;
            else break;
        }

        int length = (int)(curr_char - token_start);
        if(length == 0) return 3;
        std::string_view name(token_start, length);

        if(src->mode == JSON_MODE){
            if(name == "true"){
                set_next_token(TK("True"));
            } else if(name == "false"){
                set_next_token(TK("False"));
            } else if(name == "null"){
                set_next_token(TK("None"));
            } else {
                return 4;
            }
            return 0;
        }

        if(__KW_MAP.count(name)){
            if(name == "not"){
                if(strncmp(curr_char, " in", 3) == 0){
                    curr_char += 3;
                    set_next_token(TK("not in"));
                    return 0;
                }
            }else if(name == "is"){
                if(strncmp(curr_char, " not", 4) == 0){
                    curr_char += 4;
                    set_next_token(TK("is not"));
                    return 0;
                }
            }
            set_next_token(__KW_MAP.at(name));
        } else {
            set_next_token(TK("@id"));
        }
        return 0;
    }

    void skip_line_comment() {
        char c;
        while ((c = peekchar()) != '\0') {
            if (c == '\n') return;
            eatchar();
        }
    }
    
    bool matchchar(char c) {
        if (peekchar() != c) return false;
        eatchar_include_newline();
        return true;
    }

    void set_next_token(_TokenType type, PyVar value=nullptr) {
        switch(type){
            case TK("{"): case TK("["): case TK("("): brackets_level++; break;
            case TK(")"): case TK("]"): case TK("}"): brackets_level--; break;
        }
        nexts.push( Token{
            type,
            token_start,
            (int)(curr_char - token_start),
            current_line - ((type == TK("@eol")) ? 1 : 0),
            value
        });
    }

    void set_next_token_2(char c, _TokenType one, _TokenType two) {
        if (matchchar(c)) set_next_token(two);
        else set_next_token(one);
    }

    Parser(pkpy::shared_ptr<SourceData> src) {
        this->src = src;
        this->token_start = src->source;
        this->curr_char = src->source;
        this->nexts.push(Token{TK("@sof"), token_start, 0, current_line});
        this->indents.push(0);
    }
};


struct BaseRef {
    virtual PyVar get(VM*, Frame*) const = 0;
    virtual void set(VM*, Frame*, PyVar) const = 0;
    virtual void del(VM*, Frame*) const = 0;
    virtual ~BaseRef() = default;
};

enum NameScope {
    NAME_LOCAL = 0,
    NAME_GLOBAL,
    NAME_ATTR,
    NAME_SPECIAL,
};

struct NameRef : BaseRef {
    const std::pair<_Str, NameScope>* pair;
    NameRef(const std::pair<_Str, NameScope>& pair) : pair(&pair) {}

    PyVar get(VM* vm, Frame* frame) const;
    void set(VM* vm, Frame* frame, PyVar val) const;
    void del(VM* vm, Frame* frame) const;
};

struct AttrRef : BaseRef {
    mutable PyVar obj;
    const NameRef attr;
    AttrRef(PyVar obj, const NameRef attr) : obj(obj), attr(attr) {}

    PyVar get(VM* vm, Frame* frame) const;
    void set(VM* vm, Frame* frame, PyVar val) const;
    void del(VM* vm, Frame* frame) const;
};

struct IndexRef : BaseRef {
    mutable PyVar obj;
    PyVar index;
    IndexRef(PyVar obj, PyVar index) : obj(obj), index(index) {}

    PyVar get(VM* vm, Frame* frame) const;
    void set(VM* vm, Frame* frame, PyVar val) const;
    void del(VM* vm, Frame* frame) const;
};

struct TupleRef : BaseRef {
    PyVarList varRefs;
    TupleRef(const PyVarList& varRefs) : varRefs(varRefs) {}
    TupleRef(PyVarList&& varRefs) : varRefs(std::move(varRefs)) {}

    PyVar get(VM* vm, Frame* frame) const;
    void set(VM* vm, Frame* frame, PyVar val) const;
    void del(VM* vm, Frame* frame) const;
};


enum Opcode {
    #define OPCODE(name) OP_##name,
    #ifdef OPCODE

OPCODE(NO_OP)
OPCODE(POP_TOP)
OPCODE(DUP_TOP)
OPCODE(CALL)
OPCODE(RETURN_VALUE)

OPCODE(BINARY_OP)
OPCODE(COMPARE_OP)
OPCODE(BITWISE_OP)
OPCODE(IS_OP)
OPCODE(CONTAINS_OP)

OPCODE(UNARY_NEGATIVE)
OPCODE(UNARY_NOT)

OPCODE(BUILD_LIST)
OPCODE(BUILD_MAP)
OPCODE(BUILD_SET)
OPCODE(BUILD_SLICE)
OPCODE(BUILD_CLASS)
OPCODE(BUILD_SMART_TUPLE)
OPCODE(BUILD_STRING)

OPCODE(LIST_APPEND)
OPCODE(IMPORT_NAME)
OPCODE(PRINT_EXPR)

OPCODE(GET_ITER)
OPCODE(FOR_ITER)

OPCODE(WITH_ENTER)
OPCODE(WITH_EXIT)
OPCODE(LOOP_BREAK)
OPCODE(LOOP_CONTINUE)

OPCODE(POP_JUMP_IF_FALSE)
OPCODE(JUMP_ABSOLUTE)
OPCODE(SAFE_JUMP_ABSOLUTE)
OPCODE(JUMP_IF_TRUE_OR_POP)
OPCODE(JUMP_IF_FALSE_OR_POP)

OPCODE(GOTO)

OPCODE(LOAD_CONST)
OPCODE(LOAD_NONE)
OPCODE(LOAD_TRUE)
OPCODE(LOAD_FALSE)
OPCODE(LOAD_EVAL_FN)
OPCODE(LOAD_LAMBDA)
OPCODE(LOAD_ELLIPSIS)
OPCODE(LOAD_NAME)
OPCODE(LOAD_NAME_REF)

OPCODE(ASSERT)
OPCODE(EXCEPTION_MATCH)
OPCODE(RAISE)
OPCODE(RE_RAISE)

OPCODE(BUILD_INDEX_REF)
OPCODE(BUILD_ATTR_REF)
OPCODE(STORE_NAME)
OPCODE(STORE_FUNCTION)
OPCODE(STORE_REF)
OPCODE(DELETE_REF)

OPCODE(TRY_BLOCK_ENTER)
OPCODE(TRY_BLOCK_EXIT)

#endif
    #undef OPCODE
};

static const char* OP_NAMES[] = {
    #define OPCODE(name) #name,
    #ifdef OPCODE

OPCODE(NO_OP)
OPCODE(POP_TOP)
OPCODE(DUP_TOP)
OPCODE(CALL)
OPCODE(RETURN_VALUE)

OPCODE(BINARY_OP)
OPCODE(COMPARE_OP)
OPCODE(BITWISE_OP)
OPCODE(IS_OP)
OPCODE(CONTAINS_OP)

OPCODE(UNARY_NEGATIVE)
OPCODE(UNARY_NOT)

OPCODE(BUILD_LIST)
OPCODE(BUILD_MAP)
OPCODE(BUILD_SET)
OPCODE(BUILD_SLICE)
OPCODE(BUILD_CLASS)
OPCODE(BUILD_SMART_TUPLE)
OPCODE(BUILD_STRING)

OPCODE(LIST_APPEND)
OPCODE(IMPORT_NAME)
OPCODE(PRINT_EXPR)

OPCODE(GET_ITER)
OPCODE(FOR_ITER)

OPCODE(WITH_ENTER)
OPCODE(WITH_EXIT)
OPCODE(LOOP_BREAK)
OPCODE(LOOP_CONTINUE)

OPCODE(POP_JUMP_IF_FALSE)
OPCODE(JUMP_ABSOLUTE)
OPCODE(SAFE_JUMP_ABSOLUTE)
OPCODE(JUMP_IF_TRUE_OR_POP)
OPCODE(JUMP_IF_FALSE_OR_POP)

OPCODE(GOTO)

OPCODE(LOAD_CONST)
OPCODE(LOAD_NONE)
OPCODE(LOAD_TRUE)
OPCODE(LOAD_FALSE)
OPCODE(LOAD_EVAL_FN)
OPCODE(LOAD_LAMBDA)
OPCODE(LOAD_ELLIPSIS)
OPCODE(LOAD_NAME)
OPCODE(LOAD_NAME_REF)

OPCODE(ASSERT)
OPCODE(EXCEPTION_MATCH)
OPCODE(RAISE)
OPCODE(RE_RAISE)

OPCODE(BUILD_INDEX_REF)
OPCODE(BUILD_ATTR_REF)
OPCODE(STORE_NAME)
OPCODE(STORE_FUNCTION)
OPCODE(STORE_REF)
OPCODE(DELETE_REF)

OPCODE(TRY_BLOCK_ENTER)
OPCODE(TRY_BLOCK_EXIT)

#endif
    #undef OPCODE
};

struct Bytecode{
    uint8_t op;
    int arg;
    int line;
    uint16_t block;
};

_Str pad(const _Str& s, const int n){
    if(s.size() >= n) return s.substr(0, n);
    return s + std::string(n - s.size(), ' ');
}

enum CodeBlockType {
    NO_BLOCK,
    FOR_LOOP,
    WHILE_LOOP,
    CONTEXT_MANAGER,
    TRY_EXCEPT,
};

struct CodeBlock {
    CodeBlockType type;
    int parent;         // parent index in blocks
    int start;          // start index of this block in co_code, inclusive
    int end;            // end index of this block in co_code, exclusive

    std::string to_string() const {
        if(parent == -1) return "";
        return "[B:" + std::to_string(type) + "]";
    }
};

struct CodeObject {
    pkpy::shared_ptr<SourceData> src;
    _Str name;

    CodeObject(pkpy::shared_ptr<SourceData> src, _Str name) {
        this->src = src;
        this->name = name;
    }

    std::vector<Bytecode> co_code;
    PyVarList consts;
    std::vector<std::pair<_Str, NameScope>> names;
    emhash8::HashMap<_Str, int> global_names;
    std::vector<CodeBlock> blocks = { CodeBlock{NO_BLOCK, -1} };
    emhash8::HashMap<_Str, int> labels;

    // tmp variables
    int _curr_block_i = 0;
    bool __is_curr_block_loop() const {
        return blocks[_curr_block_i].type == FOR_LOOP || blocks[_curr_block_i].type == WHILE_LOOP;
    }

    void __enter_block(CodeBlockType type){
        blocks.push_back(CodeBlock{type, _curr_block_i, (int)co_code.size()});
        _curr_block_i = blocks.size()-1;
    }

    void __exit_block(){
        blocks[_curr_block_i].end = co_code.size();
        _curr_block_i = blocks[_curr_block_i].parent;
        if(_curr_block_i < 0) UNREACHABLE();
    }

    bool add_label(const _Str& label){
        if(labels.contains(label)) return false;
        labels[label] = co_code.size();
        return true;
    }

    int add_name(_Str name, NameScope scope){
        if(scope == NAME_LOCAL && global_names.contains(name)) scope = NAME_GLOBAL;
        auto p = std::make_pair(name, scope);
        for(int i=0; i<names.size(); i++){
            if(names[i] == p) return i;
        }
        names.push_back(p);
        return names.size() - 1;
    }

    int add_const(PyVar v){
        consts.push_back(v);
        return consts.size() - 1;
    }

    void optimize_level_1(){
        for(int i=0; i<co_code.size(); i++){
            if(co_code[i].op >= OP_BINARY_OP && co_code[i].op <= OP_CONTAINS_OP){
                for(int j=0; j<2; j++){
                    Bytecode& bc = co_code[i-j-1];
                    if(bc.op >= OP_LOAD_CONST && bc.op <= OP_LOAD_NAME_REF){
                        if(bc.op == OP_LOAD_NAME_REF){
                            bc.op = OP_LOAD_NAME;
                        }
                    }else{
                        break;
                    }
                }
            }else if(co_code[i].op == OP_CALL){
                int ARGC = co_code[i].arg & 0xFFFF;
                int KWARGC = (co_code[i].arg >> 16) & 0xFFFF;
                if(KWARGC != 0) continue;
                for(int j=0; j<ARGC+1; j++){
                    Bytecode& bc = co_code[i-j-1];
                    if(bc.op >= OP_LOAD_CONST && bc.op <= OP_LOAD_NAME_REF){
                        if(bc.op == OP_LOAD_NAME_REF){
                            bc.op = OP_LOAD_NAME;
                        }
                    }else{
                        break;
                    }
                }
            }
        }
    }

    void optimize(int level=1){
        optimize_level_1();
    }
};

static thread_local i64 kFrameGlobalId = 0;

struct Frame {
    std::vector<PyVar> _data;
    int _ip = -1;
    int _next_ip = 0;

    const _Code co;
    PyVar _module;
    pkpy::shared_ptr<PyVarDict> _locals;
    const i64 id;

    inline PyVarDict& f_locals() noexcept { return *_locals; }
    inline PyVarDict& f_globals() noexcept { return _module->attribs; }

    Frame(const _Code co, PyVar _module, pkpy::shared_ptr<PyVarDict> _locals)
        : co(co), _module(_module), _locals(_locals), id(kFrameGlobalId++) { }

    inline const Bytecode& next_bytecode() {
        _ip = _next_ip;
        _next_ip = _ip + 1;
        return co->co_code[_ip];
    }

    _Str curr_snapshot(){
        int line = co->co_code[_ip].line;
        return co->src->snapshot(line);
    }

    _Str stack_info(){
        _StrStream ss;
        ss << "[";
        for(int i=0; i<_data.size(); i++){
            ss << OBJ_TP_NAME(_data[i]);
            if(i != _data.size()-1) ss << ", ";
        }
        ss << "]";
        return ss.str();
    }

    inline bool has_next_bytecode() const {
        return _next_ip < co->co_code.size();
    }

    inline PyVar pop(){
        if(_data.empty()) throw std::runtime_error("_data.empty() is true");
        PyVar v = std::move(_data.back());
        _data.pop_back();
        return v;
    }

    inline void __pop(){
        if(_data.empty()) throw std::runtime_error("_data.empty() is true");
        _data.pop_back();
    }

    inline void try_deref(VM*, PyVar&);

    inline PyVar pop_value(VM* vm){
        PyVar value = pop();
        try_deref(vm, value);
        return value;
    }

    inline PyVar top_value(VM* vm){
        PyVar value = top();
        try_deref(vm, value);
        return value;
    }

    inline PyVar& top(){
        if(_data.empty()) throw std::runtime_error("_data.empty() is true");
        return _data.back();
    }

    inline PyVar top_value_offset(VM* vm, int n){
        PyVar value = _data[_data.size() + n];
        try_deref(vm, value);
        return value;
    }

    template<typename T>
    inline void push(T&& obj){ _data.push_back(std::forward<T>(obj)); }

    inline void jump_abs(int i){ _next_ip = i; }
    inline void jump_rel(int i){ _next_ip += i; }

    std::stack<std::pair<int, std::vector<PyVar>>> s_try_block;

    inline void on_try_block_enter(){
        s_try_block.push(std::make_pair(co->co_code[_ip].block, _data));
    }

    inline void on_try_block_exit(){
        s_try_block.pop();
    }

    bool jump_to_exception_handler(){
        if(s_try_block.empty()) return false;
        PyVar obj = pop();
        auto& p = s_try_block.top();
        _data = std::move(p.second);
        _data.push_back(obj);
        _next_ip = co->blocks[p.first].end;
        on_try_block_exit();
        return true;
    }

    void jump_abs_safe(int target){
        const Bytecode& prev = co->co_code[_ip];
        int i = prev.block;
        _next_ip = target;
        if(_next_ip >= co->co_code.size()){
            while(i>=0){
                if(co->blocks[i].type == FOR_LOOP) pop();
                i = co->blocks[i].parent;
            }
        }else{
            const Bytecode& next = co->co_code[target];
            while(i>=0 && i!=next.block){
                if(co->blocks[i].type == FOR_LOOP) pop();
                i = co->blocks[i].parent;
            }
            if(i!=next.block) throw std::runtime_error("invalid jump");
        }
    }

    pkpy::Args pop_n_values_reversed(VM* vm, int n){
        pkpy::Args v(n);
        for(int i=n-1; i>=0; i--){
            v[i] = pop();
            try_deref(vm, v[i]);
        }
        return v;
    }

    pkpy::Args pop_n_reversed(int n){
        pkpy::Args v(n);
        for(int i=n-1; i>=0; i--) v[i] = pop();
        return v;
    }
};


#define __DEF_PY_AS_C(type, ctype, ptype)                       \
    inline ctype& Py##type##_AS_C(const PyVar& obj) {           \
        check_type(obj, ptype);                                \
        return OBJ_GET(ctype, obj);                           \
    }

#define __DEF_PY(type, ctype, ptype)                            \
    inline PyVar Py##type(ctype value) {                        \
        return new_object(ptype, value);                         \
    }

#define DEF_NATIVE(type, ctype, ptype)                          \
    __DEF_PY(type, ctype, ptype)                                \
    __DEF_PY_AS_C(type, ctype, ptype)


class VM {
    std::vector<PyVar> _small_integers;             // [-5, 256]
    std::stack< std::unique_ptr<Frame> > callstack;
    PyVar __py2py_call_signal;
    
    PyVar run_frame(Frame* frame){
        while(frame->has_next_bytecode()){
            const Bytecode& byte = frame->next_bytecode();
            // if(frame->_module != builtins){
            //     printf("%d: %s (%d) %s\n", frame->_ip, OP_NAMES[byte.op], byte.arg, frame->stack_info().c_str());
            // }
            switch (byte.op)
            {
            case OP_NO_OP: break;       // do nothing
            case OP_LOAD_CONST: frame->push(frame->co->consts[byte.arg]); break;
            case OP_LOAD_LAMBDA: {
                PyVar obj = frame->co->consts[byte.arg];
                setattr(obj, __module__, frame->_module);
                frame->push(obj);
            } break;
            case OP_LOAD_NAME_REF: {
                frame->push(PyRef(NameRef(frame->co->names[byte.arg])));
            } break;
            case OP_LOAD_NAME: {
                frame->push(NameRef(frame->co->names[byte.arg]).get(this, frame));
            } break;
            case OP_STORE_NAME: {
                const auto& p = frame->co->names[byte.arg];
                NameRef(p).set(this, frame, frame->pop_value(this));
            } break;
            case OP_BUILD_ATTR_REF: {
                const auto& attr = frame->co->names[byte.arg];
                PyVar obj = frame->pop_value(this);
                frame->push(PyRef(AttrRef(obj, NameRef(attr))));
            } break;
            case OP_BUILD_INDEX_REF: {
                PyVar index = frame->pop_value(this);
                PyVarRef obj = frame->pop_value(this);
                frame->push(PyRef(IndexRef(obj, index)));
            } break;
            case OP_STORE_REF: {
                PyVar obj = frame->pop_value(this);
                PyVarRef r = frame->pop();
                PyRef_AS_C(r)->set(this, frame, std::move(obj));
            } break;
            case OP_DELETE_REF: {
                PyVarRef r = frame->pop();
                PyRef_AS_C(r)->del(this, frame);
            } break;
            case OP_BUILD_SMART_TUPLE:
            {
                pkpy::Args items = frame->pop_n_reversed(byte.arg);
                bool done = false;
                for(int i=0; i<items.size(); i++){
                    if(!items[i]->is_type(_tp_ref)) {
                        done = true;
                        PyVarList values = items.toList();
                        for(int j=i; j<values.size(); j++) frame->try_deref(this, values[j]);
                        frame->push(PyTuple(values));
                        break;
                    }
                }
                if(done) break;
                frame->push(PyRef(TupleRef(items.toList())));
            } break;
            case OP_BUILD_STRING:
            {
                pkpy::Args items = frame->pop_n_values_reversed(this, byte.arg);
                _StrStream ss;
                for(int i=0; i<items.size(); i++) ss << PyStr_AS_C(asStr(items[i]));
                frame->push(PyStr(ss.str()));
            } break;
            case OP_LOAD_EVAL_FN: {
                frame->push(builtins->attribs[m_eval]);
            } break;
            case OP_LIST_APPEND: {
                pkpy::Args args(2);
                args[1] = frame->pop_value(this);            // obj
                args[0] = frame->top_value_offset(this, -2);     // list
                fast_call(m_append, std::move(args));
            } break;
            case OP_STORE_FUNCTION:
                {
                    PyVar obj = frame->pop_value(this);
                    const _Func& fn = PyFunction_AS_C(obj);
                    setattr(obj, __module__, frame->_module);
                    frame->f_globals()[fn->name] = obj;
                } break;
            case OP_BUILD_CLASS:
                {
                    const _Str& clsName = frame->co->names[byte.arg].first;
                    PyVar clsBase = frame->pop_value(this);
                    if(clsBase == None) clsBase = _tp_object;
                    check_type(clsBase, _tp_type);
                    PyVar cls = new_user_type_object(frame->_module, clsName, clsBase);
                    while(true){
                        PyVar fn = frame->pop_value(this);
                        if(fn == None) break;
                        const _Func& f = PyFunction_AS_C(fn);
                        setattr(fn, __module__, frame->_module);
                        setattr(cls, f->name, fn);
                    }
                } break;
            case OP_RETURN_VALUE: return frame->pop_value(this);
            case OP_PRINT_EXPR:
                {
                    const PyVar expr = frame->top_value(this);
                    if(expr == None) break;
                    *_stdout << PyStr_AS_C(asRepr(expr)) << '\n';
                } break;
            case OP_POP_TOP: frame->__pop(); break;
            case OP_BINARY_OP:
                {
                    pkpy::Args args(2);
                    args[1] = frame->pop_value(this);
                    args[0] = frame->top_value(this);
                    frame->top() = fast_call(BINARY_SPECIAL_METHODS[byte.arg], std::move(args));
                } break;
            case OP_BITWISE_OP:
                {
                    frame->push(
                        fast_call(BITWISE_SPECIAL_METHODS[byte.arg],
                        frame->pop_n_values_reversed(this, 2))
                    );
                } break;
            case OP_COMPARE_OP:
                {
                    pkpy::Args args(2);
                    args[1] = frame->pop_value(this);
                    args[0] = frame->top_value(this);
                    frame->top() = fast_call(CMP_SPECIAL_METHODS[byte.arg], std::move(args));
                } break;
            case OP_IS_OP:
                {
                    PyVar rhs = frame->pop_value(this);
                    bool ret_c = rhs == frame->top_value(this);
                    if(byte.arg == 1) ret_c = !ret_c;
                    frame->top() = PyBool(ret_c);
                } break;
            case OP_CONTAINS_OP:
                {
                    PyVar rhs = frame->pop_value(this);
                    bool ret_c = PyBool_AS_C(call(rhs, __contains__, pkpy::oneArg(frame->pop_value(this))));
                    if(byte.arg == 1) ret_c = !ret_c;
                    frame->push(PyBool(ret_c));
                } break;
            case OP_UNARY_NEGATIVE:
                frame->top() = num_negated(frame->top_value(this));
                break;
            case OP_UNARY_NOT:
                {
                    PyVar obj = frame->pop_value(this);
                    const PyVar& obj_bool = asBool(obj);
                    frame->push(PyBool(!PyBool_AS_C(obj_bool)));
                } break;
            case OP_POP_JUMP_IF_FALSE:
                if(!PyBool_AS_C(asBool(frame->pop_value(this)))) frame->jump_abs(byte.arg);
                break;
            case OP_LOAD_NONE: frame->push(None); break;
            case OP_LOAD_TRUE: frame->push(True); break;
            case OP_LOAD_FALSE: frame->push(False); break;
            case OP_LOAD_ELLIPSIS: frame->push(Ellipsis); break;
            case OP_ASSERT:
                {
                    PyVar expr = frame->pop_value(this);
                    if(asBool(expr) != True) _error("AssertionError", "");
                } break;
            case OP_EXCEPTION_MATCH:
                {
                    const auto& _e = PyException_AS_C(frame->top());
                    _Str name = frame->co->names[byte.arg].first;
                    frame->push(PyBool(_e.match_type(name)));
                } break;
            case OP_RAISE:
                {
                    PyVar obj = frame->pop_value(this);
                    _Str msg = obj == None ? "" : PyStr_AS_C(asStr(obj));
                    _Str type = frame->co->names[byte.arg].first;
                    _error(type, msg);
                } break;
            case OP_RE_RAISE: _raise(); break;
            case OP_BUILD_LIST:
                frame->push(PyList(
                    frame->pop_n_values_reversed(this, byte.arg).toList()));
                break;
            case OP_BUILD_MAP:
                {
                    pkpy::Args items = frame->pop_n_values_reversed(this, byte.arg*2);
                    PyVar obj = call(builtins->attribs["dict"]);
                    for(int i=0; i<items.size(); i+=2){
                        call(obj, __setitem__, pkpy::twoArgs(items[i], items[i+1]));
                    }
                    frame->push(obj);
                } break;
            case OP_BUILD_SET:
                {
                    PyVar list = PyList(
                        frame->pop_n_values_reversed(this, byte.arg).toList()
                    );
                    PyVar obj = call(builtins->attribs["set"], pkpy::oneArg(list));
                    frame->push(obj);
                } break;
            case OP_DUP_TOP: frame->push(frame->top_value(this)); break;
            case OP_CALL:
                {
                    int ARGC = byte.arg & 0xFFFF;
                    int KWARGC = (byte.arg >> 16) & 0xFFFF;
                    pkpy::Args kwargs(0);
                    if(KWARGC > 0) kwargs = frame->pop_n_values_reversed(this, KWARGC*2);
                    pkpy::Args args = frame->pop_n_values_reversed(this, ARGC);
                    PyVar callable = frame->pop_value(this);
                    PyVar ret = call(callable, std::move(args), kwargs, true);
                    if(ret == __py2py_call_signal) return ret;
                    frame->push(std::move(ret));
                } break;
            case OP_JUMP_ABSOLUTE: frame->jump_abs(byte.arg); break;
            case OP_SAFE_JUMP_ABSOLUTE: frame->jump_abs_safe(byte.arg); break;
            case OP_GOTO: {
                const _Str& label = frame->co->names[byte.arg].first;
                int* target = frame->co->labels.try_get(label);
                if(target == nullptr) _error("KeyError", "label '" + label + "' not found");
                frame->jump_abs_safe(*target);
            } break;
            case OP_GET_ITER:
                {
                    PyVar obj = frame->pop_value(this);
                    PyVarOrNull iter_fn = getattr(obj, __iter__, false);
                    if(iter_fn != nullptr){
                        PyVar tmp = call(iter_fn);
                        PyVarRef var = frame->pop();
                        check_type(var, _tp_ref);
                        PyIter_AS_C(tmp)->var = var;
                        frame->push(std::move(tmp));
                    }else{
                        typeError("'" + OBJ_TP_NAME(obj) + "' object is not iterable");
                    }
                } break;
            case OP_FOR_ITER:
                {
                    // top() must be PyIter, so no need to try_deref()
                    auto& it = PyIter_AS_C(frame->top());
                    if(it->hasNext()){
                        PyRef_AS_C(it->var)->set(this, frame, it->next());
                    }else{
                        int blockEnd = frame->co->blocks[byte.block].end;
                        frame->jump_abs_safe(blockEnd);
                    }
                } break;
            case OP_LOOP_CONTINUE:
                {
                    int blockStart = frame->co->blocks[byte.block].start;
                    frame->jump_abs(blockStart);
                } break;
            case OP_LOOP_BREAK:
                {
                    int blockEnd = frame->co->blocks[byte.block].end;
                    frame->jump_abs_safe(blockEnd);
                } break;
            case OP_JUMP_IF_FALSE_OR_POP:
                {
                    const PyVar expr = frame->top_value(this);
                    if(asBool(expr)==False) frame->jump_abs(byte.arg);
                    else frame->pop_value(this);
                } break;
            case OP_JUMP_IF_TRUE_OR_POP:
                {
                    const PyVar expr = frame->top_value(this);
                    if(asBool(expr)==True) frame->jump_abs(byte.arg);
                    else frame->pop_value(this);
                } break;
            case OP_BUILD_SLICE:
                {
                    PyVar stop = frame->pop_value(this);
                    PyVar start = frame->pop_value(this);
                    _Slice s;
                    if(start != None) {check_type(start, _tp_int); s.start = (int)PyInt_AS_C(start);}
                    if(stop != None) {check_type(stop, _tp_int); s.stop = (int)PyInt_AS_C(stop);}
                    frame->push(PySlice(s));
                } break;
            case OP_IMPORT_NAME:
                {
                    const _Str& name = frame->co->names[byte.arg].first;
                    auto it = _modules.find(name);
                    if(it == _modules.end()){
                        auto it2 = _lazy_modules.find(name);
                        if(it2 == _lazy_modules.end()){
                            _error("ImportError", "module '" + name + "' not found");
                        }else{
                            const _Str& source = it2->second;
                            _Code code = compile(source, name, EXEC_MODE);
                            PyVar _m = new_module(name);
                            _exec(code, _m, pkpy::make_shared<PyVarDict>());
                            frame->push(_m);
                            _lazy_modules.erase(it2);
                        }
                    }else{
                        frame->push(it->second);
                    }
                } break;
            // TODO: using "goto" inside with block may cause __exit__ not called
            case OP_WITH_ENTER: call(frame->pop_value(this), __enter__); break;
            case OP_WITH_EXIT: call(frame->pop_value(this), __exit__); break;
            case OP_TRY_BLOCK_ENTER: frame->on_try_block_enter(); break;
            case OP_TRY_BLOCK_EXIT: frame->on_try_block_exit(); break;
            default:
                throw std::runtime_error(_Str("opcode ") + OP_NAMES[byte.op] + " is not implemented");
                break;
            }
        }

        if(frame->co->src->mode == EVAL_MODE || frame->co->src->mode == JSON_MODE){
            if(frame->_data.size() != 1) throw std::runtime_error("_data.size() != 1 in EVAL/JSON_MODE");
            return frame->pop_value(this);
        }

        if(!frame->_data.empty()) throw std::runtime_error("_data.size() != 0 in EXEC_MODE");
        return None;
    }

public:
    PyVarDict _types;
    PyVarDict _modules;                             // loaded modules
    emhash8::HashMap<_Str, _Str> _lazy_modules;     // lazy loaded modules
    PyVar None, True, False, Ellipsis;

    bool use_stdio;
    std::ostream* _stdout;
    std::ostream* _stderr;
    
    PyVar builtins;         // builtins module
    PyVar _main;            // __main__ module

    int maxRecursionDepth = 1000;

    VM(bool use_stdio){
        this->use_stdio = use_stdio;
        if(use_stdio){
            std::cout.setf(std::ios::unitbuf);
            std::cerr.setf(std::ios::unitbuf);
            this->_stdout = &std::cout;
            this->_stderr = &std::cerr;
        }else{
            this->_stdout = new _StrStream();
            this->_stderr = new _StrStream();
        }
        initializeBuiltinClasses();

        _small_integers.reserve(270);
        for(i64 i=-5; i<=256; i++) _small_integers.push_back(new_object(_tp_int, i));
    }

    PyVar asStr(const PyVar& obj){
        PyVarOrNull f = getattr(obj, __str__, false);
        if(f != nullptr) return call(f);
        return asRepr(obj);
    }

    inline Frame* top_frame() const {
        if(callstack.empty()) UNREACHABLE();
        return callstack.top().get();
    }

    PyVar asRepr(const PyVar& obj){
        if(obj->is_type(_tp_type)) return PyStr("<class '" + OBJ_GET(_Str, obj->attribs[__name__]) + "'>");
        return call(obj, __repr__);
    }

    const PyVar& asBool(const PyVar& obj){
        if(obj->is_type(_tp_bool)) return obj;
        if(obj == None) return False;
        if(obj->is_type(_tp_int)) return PyBool(PyInt_AS_C(obj) != 0);
        if(obj->is_type(_tp_float)) return PyBool(PyFloat_AS_C(obj) != 0.0);
        PyVarOrNull len_fn = getattr(obj, __len__, false);
        if(len_fn != nullptr){
            PyVar ret = call(len_fn);
            return PyBool(PyInt_AS_C(ret) > 0);
        }
        return True;
    }

    PyVar fast_call(const _Str& name, pkpy::Args&& args){
        PyObject* cls = args[0]->type.get();
        while(cls != None.get()) {
            PyVar* val = cls->attribs.try_get(name);
            if(val != nullptr) return call(*val, std::move(args));
            cls = cls->attribs[__base__].get();
        }
        attributeError(args[0], name);
        return nullptr;
    }

    inline PyVar call(const PyVar& _callable){
        return call(_callable, pkpy::noArg(), pkpy::noArg(), false);
    }

    template<typename ArgT>
    inline std::enable_if_t<std::is_same_v<std::remove_const_t<std::remove_reference_t<ArgT>>, pkpy::Args>, PyVar>
    call(const PyVar& _callable, ArgT&& args){
        return call(_callable, std::forward<ArgT>(args), pkpy::noArg(), false);
    }

    template<typename ArgT>
    inline std::enable_if_t<std::is_same_v<std::remove_const_t<std::remove_reference_t<ArgT>>, pkpy::Args>, PyVar>
    call(const PyVar& obj, const _Str& func, ArgT&& args){
        return call(getattr(obj, func), std::forward<ArgT>(args), pkpy::noArg(), false);
    }

    inline PyVar call(const PyVar& obj, const _Str& func){
        return call(getattr(obj, func), pkpy::noArg(), pkpy::noArg(), false);
    }

    PyVar call(const PyVar& _callable, pkpy::Args args, const pkpy::Args& kwargs, bool opCall){
        if(_callable->is_type(_tp_type)){
            auto it = _callable->attribs.find(__new__);
            PyVar obj;
            if(it != _callable->attribs.end()){
                obj = call(it->second, args, kwargs, false);
            }else{
                obj = new_object(_callable, DUMMY_VAL);
                PyVarOrNull init_fn = getattr(obj, __init__, false);
                if (init_fn != nullptr) call(init_fn, args, kwargs, false);
            }
            return obj;
        }

        const PyVar* callable = &_callable;
        if((*callable)->is_type(_tp_bound_method)){
            auto& bm = PyBoundMethod_AS_C((*callable));
            callable = &bm.method;      // get unbound method
            args.extend_self(bm.obj);
        }
        
        if((*callable)->is_type(_tp_native_function)){
            const auto& f = OBJ_GET(_CppFunc, *callable);
            // _CppFunc do not support kwargs
            return f(this, args);
        } else if((*callable)->is_type(_tp_function)){
            const _Func& fn = PyFunction_AS_C((*callable));
            pkpy::shared_ptr<PyVarDict> _locals = pkpy::make_shared<PyVarDict>();
            PyVarDict& locals = *_locals;

            int i = 0;
            for(const auto& name : fn->args){
                if(i < args.size()){
                    locals.emplace(name, args[i++]);
                    continue;
                }
                typeError("missing positional argument '" + name + "'");
            }

            locals.insert(fn->kwArgs.begin(), fn->kwArgs.end());

            std::vector<_Str> positional_overrided_keys;
            if(!fn->starredArg.empty()){
                // handle *args
                PyVarList vargs;
                while(i < args.size()) vargs.push_back(args[i++]);
                locals.emplace(fn->starredArg, PyTuple(std::move(vargs)));
            }else{
                for(const auto& key : fn->kwArgsOrder){
                    if(i < args.size()){
                        locals[key] = args[i++];
                        positional_overrided_keys.push_back(key);
                    }else{
                        break;
                    }
                }
                if(i < args.size()) typeError("too many arguments");
            }
            
            for(int i=0; i<kwargs.size(); i+=2){
                const _Str& key = PyStr_AS_C(kwargs[i]);
                if(!fn->kwArgs.contains(key)){
                    typeError(key.__escape(true) + " is an invalid keyword argument for " + fn->name + "()");
                }
                const PyVar& val = kwargs[i+1];
                if(!positional_overrided_keys.empty()){
                    auto it = std::find(positional_overrided_keys.begin(), positional_overrided_keys.end(), key);
                    if(it != positional_overrided_keys.end()){
                        typeError("multiple values for argument '" + key + "'");
                    }
                }
                locals[key] = val;
            }

            PyVar* it_m = (*callable)->attribs.try_get(__module__);
            PyVar _module = it_m != nullptr ? *it_m : top_frame()->_module;
            if(opCall){
                __new_frame(fn->code, _module, _locals);
                return __py2py_call_signal;
            }
            return _exec(fn->code, _module, _locals);
        }
        typeError("'" + OBJ_TP_NAME(*callable) + "' object is not callable");
        return None;
    }


    // repl mode is only for setting `frame->id` to 0
    PyVarOrNull exec(_Str source, _Str filename, CompileMode mode, PyVar _module=nullptr){
        if(_module == nullptr) _module = _main;
        try {
            _Code code = compile(source, filename, mode);
            return _exec(code, _module, pkpy::make_shared<PyVarDict>());
        }catch (const _Exception& e){
            *_stderr << e.summary() << '\n';
        }
        catch (const std::exception& e) {
            *_stderr << "A std::exception occurred! It may be a bug, please report it!!\n";
            *_stderr << e.what() << '\n';
        }
        callstack = {};
        return nullptr;
    }

    template<typename ...Args>
    Frame* __new_frame(Args&&... args){
        if(callstack.size() > maxRecursionDepth){
            _error("RecursionError", "maximum recursion depth exceeded");
        }
        callstack.emplace(std::make_unique<Frame>(std::forward<Args>(args)...));
        return callstack.top().get();
    }

    template<typename ...Args>
    PyVar _exec(Args&&... args){
        Frame* frame = __new_frame(std::forward<Args>(args)...);
        i64 base_id = frame->id;
        PyVar ret = nullptr;
        bool need_raise = false;

        while(true){
            if(frame->id < base_id) UNREACHABLE();
            try{
                if(need_raise){ need_raise = false; _raise(); }
                ret = run_frame(frame);

                if(ret != __py2py_call_signal){
                    if(frame->id == base_id){      // [ frameBase<- ]
                        callstack.pop();
                        return ret;
                    }else{
                        callstack.pop();
                        frame = callstack.top().get();
                        frame->push(ret);
                    }
                }else{
                    frame = callstack.top().get();  // [ frameBase, newFrame<- ]
                }
            }catch(HandledException& e){
                continue;
            }catch(UnhandledException& e){
                PyVar obj = frame->pop();
                _Exception& _e = PyException_AS_C(obj);
                _e.st_push(frame->curr_snapshot());
                callstack.pop();
                if(callstack.empty()) throw _e;
                frame = callstack.top().get();
                frame->push(obj);
                if(frame->id < base_id) throw ToBeRaisedException();
                need_raise = true;
            }catch(ToBeRaisedException& e){
                need_raise = true;
            }
        }
    }

    PyVar new_user_type_object(PyVar mod, _Str name, PyVar base){
        PyVar obj = pkpy::make_shared<PyObject, Py_<i64>>(_tp_type, DUMMY_VAL);
        setattr(obj, __base__, base);
        _Str fullName = name;
        if(mod != builtins) fullName = OBJ_NAME(mod) + "." + name;
        setattr(obj, __name__, PyStr(fullName));
        setattr(mod, name, obj);
        return obj;
    }

    PyVar new_type_object(_Str name, PyVar base=nullptr) {
        if(base == nullptr) base = _tp_object;
        PyVar obj = pkpy::make_shared<PyObject, Py_<i64>>(_tp_type, DUMMY_VAL);
        setattr(obj, __base__, base);
        _types[name] = obj;
        return obj;
    }

    template<typename T>
    inline PyVar new_object(PyVar type, T _value) {
        if(!type->is_type(_tp_type)) UNREACHABLE();
        return pkpy::make_shared<PyObject, Py_<T>>(type, _value);
    }

    template<typename T, typename... Args>
    inline PyVar new_object_c(Args&&... args) {
        return new_object(T::_tp(this), T(std::forward<Args>(args)...));
    }

    PyVar new_module(_Str name) {
        PyVar obj = new_object(_tp_module, DUMMY_VAL);
        setattr(obj, __name__, PyStr(name));
        _modules[name] = obj;
        return obj;
    }

    PyVar new_module_if_not_existed(_Str name) {
        PyVar* it = _modules.try_get(name);
        if(it != nullptr) return *it;
        return new_module(name);
    }

    PyVarOrNull getattr(const PyVar& obj, const _Str& name, bool throw_err=true) {
        PyVarDict::iterator it;
        PyObject* cls;

        if(obj->is_type(_tp_super)){
            const PyVar* root = &obj;
            int depth = 1;
            while(true){
                root = &OBJ_GET(PyVar, *root);
                if(!(*root)->is_type(_tp_super)) break;
                depth++;
            }
            cls = (*root)->type.get();
            for(int i=0; i<depth; i++) cls = cls->attribs[__base__].get();

            it = (*root)->attribs.find(name);
            if(it != (*root)->attribs.end()) return it->second;        
        }else{
            it = obj->attribs.find(name);
            if(it != obj->attribs.end()) return it->second;
            cls = obj->type.get();
        }

        while(cls != None.get()) {
            it = cls->attribs.find(name);
            if(it != cls->attribs.end()){
                PyVar valueFromCls = it->second;
                if(valueFromCls->is_type(_tp_function) || valueFromCls->is_type(_tp_native_function)){
                    return PyBoundMethod({obj, std::move(valueFromCls)});
                }else{
                    return valueFromCls;
                }
            }
            cls = cls->attribs[__base__].get();
        }
        if(throw_err) attributeError(obj, name);
        return nullptr;
    }

    template<typename T>
    inline void setattr(PyVar& obj, const _Str& name, T&& value) {
        PyObject* p = obj.get();
        while(p->is_type(_tp_super)) p = static_cast<PyVar*>(p->value())->get();
        p->attribs[name] = std::forward<T>(value);
    }

    template<int ARGC>
    void bindMethod(PyVar obj, _Str funcName, _CppFuncRaw fn) {
        check_type(obj, _tp_type);
        setattr(obj, funcName, PyNativeFunction(_CppFunc(fn, ARGC, true)));
    }

    template<int ARGC>
    void bindFunc(PyVar obj, _Str funcName, _CppFuncRaw fn) {
        setattr(obj, funcName, PyNativeFunction(_CppFunc(fn, ARGC, false)));
    }

    template<int ARGC>
    void bindMethod(_Str typeName, _Str funcName, _CppFuncRaw fn) {
        bindMethod<ARGC>(_types[typeName], funcName, fn);
    }

    template<int ARGC>
    void bindStaticMethod(_Str typeName, _Str funcName, _CppFuncRaw fn) {
        bindFunc<ARGC>(_types[typeName], funcName, fn);
    }

    template<int ARGC>
    void bindMethodMulti(std::vector<_Str> typeNames, _Str funcName, _CppFuncRaw fn) {
        for(auto& typeName : typeNames) bindMethod<ARGC>(typeName, funcName, fn);
    }

    template<int ARGC>
    void bindBuiltinFunc(_Str funcName, _CppFuncRaw fn) {
        bindFunc<ARGC>(builtins, funcName, fn);
    }

    inline f64 num_to_float(const PyVar& obj){
        if (obj->is_type(_tp_int)){
            return (f64)PyInt_AS_C(obj);
        }else if(obj->is_type(_tp_float)){
            return PyFloat_AS_C(obj);
        }
        typeError("expected int or float, got " + OBJ_TP_NAME(obj));
        return 0;
    }

    PyVar num_negated(const PyVar& obj){
        if (obj->is_type(_tp_int)){
            return PyInt(-PyInt_AS_C(obj));
        }else if(obj->is_type(_tp_float)){
            return PyFloat(-PyFloat_AS_C(obj));
        }
        typeError("unsupported operand type(s) for -");
        return nullptr;
    }

    int normalized_index(int index, int size){
        if(index < 0) index += size;
        if(index < 0 || index >= size){
            indexError("index out of range, " + std::to_string(index) + " not in [0, " + std::to_string(size) + ")");
        }
        return index;
    }

    _Str disassemble(_Code code){
        std::vector<int> jumpTargets;
        for(auto byte : code->co_code){
            if(byte.op == OP_JUMP_ABSOLUTE || byte.op == OP_SAFE_JUMP_ABSOLUTE || byte.op == OP_POP_JUMP_IF_FALSE){
                jumpTargets.push_back(byte.arg);
            }
        }
        _StrStream ss;
        ss << std::string(54, '-') << '\n';
        ss << code->name << ":\n";
        int prev_line = -1;
        for(int i=0; i<code->co_code.size(); i++){
            const Bytecode& byte = code->co_code[i];
            _Str line = std::to_string(byte.line);
            if(byte.line == prev_line) line = "";
            else{
                if(prev_line != -1) ss << "\n";
                prev_line = byte.line;
            }

            std::string pointer;
            if(std::find(jumpTargets.begin(), jumpTargets.end(), i) != jumpTargets.end()){
                pointer = "-> ";
            }else{
                pointer = "   ";
            }
            ss << pad(line, 8) << pointer << pad(std::to_string(i), 3);
            ss << " " << pad(OP_NAMES[byte.op], 20) << " ";
            // ss << pad(byte.arg == -1 ? "" : std::to_string(byte.arg), 5);
            std::string argStr = byte.arg == -1 ? "" : std::to_string(byte.arg);
            if(byte.op == OP_LOAD_CONST){
                argStr += " (" + PyStr_AS_C(asRepr(code->consts[byte.arg])) + ")";
            }
            if(byte.op == OP_LOAD_NAME_REF || byte.op == OP_LOAD_NAME || byte.op == OP_RAISE){
                argStr += " (" + code->names[byte.arg].first.__escape(true) + ")";
            }
            ss << pad(argStr, 20);      // may overflow
            ss << code->blocks[byte.block].to_string();
            if(i != code->co_code.size() - 1) ss << '\n';
        }
        _StrStream consts;
        consts << "consts: ";
        consts << PyStr_AS_C(asRepr(PyList(code->consts)));

        _StrStream names;
        names << "names: ";
        PyVarList list;
        for(int i=0; i<code->names.size(); i++){
            list.push_back(PyStr(code->names[i].first));
        }
        names << PyStr_AS_C(asRepr(PyList(list)));
        ss << '\n' << consts.str() << '\n' << names.str() << '\n';

        for(int i=0; i<code->consts.size(); i++){
            PyVar obj = code->consts[i];
            if(obj->is_type(_tp_function)){
                const auto& f = PyFunction_AS_C(obj);
                ss << disassemble(f->code);
            }
        }
        return _Str(ss.str());
    }

    // for quick access
    PyVar _tp_object, _tp_type, _tp_int, _tp_float, _tp_bool, _tp_str;
    PyVar _tp_list, _tp_tuple;
    PyVar _tp_function, _tp_native_function, _tp_native_iterator, _tp_bound_method;
    PyVar _tp_slice, _tp_range, _tp_module, _tp_ref;
    PyVar _tp_super, _tp_exception;

    template<typename P>
    inline PyVarRef PyRef(P&& value) {
        static_assert(std::is_base_of<BaseRef, P>::value, "P should derive from BaseRef");
        return new_object(_tp_ref, std::forward<P>(value));
    }

    inline const BaseRef* PyRef_AS_C(const PyVar& obj)
    {
        if(!obj->is_type(_tp_ref)) typeError("expected an l-value");
        return (const BaseRef*)(obj->value());
    }

    __DEF_PY_AS_C(Int, i64, _tp_int)
    inline PyVar PyInt(i64 value) { 
        if(value >= -5 && value <= 256) return _small_integers[value + 5];
        return new_object(_tp_int, value);
    }

    DEF_NATIVE(Float, f64, _tp_float)
    DEF_NATIVE(Str, _Str, _tp_str)
    DEF_NATIVE(List, PyVarList, _tp_list)
    DEF_NATIVE(Tuple, PyVarList, _tp_tuple)
    DEF_NATIVE(Function, _Func, _tp_function)
    DEF_NATIVE(NativeFunction, _CppFunc, _tp_native_function)
    DEF_NATIVE(Iter, _Iterator, _tp_native_iterator)
    DEF_NATIVE(BoundMethod, _BoundMethod, _tp_bound_method)
    DEF_NATIVE(Range, _Range, _tp_range)
    DEF_NATIVE(Slice, _Slice, _tp_slice)
    DEF_NATIVE(Exception, _Exception, _tp_exception)
    
    // there is only one True/False, so no need to copy them!
    inline bool PyBool_AS_C(const PyVar& obj){return obj == True;}
    inline const PyVar& PyBool(bool value){return value ? True : False;}

    void initializeBuiltinClasses(){
        _tp_object = pkpy::make_shared<PyObject, Py_<i64>>(nullptr, DUMMY_VAL);
        _tp_type = pkpy::make_shared<PyObject, Py_<i64>>(nullptr, DUMMY_VAL);
        _types["object"] = _tp_object;
        _types["type"] = _tp_type;

        _tp_bool = new_type_object("bool");
        _tp_int = new_type_object("int");
        _tp_float = new_type_object("float");
        _tp_str = new_type_object("str");
        _tp_list = new_type_object("list");
        _tp_tuple = new_type_object("tuple");
        _tp_slice = new_type_object("slice");
        _tp_range = new_type_object("range");
        _tp_module = new_type_object("module");
        _tp_ref = new_type_object("_ref");
        
        _tp_function = new_type_object("function");
        _tp_native_function = new_type_object("_native_function");
        _tp_native_iterator = new_type_object("_native_iterator");
        _tp_bound_method = new_type_object("bound_method");
        _tp_super = new_type_object("super");
        _tp_exception = new_type_object("Exception");

        this->None = new_object(new_type_object("NoneType"), DUMMY_VAL);
        this->Ellipsis = new_object(new_type_object("ellipsis"), DUMMY_VAL);
        this->True = new_object(_tp_bool, true);
        this->False = new_object(_tp_bool, false);
        this->builtins = new_module("builtins");
        this->_main = new_module("__main__");
        this->__py2py_call_signal = new_object(new_type_object("_signal"), DUMMY_VAL);

        setattr(_tp_type, __base__, _tp_object);
        _tp_type->type = _tp_type;
        setattr(_tp_object, __base__, None);
        _tp_object->type = _tp_type;
        
        for (auto& [name, type] : _types) {
            setattr(type, __name__, PyStr(name));
        }

        std::vector<_Str> publicTypes = {"type", "object", "bool", "int", "float", "str", "list", "tuple", "range"};
        for (auto& name : publicTypes) {
            setattr(builtins, name, _types[name]);
        }
    }

    i64 hash(const PyVar& obj){
        if (obj->is_type(_tp_int)) return PyInt_AS_C(obj);
        if (obj->is_type(_tp_bool)) return PyBool_AS_C(obj) ? 1 : 0;
        if (obj->is_type(_tp_float)){
            f64 val = PyFloat_AS_C(obj);
            return (i64)std::hash<f64>()(val);
        }
        if (obj->is_type(_tp_str)) return PyStr_AS_C(obj).hash();
        if (obj->is_type(_tp_type)) return (i64)obj.get();
        if (obj->is_type(_tp_tuple)) {
            i64 x = 1000003;
            for (const auto& item : PyTuple_AS_C(obj)) {
                i64 y = hash(item);
                x = x ^ (y + 0x9e3779b9 + (x << 6) + (x >> 2)); // recommended by Github Copilot
            }
            return x;
        }
        typeError("unhashable type: " +  OBJ_TP_NAME(obj));
        return 0;
    }

    /***** Error Reporter *****/
private:
    void _error(const _Str& name, const _Str& msg){
        _error(_Exception(name, msg));
    }

    void _error(_Exception e){
        if(callstack.empty()){
            e.is_re = false;
            throw e;
        }
        top_frame()->push(PyException(e));
        _raise();
    }

    void _raise(){
        bool ok = top_frame()->jump_to_exception_handler();
        if(ok) throw HandledException();
        else throw UnhandledException();
    }

public:
    void typeError(const _Str& msg){ _error("TypeError", msg); }
    void zeroDivisionError(){ _error("ZeroDivisionError", "division by zero"); }
    void indexError(const _Str& msg){ _error("IndexError", msg); }
    void valueError(const _Str& msg){ _error("ValueError", msg); }
    void nameError(const _Str& name){ _error("NameError", "name '" + name + "' is not defined"); }

    void attributeError(PyVar obj, const _Str& name){
        _error("AttributeError", "type '" +  OBJ_TP_NAME(obj) + "' has no attribute '" + name + "'");
    }

    inline void check_type(const PyVar& obj, const PyVar& type){
        if(!obj->is_type(type)) typeError("expected '" + OBJ_NAME(type) + "', but got '" + OBJ_TP_NAME(obj) + "'");
    }

    ~VM() {
        if(!use_stdio){
            delete _stdout;
            delete _stderr;
        }
    }

    _Code compile(_Str source, _Str filename, CompileMode mode);
};

/***** Pointers' Impl *****/
PyVar NameRef::get(VM* vm, Frame* frame) const{
    PyVar* val;
    val = frame->f_locals().try_get(pair->first);
    if(val) return *val;
    val = frame->f_globals().try_get(pair->first);
    if(val) return *val;
    val = vm->builtins->attribs.try_get(pair->first);
    if(val) return *val;
    vm->nameError(pair->first);
    return nullptr;
}

void NameRef::set(VM* vm, Frame* frame, PyVar val) const{
    switch(pair->second) {
        case NAME_LOCAL: frame->f_locals()[pair->first] = std::move(val); break;
        case NAME_GLOBAL:
        {
            PyVar* existing = frame->f_locals().try_get(pair->first);
            if(existing != nullptr){
                *existing = std::move(val);
            }else{
                frame->f_globals()[pair->first] = std::move(val);
            }
        } break;
        default: UNREACHABLE();
    }
}

void NameRef::del(VM* vm, Frame* frame) const{
    switch(pair->second) {
        case NAME_LOCAL: {
            if(frame->f_locals().contains(pair->first)){
                frame->f_locals().erase(pair->first);
            }else{
                vm->nameError(pair->first);
            }
        } break;
        case NAME_GLOBAL:
        {
            if(frame->f_locals().contains(pair->first)){
                frame->f_locals().erase(pair->first);
            }else{
                if(frame->f_globals().contains(pair->first)){
                    frame->f_globals().erase(pair->first);
                }else{
                    vm->nameError(pair->first);
                }
            }
        } break;
        default: UNREACHABLE();
    }
}

PyVar AttrRef::get(VM* vm, Frame* frame) const{
    return vm->getattr(obj, attr.pair->first);
}

void AttrRef::set(VM* vm, Frame* frame, PyVar val) const{
    vm->setattr(obj, attr.pair->first, val);
}

void AttrRef::del(VM* vm, Frame* frame) const{
    vm->typeError("cannot delete attribute");
}

PyVar IndexRef::get(VM* vm, Frame* frame) const{
    return vm->call(obj, __getitem__, pkpy::oneArg(index));
}

void IndexRef::set(VM* vm, Frame* frame, PyVar val) const{
    vm->call(obj, __setitem__, pkpy::twoArgs(index, val));
}

void IndexRef::del(VM* vm, Frame* frame) const{
    vm->call(obj, __delitem__, pkpy::oneArg(index));
}

PyVar TupleRef::get(VM* vm, Frame* frame) const{
    PyVarList args(varRefs.size());
    for (int i = 0; i < varRefs.size(); i++) {
        args[i] = vm->PyRef_AS_C(varRefs[i])->get(vm, frame);
    }
    return vm->PyTuple(args);
}

void TupleRef::set(VM* vm, Frame* frame, PyVar val) const{
    if(!val->is_type(vm->_tp_tuple) && !val->is_type(vm->_tp_list)){
        vm->typeError("only tuple or list can be unpacked");
    }
    const PyVarList& args = OBJ_GET(PyVarList, val);
    if(args.size() > varRefs.size()) vm->valueError("too many values to unpack");
    if(args.size() < varRefs.size()) vm->valueError("not enough values to unpack");
    for (int i = 0; i < varRefs.size(); i++) {
        vm->PyRef_AS_C(varRefs[i])->set(vm, frame, args[i]);
    }
}

void TupleRef::del(VM* vm, Frame* frame) const{
    for (auto& r : varRefs) vm->PyRef_AS_C(r)->del(vm, frame);
}

/***** Frame's Impl *****/
inline void Frame::try_deref(VM* vm, PyVar& v){
    if(v->is_type(vm->_tp_ref)) v = vm->PyRef_AS_C(v)->get(vm, this);
}

/***** Iterators' Impl *****/
PyVar RangeIterator::next(){
    PyVar val = vm->PyInt(current);
    current += r.step;
    return val;
}

PyVar StringIterator::next(){
    return vm->PyStr(str.u8_getitem(index++));
}

PyVar _CppFunc::operator()(VM* vm, const pkpy::Args& args) const{
    int args_size = args.size() - (int)method;  // remove self
    if(argc != -1 && args_size != argc) {
        vm->typeError("expected " + std::to_string(argc) + " arguments, but got " + std::to_string(args_size));
    }
    return f(vm, args);
}


struct Compiler;

typedef void (Compiler::*GrammarFn)();
typedef void (Compiler::*CompilerAction)();

struct GrammarRule{
    GrammarFn prefix;
    GrammarFn infix;
    Precedence precedence;
};

enum StringType { NORMAL_STRING, RAW_STRING, F_STRING };

struct Compiler {
    std::unique_ptr<Parser> parser;
    std::stack<_Code> codes;
    bool isCompilingClass = false;
    int lexingCnt = 0;
    VM* vm;
    emhash8::HashMap<_TokenType, GrammarRule> rules;

    _Code co() const{ return codes.top(); }
    CompileMode mode() const{ return parser->src->mode;}

    Compiler(VM* vm, const char* source, _Str filename, CompileMode mode){
        this->vm = vm;
        this->parser = std::make_unique<Parser>(
            pkpy::make_shared<SourceData>(source, filename, mode)
        );

// http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
#define METHOD(name) &Compiler::name
#define NO_INFIX nullptr, PREC_NONE
        for(_TokenType i=0; i<__TOKENS_LEN; i++) rules[i] = { nullptr, NO_INFIX };
        rules[TK(".")] =    { nullptr,               METHOD(exprAttrib),         PREC_ATTRIB };
        rules[TK("(")] =    { METHOD(exprGrouping),  METHOD(exprCall),           PREC_CALL };
        rules[TK("[")] =    { METHOD(exprList),      METHOD(exprSubscript),      PREC_SUBSCRIPT };
        rules[TK("{")] =    { METHOD(exprMap),       NO_INFIX };
        rules[TK("%")] =    { nullptr,               METHOD(exprBinaryOp),       PREC_FACTOR };
        rules[TK("+")] =    { nullptr,               METHOD(exprBinaryOp),       PREC_TERM };
        rules[TK("-")] =    { METHOD(exprUnaryOp),   METHOD(exprBinaryOp),       PREC_TERM };
        rules[TK("*")] =    { METHOD(exprUnaryOp),   METHOD(exprBinaryOp),       PREC_FACTOR };
        rules[TK("/")] =    { nullptr,               METHOD(exprBinaryOp),       PREC_FACTOR };
        rules[TK("//")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_FACTOR };
        rules[TK("**")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_EXPONENT };
        rules[TK(">")] =    { nullptr,               METHOD(exprBinaryOp),       PREC_COMPARISION };
        rules[TK("<")] =    { nullptr,               METHOD(exprBinaryOp),       PREC_COMPARISION };
        rules[TK("==")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_EQUALITY };
        rules[TK("!=")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_EQUALITY };
        rules[TK(">=")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_COMPARISION };
        rules[TK("<=")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_COMPARISION };
        rules[TK("in")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_TEST };
        rules[TK("is")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_TEST };
        rules[TK("not in")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_TEST };
        rules[TK("is not")] =   { nullptr,               METHOD(exprBinaryOp),       PREC_TEST };
        rules[TK("and") ] =     { nullptr,               METHOD(exprAnd),            PREC_LOGICAL_AND };
        rules[TK("or")] =       { nullptr,               METHOD(exprOr),             PREC_LOGICAL_OR };
        rules[TK("not")] =      { METHOD(exprUnaryOp),   nullptr,                    PREC_UNARY };
        rules[TK("True")] =     { METHOD(exprValue),     NO_INFIX };
        rules[TK("False")] =    { METHOD(exprValue),     NO_INFIX };
        rules[TK("lambda")] =   { METHOD(exprLambda),    NO_INFIX };
        rules[TK("None")] =     { METHOD(exprValue),     NO_INFIX };
        rules[TK("...")] =      { METHOD(exprValue),     NO_INFIX };
        rules[TK("@id")] =      { METHOD(exprName),      NO_INFIX };
        rules[TK("@num")] =     { METHOD(exprLiteral),   NO_INFIX };
        rules[TK("@str")] =     { METHOD(exprLiteral),   NO_INFIX };
        rules[TK("@fstr")] =    { METHOD(exprFString),   NO_INFIX };
        rules[TK("?")] =        { nullptr,               METHOD(exprTernary),        PREC_TERNARY };
        rules[TK("=")] =        { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("+=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("-=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("*=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("/=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("//=")] =      { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("%=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("&=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("|=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK("^=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
        rules[TK(",")] =        { nullptr,               METHOD(exprComma),          PREC_COMMA };
        rules[TK("<<")] =       { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_SHIFT };
        rules[TK(">>")] =       { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_SHIFT };
        rules[TK("&")] =        { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_AND };
        rules[TK("|")] =        { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_OR };
        rules[TK("^")] =        { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_XOR };
#undef METHOD
#undef NO_INFIX

#define EXPR() parsePrecedence(PREC_TERNARY)             // no '=' and ',' just a simple expression
#define EXPR_TUPLE() parsePrecedence(PREC_COMMA)         // no '=', but ',' is allowed
#define EXPR_ANY() parsePrecedence(PREC_ASSIGNMENT)
    }

    _Str eatStringUntil(char quote, bool raw) {
        bool quote3 = parser->match_n_chars(2, quote);
        std::vector<char> buff;
        while (true) {
            char c = parser->eatchar_include_newline();
            if (c == quote){
                if(quote3 && !parser->match_n_chars(2, quote)){
                    buff.push_back(c);
                    continue;
                }
                break;
            }
            if (c == '\0'){
                if(quote3 && parser->src->mode == SINGLE_MODE){
                    throw NeedMoreLines(false);
                }
                syntaxError("EOL while scanning string literal");
            }
            if (c == '\n'){
                if(!quote3) syntaxError("EOL while scanning string literal");
                else{
                    buff.push_back(c);
                    continue;
                }
            }
            if (!raw && c == '\\') {
                switch (parser->eatchar_include_newline()) {
                    case '"':  buff.push_back('"');  break;
                    case '\'': buff.push_back('\''); break;
                    case '\\': buff.push_back('\\'); break;
                    case 'n':  buff.push_back('\n'); break;
                    case 'r':  buff.push_back('\r'); break;
                    case 't':  buff.push_back('\t'); break;
                    default: syntaxError("invalid escape character");
                }
            } else {
                buff.push_back(c);
            }
        }
        return _Str(buff.data(), buff.size());
    }

    void eatString(char quote, StringType type) {
        _Str s = eatStringUntil(quote, type == RAW_STRING);
        if(type == F_STRING){
            parser->set_next_token(TK("@fstr"), vm->PyStr(s));
        }else{
            parser->set_next_token(TK("@str"), vm->PyStr(s));
        }
    }

    void eatNumber() {
        static const std::regex pattern("^(0x)?[0-9a-fA-F]+(\\.[0-9]+)?");
        std::smatch m;

        const char* i = parser->token_start;
        while(*i != '\n' && *i != '\0') i++;
        std::string s = std::string(parser->token_start, i);

        try{
            if (std::regex_search(s, m, pattern)) {
                // here is m.length()-1, since the first char was eaten by lexToken()
                for(int j=0; j<m.length()-1; j++) parser->eatchar();

                int base = 10;
                size_t size;
                if (m[1].matched) base = 16;
                if (m[2].matched) {
                    if(base == 16) syntaxError("hex literal should not contain a dot");
                    parser->set_next_token(TK("@num"), vm->PyFloat(std::stod(m[0], &size)));
                } else {
                    parser->set_next_token(TK("@num"), vm->PyInt(std::stoll(m[0], &size, base)));
                }
                if (size != m.length()) UNREACHABLE();
            }
        }catch(std::exception& _){
            syntaxError("invalid number literal");
        } 
    }

    void lexToken(){
        lexingCnt++;
        _lexToken();
        lexingCnt--;
    }

    // Lex the next token and set it as the next token.
    void _lexToken() {
        parser->prev = parser->curr;
        parser->curr = parser->next_token();

        //_Str _info = parser->curr.info(); std::cout << _info << '[' << parser->current_line << ']' << std::endl;

        while (parser->peekchar() != '\0') {
            parser->token_start = parser->curr_char;
            char c = parser->eatchar_include_newline();
            switch (c) {
                case '\'': case '"': eatString(c, NORMAL_STRING); return;
                case '#': parser->skip_line_comment(); break;
                case '{': parser->set_next_token(TK("{")); return;
                case '}': parser->set_next_token(TK("}")); return;
                case ',': parser->set_next_token(TK(",")); return;
                case ':': parser->set_next_token(TK(":")); return;
                case ';': parser->set_next_token(TK(";")); return;
                case '(': parser->set_next_token(TK("(")); return;
                case ')': parser->set_next_token(TK(")")); return;
                case '[': parser->set_next_token(TK("[")); return;
                case ']': parser->set_next_token(TK("]")); return;
                case '%': parser->set_next_token_2('=', TK("%"), TK("%=")); return;
                case '&': parser->set_next_token_2('=', TK("&"), TK("&=")); return;
                case '|': parser->set_next_token_2('=', TK("|"), TK("|=")); return;
                case '^': parser->set_next_token_2('=', TK("^"), TK("^=")); return;
                case '?': parser->set_next_token(TK("?")); return;
                case '.': {
                    if(parser->matchchar('.')) {
                        if(parser->matchchar('.')) {
                            parser->set_next_token(TK("..."));
                        } else {
                            syntaxError("invalid token '..'");
                        }
                    } else {
                        parser->set_next_token(TK("."));
                    }
                    return;
                }
                case '=': parser->set_next_token_2('=', TK("="), TK("==")); return;
                case '+': parser->set_next_token_2('=', TK("+"), TK("+=")); return;
                case '>': {
                    if(parser->matchchar('=')) parser->set_next_token(TK(">="));
                    else if(parser->matchchar('>')) parser->set_next_token(TK(">>"));
                    else parser->set_next_token(TK(">"));
                    return;
                }
                case '<': {
                    if(parser->matchchar('=')) parser->set_next_token(TK("<="));
                    else if(parser->matchchar('<')) parser->set_next_token(TK("<<"));
                    else parser->set_next_token(TK("<"));
                    return;
                }
                case '-': {
                    if(parser->matchchar('=')) parser->set_next_token(TK("-="));
                    else if(parser->matchchar('>')) parser->set_next_token(TK("->"));
                    else parser->set_next_token(TK("-"));
                    return;
                }
                case '!':
                    if(parser->matchchar('=')) parser->set_next_token(TK("!="));
                    else syntaxError("expected '=' after '!'");
                    break;
                case '*':
                    if (parser->matchchar('*')) {
                        parser->set_next_token(TK("**"));  // '**'
                    } else {
                        parser->set_next_token_2('=', TK("*"), TK("*="));
                    }
                    return;
                case '/':
                    if(parser->matchchar('/')) {
                        parser->set_next_token_2('=', TK("//"), TK("//="));
                    } else {
                        parser->set_next_token_2('=', TK("/"), TK("/="));
                    }
                    return;
                case '\r': break;       // just ignore '\r'
                case ' ': case '\t': parser->eat_spaces(); break;
                case '\n': {
                    parser->set_next_token(TK("@eol"));
                    if(!parser->eat_indentation()) indentationError("unindent does not match any outer indentation level");
                    return;
                }
                default: {
                    if(c == 'f'){
                        if(parser->matchchar('\'')) {eatString('\'', F_STRING); return;}
                        if(parser->matchchar('"')) {eatString('"', F_STRING); return;}
                    }else if(c == 'r'){
                        if(parser->matchchar('\'')) {eatString('\'', RAW_STRING); return;}
                        if(parser->matchchar('"')) {eatString('"', RAW_STRING); return;}
                    }

                    if (c >= '0' && c <= '9') {
                        eatNumber();
                        return;
                    }
                    
                    switch (parser->eat_name())
                    {
                        case 0: break;
                        case 1: syntaxError("invalid char: " + std::string(1, c));
                        case 2: syntaxError("invalid utf8 sequence: " + std::string(1, c));
                        case 3: syntaxError("@id contains invalid char"); break;
                        case 4: syntaxError("invalid JSON token"); break;
                        default: UNREACHABLE();
                    }
                    return;
                }
            }
        }

        parser->token_start = parser->curr_char;
        parser->set_next_token(TK("@eof"));
    }

    inline _TokenType peek() {
        return parser->curr.type;
    }

    // not sure this will work
    _TokenType peek_next() {
        if(parser->nexts.empty()) return TK("@eof");
        return parser->nexts.front().type;
    }

    bool match(_TokenType expected) {
        if (peek() != expected) return false;
        lexToken();
        return true;
    }

    void consume(_TokenType expected) {
        if (!match(expected)){
            _StrStream ss;
            ss << "expected '" << TK_STR(expected) << "', but got '" << TK_STR(peek()) << "'";
            syntaxError(ss.str());
        }
    }

    bool match_newlines(bool repl_throw=false) {
        bool consumed = false;
        if (peek() == TK("@eol")) {
            while (peek() == TK("@eol")) lexToken();
            consumed = true;
        }
        if (repl_throw && peek() == TK("@eof")){
            throw NeedMoreLines(isCompilingClass);
        }
        return consumed;
    }

    bool matchEndStatement() {
        if (match(TK(";"))) { match_newlines(); return true; }
        if (match_newlines() || peek()==TK("@eof")) return true;
        if (peek() == TK("@dedent")) return true;
        return false;
    }

    void consumeEndStatement() {
        if (!matchEndStatement()) syntaxError("expected statement end");
    }

    void exprLiteral() {
        PyVar value = parser->prev.value;
        int index = co()->add_const(value);
        emit(OP_LOAD_CONST, index);
    }

    void exprFString() {
        static const std::regex pattern(R"(\{(.*?)\})");
        PyVar value = parser->prev.value;
        _Str s = vm->PyStr_AS_C(value);
        std::sregex_iterator begin(s.begin(), s.end(), pattern);
        std::sregex_iterator end;
        int size = 0;
        int i = 0;
        for(auto it = begin; it != end; it++) {
            std::smatch m = *it;
            if (i < m.position()) {
                std::string literal = s.substr(i, m.position() - i);
                emit(OP_LOAD_CONST, co()->add_const(vm->PyStr(literal)));
                size++;
            }
            emit(OP_LOAD_EVAL_FN);
            emit(OP_LOAD_CONST, co()->add_const(vm->PyStr(m[1].str())));
            emit(OP_CALL, 1);
            size++;
            i = (int)(m.position() + m.length());
        }
        if (i < s.size()) {
            std::string literal = s.substr(i, s.size() - i);
            emit(OP_LOAD_CONST, co()->add_const(vm->PyStr(literal)));
            size++;
        }
        emit(OP_BUILD_STRING, size);
    }

    void exprLambda() {
        _Func func = pkpy::make_shared<Function>();
        func->name = "<lambda>";
        if(!match(TK(":"))){
            __compileFunctionArgs(func, false);
            consume(TK(":"));
        }
        func->code = pkpy::make_shared<CodeObject>(parser->src, func->name);
        this->codes.push(func->code);
        EXPR_TUPLE();
        emit(OP_RETURN_VALUE);
        func->code->optimize();
        this->codes.pop();
        emit(OP_LOAD_LAMBDA, co()->add_const(vm->PyFunction(func)));
    }

    void exprAssign() {
        _TokenType op = parser->prev.type;
        if(op == TK("=")) {     // a = (expr)
            EXPR_TUPLE();
            emit(OP_STORE_REF);
        }else{                  // a += (expr) -> a = a + (expr)
            emit(OP_DUP_TOP);
            EXPR();
            switch (op) {
                case TK("+="):      emit(OP_BINARY_OP, 0);  break;
                case TK("-="):      emit(OP_BINARY_OP, 1);  break;
                case TK("*="):      emit(OP_BINARY_OP, 2);  break;
                case TK("/="):      emit(OP_BINARY_OP, 3);  break;
                case TK("//="):     emit(OP_BINARY_OP, 4);  break;
                case TK("%="):      emit(OP_BINARY_OP, 5);  break;
                case TK("&="):      emit(OP_BITWISE_OP, 2);  break;
                case TK("|="):      emit(OP_BITWISE_OP, 3);  break;
                case TK("^="):      emit(OP_BITWISE_OP, 4);  break;
                default: UNREACHABLE();
            }
            emit(OP_STORE_REF);
        }
    }

    void exprComma() {
        int size = 1;       // an expr is in the stack now
        do {
            EXPR();         // NOTE: "1," will fail, "1,2" will be ok
            size++;
        } while(match(TK(",")));
        emit(OP_BUILD_SMART_TUPLE, size);
    }

    void exprOr() {
        int patch = emit(OP_JUMP_IF_TRUE_OR_POP);
        parsePrecedence(PREC_LOGICAL_OR);
        patch_jump(patch);
    }

    void exprAnd() {
        int patch = emit(OP_JUMP_IF_FALSE_OR_POP);
        parsePrecedence(PREC_LOGICAL_AND);
        patch_jump(patch);
    }

    void exprTernary() {
        int patch = emit(OP_POP_JUMP_IF_FALSE);
        EXPR();         // if true
        int patch2 = emit(OP_JUMP_ABSOLUTE);
        consume(TK(":"));
        patch_jump(patch);
        EXPR();         // if false
        patch_jump(patch2);
    }

    void exprBinaryOp() {
        _TokenType op = parser->prev.type;
        parsePrecedence((Precedence)(rules[op].precedence + 1));

        switch (op) {
            case TK("+"):   emit(OP_BINARY_OP, 0);  break;
            case TK("-"):   emit(OP_BINARY_OP, 1);  break;
            case TK("*"):   emit(OP_BINARY_OP, 2);  break;
            case TK("/"):   emit(OP_BINARY_OP, 3);  break;
            case TK("//"):  emit(OP_BINARY_OP, 4);  break;
            case TK("%"):   emit(OP_BINARY_OP, 5);  break;
            case TK("**"):  emit(OP_BINARY_OP, 6);  break;

            case TK("<"):   emit(OP_COMPARE_OP, 0);    break;
            case TK("<="):  emit(OP_COMPARE_OP, 1);    break;
            case TK("=="):  emit(OP_COMPARE_OP, 2);    break;
            case TK("!="):  emit(OP_COMPARE_OP, 3);    break;
            case TK(">"):   emit(OP_COMPARE_OP, 4);    break;
            case TK(">="):  emit(OP_COMPARE_OP, 5);    break;
            case TK("in"):      emit(OP_CONTAINS_OP, 0);   break;
            case TK("not in"):  emit(OP_CONTAINS_OP, 1);   break;
            case TK("is"):      emit(OP_IS_OP, 0);         break;
            case TK("is not"):  emit(OP_IS_OP, 1);         break;

            case TK("<<"):  emit(OP_BITWISE_OP, 0);    break;
            case TK(">>"):  emit(OP_BITWISE_OP, 1);    break;
            case TK("&"):   emit(OP_BITWISE_OP, 2);    break;
            case TK("|"):   emit(OP_BITWISE_OP, 3);    break;
            case TK("^"):   emit(OP_BITWISE_OP, 4);    break;
            default: UNREACHABLE();
        }
    }

    void exprUnaryOp() {
        _TokenType op = parser->prev.type;
        parsePrecedence((Precedence)(PREC_UNARY + 1));
        switch (op) {
            case TK("-"):     emit(OP_UNARY_NEGATIVE); break;
            case TK("not"):   emit(OP_UNARY_NOT);      break;
            case TK("*"):     syntaxError("cannot use '*' as unary operator"); break;
            default: UNREACHABLE();
        }
    }

    void exprGrouping() {
        match_newlines(mode()==SINGLE_MODE);
        EXPR_TUPLE();
        match_newlines(mode()==SINGLE_MODE);
        consume(TK(")"));
    }

    void exprList() {
        int _patch = emit(OP_NO_OP);
        int _body_start = co()->co_code.size();
        int ARGC = 0;
        do {
            match_newlines(mode()==SINGLE_MODE);
            if (peek() == TK("]")) break;
            EXPR(); ARGC++;
            match_newlines(mode()==SINGLE_MODE);
            if(ARGC == 1 && match(TK("for"))) goto __LISTCOMP;
        } while (match(TK(",")));
        match_newlines(mode()==SINGLE_MODE);
        consume(TK("]"));
        emit(OP_BUILD_LIST, ARGC);
        return;

__LISTCOMP:
        int _body_end_return = emit(OP_JUMP_ABSOLUTE, -1);
        int _body_end = co()->co_code.size();
        co()->co_code[_patch].op = OP_JUMP_ABSOLUTE;
        co()->co_code[_patch].arg = _body_end;
        emit(OP_BUILD_LIST, 0);
        EXPR_FOR_VARS();consume(TK("in"));EXPR_TUPLE();
        match_newlines(mode()==SINGLE_MODE);
        
        int _skipPatch = emit(OP_JUMP_ABSOLUTE);
        int _cond_start = co()->co_code.size();
        int _cond_end_return = -1;
        if(match(TK("if"))) {
            EXPR_TUPLE();
            _cond_end_return = emit(OP_JUMP_ABSOLUTE, -1);
        }
        patch_jump(_skipPatch);

        emit(OP_GET_ITER);
        co()->__enter_block(FOR_LOOP);
        emit(OP_FOR_ITER);

        if(_cond_end_return != -1) {      // there is an if condition
            emit(OP_JUMP_ABSOLUTE, _cond_start);
            patch_jump(_cond_end_return);
            int ifpatch = emit(OP_POP_JUMP_IF_FALSE);
            emit(OP_JUMP_ABSOLUTE, _body_start);
            patch_jump(_body_end_return);
            emit(OP_LIST_APPEND);
            patch_jump(ifpatch);
        }else{
            emit(OP_JUMP_ABSOLUTE, _body_start);
            patch_jump(_body_end_return);
            emit(OP_LIST_APPEND);
        }

        emit(OP_LOOP_CONTINUE, -1, true);
        co()->__exit_block();
        match_newlines(mode()==SINGLE_MODE);
        consume(TK("]"));
    }

    void exprMap() {
        bool parsing_dict = false;
        int size = 0;
        do {
            match_newlines(mode()==SINGLE_MODE);
            if (peek() == TK("}")) break;
            EXPR();
            if(peek() == TK(":")) parsing_dict = true;
            if(parsing_dict){
                consume(TK(":"));
                EXPR();
            }
            size++;
            match_newlines(mode()==SINGLE_MODE);
        } while (match(TK(",")));
        consume(TK("}"));

        if(size == 0 || parsing_dict) emit(OP_BUILD_MAP, size);
        else emit(OP_BUILD_SET, size);
    }

    void exprCall() {
        int ARGC = 0;
        int KWARGC = 0;
        do {
            match_newlines(mode()==SINGLE_MODE);
            if (peek() == TK(")")) break;
            if(peek() == TK("@id") && peek_next() == TK("=")) {
                consume(TK("@id"));
                const _Str& key = parser->prev.str();
                emit(OP_LOAD_CONST, co()->add_const(vm->PyStr(key)));
                consume(TK("="));
                EXPR();
                KWARGC++;
            } else{
                if(KWARGC > 0) syntaxError("positional argument follows keyword argument");
                EXPR();
                ARGC++;
            }
            match_newlines(mode()==SINGLE_MODE);
        } while (match(TK(",")));
        consume(TK(")"));
        emit(OP_CALL, (KWARGC << 16) | ARGC);
    }

    void exprName() {
        Token tkname = parser->prev;
        int index = co()->add_name(
            tkname.str(),
            codes.size()>1 ? NAME_LOCAL : NAME_GLOBAL
        );
        emit(OP_LOAD_NAME_REF, index);
    }

    void exprAttrib() {
        consume(TK("@id"));
        const _Str& name = parser->prev.str();
        int index = co()->add_name(name, NAME_ATTR);
        emit(OP_BUILD_ATTR_REF, index);
    }

    // [:], [:b]
    // [a], [a:], [a:b]
    void exprSubscript() {
        if(match(TK(":"))){
            emit(OP_LOAD_NONE);
            if(match(TK("]"))){
                emit(OP_LOAD_NONE);
            }else{
                EXPR_TUPLE();
                consume(TK("]"));
            }
            emit(OP_BUILD_SLICE);
        }else{
            EXPR_TUPLE();
            if(match(TK(":"))){
                if(match(TK("]"))){
                    emit(OP_LOAD_NONE);
                }else{
                    EXPR_TUPLE();
                    consume(TK("]"));
                }
                emit(OP_BUILD_SLICE);
            }else{
                consume(TK("]"));
            }
        }
        emit(OP_BUILD_INDEX_REF);
    }

    void exprValue() {
        _TokenType op = parser->prev.type;
        switch (op) {
            case TK("None"):    emit(OP_LOAD_NONE);  break;
            case TK("True"):    emit(OP_LOAD_TRUE);  break;
            case TK("False"):   emit(OP_LOAD_FALSE); break;
            case TK("..."):     emit(OP_LOAD_ELLIPSIS); break;
            default: UNREACHABLE();
        }
    }

    int emit(Opcode opcode, int arg=-1, bool keepline=false) {
        int line = parser->prev.line;
        co()->co_code.push_back(
            Bytecode{(uint8_t)opcode, arg, line, (uint16_t)co()->_curr_block_i}
        );
        int i = co()->co_code.size() - 1;
        if(keepline && i>=1) co()->co_code[i].line = co()->co_code[i-1].line;
        return i;
    }

    inline void patch_jump(int addr_index) {
        int target = co()->co_code.size();
        co()->co_code[addr_index].arg = target;
    }

    void compileBlockBody(){
        __compileBlockBody(&Compiler::compileStatement);
    }
    
    void __compileBlockBody(CompilerAction action) {
        consume(TK(":"));
        if(!match_newlines(mode()==SINGLE_MODE)){
            syntaxError("expected a new line after ':'");
        }
        consume(TK("@indent"));
        while (peek() != TK("@dedent")) {
            match_newlines();
            (this->*action)();
            match_newlines();
        }
        consume(TK("@dedent"));
    }

    Token compileImportPath() {
        consume(TK("@id"));
        Token tkmodule = parser->prev;
        int index = co()->add_name(tkmodule.str(), NAME_SPECIAL);
        emit(OP_IMPORT_NAME, index);
        return tkmodule;
    }

    // import a as b
    void compileRegularImport() {
        do {
            Token tkmodule = compileImportPath();
            if (match(TK("as"))) {
                consume(TK("@id"));
                tkmodule = parser->prev;
            }
            int index = co()->add_name(tkmodule.str(), NAME_GLOBAL);
            emit(OP_STORE_NAME, index);
        } while (match(TK(",")));
        consumeEndStatement();
    }

    // from a import b as c, d as e
    void compileFromImport() {
        Token tkmodule = compileImportPath();
        consume(TK("import"));
        do {
            emit(OP_DUP_TOP);
            consume(TK("@id"));
            Token tkname = parser->prev;
            int index = co()->add_name(tkname.str(), NAME_ATTR);
            emit(OP_BUILD_ATTR_REF, index);
            if (match(TK("as"))) {
                consume(TK("@id"));
                tkname = parser->prev;
            }
            index = co()->add_name(tkname.str(), NAME_GLOBAL);
            emit(OP_STORE_NAME, index);
        } while (match(TK(",")));
        emit(OP_POP_TOP);
        consumeEndStatement();
    }

    void parsePrecedence(Precedence precedence) {
        lexToken();
        GrammarFn prefix = rules[parser->prev.type].prefix;
        if (prefix == nullptr) syntaxError(_Str("expected an expression, but got ") + TK_STR(parser->prev.type));
        (this->*prefix)();
        while (rules[peek()].precedence >= precedence) {
            lexToken();
            _TokenType op = parser->prev.type;
            GrammarFn infix = rules[op].infix;
            if(infix == nullptr) throw std::runtime_error("(infix == nullptr) is true");
            (this->*infix)();
        }
    }

    void compileIfStatement() {
        match_newlines();
        EXPR_TUPLE();

        int ifpatch = emit(OP_POP_JUMP_IF_FALSE);
        compileBlockBody();

        if (match(TK("elif"))) {
            int exit_jump = emit(OP_JUMP_ABSOLUTE);
            patch_jump(ifpatch);
            compileIfStatement();
            patch_jump(exit_jump);
        } else if (match(TK("else"))) {
            int exit_jump = emit(OP_JUMP_ABSOLUTE);
            patch_jump(ifpatch);
            compileBlockBody();
            patch_jump(exit_jump);
        } else {
            patch_jump(ifpatch);
        }
    }

    void compileWhileLoop() {
        co()->__enter_block(WHILE_LOOP);
        EXPR_TUPLE();
        int patch = emit(OP_POP_JUMP_IF_FALSE);
        compileBlockBody();
        emit(OP_LOOP_CONTINUE, -1, true);
        patch_jump(patch);
        co()->__exit_block();
    }

    void EXPR_FOR_VARS(){
        int size = 0;
        do {
            consume(TK("@id"));
            exprName(); size++;
        } while (match(TK(",")));
        if(size > 1) emit(OP_BUILD_SMART_TUPLE, size);
    }

    void compileForLoop() {
        EXPR_FOR_VARS();consume(TK("in")); EXPR_TUPLE();
        emit(OP_GET_ITER);
        co()->__enter_block(FOR_LOOP);
        emit(OP_FOR_ITER);
        compileBlockBody();
        emit(OP_LOOP_CONTINUE, -1, true);
        co()->__exit_block();
    }

    void compileTryExcept() {
        co()->__enter_block(TRY_EXCEPT);
        emit(OP_TRY_BLOCK_ENTER);
        compileBlockBody();
        emit(OP_TRY_BLOCK_EXIT);
        std::vector<int> patches = { emit(OP_JUMP_ABSOLUTE) };
        co()->__exit_block();

        do {
            consume(TK("except"));
            if(match(TK("@id"))){
                int name_idx = co()->add_name(parser->prev.str(), NAME_SPECIAL);
                emit(OP_EXCEPTION_MATCH, name_idx);
            }else{
                emit(OP_LOAD_TRUE);
            }
            int patch = emit(OP_POP_JUMP_IF_FALSE);
            emit(OP_POP_TOP);       // pop the exception on match
            compileBlockBody();
            patches.push_back(emit(OP_JUMP_ABSOLUTE));
            patch_jump(patch);
        }while(peek() == TK("except"));
        emit(OP_RE_RAISE);      // no match, re-raise
        for (int patch : patches) patch_jump(patch);
    }

    void compileStatement() {
        if (match(TK("break"))) {
            if (!co()->__is_curr_block_loop()) syntaxError("'break' outside loop");
            consumeEndStatement();
            emit(OP_LOOP_BREAK);
        } else if (match(TK("continue"))) {
            if (!co()->__is_curr_block_loop()) syntaxError("'continue' not properly in loop");
            consumeEndStatement();
            emit(OP_LOOP_CONTINUE);
        } else if (match(TK("return"))) {
            if (codes.size() == 1)
                syntaxError("'return' outside function");
            if(matchEndStatement()){
                emit(OP_LOAD_NONE);
            }else{
                EXPR_TUPLE();
                consumeEndStatement();
            }
            emit(OP_RETURN_VALUE, -1, true);
        } else if (match(TK("if"))) {
            compileIfStatement();
        } else if (match(TK("while"))) {
            compileWhileLoop();
        } else if (match(TK("for"))) {
            compileForLoop();
        } else if (match(TK("try"))) {
            compileTryExcept();
        }else if(match(TK("assert"))){
            EXPR();
            emit(OP_ASSERT);
            consumeEndStatement();
        } else if(match(TK("with"))){
            EXPR();
            consume(TK("as"));
            consume(TK("@id"));
            Token tkname = parser->prev;
            int index = co()->add_name(
                tkname.str(),
                codes.size()>1 ? NAME_LOCAL : NAME_GLOBAL
            );
            emit(OP_STORE_NAME, index);
            emit(OP_LOAD_NAME_REF, index);
            emit(OP_WITH_ENTER);
            compileBlockBody();
            emit(OP_LOAD_NAME_REF, index);
            emit(OP_WITH_EXIT);
        } else if(match(TK("label"))){
            if(mode() != EXEC_MODE) syntaxError("'label' is only available in EXEC_MODE");
            consume(TK(".")); consume(TK("@id"));
            _Str label = parser->prev.str();
            bool ok = co()->add_label(label);
            if(!ok) syntaxError("label '" + label + "' already exists");
            consumeEndStatement();
        } else if(match(TK("goto"))){ // https://entrian.com/goto/
            if(mode() != EXEC_MODE) syntaxError("'goto' is only available in EXEC_MODE");
            consume(TK(".")); consume(TK("@id"));
            emit(OP_GOTO, co()->add_name(parser->prev.str(), NAME_SPECIAL));
            consumeEndStatement();
        } else if(match(TK("raise"))){
            consume(TK("@id"));
            int dummy_t = co()->add_name(parser->prev.str(), NAME_SPECIAL);
            if(match(TK("("))){
                EXPR(); consume(TK(")"));
            }else{
                emit(OP_LOAD_NONE);
            }
            emit(OP_RAISE, dummy_t);
            consumeEndStatement();
        } else if(match(TK("del"))){
            EXPR();
            emit(OP_DELETE_REF);
            consumeEndStatement();
        } else if(match(TK("global"))){
            do {
                consume(TK("@id"));
                co()->global_names[parser->prev.str()] = 1;
            } while (match(TK(",")));
            consumeEndStatement();
        } else if(match(TK("pass"))){
            consumeEndStatement();
        } else {
            EXPR_ANY();
            consumeEndStatement();
            // If last op is not an assignment, pop the result.
            uint8_t lastOp = co()->co_code.back().op;
            if( lastOp!=OP_STORE_NAME && lastOp!=OP_STORE_REF){
                if(mode()==SINGLE_MODE && parser->indents.top()==0) emit(OP_PRINT_EXPR, -1, true);
                emit(OP_POP_TOP, -1, true);
            }
        }
    }

    void compileClass(){
        consume(TK("@id"));
        int clsNameIdx = co()->add_name(parser->prev.str(), NAME_GLOBAL);
        int superClsNameIdx = -1;
        if(match(TK("(")) && match(TK("@id"))){
            superClsNameIdx = co()->add_name(parser->prev.str(), NAME_GLOBAL);
            consume(TK(")"));
        }
        emit(OP_LOAD_NONE);
        isCompilingClass = true;
        __compileBlockBody(&Compiler::compileFunction);
        isCompilingClass = false;
        if(superClsNameIdx == -1) emit(OP_LOAD_NONE);
        else emit(OP_LOAD_NAME_REF, superClsNameIdx);
        emit(OP_BUILD_CLASS, clsNameIdx);
    }

    void __compileFunctionArgs(_Func func, bool enableTypeHints){
        int state = 0;      // 0 for args, 1 for *args, 2 for k=v, 3 for **kwargs
        do {
            if(state == 3) syntaxError("**kwargs should be the last argument");
            match_newlines();
            if(match(TK("*"))){
                if(state < 1) state = 1;
                else syntaxError("*args should be placed before **kwargs");
            }
            else if(match(TK("**"))){
                state = 3;
            }

            consume(TK("@id"));
            const _Str& name = parser->prev.str();
            if(func->hasName(name)) syntaxError("duplicate argument name");

            // eat type hints
            if(enableTypeHints && match(TK(":"))) consume(TK("@id"));

            if(state == 0 && peek() == TK("=")) state = 2;

            switch (state)
            {
                case 0: func->args.push_back(name); break;
                case 1: func->starredArg = name; state+=1; break;
                case 2: {
                    consume(TK("="));
                    PyVarOrNull value = readLiteral();
                    if(value == nullptr){
                        syntaxError(_Str("expect a literal, not ") + TK_STR(parser->curr.type));
                    }
                    func->kwArgs[name] = value;
                    func->kwArgsOrder.push_back(name);
                } break;
                case 3: syntaxError("**kwargs is not supported yet"); break;
            }
        } while (match(TK(",")));
    }

    void compileFunction(){
        if(isCompilingClass){
            if(match(TK("pass"))) return;
            consume(TK("def"));
        }
        _Func func = pkpy::make_shared<Function>();
        consume(TK("@id"));
        func->name = parser->prev.str();

        if (match(TK("(")) && !match(TK(")"))) {
            __compileFunctionArgs(func, true);
            consume(TK(")"));
        }

        // eat type hints
        if(match(TK("->"))) consume(TK("@id"));

        func->code = pkpy::make_shared<CodeObject>(parser->src, func->name);
        this->codes.push(func->code);
        compileBlockBody();
        func->code->optimize();
        this->codes.pop();
        emit(OP_LOAD_CONST, co()->add_const(vm->PyFunction(func)));
        if(!isCompilingClass) emit(OP_STORE_FUNCTION);
    }

    PyVarOrNull readLiteral(){
        if(match(TK("-"))){
            consume(TK("@num"));
            PyVar val = parser->prev.value;
            return vm->num_negated(val);
        }
        if(match(TK("@num"))) return parser->prev.value;
        if(match(TK("@str"))) return parser->prev.value;
        if(match(TK("True"))) return vm->PyBool(true);
        if(match(TK("False"))) return vm->PyBool(false);
        if(match(TK("None"))) return vm->None;
        if(match(TK("..."))) return vm->Ellipsis;
        return nullptr;
    }

    void compileTopLevelStatement() {
        if (match(TK("class"))) {
            compileClass();
        } else if (match(TK("def"))) {
            compileFunction();
        } else if (match(TK("import"))) {
            compileRegularImport();
        } else if (match(TK("from"))) {
            compileFromImport();
        } else {
            compileStatement();
        }
    }

    bool _used = false;
    _Code __fillCode(){
        // can only be called once
        if(_used) UNREACHABLE();
        _used = true;

        _Code code = pkpy::make_shared<CodeObject>(parser->src, _Str("<module>"));
        codes.push(code);

        // Lex initial tokens. current <-- next.
        lexToken();
        lexToken();
        match_newlines();

        if(mode()==EVAL_MODE) {
            EXPR_TUPLE();
            consume(TK("@eof"));
            code->optimize();
            return code;
        }else if(mode()==JSON_MODE){
            PyVarOrNull value = readLiteral();
            if(value != nullptr) emit(OP_LOAD_CONST, code->add_const(value));
            else if(match(TK("{"))) exprMap();
            else if(match(TK("["))) exprList();
            else syntaxError("expect a JSON object or array");
            consume(TK("@eof"));
            return code;    // no need to optimize for JSON decoding
        }

        while (!match(TK("@eof"))) {
            compileTopLevelStatement();
            match_newlines();
        }
        code->optimize();
        return code;
    }

    /***** Error Reporter *****/
    _Str getLineSnapshot(){
        int lineno = parser->curr.line;
        const char* cursor = parser->curr.start;
        // if error occurs in lexing, lineno should be `parser->current_line`
        if(lexingCnt > 0){
            lineno = parser->current_line;
            cursor = parser->curr_char;
        }
        if(parser->peekchar() == '\n') lineno--;
        return parser->src->snapshot(lineno, cursor);
    }

    void __throw_e(_Str type, _Str msg){
        auto e = _Exception("SyntaxError", msg);
        e.st_push(getLineSnapshot());
        throw e;
    }
    void syntaxError(_Str msg){ __throw_e("SyntaxError", msg); }
    void indentationError(_Str msg){ __throw_e("IndentationError", msg); }
};


class REPL {
protected:
    int need_more_lines = 0;
    std::string buffer;
    VM* vm;
public:
    REPL(VM* vm) : vm(vm){
        (*vm->_stdout) << ("pocketpy " PK_VERSION " (" __DATE__ ", " __TIME__ ")\n");
        (*vm->_stdout) << ("https://github.com/blueloveTH/pocketpy" "\n");
        (*vm->_stdout) << ("Type \"exit()\" to exit." "\n");
    }

    bool input(std::string line){
        CompileMode mode = SINGLE_MODE;
        if(need_more_lines){
            buffer += line;
            buffer += '\n';
            int n = buffer.size();
            if(n>=need_more_lines){
                for(int i=buffer.size()-need_more_lines; i<buffer.size(); i++){
                    if(buffer[i] != '\n') goto __NOT_ENOUGH_LINES;
                }
                need_more_lines = 0;
                line = buffer;
                buffer.clear();
                mode = EXEC_MODE;
            }else{
__NOT_ENOUGH_LINES:
                return true;
            }
        }
        
        try{
            vm->exec(line, "<stdin>", mode);
        }catch(NeedMoreLines& ne){
            buffer += line;
            buffer += '\n';
            need_more_lines = ne.isClassDef ? 3 : 2;
            if (need_more_lines) return true;
        }
        return false;
    }
};


_Code VM::compile(_Str source, _Str filename, CompileMode mode) {
    Compiler compiler(this, source.c_str(), filename, mode);
    try{
        return compiler.__fillCode();
    }catch(_Exception& e){
        _error(e);
        return nullptr;
    }
}

#define BIND_NUM_ARITH_OPT(name, op)                                                                    \
    _vm->bindMethodMulti<1>({"int","float"}, #name, [](VM* vm, const pkpy::Args& args){                 \
        if(args[0]->is_type(vm->_tp_int) && args[1]->is_type(vm->_tp_int)){                             \
            return vm->PyInt(vm->PyInt_AS_C(args[0]) op vm->PyInt_AS_C(args[1]));                       \
        }else{                                                                                          \
            return vm->PyFloat(vm->num_to_float(args[0]) op vm->num_to_float(args[1]));                 \
        }                                                                                               \
    });

#define BIND_NUM_LOGICAL_OPT(name, op, is_eq)                                                           \
    _vm->bindMethodMulti<1>({"int","float"}, #name, [](VM* vm, const pkpy::Args& args){                 \
        bool _0 = args[0]->is_type(vm->_tp_int) || args[0]->is_type(vm->_tp_float);                     \
        bool _1 = args[1]->is_type(vm->_tp_int) || args[1]->is_type(vm->_tp_float);                     \
        if(!_0 || !_1){                                                                                 \
            if constexpr(is_eq) return vm->PyBool(args[0].get() op args[1].get());                      \
            vm->typeError("unsupported operand type(s) for " #op );                                     \
        }                                                                                               \
        return vm->PyBool(vm->num_to_float(args[0]) op vm->num_to_float(args[1]));                      \
    });
    

void __initializeBuiltinFunctions(VM* _vm) {
    BIND_NUM_ARITH_OPT(__add__, +)
    BIND_NUM_ARITH_OPT(__sub__, -)
    BIND_NUM_ARITH_OPT(__mul__, *)

    BIND_NUM_LOGICAL_OPT(__lt__, <, false)
    BIND_NUM_LOGICAL_OPT(__le__, <=, false)
    BIND_NUM_LOGICAL_OPT(__gt__, >, false)
    BIND_NUM_LOGICAL_OPT(__ge__, >=, false)
    BIND_NUM_LOGICAL_OPT(__eq__, ==, true)
    BIND_NUM_LOGICAL_OPT(__ne__, !=, true)

#undef BIND_NUM_ARITH_OPT
#undef BIND_NUM_LOGICAL_OPT

    _vm->bindBuiltinFunc<1>("__sys_stdout_write", [](VM* vm, const pkpy::Args& args) {
        (*vm->_stdout) << vm->PyStr_AS_C(args[0]);
        return vm->None;
    });

    _vm->bindBuiltinFunc<0>("super", [](VM* vm, const pkpy::Args& args) {
        auto it = vm->top_frame()->f_locals().find(m_self);
        if(it == vm->top_frame()->f_locals().end()) vm->typeError("super() can only be called in a class method");
        return vm->new_object(vm->_tp_super, it->second);
    });

    _vm->bindBuiltinFunc<1>("eval", [](VM* vm, const pkpy::Args& args) {
        _Code code = vm->compile(vm->PyStr_AS_C(args[0]), "<eval>", EVAL_MODE);
        return vm->_exec(code, vm->top_frame()->_module, vm->top_frame()->_locals);
    });

    _vm->bindBuiltinFunc<1>("exec", [](VM* vm, const pkpy::Args& args) {
        _Code code = vm->compile(vm->PyStr_AS_C(args[0]), "<exec>", EXEC_MODE);
        vm->_exec(code, vm->top_frame()->_module, vm->top_frame()->_locals);
        return vm->None;
    });

    _vm->bindBuiltinFunc<-1>("exit", [](VM* vm, const pkpy::Args& args) {
        if(args.size() == 0) std::exit(0);
        else if(args.size() == 1) std::exit((int)vm->PyInt_AS_C(args[0]));
        else vm->typeError("exit() takes at most 1 argument");
        return vm->None;
    });

    _vm->bindBuiltinFunc<1>("repr", CPP_LAMBDA(vm->asRepr(args[0])));
    _vm->bindBuiltinFunc<1>("hash", CPP_LAMBDA(vm->PyInt(vm->hash(args[0]))));
    _vm->bindBuiltinFunc<1>("len", CPP_LAMBDA(vm->call(args[0], __len__, pkpy::noArg())));

    _vm->bindBuiltinFunc<1>("chr", [](VM* vm, const pkpy::Args& args) {
        i64 i = vm->PyInt_AS_C(args[0]);
        if (i < 0 || i > 128) vm->valueError("chr() arg not in range(128)");
        return vm->PyStr(std::string(1, (char)i));
    });

    _vm->bindBuiltinFunc<1>("ord", [](VM* vm, const pkpy::Args& args) {
        _Str s = vm->PyStr_AS_C(args[0]);
        if (s.size() != 1) vm->typeError("ord() expected an ASCII character");
        return vm->PyInt((i64)(s.c_str()[0]));
    });

    _vm->bindBuiltinFunc<2>("hasattr", [](VM* vm, const pkpy::Args& args) {
        return vm->PyBool(vm->getattr(args[0], vm->PyStr_AS_C(args[1]), false) != nullptr);
    });

    _vm->bindBuiltinFunc<3>("setattr", [](VM* vm, const pkpy::Args& args) {
        PyVar obj = args[0];
        vm->setattr(obj, vm->PyStr_AS_C(args[1]), args[2]);
        return vm->None;
    });

    _vm->bindBuiltinFunc<2>("getattr", [](VM* vm, const pkpy::Args& args) {
        _Str name = vm->PyStr_AS_C(args[1]);
        return vm->getattr(args[0], name);
    });

    _vm->bindBuiltinFunc<1>("hex", [](VM* vm, const pkpy::Args& args) {
        std::stringstream ss;
        ss << std::hex << vm->PyInt_AS_C(args[0]);
        return vm->PyStr("0x" + ss.str());
    });

    _vm->bindBuiltinFunc<1>("dir", [](VM* vm, const pkpy::Args& args) {
        std::vector<_Str> names;
        for (auto& [k, _] : args[0]->attribs) names.push_back(k);
        for (auto& [k, _] : args[0]->type->attribs) {
            if (k.find("__") == 0) continue;
            if (std::find(names.begin(), names.end(), k) == names.end()) names.push_back(k);
        }
        PyVarList ret;
        for (const auto& name : names) ret.push_back(vm->PyStr(name));
        std::sort(ret.begin(), ret.end(), [vm](const PyVar& a, const PyVar& b) {
            return vm->PyStr_AS_C(a) < vm->PyStr_AS_C(b);
        });
        return vm->PyList(ret);
    });

    _vm->bindMethod<0>("object", "__repr__", [](VM* vm, const pkpy::Args& args) {
        PyVar _self = args[0];
        std::stringstream ss;
        ss << std::hex << (uintptr_t)_self.get();
        _Str s = "<" + OBJ_TP_NAME(_self) + " object at 0x" + ss.str() + ">";
        return vm->PyStr(s);
    });

    _vm->bindMethod<1>("object", "__eq__", CPP_LAMBDA(vm->PyBool(args[0] == args[1])));
    _vm->bindMethod<1>("object", "__ne__", CPP_LAMBDA(vm->PyBool(args[0] != args[1])));

    _vm->bindStaticMethod<1>("type", "__new__", CPP_LAMBDA(args[0]->type));

    _vm->bindStaticMethod<-1>("range", "__new__", [](VM* vm, const pkpy::Args& args) {
        _Range r;
        switch (args.size()) {
            case 1: r.stop = vm->PyInt_AS_C(args[0]); break;
            case 2: r.start = vm->PyInt_AS_C(args[0]); r.stop = vm->PyInt_AS_C(args[1]); break;
            case 3: r.start = vm->PyInt_AS_C(args[0]); r.stop = vm->PyInt_AS_C(args[1]); r.step = vm->PyInt_AS_C(args[2]); break;
            default: vm->typeError("expected 1-3 arguments, but got " + std::to_string(args.size()));
        }
        return vm->PyRange(r);
    });

    _vm->bindMethod<0>("range", "__iter__", CPP_LAMBDA(
        vm->PyIter(pkpy::make_shared<BaseIterator, RangeIterator>(vm, args[0]))
    ));

    _vm->bindMethod<0>("NoneType", "__repr__", CPP_LAMBDA(vm->PyStr("None")));
    _vm->bindMethod<0>("NoneType", "__json__", CPP_LAMBDA(vm->PyStr("null")));

    _vm->bindMethodMulti<1>({"int", "float"}, "__truediv__", [](VM* vm, const pkpy::Args& args) {
        f64 rhs = vm->num_to_float(args[1]);
        if (rhs == 0) vm->zeroDivisionError();
        return vm->PyFloat(vm->num_to_float(args[0]) / rhs);
    });

    _vm->bindMethodMulti<1>({"int", "float"}, "__pow__", [](VM* vm, const pkpy::Args& args) {
        if(args[0]->is_type(vm->_tp_int) && args[1]->is_type(vm->_tp_int)){
            return vm->PyInt((i64)round(pow(vm->PyInt_AS_C(args[0]), vm->PyInt_AS_C(args[1]))));
        }else{
            return vm->PyFloat((f64)pow(vm->num_to_float(args[0]), vm->num_to_float(args[1])));
        }
    });

    /************ PyInt ************/
    _vm->bindStaticMethod<1>("int", "__new__", [](VM* vm, const pkpy::Args& args) {
        if (args[0]->is_type(vm->_tp_int)) return args[0];
        if (args[0]->is_type(vm->_tp_float)) return vm->PyInt((i64)vm->PyFloat_AS_C(args[0]));
        if (args[0]->is_type(vm->_tp_bool)) return vm->PyInt(vm->PyBool_AS_C(args[0]) ? 1 : 0);
        if (args[0]->is_type(vm->_tp_str)) {
            const _Str& s = vm->PyStr_AS_C(args[0]);
            try{
                size_t parsed = 0;
                i64 val = std::stoll(s, &parsed, 10);
                if(parsed != s.size()) throw std::invalid_argument("");
                return vm->PyInt(val);
            }catch(std::invalid_argument&){
                vm->valueError("invalid literal for int(): '" + s + "'");
            }
        }
        vm->typeError("int() argument must be a int, float, bool or str");
        return vm->None;
    });

    _vm->bindMethod<1>("int", "__floordiv__", [](VM* vm, const pkpy::Args& args) {
        i64 rhs = vm->PyInt_AS_C(args[1]);
        if(rhs == 0) vm->zeroDivisionError();
        return vm->PyInt(vm->PyInt_AS_C(args[0]) / rhs);
    });

    _vm->bindMethod<1>("int", "__mod__", [](VM* vm, const pkpy::Args& args) {
        i64 rhs = vm->PyInt_AS_C(args[1]);
        if(rhs == 0) vm->zeroDivisionError();
        return vm->PyInt(vm->PyInt_AS_C(args[0]) % rhs);
    });

    _vm->bindMethod<0>("int", "__repr__", [](VM* vm, const pkpy::Args& args) {
        return vm->PyStr(std::to_string(vm->PyInt_AS_C(args[0])));
    });

    _vm->bindMethod<0>("int", "__json__", [](VM* vm, const pkpy::Args& args) {
        return vm->PyStr(std::to_string(vm->PyInt_AS_C(args[0])));
    });

#define __INT_BITWISE_OP(name,op) \
    _vm->bindMethod<1>("int", #name, [](VM* vm, const pkpy::Args& args) {                    \
        return vm->PyInt(vm->PyInt_AS_C(args[0]) op vm->PyInt_AS_C(args[1]));     \
    });

    __INT_BITWISE_OP(__lshift__, <<)
    __INT_BITWISE_OP(__rshift__, >>)
    __INT_BITWISE_OP(__and__, &)
    __INT_BITWISE_OP(__or__, |)
    __INT_BITWISE_OP(__xor__, ^)

#undef __INT_BITWISE_OP

    /************ PyFloat ************/
    _vm->bindStaticMethod<1>("float", "__new__", [](VM* vm, const pkpy::Args& args) {
        if (args[0]->is_type(vm->_tp_int)) return vm->PyFloat((f64)vm->PyInt_AS_C(args[0]));
        if (args[0]->is_type(vm->_tp_float)) return args[0];
        if (args[0]->is_type(vm->_tp_bool)) return vm->PyFloat(vm->PyBool_AS_C(args[0]) ? 1.0 : 0.0);
        if (args[0]->is_type(vm->_tp_str)) {
            const _Str& s = vm->PyStr_AS_C(args[0]);
            if(s == "inf") return vm->PyFloat(INFINITY);
            if(s == "-inf") return vm->PyFloat(-INFINITY);
            try{
                f64 val = std::stod(s);
                return vm->PyFloat(val);
            }catch(std::invalid_argument&){
                vm->valueError("invalid literal for float(): '" + s + "'");
            }
        }
        vm->typeError("float() argument must be a int, float, bool or str");
        return vm->None;
    });

    _vm->bindMethod<0>("float", "__repr__", [](VM* vm, const pkpy::Args& args) {
        f64 val = vm->PyFloat_AS_C(args[0]);
        if(std::isinf(val) || std::isnan(val)) return vm->PyStr(std::to_string(val));
        _StrStream ss;
        ss << std::setprecision(std::numeric_limits<f64>::max_digits10-1) << val;
        std::string s = ss.str();
        if(std::all_of(s.begin()+1, s.end(), isdigit)) s += ".0";
        return vm->PyStr(s);
    });

    _vm->bindMethod<0>("float", "__json__", [](VM* vm, const pkpy::Args& args) {
        f64 val = vm->PyFloat_AS_C(args[0]);
        if(std::isinf(val) || std::isnan(val)) vm->valueError("cannot jsonify 'nan' or 'inf'");
        return vm->PyStr(std::to_string(val));
    });

    /************ PyString ************/
    _vm->bindStaticMethod<1>("str", "__new__", CPP_LAMBDA(vm->asStr(args[0])));

    _vm->bindMethod<1>("str", "__add__", [](VM* vm, const pkpy::Args& args) {
        const _Str& lhs = vm->PyStr_AS_C(args[0]);
        const _Str& rhs = vm->PyStr_AS_C(args[1]);
        return vm->PyStr(lhs + rhs);
    });

    _vm->bindMethod<0>("str", "__len__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        return vm->PyInt(_self.u8_length());
    });

    _vm->bindMethod<1>("str", "__contains__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        const _Str& _other = vm->PyStr_AS_C(args[1]);
        return vm->PyBool(_self.find(_other) != _Str::npos);
    });

    _vm->bindMethod<0>("str", "__str__", CPP_LAMBDA(args[0]));

    _vm->bindMethod<0>("str", "__iter__", CPP_LAMBDA(
        vm->PyIter(pkpy::make_shared<BaseIterator, StringIterator>(vm, args[0]))
    ));

    _vm->bindMethod<0>("str", "__repr__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        return vm->PyStr(_self.__escape(true));
    });

    _vm->bindMethod<0>("str", "__json__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        return vm->PyStr(_self.__escape(false));
    });

    _vm->bindMethod<1>("str", "__eq__", [](VM* vm, const pkpy::Args& args) {
        if(args[0]->is_type(vm->_tp_str) && args[1]->is_type(vm->_tp_str))
            return vm->PyBool(vm->PyStr_AS_C(args[0]) == vm->PyStr_AS_C(args[1]));
        return vm->PyBool(args[0] == args[1]);
    });

    _vm->bindMethod<1>("str", "__ne__", [](VM* vm, const pkpy::Args& args) {
        if(args[0]->is_type(vm->_tp_str) && args[1]->is_type(vm->_tp_str))
            return vm->PyBool(vm->PyStr_AS_C(args[0]) != vm->PyStr_AS_C(args[1]));
        return vm->PyBool(args[0] != args[1]);
    });

    _vm->bindMethod<1>("str", "__getitem__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self (vm->PyStr_AS_C(args[0]));

        if(args[1]->is_type(vm->_tp_slice)){
            _Slice s = vm->PySlice_AS_C(args[1]);
            s.normalize(_self.u8_length());
            return vm->PyStr(_self.u8_substr(s.start, s.stop));
        }

        int _index = (int)vm->PyInt_AS_C(args[1]);
        _index = vm->normalized_index(_index, _self.u8_length());
        return vm->PyStr(_self.u8_getitem(_index));
    });

    _vm->bindMethod<1>("str", "__gt__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self (vm->PyStr_AS_C(args[0]));
        const _Str& _obj (vm->PyStr_AS_C(args[1]));
        return vm->PyBool(_self > _obj);
    });

    _vm->bindMethod<1>("str", "__lt__", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self (vm->PyStr_AS_C(args[0]));
        const _Str& _obj (vm->PyStr_AS_C(args[1]));
        return vm->PyBool(_self < _obj);
    });

    _vm->bindMethod<2>("str", "replace", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        const _Str& _old = vm->PyStr_AS_C(args[1]);
        const _Str& _new = vm->PyStr_AS_C(args[2]);
        _Str _copy = _self;
        // replace all occurences of _old with _new in _copy
        size_t pos = 0;
        while ((pos = _copy.find(_old, pos)) != std::string::npos) {
            _copy.replace(pos, _old.length(), _new);
            pos += _new.length();
        }
        return vm->PyStr(_copy);
    });

    _vm->bindMethod<1>("str", "startswith", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        const _Str& _prefix = vm->PyStr_AS_C(args[1]);
        return vm->PyBool(_self.find(_prefix) == 0);
    });

    _vm->bindMethod<1>("str", "endswith", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        const _Str& _suffix = vm->PyStr_AS_C(args[1]);
        return vm->PyBool(_self.rfind(_suffix) == _self.length() - _suffix.length());
    });

    _vm->bindMethod<1>("str", "join", [](VM* vm, const pkpy::Args& args) {
        const _Str& _self = vm->PyStr_AS_C(args[0]);
        PyVarList* _list = nullptr;
        if(args[1]->is_type(vm->_tp_list)){
            _list = &vm->PyList_AS_C(args[1]);
        }else if(args[1]->is_type(vm->_tp_tuple)){
            _list = &vm->PyTuple_AS_C(args[1]);
        }else{
            vm->typeError("can only join a list or tuple");
        }
        _StrStream ss;
        for(int i = 0; i < _list->size(); i++){
            if(i > 0) ss << _self;
            ss << vm->PyStr_AS_C(vm->asStr(_list->operator[](i)));
        }
        return vm->PyStr(ss.str());
    });

    /************ PyList ************/
    _vm->bindMethod<0>("list", "__iter__", [](VM* vm, const pkpy::Args& args) {
        return vm->PyIter(
            pkpy::make_shared<BaseIterator, VectorIterator>(vm, args[0])
        );
    });

    _vm->bindMethod<1>("list", "append", [](VM* vm, const pkpy::Args& args) {
        PyVarList& _self = vm->PyList_AS_C(args[0]);
        _self.push_back(args[1]);
        return vm->None;
    });

    _vm->bindMethod<2>("list", "insert", [](VM* vm, const pkpy::Args& args) {
        PyVarList& _self = vm->PyList_AS_C(args[0]);
        int _index = (int)vm->PyInt_AS_C(args[1]);
        if(_index < 0) _index += _self.size();
        if(_index < 0) _index = 0;
        if(_index > _self.size()) _index = _self.size();
        _self.insert(_self.begin() + _index, args[2]);
        return vm->None;
    });

    _vm->bindMethod<0>("list", "clear", [](VM* vm, const pkpy::Args& args) {
        vm->PyList_AS_C(args[0]).clear();
        return vm->None;
    });

    _vm->bindMethod<0>("list", "copy", [](VM* vm, const pkpy::Args& args) {
        return vm->PyList(vm->PyList_AS_C(args[0]));
    });

    _vm->bindMethod<1>("list", "__add__", [](VM* vm, const pkpy::Args& args) {
        const PyVarList& _self = vm->PyList_AS_C(args[0]);
        const PyVarList& _obj = vm->PyList_AS_C(args[1]);
        PyVarList _new_list = _self;
        _new_list.insert(_new_list.end(), _obj.begin(), _obj.end());
        return vm->PyList(_new_list);
    });

    _vm->bindMethod<0>("list", "__len__", [](VM* vm, const pkpy::Args& args) {
        const PyVarList& _self = vm->PyList_AS_C(args[0]);
        return vm->PyInt(_self.size());
    });

    _vm->bindMethodMulti<1>({"list", "tuple"}, "__getitem__", [](VM* vm, const pkpy::Args& args) {
        bool list = args[0]->is_type(vm->_tp_list);
        const PyVarList& _self = list ? vm->PyList_AS_C(args[0]) : vm->PyTuple_AS_C(args[0]);

        if(args[1]->is_type(vm->_tp_slice)){
            _Slice s = vm->PySlice_AS_C(args[1]);
            s.normalize(_self.size());
            PyVarList _new_list;
            for(size_t i = s.start; i < s.stop; i++) _new_list.push_back(_self[i]);
            return list ? vm->PyList(_new_list) : vm->PyTuple(_new_list);
        }

        int _index = (int)vm->PyInt_AS_C(args[1]);
        _index = vm->normalized_index(_index, _self.size());
        return _self[_index];
    });

    _vm->bindMethod<2>("list", "__setitem__", [](VM* vm, const pkpy::Args& args) {
        PyVarList& _self = vm->PyList_AS_C(args[0]);
        int _index = (int)vm->PyInt_AS_C(args[1]);
        _index = vm->normalized_index(_index, _self.size());
        _self[_index] = args[2];
        return vm->None;
    });

    _vm->bindMethod<1>("list", "__delitem__", [](VM* vm, const pkpy::Args& args) {
        PyVarList& _self = vm->PyList_AS_C(args[0]);
        int _index = (int)vm->PyInt_AS_C(args[1]);
        _index = vm->normalized_index(_index, _self.size());
        _self.erase(_self.begin() + _index);
        return vm->None;
    });

    /************ PyTuple ************/
    _vm->bindStaticMethod<1>("tuple", "__new__", [](VM* vm, const pkpy::Args& args) {
        PyVarList _list = vm->PyList_AS_C(vm->call(vm->builtins->attribs["list"], args));
        return vm->PyTuple(_list);
    });

    _vm->bindMethod<0>("tuple", "__iter__", [](VM* vm, const pkpy::Args& args) {
        return vm->PyIter(pkpy::make_shared<BaseIterator, VectorIterator>(vm, args[0]));
    });

    _vm->bindMethod<0>("tuple", "__len__", [](VM* vm, const pkpy::Args& args) {
        const PyVarList& _self = vm->PyTuple_AS_C(args[0]);
        return vm->PyInt(_self.size());
    });

    /************ PyBool ************/
    _vm->bindStaticMethod<1>("bool", "__new__", CPP_LAMBDA(vm->asBool(args[0])));

    _vm->bindMethod<0>("bool", "__repr__", [](VM* vm, const pkpy::Args& args) {
        bool val = vm->PyBool_AS_C(args[0]);
        return vm->PyStr(val ? "True" : "False");
    });

    _vm->bindMethod<0>("bool", "__json__", [](VM* vm, const pkpy::Args& args) {
        bool val = vm->PyBool_AS_C(args[0]);
        return vm->PyStr(val ? "true" : "false");
    });

    _vm->bindMethod<1>("bool", "__xor__", [](VM* vm, const pkpy::Args& args) {
        bool _self = vm->PyBool_AS_C(args[0]);
        bool _obj = vm->PyBool_AS_C(args[1]);
        return vm->PyBool(_self ^ _obj);
    });

    _vm->bindMethod<0>("ellipsis", "__repr__", CPP_LAMBDA(vm->PyStr("Ellipsis")));
}

#ifdef _WIN32
#define __EXPORT __declspec(dllexport)
#elif __APPLE__
#define __EXPORT __attribute__((visibility("default"))) __attribute__((used))
#elif __EMSCRIPTEN__
#define __EXPORT EMSCRIPTEN_KEEPALIVE
#define __NO_MAIN
#else
#define __EXPORT
#endif


void __add_module_time(VM* vm){
    PyVar mod = vm->new_module("time");
    vm->bindFunc<0>(mod, "time", [](VM* vm, const pkpy::Args& args) {
        auto now = std::chrono::high_resolution_clock::now();
        return vm->PyFloat(std::chrono::duration_cast<std::chrono::microseconds>(now.time_since_epoch()).count() / 1000000.0);
    });
}

void __add_module_sys(VM* vm){
    PyVar mod = vm->new_module("sys");
    vm->bindFunc<1>(mod, "getrefcount", [](VM* vm, const pkpy::Args& args) {
        return vm->PyInt(args[0].use_count());
    });

    vm->bindFunc<0>(mod, "getrecursionlimit", [](VM* vm, const pkpy::Args& args) {
        return vm->PyInt(vm->maxRecursionDepth);
    });

    vm->bindFunc<1>(mod, "setrecursionlimit", [](VM* vm, const pkpy::Args& args) {
        vm->maxRecursionDepth = (int)vm->PyInt_AS_C(args[0]);
        return vm->None;
    });

    vm->setattr(mod, "version", vm->PyStr(PK_VERSION));
}

void __add_module_json(VM* vm){
    PyVar mod = vm->new_module("json");
    vm->bindFunc<1>(mod, "loads", [](VM* vm, const pkpy::Args& args) {
        const _Str& expr = vm->PyStr_AS_C(args[0]);
        _Code code = vm->compile(expr, "<json>", JSON_MODE);
        return vm->_exec(code, vm->top_frame()->_module, vm->top_frame()->_locals);
    });

    vm->bindFunc<1>(mod, "dumps", CPP_LAMBDA(vm->call(args[0], __json__)));
}

void __add_module_math(VM* vm){
    PyVar mod = vm->new_module("math");
    vm->setattr(mod, "pi", vm->PyFloat(3.1415926535897932384));
    vm->setattr(mod, "e" , vm->PyFloat(2.7182818284590452354));

    vm->bindFunc<1>(mod, "log", CPP_LAMBDA(vm->PyFloat(log(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "log10", CPP_LAMBDA(vm->PyFloat(log10(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "log2", CPP_LAMBDA(vm->PyFloat(log2(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "sin", CPP_LAMBDA(vm->PyFloat(sin(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "cos", CPP_LAMBDA(vm->PyFloat(cos(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "tan", CPP_LAMBDA(vm->PyFloat(tan(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "isnan", CPP_LAMBDA(vm->PyBool(std::isnan(vm->num_to_float(args[0])))));
    vm->bindFunc<1>(mod, "isinf", CPP_LAMBDA(vm->PyBool(std::isinf(vm->num_to_float(args[0])))));
}

void __add_module_dis(VM* vm){
    PyVar mod = vm->new_module("dis");
    vm->bindFunc<1>(mod, "dis", [](VM* vm, const pkpy::Args& args) {
        _Code code = vm->PyFunction_AS_C(args[0])->code;
        (*vm->_stdout) << vm->disassemble(code);
        return vm->None;
    });
}

#define PY_CLASS(mod, name) inline static PyVar _tp(VM* vm) { return vm->_modules[#mod]->attribs[#name]; }

struct ReMatch {
    PY_CLASS(re, Match)

    i64 start;
    i64 end;
    std::smatch m;
    ReMatch(i64 start, i64 end, std::smatch m) : start(start), end(end), m(m) {}

    static PyVar _bind(VM* vm){
        PyVar _tp_match = vm->new_user_type_object(vm->_modules["re"], "Match", vm->_tp_object);
        vm->bindMethod<0>(_tp_match, "start", CPP_LAMBDA(vm->PyInt(OBJ_GET(ReMatch, args[0]).start)));
        vm->bindMethod<0>(_tp_match, "end", CPP_LAMBDA(vm->PyInt(OBJ_GET(ReMatch, args[0]).end)));

        vm->bindMethod<0>(_tp_match, "span", [](VM* vm, const pkpy::Args& args) {
            auto& m = OBJ_GET(ReMatch, args[0]);
            return vm->PyTuple({ vm->PyInt(m.start), vm->PyInt(m.end) });
        });

        vm->bindMethod<1>(_tp_match, "group", [](VM* vm, const pkpy::Args& args) {
            auto& m = OBJ_GET(ReMatch, args[0]);
            int index = (int)vm->PyInt_AS_C(args[1]);
            index = vm->normalized_index(index, m.m.size());
            return vm->PyStr(m.m[index].str());
        });
        return _tp_match;
    }
};

PyVar __regex_search(const _Str& pattern, const _Str& string, bool fromStart, VM* vm){
    std::regex re(pattern);
    std::smatch m;
    if(std::regex_search(string, m, re)){
        if(fromStart && m.position() != 0) return vm->None;
        i64 start = string.__to_u8_index(m.position());
        i64 end = string.__to_u8_index(m.position() + m.length());
        return vm->new_object_c<ReMatch>(start, end, m);
    }
    return vm->None;
};

void __add_module_re(VM* vm){
    PyVar mod = vm->new_module("re");
    ReMatch::_bind(vm);

    vm->bindFunc<2>(mod, "match", [](VM* vm, const pkpy::Args& args) {
        const _Str& pattern = vm->PyStr_AS_C(args[0]);
        const _Str& string = vm->PyStr_AS_C(args[1]);
        return __regex_search(pattern, string, true, vm);
    });

    vm->bindFunc<2>(mod, "search", [](VM* vm, const pkpy::Args& args) {
        const _Str& pattern = vm->PyStr_AS_C(args[0]);
        const _Str& string = vm->PyStr_AS_C(args[1]);
        return __regex_search(pattern, string, false, vm);
    });

    vm->bindFunc<3>(mod, "sub", [](VM* vm, const pkpy::Args& args) {
        const _Str& pattern = vm->PyStr_AS_C(args[0]);
        const _Str& repl = vm->PyStr_AS_C(args[1]);
        const _Str& string = vm->PyStr_AS_C(args[2]);
        std::regex re(pattern);
        return vm->PyStr(std::regex_replace(string, re, repl));
    });

    vm->bindFunc<2>(mod, "split", [](VM* vm, const pkpy::Args& args) {
        const _Str& pattern = vm->PyStr_AS_C(args[0]);
        const _Str& string = vm->PyStr_AS_C(args[1]);
        std::regex re(pattern);
        std::sregex_token_iterator it(string.begin(), string.end(), re, -1);
        std::sregex_token_iterator end;
        PyVarList vec;
        for(; it != end; ++it){
            vec.push_back(vm->PyStr(it->str()));
        }
        return vm->PyList(vec);
    });
}

class _PkExported{
public:
    virtual ~_PkExported() = default;
    virtual void* get() = 0;
};

static std::vector<_PkExported*> _pkLookupTable;

template<typename T>
class PkExported : public _PkExported{
    T* _ptr;
public:
    template<typename... Args>
    PkExported(Args&&... args) {
        _ptr = new T(std::forward<Args>(args)...);
        _pkLookupTable.push_back(this);
    }
    
    ~PkExported() override { delete _ptr; }
    void* get() override { return _ptr; }
    operator T*() { return _ptr; }
};

#define pkpy_allocate(T, ...) *(new PkExported<T>(__VA_ARGS__))


extern "C" {
    __EXPORT
    /// Delete a pointer allocated by `pkpy_xxx_xxx`.
    /// It can be `VM*`, `REPL*`, `char*`, etc.
    /// 
    /// !!!
    /// If the pointer is not allocated by `pkpy_xxx_xxx`, the behavior is undefined.
    /// !!!
    void pkpy_delete(void* p){
        for(int i = 0; i < _pkLookupTable.size(); i++){
            if(_pkLookupTable[i]->get() == p){
                delete _pkLookupTable[i];
                _pkLookupTable.erase(_pkLookupTable.begin() + i);
                return;
            }
        }
        free(p);
    }

    __EXPORT
    /// Run a given source on a virtual machine.
    void pkpy_vm_exec(VM* vm, const char* source){
        vm->exec(source, "main.py", EXEC_MODE);
    }

    __EXPORT
    /// Get a global variable of a virtual machine.
    /// 
    /// Return `__repr__` of the result.
    /// If the variable is not found, return `nullptr`.
    char* pkpy_vm_get_global(VM* vm, const char* name){
        auto it = vm->_main->attribs.find(name);
        if(it == vm->_main->attribs.end()) return nullptr;
        try{
            _Str _repr = vm->PyStr_AS_C(vm->asRepr(it->second));
            return strdup(_repr.c_str());
        }catch(...){
            return nullptr;
        }
    }

    __EXPORT
    /// Evaluate an expression.
    /// 
    /// Return `__repr__` of the result.
    /// If there is any error, return `nullptr`.
    char* pkpy_vm_eval(VM* vm, const char* source){
        PyVarOrNull ret = vm->exec(source, "<eval>", EVAL_MODE);
        if(ret == nullptr) return nullptr;
        try{
            _Str _repr = vm->PyStr_AS_C(vm->asRepr(ret));
            return strdup(_repr.c_str());
        }catch(...){
            return nullptr;
        }
    }

    __EXPORT
    /// Create a REPL, using the given virtual machine as the backend.
    REPL* pkpy_new_repl(VM* vm){
        return pkpy_allocate(REPL, vm);
    }

    __EXPORT
    /// Input a source line to an interactive console. Return true if need more lines.
    bool pkpy_repl_input(REPL* r, const char* line){
        return r->input(line);
    }

    __EXPORT
    /// Add a source module into a virtual machine.
    void pkpy_vm_add_module(VM* vm, const char* name, const char* source){
        vm->_lazy_modules[name] = source;
    }

    __EXPORT
    /// Create a virtual machine.
    VM* pkpy_new_vm(bool use_stdio){
        VM* vm = pkpy_allocate(VM, use_stdio);
        __initializeBuiltinFunctions(vm);
        __add_module_sys(vm);
        __add_module_time(vm);
        __add_module_json(vm);
        __add_module_math(vm);
        __add_module_re(vm);
        __add_module_dis(vm);

        // add builtins | no exception handler | must succeed
        _Code code = vm->compile(__BUILTINS_CODE, "<builtins>", EXEC_MODE);
        vm->_exec(code, vm->builtins, pkpy::make_shared<PyVarDict>());

        pkpy_vm_add_module(vm, "random", __RANDOM_CODE);
        return vm;
    }

    __EXPORT
    /// Read the standard output and standard error as string of a virtual machine.
    /// The `vm->use_stdio` should be `false`.
    /// After this operation, both stream will be cleared.
    ///
    /// Return a json representing the result.
    char* pkpy_vm_read_output(VM* vm){
        if(vm->use_stdio) return nullptr;
        _StrStream* s_out = (_StrStream*)(vm->_stdout);
        _StrStream* s_err = (_StrStream*)(vm->_stderr);
        _Str _stdout = s_out->str();
        _Str _stderr = s_err->str();
        _StrStream ss;
        ss << '{' << "\"stdout\": " << _stdout.__escape(false);
        ss << ", " << "\"stderr\": " << _stderr.__escape(false) << '}';
        s_out->str(""); s_err->str("");
        return strdup(ss.str().c_str());
    }

    typedef i64 (*f_int_t)(char*);
    typedef f64 (*f_float_t)(char*);
    typedef bool (*f_bool_t)(char*);
    typedef char* (*f_str_t)(char*);
    typedef void (*f_None_t)(char*);

    static f_int_t f_int = nullptr;
    static f_float_t f_float = nullptr;
    static f_bool_t f_bool = nullptr;
    static f_str_t f_str = nullptr;
    static f_None_t f_None = nullptr;

    __EXPORT
    /// Setup the callback functions.
    void pkpy_setup_callbacks(f_int_t f_int, f_float_t f_float, f_bool_t f_bool, f_str_t f_str, f_None_t f_None){
        ::f_int = f_int;
        ::f_float = f_float;
        ::f_bool = f_bool;
        ::f_str = f_str;
        ::f_None = f_None;
    }

    __EXPORT
    /// Bind a function to a virtual machine.
    char* pkpy_vm_bind(VM* vm, const char* mod, const char* name, int ret_code){
        if(!f_int || !f_float || !f_bool || !f_str || !f_None) return nullptr;
        static int kGlobalBindId = 0;
        for(int i=0; mod[i]; i++) if(mod[i] == ' ') return nullptr;
        for(int i=0; name[i]; i++) if(name[i] == ' ') return nullptr;
        std::string f_header = std::string(mod) + '.' + name + '#' + std::to_string(kGlobalBindId++);
        PyVar obj = vm->new_module_if_not_existed(mod);
        vm->bindFunc<-1>(obj, name, [ret_code, f_header](VM* vm, const pkpy::Args& args){
            _StrStream ss;
            ss << f_header;
            for(int i=0; i<args.size(); i++){
                ss << ' ';
                PyVar x = vm->call(args[i], __json__);
                ss << vm->PyStr_AS_C(x);
            }
            char* packet = strdup(ss.str().c_str());
            switch(ret_code){
                case 'i': return vm->PyInt(f_int(packet));
                case 'f': return vm->PyFloat(f_float(packet));
                case 'b': return vm->PyBool(f_bool(packet));
                case 's': {
                    char* p = f_str(packet);
                    if(p == nullptr) return vm->None;
                    return vm->PyStr(p); // no need to free(p)
                }
                case 'N': f_None(packet); return vm->None;
            }
            free(packet);
            UNREACHABLE();
            return vm->None;
        });
        return strdup(f_header.c_str());
    }
}

#endif // POCKETPY_H