pocketpy/include/pocketpy/bindings.h

#pragma once

#include "cffi.h"
#include "vm.h"

namespace pkpy{
struct NativeProxyFuncCBase {
    virtual PyVar operator()(VM* vm, ArgsView args) = 0;
};

template<typename Ret, typename... Params>
struct NativeProxyFuncC final: NativeProxyFuncCBase {
    static constexpr int N = sizeof...(Params);
    using _Fp = Ret(*)(Params...);
    _Fp func;
    NativeProxyFuncC(_Fp func) : func(func) {}

    PyVar operator()(VM* vm, ArgsView args) override {
        PK_DEBUG_ASSERT(args.size() == N);
        return call<Ret>(vm, args, std::make_index_sequence<N>());
    }

    template<typename __Ret, size_t... Is>
    PyVar call(VM* vm, ArgsView args, std::index_sequence<Is...>){
        if constexpr(std::is_void_v<__Ret>){
            func(py_cast<Params>(vm, args[Is])...);
            return vm->None;
        }else{
            __Ret ret = func(py_cast<Params>(vm, args[Is])...);
            return VAR(std::move(ret));
        }
    }
};

template<typename Ret, typename T, typename... Params>
struct NativeProxyMethodC final: NativeProxyFuncCBase {
    static constexpr int N = sizeof...(Params);
    using _Fp = Ret(T::*)(Params...);
    _Fp func;
    NativeProxyMethodC(_Fp func) : func(func) {}

    PyVar operator()(VM* vm, ArgsView args) override {
        PK_DEBUG_ASSERT(args.size() == N+1);
        return call<Ret>(vm, args, std::make_index_sequence<N>());
    }

    template<typename __Ret, size_t... Is>
    PyVar call(VM* vm, ArgsView args, std::index_sequence<Is...>){
        obj_get_t<T> self = PK_OBJ_GET(T, args[0]);   // use unsafe cast for derived classes
        if constexpr(std::is_void_v<__Ret>){
            (self.*func)(py_cast<Params>(vm, args[Is+1])...);
            return vm->None;
        }else{
            __Ret ret = (self.*func)(py_cast<Params>(vm, args[Is+1])...);
            return VAR(std::move(ret));
        }
    }
};
/*****************************************************************/
inline PyVar __proxy_wrapper(VM* vm, ArgsView args){
    NativeProxyFuncCBase* pf = lambda_get_userdata<NativeProxyFuncCBase*>(args.begin());
    return (*pf)(vm, args);
}

template<typename Ret, typename... Params>
PyObject* VM::bind(PyObject* obj, const char* sig, Ret(*func)(Params...), BindType bt){
    NativeProxyFuncCBase* proxy = new NativeProxyFuncC<Ret, Params...>(func);
    return vm->bind(obj, sig, __proxy_wrapper, proxy, bt);
}

template<typename Ret, typename T, typename... Params>
PyObject* VM::bind(PyObject* obj, const char* sig, Ret(T::*func)(Params...), BindType bt){
    NativeProxyFuncCBase* proxy = new NativeProxyMethodC<Ret, T, Params...>(func);
    return vm->bind(obj, sig, __proxy_wrapper, proxy, bt);
}

template<typename Ret, typename... Params>
PyObject* VM::bind(PyObject* obj, const char* sig, const char* docstring, Ret(*func)(Params...), BindType bt){
    NativeProxyFuncCBase* proxy = new NativeProxyFuncC<Ret, Params...>(func);
    return vm->bind(obj, sig, docstring, __proxy_wrapper, proxy, bt);
}

template<typename Ret, typename T, typename... Params>
PyObject* VM::bind(PyObject* obj, const char* sig, const char* docstring, Ret(T::*func)(Params...), BindType bt){
    NativeProxyFuncCBase* proxy = new NativeProxyMethodC<Ret, T, Params...>(func);
    return vm->bind(obj, sig, docstring, __proxy_wrapper, proxy, bt);
}

template<typename T, typename F, bool ReadOnly>
PyObject* VM::bind_field(PyObject* obj, const char* name, F T::*field){
    static_assert(!std::is_reference_v<F>);
    PK_ASSERT(is_type(obj, tp_type));
    std::string_view name_sv(name); int pos = name_sv.find(':');
    if(pos > 0) name_sv = name_sv.substr(0, pos);
    auto fget = [](VM* vm, ArgsView args) -> PyVar{
        obj_get_t<T> self = PK_OBJ_GET(T, args[0]);
        F T::*field = lambda_get_userdata<F T::*>(args.begin());
        return VAR(self.*field);
    };
    PyVar _0 = new_object<NativeFunc>(tp_native_func, fget, 1, field);
    PyVar _1 = vm->None;
    if constexpr (!ReadOnly){
        auto fset = [](VM* vm, ArgsView args){
            obj_get_t<T> self = PK_OBJ_GET(T, args[0]);
            F T::*field = lambda_get_userdata<F T::*>(args.begin());
            self.*field = py_cast<F>(vm, args[1]);
            return vm->None;
        };
        _1 = new_object<NativeFunc>(tp_native_func, fset, 2, field);
    }
    PyObject* prop = heap.gcnew<Property>(tp_property, _0, _1);
    obj->attr().set(StrName(name_sv), prop);
    return prop;
}

/*****************************************************************/

#define PY_FIELD(T, NAME, EXPR)                     \
        vm->bind_property(type, NAME,               \
            [](VM* vm, ArgsView args){              \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                return VAR(self.EXPR);              \
            },                                      \
            [](VM* vm, ArgsView args){              \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                self.EXPR = CAST(decltype(self.EXPR), args[1]);                     \
                return vm->None;                                                    \
            });

#define PY_READONLY_FIELD(T, NAME, EXPR)                    \
        vm->bind_property(type, NAME,                       \
            [](VM* vm, ArgsView args){                      \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                return VAR(self.EXPR);                      \
            });

#define PY_PROPERTY(T, NAME, FGET, FSET)                    \
        vm->bind_property(type, NAME,                       \
            [](VM* vm, ArgsView args){                      \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                return VAR(self.FGET());                    \
            },                                              \
            [](VM* vm, ArgsView args){                      \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                using __NT = decltype(self.FGET());         \
                self.FSET(CAST(__NT, args[1]));             \
                return vm->None;                            \
            });

#define PY_READONLY_PROPERTY(T, NAME, FGET)                 \
        vm->bind_property(type, NAME,                       \
            [](VM* vm, ArgsView args){                      \
                obj_get_t<T> self = PK_OBJ_GET(T, args[0]); \
                return VAR(self.FGET());                    \
            });
/*****************************************************************/
#define PY_STRUCT_LIKE(wT)   \
        static_assert(std::is_trivially_copyable<wT>::value);                       \
        static_assert(!is_sso_v<wT>);                                               \
        type->attr().set("__struct__", vm->True);                                   \
        vm->bind_func(type, "fromstruct", 1, [](VM* vm, ArgsView args){             \
            Struct& s = CAST(Struct&, args[0]);                                     \
            if(s.size != sizeof(wT)) vm->ValueError("size mismatch");               \
            PyVar obj = vm->new_user_object<wT>();                                  \
            memcpy(&_CAST(wT&, obj), s.p, sizeof(wT));                              \
            return obj;                                                             \
        }, {}, BindType::STATICMETHOD);                                             \
        vm->bind_func(type, "tostruct", 1, [](VM* vm, ArgsView args){               \
            wT& self = _CAST(wT&, args[0]);                                         \
            return vm->new_user_object<Struct>(&self, sizeof(wT));                  \
        });                                                                         \
        vm->bind_func(type, "addr", 1, [](VM* vm, ArgsView args){                   \
            wT& self = _CAST(wT&, args[0]);                                         \
            return vm->new_user_object<VoidP>(&self);                               \
        });                                                                         \
        vm->bind_func(type, "copy", 1, [](VM* vm, ArgsView args){                   \
            wT& self = _CAST(wT&, args[0]);                                         \
            return vm->new_user_object<wT>(self);                                   \
        });                                                                         \
        vm->bind_func(type, "sizeof", 1, [](VM* vm, ArgsView args){                 \
            return VAR(sizeof(wT));                                                 \
        });                                                                         \
        vm->bind__eq__(type->as<Type>(), [](VM* vm, PyVar _0, PyVar _1){      \
            wT& self = _CAST(wT&, _0);                                              \
            if(!vm->isinstance(_1, vm->_tp_user<wT>())) return vm->NotImplemented;  \
            wT& other = _CAST(wT&, _1);                                             \
            return VAR(self == other);                                              \
        });                                                                         \

#define PY_POINTER_SETGETITEM(T) \
        vm->bind__getitem__(type->as<Type>(), [](VM* vm, PyVar _0, PyVar _1){     \
            obj_get_t<VoidP> self = PK_OBJ_GET(VoidP, _0);                                        \
            i64 i = CAST(i64, _1);                                                      \
            T* tgt = reinterpret_cast<T*>(self.ptr);                                    \
            return VAR(tgt[i]);                                                         \
        });                                                                             \
        vm->bind__setitem__(type->as<Type>(), [](VM* vm, PyVar _0, PyVar _1, PyVar _2){   \
            obj_get_t<VoidP> self = PK_OBJ_GET(VoidP, _0);                                                \
            i64 i = CAST(i64, _1);                                                              \
            T* tgt = reinterpret_cast<T*>(self.ptr);                                            \
            tgt[i] = CAST(T, _2);                                                               \
        });                                                                                     \

}   // namespace pkpy