feat: improve RenPy conversion and support MIST runtime

backend/app/converter/pyexpr.py

@@ -25,7 +25,7 @@ UNARY_OPS = {ast.Not: "not", ast.USub: "-", ast.UAdd: "+", ast.Invert: "~"}
 
 # Modules whose import is harmless: the player provides the functions it supports.
 KNOWN_MODULES = {"random", "math", "renpy", "store", "time", "datetime", "re", "copy", "collections",
-                 "itertools", "string", "functools", "operator", "json"}
+                 "itertools", "string", "functools", "operator", "json", "gc"}
 
 
 class Unsupported(Exception):
@@ -36,25 +36,67 @@ def const(v: Any) -> Expr:
     return {"k": "const", "v": v}
 
 
+def python2_operators(source: str) -> str:
+    """Ren'Py 7 games are Python 2: `a <> b` means `a != b`. Quoted text is left alone."""
+    out: list[str] = []
+    quote = ""
+    i = 0
+    while i < len(source):
+        ch = source[i]
+        if quote:
+            out.append(ch)
+            if ch == "\\" and i + 1 < len(source):
+                out.append(source[i + 1])
+                i += 1
+            elif ch == quote:
+                quote = ""
+        elif ch in "\"'":
+            quote = ch
+            out.append(ch)
+        elif source.startswith("<>", i):
+            out.append("!=")
+            i += 1
+        else:
+            out.append(ch)
+        i += 1
+    return "".join(out)
+
+
 def parse_expr(source: str) -> Expr:
     try:
         tree = ast.parse(source.strip(), mode="eval")
     except SyntaxError as e:
-        raise Unsupported(f"синтаксическая ошибка в выражении: {source!r}") from e
+        try:
+            tree = ast.parse(python2_operators(source).strip(), mode="eval")
+        except SyntaxError:
+            raise Unsupported(f"синтаксическая ошибка в выражении: {source!r}") from e
     return expr(tree.body)
 
 
 def parse_stmts(source: str) -> list[Stmt]:
     try:
-        tree = ast.parse(_dedent(source))
+        tree = python_ast(source)
     except SyntaxError as e:
-        raise Unsupported(f"синтаксическая ошибка в python: {e.msg} ({source[:60]!r})") from e
+        try:
+            tree = python_ast(python2_operators(source))
+        except SyntaxError:
+            raise Unsupported(f"синтаксическая ошибка в python: {e.msg} ({source[:60]!r})") from e
     return stmts(tree.body)
 
 
-def _dedent(source: str) -> str:
-    import textwrap
-    return textwrap.dedent(source)
+def python_ast(source: str, mode: str = "exec") -> ast.AST:
+    """Parse an embedded block as Ren'Py does, preserving string contents/columns.
+
+    Physical continuation lines may start at column zero. Wrapping the indented
+    code avoids dedenting those lines or changing whitespace inside literals.
+    """
+    first = next((line for line in source.splitlines() if line.strip()), "")
+    indented = mode == "exec" and first.startswith((" ", "\t"))
+    tree = ast.parse("if True:\n" + source if indented else source, mode=mode)
+    if indented:
+        tree.body = tree.body[0].body
+        ast.increment_lineno(tree, -1)
+    return tree
 
 
 def literal(source: str) -> Any:
@@ -164,6 +206,8 @@ def stmt(node: ast.stmt) -> list[Stmt]:
             if type(op) not in BIN_OPS:
                 raise Unsupported(f"оператор {type(op).__name__}")
             return [{"op": "aug", "t": target(t), "o": BIN_OPS[type(op)], "v": expr(value)}]
+        case ast.Expr(value=ast.Call(func=func)) if ast.unparse(func).startswith("build."):
+            return []  # distribution settings (build.classify, build.archive ...) have no meaning in the browser
         case ast.Expr(value=ast.Constant()):
             return []  # docstring / bare literal
         case ast.Expr(value=value):
@@ -220,7 +264,7 @@ def stmt(node: ast.stmt) -> list[Stmt]:
 
 # Methods the player can run implicitly. Any other dunder method would silently
 # never be called, so the converter refuses it instead.
-SUPPORTED_DUNDERS = {"__init__", "__str__", "__repr__"}
+SUPPORTED_DUNDERS = {"__init__", "__str__", "__repr__", "__call__", "__eq__"}
 INACTIVE_VARIANTS = {"gui.variant", "renpy.variant"}
 TRANSPARENT_DECORATORS = {"renpy.pure"}  # marks a function as side-effect free; no runtime meaning
 DECORATORS = {"staticmethod", "classmethod", "property"}