"""vast.parser - Viper/Python 语句级语法分析器

基于 vast.tokenizer + vast.exprparser，实现与 CPython 3.12 ``ast.parse``
结构完全一致的语句解析：

- 简单语句：赋值/增强赋值/带注解赋值/表达式/import/from-import/global/
  nonlocal/del/assert/pass/break/continue/return/raise
- 复合语句：if/while/for/try/with/match/def/class/async def-for-with
- 装饰器、嵌套块（INDENT/DEDENT）、分号分隔、类型注解
- Viper 软关键字 fn/fun/func/function → FunctionDef（并入解析器，无需
  ExpandSoftKeywords 预处理）

产出与 CPython ast 完全一致的节点，含 4 位置属性。
"""
from __future__ import annotations

from lib.vast import Nodes as N
from lib.vast.ExprParser import ExprParserMixin
from lib.vast.Tokenizer import (
    Token, NAME, NUMBER, STRING, FSTRING, OP, NEWLINE, NL, INDENT, DEDENT,
    ENDMARKER, SOFT_KEYWORDS,
)


class Parser(ExprParserMixin):
    """Viper/Python 完整语法分析器。"""

    # ==================================================================
    # 模块级入口
    # ==================================================================
    def ParseModule(self) -> N.Module:
        """解析整个模块：返回 Module(body=..., type_ignores=[])。"""
        body: list[N.stmt] = []
        self._SkipNEWLINE()
        while self._Peek().Type != ENDMARKER:
            stmt: N.stmt = self.ParseStatement()
            body.append(stmt)
            # 分号分隔后续语句（简单语句一行多条）
            while self._AtOp(';'):
                self._Next()
                if self._At(NEWLINE):
                    break
                extra: N.stmt = self.ParseStatement()
                body.append(extra)
            self._SkipNEWLINE()
        module: N.Module = N.Module(body=body, type_ignores=[])
        return module

    # ==================================================================
    # 语句分派
    # ==================================================================
    def ParseStatement(self) -> N.stmt:
        """解析单条语句（含复合语句分派）。"""
        tok: Token = self._Peek()
        if tok.Type == NAME:
            v: str = tok.Value
            # 软关键字函数定义：fn/fun/func/function + 标识符
            if v in SOFT_KEYWORDS and self._Peek(1).Type == NAME:
                return self._ParseFunctionDef()
            if v == 'async':
                nxt: Token = self._Peek(1)
                if nxt.Type == NAME and nxt.Value == 'def':
                    return self._ParseFunctionDef(is_async=True)
                if nxt.Type == NAME and nxt.Value == 'for':
                    return self._ParseFor(is_async=True)
                if nxt.Type == NAME and nxt.Value == 'with':
                    return self._ParseWith(is_async=True)
            if v == 'def':
                return self._ParseFunctionDef()
            if v == 'class':
                return self._ParseClassDef()
            if v == 'if':
                return self._ParseIf()
            if v == 'while':
                return self._ParseWhile()
            if v == 'for':
                return self._ParseFor()
            if v == 'try':
                return self._ParseTry()
            if v == 'with':
                return self._ParseWith()
            if v == 'match':
                # 软关键字 match：尝试 match 语句，失败回退为表达式
                save: int = self.Idx
                try:
                    return self._ParseMatch()
                except SyntaxError:
                    self.Idx = save
            if v == 'return':
                return self._ParseReturn()
            if v == 'raise':
                return self._ParseRaise()
            if v == 'import':
                return self._ParseImport()
            if v == 'from':
                return self._ParseImportFrom()
            if v == 'global':
                return self._ParseGlobal('global')
            if v == 'nonlocal':
                return self._ParseGlobal('nonlocal')
            if v == 'del':
                return self._ParseDelete()
            if v == 'assert':
                return self._ParseAssert()
            if v == 'pass':
                self._Next()
                node: N.Pass = N.Pass()
                self._FixLoc(node, tok)
                return node
            if v == 'break':
                self._Next()
                node = N.Break()
                self._FixLoc(node, tok)
                return node
            if v == 'continue':
                self._Next()
                node = N.Continue()
                self._FixLoc(node, tok)
                return node
            if v == 'yield':
                # yield 作为表达式语句
                return self._ParseExprStmt()
        if tok.Type == OP and tok.Value == '@':
            return self._ParseDecorated()
        return self._ParseSimpleStmt()

    # ==================================================================
    # 简单语句
    # ==================================================================
    def _ParseSimpleStmt(self) -> N.stmt:
        """解析简单语句（赋值/增强赋值/带注解赋值/表达式）。

        不消费分号/NEWLINE，由调用方循环（ParseModule/_ParseSuite）统一处理。
        """
        start: Token = self._Peek()
        # 尝试带注解赋值 x: T [= v]
        ann: N.stmt | None = self._TryParseAnnAssign()
        if ann is not None:
            return ann
        # 表达式/赋值（testlist_star_expr）
        expr: N.expr = self.ParseExprList()
        # 赋值链
        if self._AtOp('='):
            targets: list[N.expr] = [self._AsLoadTarget(expr)]
            while True:
                self._Next()  # '='
                value: N.expr = self.ParseExprList()
                if self._AtOp('='):
                    targets.append(self._AsLoadTarget(value))
                    continue
                break
            node: N.Assign = N.Assign(targets=targets, value=value, type_comment=None)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('+='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Add(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('-='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Sub(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('*='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Mult(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('/='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Div(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('//='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.FloorDiv(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('%='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Mod(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('**='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.Pow(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('<<='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.LShift(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('>>='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.RShift(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('&='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.BitAnd(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('|='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.BitOr(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('^='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.BitXor(), value=value)
            self._FixLoc(node, start)
            stmt = node
        elif self._AtOp('@='):
            self._Next()
            value = self.ParseExpr()
            node = N.AugAssign(target=self._AsLoadTarget(expr), op=N.MatMult(), value=value)
            self._FixLoc(node, start)
            stmt = node
        else:
            node = N.Expr(value=expr)
            self._FixLoc(node, start)
            stmt = node
        return stmt

    def _AsLoadTarget(self, expr: N.expr) -> N.expr:
        """将已解析表达式（Load 上下文）转为赋值目标（Store 上下文）。"""
        self._SetStoreContext(expr)
        return expr

    def _TryParseAnnAssign(self) -> N.AnnAssign | None:
        """尝试解析带注解赋值：x: T [= v] 或 x: T（目标为 Name/Attribute/Subscript）。

        注意：仅当目标为简单 Name/Attribute/Subscript 且后随 ':' 时匹配；
        元组/列表解包不做注解（返回 None 走普通路径）。
        """
        start: Token = self._Peek()
        # 名称
        if self._At(NAME) and self._Peek(1).Type == OP and self._Peek(1).Value == ':':
            name_tok: Token = self._Next()
            self._Next()  # ':'
            annotation: N.expr = self.ParseExpr()
            value: N.expr | None = None
            if self._AtOp('='):
                self._Next()
                value = self.ParseExpr()
            target: N.Name = N.Name(id=name_tok.Value, ctx=N.Store())
            self._FixLoc(target, name_tok)
            node: N.AnnAssign = N.AnnAssign(target=target, annotation=annotation,
                                            value=value, simple=1)
            self._FixLoc(node, start)
            return node
        # 属性/下标目标（无简单解包）
        if self._At(NAME) or (self._At(OP) and self._Peek().Value in ('(', '[')):
            save: int = self.Idx
            try:
                expr: N.expr = self.ParseExpr()
            except SyntaxError:
                self.Idx = save
                return None
            if self._AtOp(':') and isinstance(expr, (N.Name, N.Attribute, N.Subscript)):
                self._Next()
                annotation = self.ParseExpr()
                value = None
                if self._AtOp('='):
                    self._Next()
                    value = self.ParseExpr()
                self._SetStoreContext(expr)
                simple: int = 1 if isinstance(expr, N.Name) else 0
                node = N.AnnAssign(target=expr, annotation=annotation, value=value, simple=simple)
                self._FixLoc(node, start)
                return node
            self.Idx = save
        return None

    # ------------------------------------------------------------------
    # return / raise / import / global / del / assert
    # ------------------------------------------------------------------
    def _ParseReturn(self) -> N.Return:
        start: Token = self._Next()  # 'return'
        value: N.expr | None = None
        if not self._At(NEWLINE) and not self._AtOp(';'):
            value = self.ParseExprList()
        node: N.Return = N.Return(value=value)
        self._FixLoc(node, start)
        return node

    def _ParseRaise(self) -> N.Raise:
        start: Token = self._Next()  # 'raise'
        exc: N.expr | None = None
        cause: N.expr | None = None
        if not self._At(NEWLINE) and not self._AtOp(';'):
            exc = self.ParseExpr()
            if self._AtName('from'):
                self._Next()
                cause = self.ParseExpr()
        node: N.Raise = N.Raise(exc=exc, cause=cause)
        self._FixLoc(node, start)
        return node

    def _ParseImport(self) -> N.Import:
        start: Token = self._Next()  # 'import'
        names: list[N.alias] = []
        while True:
            # 点分模块名：alias 位置从首个名称起、到末个名称（或 asname）止
            name_tok: Token = self._ExpectName()
            end_tok: Token = name_tok
            name_parts: list[str] = [name_tok.Value]
            while self._AtOp('.'):
                self._Next()
                end_tok = self._ExpectName()
                name_parts.append(end_tok.Value)
            full: str = '.'.join(name_parts)
            asname: str | None = None
            if self._AtName('as'):
                self._Next()
                as_tok: Token = self._ExpectName()
                asname = as_tok.Value
                end_tok = as_tok
            alias: N.alias = N.alias(name=full, asname=asname)
            self._FixLoc(alias, name_tok, end_tok)
            names.append(alias)
            if self._AtOp(','):
                self._Next()
                continue
            break
        node: N.Import = N.Import(names=names)
        self._FixLoc(node, start)
        return node

    def _ParseImportFrom(self) -> N.ImportFrom:
        start: Token = self._Next()  # 'from'
        level: int = 0
        while self._AtOp('.'):
            self._Next()
            level += 1
        module: str | None = None
        # from . import x → 点后直接是 import（无模块名）
        if not self._AtName('import'):
            parts: list[str] = [self._ExpectName().Value]
            while self._AtOp('.'):
                self._Next()
                parts.append(self._ExpectName().Value)
            module = '.'.join(parts)
        self._ExpectName('import')
        names: list[N.alias] = []
        # from x import * | (a, b) | a, b
        if self._AtOp('('):
            self._Next()
            self._SkipNL()
            if not self._AtOp(')'):
                while True:
                    names.append(self._ParseImportAlias())
                    self._SkipNL()
                    if self._AtOp(','):
                        self._Next()
                        self._SkipNL()
                        if self._AtOp(')'):
                            break
                        continue
                    break
            self._ExpectOp(')')
        else:
            if self._AtOp('*'):
                star_tok: Token = self._Next()
                alias = N.alias(name='*', asname=None)
                self._FixLoc(alias, star_tok)
                names.append(alias)
            else:
                while True:
                    names.append(self._ParseImportAlias())
                    if self._AtOp(','):
                        self._Next()
                        continue
                    break
        node: N.ImportFrom = N.ImportFrom(module=module, names=names, level=level)
        self._FixLoc(node, start)
        return node

    def _ParseImportAlias(self) -> N.alias:
        """解析单个 import 别名：name [as alias]。

        alias 节点位置与 CPython 一致：起点为首个名称 token，
        终点为 asname（存在时）或名称结束 token。
        """
        name_tok: Token = self._ExpectName()
        asname: str | None = None
        end_tok: Token = name_tok
        if self._AtName('as'):
            self._Next()
            as_tok: Token = self._ExpectName()
            asname = as_tok.Value
            end_tok = as_tok
        alias: N.alias = N.alias(name=name_tok.Value, asname=asname)
        self._FixLoc(alias, name_tok, end_tok)
        return alias

    def _ParseGlobal(self, kw: str) -> N.AST:
        start: Token = self._Next()
        names: list[str] = []
        while True:
            names.append(self._ExpectName().Value)
            if self._AtOp(','):
                self._Next()
                continue
            break
        node: N.AST = N.Global(names=names) if kw == 'global' else N.Nonlocal(names=names)
        self._FixLoc(node, start)
        return node

    def _ParseDelete(self) -> N.Delete:
        start: Token = self._Next()  # 'del'
        targets: list[N.expr] = []
        while True:
            expr: N.expr = self.ParseExpr()
            self._SetDelContext(expr)
            targets.append(expr)
            if self._AtOp(','):
                self._Next()
                continue
            break
        node: N.Delete = N.Delete(targets=targets)
        self._FixLoc(node, start)
        return node

    def _SetDelContext(self, node: N.AST) -> None:
        """将 Load 上下文节点递归改为 Del（del 语句目标）。"""
        if isinstance(node, N.Name):
            node.ctx = N.Del()
        elif isinstance(node, N.Attribute):
            node.ctx = N.Del()
        elif isinstance(node, N.Subscript):
            node.ctx = N.Del()
        elif isinstance(node, (N.Tuple, N.List)):
            node.ctx = N.Del()
            for elt in node.elts:
                self._SetDelContext(elt)

    def _ParseAssert(self) -> N.Assert:
        start: Token = self._Next()  # 'assert'
        test: N.expr = self.ParseExpr()
        msg: N.expr | None = None
        if self._AtOp(','):
            self._Next()
            msg = self.ParseExpr()
        node: N.Assert = N.Assert(test=test, msg=msg)
        self._FixLoc(node, start)
        return node

    def _ConsumeSemicolons(self) -> None:
        """消费语句后的分号（允许空语句 ;;）。"""
        while self._AtOp(';'):
            self._Next()

    # ------------------------------------------------------------------
    # 表达式语句（含 yield）
    # ------------------------------------------------------------------
    def _ParseExprStmt(self) -> N.stmt:
        start: Token = self._Peek()
        # yield 语句：yield [expr_list]
        if self._AtName('yield'):
            expr: N.expr = self._ParseYield()
        else:
            expr = self.ParseExprList()
        node: N.Expr = N.Expr(value=expr)
        self._FixLoc(node, start)
        return node

    # ==================================================================
    # 装饰器
    # ==================================================================
    def _ParseDecorated(self) -> N.stmt:
        """解析装饰器列表 + def/class。"""
        decorator_list: list[N.expr] = []
        while self._AtOp('@'):
            deco_start: Token = self._Next()  # '@'
            deco: N.expr = self.ParseExpr()
            self._FixLoc(deco, deco_start)
            decorator_list.append(deco)
            self._ExpectNEWLINE()
            self._SkipNEWLINE()
        tok: Token = self._Peek()
        if tok.Type == NAME and tok.Value == 'def':
            return self._ParseFunctionDef(decorators=decorator_list)
        if tok.Type == NAME and tok.Value == 'async':
            nxt: Token = self._Peek(1)
            if nxt.Type == NAME and nxt.Value == 'def':
                return self._ParseFunctionDef(is_async=True, decorators=decorator_list)
        if tok.Type == NAME and tok.Value == 'class':
            return self._ParseClassDef(decorators=decorator_list)
        raise SyntaxError(f"decorator must be followed by def/class, got {tok.Value!r}")

    # ==================================================================
    # 函数定义（含软关键字 fn/fun/func/function）
    # ==================================================================
    def _ParseFunctionDef(self, is_async: bool = False,
                          decorators: list[N.expr] | None = None) -> N.FunctionDef:
        start: Token = self._Next()  # def/fn/...（或 async）
        if start.Value == 'async':
            start = self._Next()  # def
        name_tok: Token = self._ExpectName()
        # 类型参数（PEP 695）：def f[T](
        type_params: list[N.AST] = []
        if self._AtOp('['):
            type_params = self._ParseTypeParams()
        args: N.arguments = self._ParseArguments()
        returns: N.expr | None = None
        if self._AtOp('->'):
            self._Next()
            returns = self.ParseExpr()
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        cls: type = N.AsyncFunctionDef if is_async else N.FunctionDef
        node: N.FunctionDef = cls(
            name=name_tok.Value, args=args, body=body,
            decorator_list=decorators or [], returns=returns,
            type_comment=None, type_params=type_params,
        )
        self._FixLoc(node, start)
        return node

    def _ParseTypeParams(self) -> list[N.AST]:
        """解析 PEP 695 类型参数：[T, *Ts, **P, U: Bound]"""
        self._ExpectOp('[')
        self._SkipNL()
        params: list[N.AST] = []
        if not self._AtOp(']'):
            while True:
                self._SkipNL()
                star: int = 0
                if self._AtOp('*'):
                    self._Next()
                    star = 1
                elif self._AtOp('**'):
                    self._Next()
                    star = 2
                name_tok: Token = self._ExpectName()
                bound: N.expr | None = None
                if star == 0 and self._AtOp(':'):
                    self._Next()
                    bound = self.ParseExpr()
                if star == 1:
                    tvt: N.TypeVarTuple = N.TypeVarTuple(name=name_tok.Value)
                    self._FixLoc(tvt, name_tok)
                    params.append(tvt)
                elif star == 2:
                    ps: N.ParamSpec = N.ParamSpec(name=name_tok.Value)
                    self._FixLoc(ps, name_tok)
                    params.append(ps)
                else:
                    tv: N.TypeVar = N.TypeVar(name=name_tok.Value, bound=bound)
                    self._FixLoc(tv, name_tok)
                    params.append(tv)
                self._SkipNL()
                if self._AtOp(','):
                    self._Next()
                    continue
                break
        self._ExpectOp(']')
        return params

    # ==================================================================
    # 类定义
    # ==================================================================
    def _ParseClassDef(self, decorators: list[N.expr] | None = None) -> N.ClassDef:
        start: Token = self._Next()  # class
        name_tok: Token = self._ExpectName()
        type_params: list[N.AST] = []
        if self._AtOp('['):
            type_params = self._ParseTypeParams()
        bases: list[N.expr] = []
        keywords: list[N.keyword] = []
        if self._AtOp('('):
            self._Next()
            self._SkipNL()
            if not self._AtOp(')'):
                while True:
                    self._SkipNL()
                    if self._AtOp('**'):
                        self._Next()
                        value: N.expr = self.ParseExpr()
                        kw: N.keyword = N.keyword(arg=None, value=value)
                        self._FixLoc(kw, self._Prev())
                        keywords.append(kw)
                    elif self._At(NAME) and self._Peek(1).Type == OP and self._Peek(1).Value == '=':
                        arg_tok: Token = self._Next()
                        self._Next()  # '='
                        value = self.ParseExpr()
                        kw = N.keyword(arg=arg_tok.Value, value=value)
                        self._FixLoc(kw, arg_tok)
                        keywords.append(kw)
                    else:
                        bases.append(self.ParseExpr())
                    self._SkipNL()
                    if self._AtOp(','):
                        self._Next()
                        self._SkipNL()
                        if self._AtOp(')'):
                            break
                        continue
                    break
            self._ExpectOp(')')
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        node: N.ClassDef = N.ClassDef(
            name=name_tok.Value, bases=bases, keywords=keywords, body=body,
            decorator_list=decorators or [], type_params=type_params,
        )
        self._FixLoc(node, start)
        return node

    # ==================================================================
    # 语句块（套件）
    # ==================================================================
    def _ParseSuite(self) -> list[N.stmt]:
        """解析语句块：':' NEWLINE INDENT ... DEDENT 或单行简单语句。

        块首允许出现空行/注释行（NL），跳过后再检测 INDENT。
        """
        # 已消费 ':' 后的情况：检查是否换行
        if self._At(NEWLINE):
            self._Next()
            # 跳过空行/注释行
            while self._At(NL):
                self._Next()
            if self._At(INDENT):
                self._Next()
                body: list[N.stmt] = []
                self._SkipNEWLINE()
                while self._Peek().Type != DEDENT and self._Peek().Type != ENDMARKER:
                    stmt: N.stmt = self.ParseStatement()
                    body.append(stmt)
                    # 分号分隔后续语句
                    while self._AtOp(';'):
                        self._Next()
                        if self._At(NEWLINE):
                            break
                        extra: N.stmt = self.ParseStatement()
                        body.append(extra)
                    self._SkipNEWLINE()
                self._Expect(DEDENT)
                return body
            # 空套件（语法错误，宽松返回空）
            return []
        # 单行套件：statement (; statement)* NEWLINE
        body = [self.ParseStatement()]
        while self._AtOp(';'):
            self._Next()
            if self._At(NEWLINE):
                break
            body.append(self.ParseStatement())
        self._ExpectNEWLINE()
        return body

    def _Expect(self, tok_type: str, value: str | None = None) -> Token:
        """期望指定类型的 token。"""
        tok: Token = self._Next()
        if tok.Type != tok_type or (value is not None and tok.Value != value):
            raise SyntaxError(
                f"expected {tok_type}({value!r}), got {tok.Type}({tok.Value!r}) "
                f"at line {tok.Line}"
            )
        return tok

    def _ConsumeNewlines(self) -> None:
        """消费连续 NEWLINE（空行）。"""
        while self._At(NEWLINE):
            self._Next()

    # ==================================================================
    # if / while / for / try / with / match
    # ==================================================================
    def _ParseIf(self) -> N.If:
        start: Token = self._Next()  # if
        test: N.expr = self.ParseExpr()
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        orelse: list[N.stmt] = []
        if self._AtName('elif'):
            # elif → 嵌套 If 于 orelse
            orelse.append(self._ParseIf())
        elif self._AtName('else'):
            self._Next()
            self._ExpectOp(':')
            orelse = self._ParseSuite()
        node: N.If = N.If(test=test, body=body, orelse=orelse)
        self._FixLoc(node, start)
        return node

    def _ParseWhile(self) -> N.While:
        start: Token = self._Next()  # while
        test: N.expr = self.ParseExpr()
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        orelse: list[N.stmt] = []
        if self._AtName('else'):
            self._Next()
            self._ExpectOp(':')
            orelse = self._ParseSuite()
        node: N.While = N.While(test=test, body=body, orelse=orelse)
        self._FixLoc(node, start)
        return node

    def _ParseFor(self, is_async: bool = False) -> N.For:
        start: Token = self._Next()
        if start.Value == 'async':
            start = self._Next()  # for
        target: N.expr = self._ParseTargetList()
        self._ExpectName('in')
        iterable: N.expr = self.ParseExpr()
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        orelse: list[N.stmt] = []
        if self._AtName('else'):
            self._Next()
            self._ExpectOp(':')
            orelse = self._ParseSuite()
        cls: type = N.AsyncFor if is_async else N.For
        node: N.For = cls(target=target, iter=iterable, body=body, orelse=orelse,
                          type_comment=None)
        self._FixLoc(node, start)
        return node

    def _ParseTargetList(self) -> N.expr:
        """解析 for 目标列表（支持裸元组 a, b = ...）。"""
        start: Token = self._Peek()
        first: N.expr = self._ParseTarget()
        if self._AtOp(','):
            elts: list[N.expr] = [first]
            while self._AtOp(','):
                self._Next()
                self._SkipNL()
                elts.append(self._ParseTarget())
            tup: N.Tuple = N.Tuple(elts=elts, ctx=N.Store())
            self._FixLoc(tup, start)
            return tup
        return first

    def _ParseTry(self) -> N.Try:
        start: Token = self._Next()  # try
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        handlers: list[N.ExceptHandler] = []
        orelse: list[N.stmt] = []
        finalbody: list[N.stmt] = []
        is_star: bool = False
        while self._AtName('except'):
            self._Next()
            if self._AtOp('*'):
                is_star = True
                self._Next()
            handlers.append(self._ParseExceptHandler())
        if self._AtName('else'):
            self._Next()
            self._ExpectOp(':')
            orelse = self._ParseSuite()
        if self._AtName('finally'):
            self._Next()
            self._ExpectOp(':')
            finalbody = self._ParseSuite()
        cls: type = N.TryStar if is_star else N.Try
        node: N.Try = cls(body=body, handlers=handlers, orelse=orelse, finalbody=finalbody)
        self._FixLoc(node, start)
        return node

    def _ParseExceptHandler(self) -> N.ExceptHandler:
        start: Token = self._Peek()
        exc_type: N.expr | None = None
        name: str | None = None
        if not self._AtOp(':'):
            exc_type = self.ParseExpr()
            if self._AtName('as'):
                self._Next()
                name = self._ExpectName().Value
        self._ExpectOp(':')
        handler_body: list[N.stmt] = self._ParseSuite()
        node: N.ExceptHandler = N.ExceptHandler(type=exc_type, name=name, body=handler_body)
        self._FixLoc(node, start)
        return node

    def _ParseWith(self, is_async: bool = False) -> N.With:
        start: Token = self._Next()
        if start.Value == 'async':
            start = self._Next()  # with
        items: list[N.withitem] = []
        while True:
            ctx: N.expr = self.ParseExpr()
            optional_vars: N.expr | None = None
            if self._AtName('as'):
                self._Next()
                optional_vars = self._ParseTarget()
            item: N.withitem = N.withitem(context_expr=ctx, optional_vars=optional_vars)
            self._FixLoc(item, start)
            items.append(item)
            if self._AtOp(','):
                self._Next()
                continue
            break
        self._ExpectOp(':')
        body: list[N.stmt] = self._ParseSuite()
        cls: type = N.AsyncWith if is_async else N.With
        node: N.With = cls(items=items, body=body, type_comment=None)
        self._FixLoc(node, start)
        return node

    # ==================================================================
    # match 语句（PEP 634）
    # ==================================================================
    def _ParseMatch(self) -> N.Match:
        start: Token = self._Next()  # match
        subject: N.expr = self.ParseExpr()
        self._ExpectOp(':')
        self._ExpectNEWLINE()
        self._Expect(INDENT)
        cases: list[N.match_case] = []
        self._SkipNEWLINE()
        while self._AtName('case'):
            case_start: Token = self._Next()  # case
            pattern: N.pattern = self._ParsePattern()
            guard: N.expr | None = None
            if self._AtName('if'):
                self._Next()
                guard = self.ParseExpr()
            self._ExpectOp(':')
            case_body: list[N.stmt] = self._ParseSuite()
            mc: N.match_case = N.match_case(pattern=pattern, guard=guard, body=case_body)
            self._FixLoc(mc, case_start)
            cases.append(mc)
            self._SkipNEWLINE()
        self._Expect(DEDENT)
        node: N.Match = N.Match(subject=subject, cases=cases)
        self._FixLoc(node, start)
        return node

    def _ParsePattern(self) -> N.pattern:
        """解析 match 模式（顶层，处理 | 或模式）。"""
        start: Token = self._Peek()
        patterns: list[N.pattern] = [self._ParsePatternOr()]
        while self._AtOp('|'):
            self._Next()
            patterns.append(self._ParsePatternOr())
        if len(patterns) == 1:
            return patterns[0]
        node: N.MatchOr = N.MatchOr(patterns=patterns)
        self._FixLoc(node, start)
        return node

    def _ParsePatternOr(self) -> N.pattern:
        """解析单模式（含 as 绑定）。"""
        start: Token = self._Peek()
        pat: N.pattern = self._ParsePatternAtom()
        if self._AtName('as'):
            self._Next()
            name: str = self._ExpectName().Value
            node: N.MatchAs = N.MatchAs(pattern=pat, name=name)
            self._FixLoc(node, start)
            return node
        return pat

    def _ParsePatternAtom(self) -> N.pattern:
        """解析模式原子：字面量/捕获/序列/映射/类/通配符。"""
        start: Token = self._Peek()
        tok: Token = self._Peek()
        # 通配符 / 捕获
        if tok.Type == NAME:
            # 字面量 True/False/None
            if tok.Value in ('True', 'False', 'None'):
                self._Next()
                node: N.MatchSingleton = N.MatchSingleton(
                    value={'True': True, 'False': False, 'None': None}[tok.Value])
                self._FixLoc(node, tok)
                return node
            # 类模式：Name(...) 或 a.b.c(...)——扫描属性链末尾判断 '('
            peek_i: int = 1
            while (self._Peek(peek_i).Type == OP and self._Peek(peek_i).Value == '.'
                   and self._Peek(peek_i + 1).Type == NAME):
                peek_i += 2
            if self._Peek(peek_i).Type == OP and self._Peek(peek_i).Value == '(':
                return self._ParseMatchClass()
            # 属性值模式 a.b（无括号）
            if self._Peek(1).Type == OP and self._Peek(1).Value == '.':
                return self._ParseMatchValueAttr()
            # 捕获模式（含 _ 通配符；_ 产生空 MatchAs 与 CPython 一致）
            self._Next()
            node = N.MatchAs(pattern=None, name=None if tok.Value == '_' else tok.Value)
            self._FixLoc(node, tok)
            return node
        # 序列模式 [a, b] / (a, b)
        if tok.Type == OP and tok.Value in ('[', '('):
            return self._ParseMatchSequence()
        # 映射模式 {k: v, **rest}
        if tok.Type == OP and tok.Value == '{':
            return self._ParseMatchMapping()
        # 值模式：数字/字符串/f-string/带符号字面量（不消费顶层 '|'，留给 _ParsePattern 组 MatchOr）
        if tok.Type == NUMBER or tok.Type == STRING or tok.Type == FSTRING or (
                tok.Type == OP and tok.Value in ('-', '+')):
            value: N.expr = self._ParsePatternValue()
            node = N.MatchValue(value=value)
            self._FixLoc(node, start)
            return node
        if tok.Type == OP and tok.Value == '*':
            self._Next()
            name = None
            if not self._At(NEWLINE) and not self._AtOp(','):
                name = self._ExpectName().Value
            node = N.MatchStar(name=name)
            self._FixLoc(node, tok)
            return node
        raise SyntaxError(f"unexpected pattern token {tok.Type}({tok.Value!r})")

    def _ParsePatternValue(self) -> N.expr:
        """解析值模式表达式：带可选 +/- 前缀的字面量。

        与 CPython 一致：'|' 是模式或分隔符，这里只解析单个字面量
        （数字/字符串/f-string），不消费顶层 '|'。
        """
        start: Token = self._Peek()
        tok: Token = self._Peek()
        if tok.Type == OP and tok.Value in ('-', '+'):
            op_tok: Token = self._Next()
            inner: N.expr
            if self._Peek().Type == NUMBER:
                inner = self._ParseNumber()
            elif self._Peek().Type in (STRING, FSTRING):
                inner = self._ParseStringConcat()
            else:
                raise SyntaxError(
                    f"expected literal after '{op_tok.Value}' in pattern at line {op_tok.Line}"
                )
            node: N.expr
            if op_tok.Value == '-':
                node = N.UnaryOp(op=N.USub(), operand=inner)
            else:
                node = N.UnaryOp(op=N.UAdd(), operand=inner)
            self._FixLoc(node, start)
            return node
        if tok.Type == NUMBER:
            return self._ParseNumber()
        return self._ParseStringConcat()

    def _ParseMatchValueAttr(self) -> N.pattern:
        """解析值模式属性访问：a.b.c（无括号）。"""
        start: Token = self._Peek()
        expr: N.expr = self.ParseExpr()
        node: N.MatchValue = N.MatchValue(value=expr)
        self._FixLoc(node, start)
        return node

    def _ParseMatchClass(self) -> N.pattern:
        """解析类模式：Name(pos, kw=v, ...) 或 a.b.c(...)。

        类名仅解析 Name/Attribute 链（不消费调用括号），括号由本方法消费。
        """
        start: Token = self._Peek()
        cls_name: N.expr = self._ParsePatternClassName()
        self._ExpectOp('(')
        self._SkipNL()
        patterns: list[N.pattern] = []
        kwd_attrs: list[str] = []
        kwd_patterns: list[N.pattern] = []
        if not self._AtOp(')'):
            while True:
                self._SkipNL()
                if self._AtOp('*'):
                    self._Next()
                    patterns.append(self._ParsePattern())
                elif self._At(NAME) and self._Peek(1).Type == OP and self._Peek(1).Value == '=':
                    attr_tok: Token = self._Next()
                    self._Next()  # '='
                    kwd_attrs.append(attr_tok.Value)
                    kwd_patterns.append(self._ParsePattern())
                else:
                    patterns.append(self._ParsePattern())
                self._SkipNL()
                if self._AtOp(','):
                    self._Next()
                    if self._AtOp(')'):
                        break
                    continue
                break
        self._ExpectOp(')')
        node: N.MatchClass = N.MatchClass(cls=cls_name, patterns=patterns,
                                          kwd_attrs=kwd_attrs, kwd_patterns=kwd_patterns)
        self._FixLoc(node, start)
        return node

    def _ParsePatternClassName(self) -> N.expr:
        """解析类模式的类名（Name / a.b.c 属性链，不含调用括号）。"""
        start: Token = self._Peek()
        name_tok: Token = self._ExpectName()
        node: N.expr = N.Name(id=name_tok.Value, ctx=N.Load())
        self._FixLoc(node, name_tok)
        while self._AtOp('.'):
            self._Next()
            attr_tok: Token = self._ExpectName()
            attr_node: N.Attribute = N.Attribute(value=node, attr=attr_tok.Value, ctx=N.Load())
            self._FixLoc(attr_node, start)
            node = attr_node
        return node

    def _ParseMatchSequence(self) -> N.pattern:
        start: Token = self._Next()  # '[' 或 '('
        close: str = ']' if start.Value == '[' else ')'
        patterns: list[N.pattern] = []
        self._SkipNL()
        if not self._AtOp(close):
            while True:
                self._SkipNL()
                patterns.append(self._ParsePattern())
                self._SkipNL()
                if self._AtOp(','):
                    self._Next()
                    if self._AtOp(close):
                        break
                    continue
                break
        self._ExpectOp(close)
        node: N.MatchSequence = N.MatchSequence(patterns=patterns)
        self._FixLoc(node, start)
        return node

    def _ParseMatchMapping(self) -> N.pattern:
        start: Token = self._Next()  # '{'
        keys: list[N.expr] = []
        patterns: list[N.pattern] = []
        rest: str | None = None
        self._SkipNL()
        if not self._AtOp('}'):
            while True:
                self._SkipNL()
                if self._AtOp('**'):
                    self._Next()
                    rest = self._ExpectName().Value
                else:
                    key: N.expr = self.ParseExpr()
                    self._ExpectOp(':')
                    keys.append(key)
                    patterns.append(self._ParsePattern())
                self._SkipNL()
                if self._AtOp(','):
                    self._Next()
                    if self._AtOp('}'):
                        break
                    continue
                break
        self._ExpectOp('}')
        node: N.MatchMapping = N.MatchMapping(keys=keys, patterns=patterns, rest=rest)
        self._FixLoc(node, start)
        return node


def Parse(source: str) -> N.Module:
    """便捷入口：源码字符串 → Module AST（供 vast.parse 调用）。"""
    from lib.vast.Tokenizer import Tokenizer

    tokens = Tokenizer(source).Tokenize()
    line_starts: list[int] = [0]
    # 从 token 流重建行起始表（由 Tokenizer 维护，此处直接计算）
    line_starts = _ComputeLineStarts(source)
    parser: Parser = Parser(tokens, source, line_starts)
    return parser.ParseModule()


def _ComputeLineStarts(source: str) -> list[int]:
    """计算源码所有行起始字符索引（含首行 0）。"""
    starts: list[int] = [0]
    for i, ch in enumerate(source):
        if ch == '\n':
            starts.append(i + 1)
    return starts