reimpl `goto`

docs/features/goto.md

@@ -3,13 +3,18 @@ icon: dot
 title: Goto Statement
 ---
 
-pkpy supports `goto` and `label` just like C. You are allowed to change the control flow unconditionally.
+pkpy supports goto/label just like C. You are allowed to **change the control flow unconditionally**.
 
-## Syntax
+## Define a label
 
 ```
-$goto <identifier>
-$label <identifier>
+== <identifier> ==
+```
+
+## Goto a label
+
+```
+-> <identifier>
 ```
 
 ## Example
@@ -18,7 +23,8 @@ $label <identifier>
 for i in range(10):
   for j in range(10):
     for k in range(10):
-      $goto exit
+      -> exit
 
-$label exit
+== exit ==
+print('exit')
 ```

include/pocketpy/lexer.h

@@ -22,8 +22,6 @@ constexpr const char* kTokens[] = {
     ".", ",", ":", ";", "#", "(", ")", "[", "]", "{", "}",
     "**", "=", ">", "<", "..", "...", "->", "?", "@", "==", "!=", ">=", "<=",
     "++", "--", "~",
-    /** SPEC_BEGIN **/
-    "$goto", "$label",
     /** KW_BEGIN **/
     "class", "import", "as", "def", "lambda", "pass", "del", "from", "with", "yield",
     "None", "in", "is", "and", "or", "not", "True", "False", "global", "try", "except", "finally",

src/compiler.cpp

@@ -844,16 +844,17 @@ __EAT_DOTS_END:
                 ctx()->emit(OP_WITH_EXIT, BC_NOARG, prev().line);
             } break;
             /*************************************************/
-            case TK("$label"): {
-                if(mode()!=EXEC_MODE) SyntaxError("'label' is only available in EXEC_MODE");
+            case TK("=="): {
                 consume(TK("@id"));
+                if(mode()!=EXEC_MODE) SyntaxError("'label' is only available in EXEC_MODE");
                 bool ok = ctx()->add_label(prev().str());
+                consume(TK("=="));
                 if(!ok) SyntaxError("label " + prev().str().escape() + " already exists");
                 consume_end_stmt();
             } break;
-            case TK("$goto"):
-                if(mode()!=EXEC_MODE) SyntaxError("'goto' is only available in EXEC_MODE");
+            case TK("->"):
                 consume(TK("@id"));
+                if(mode()!=EXEC_MODE) SyntaxError("'goto' is only available in EXEC_MODE");
                 ctx()->emit(OP_GOTO, StrName(prev().str()).index, prev().line);
                 consume_end_stmt();
                 break;

src/lexer.cpp

@@ -325,16 +325,6 @@ static bool is_unicode_Lo_char(uint32_t c) {
                     eat_spaces();
                     return true;
                 }
-                case '$': {
-                    for(int i=TK("$goto"); i<=TK("$label"); i++){
-                        // +1 to skip the '$'
-                        if(match_string(TK_STR(i) + 1)){
-                            add_token((TokenIndex)i);
-                            return true;
-                        }
-                    }
-                    SyntaxError("invalid special token");
-                } return false;
                 case '%': add_token_2('=', TK("%"), TK("%=")); return true;
                 case '&': add_token_2('=', TK("&"), TK("&=")); return true;
                 case '|': add_token_2('=', TK("|"), TK("|=")); return true;

tests/27_goto.py

@@ -2,9 +2,9 @@ a = []
 
 for i in range(10):         # [0]
     for j in range(10):     # [0-0]
-        $goto test 
+        -> test
         print(2)
-    $label test
+    == test ==
     a.append(i)
     for k in range(5):      # [0-1]
         for t in range(7):  # [0-1-0]
@@ -16,7 +16,7 @@ b = False
 
 for i in range(10):         # [1]
     for j in range(10):     # [1-0]
-        $goto out
+        -> out
         b = True
-$label out
+== out ==
 assert not b