feat(match): fallthrough 软关键字 + case 内 break 跳出 match
- vast/Parser：语句位置识别裸 `fallthrough`（仅整条语句命中），脱糖为 c.NoBreak() 标记调用；作标识符的写法不受影响 - HandlesBody：`c.NoBreak()` 标记语句不产出 IR（语义由 HandlesMatch 消费） - HandlesMatch：新增 _HandleMatchCaseBody（case 内 break 目标 = match 的 AfterBB， 经 loop_break_targets 压栈/出栈，不影响外层循环）与 _FallThroughTarget； 9 处 fallthrough 由"只留无终结符块"改为显式 br 下一个 case body
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@@ -19,7 +19,13 @@ class BodyHandle(BaseHandle):
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Gen._set_node_info(Node)
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try:
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if isinstance(Node, ast.Expr):
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self.HandleExprLlvm(Node.value)
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# `fallthrough`（vast 软关键字已脱糖为 c.NoBreak()）是 match 的
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# 标记语句，本身不产出 IR，语义由 HandlesMatch 消费；后续步骤
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# （含 _EmitTempFrees）保持原样执行。
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if self._IsNoBreakMarkerStmt(Node):
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pass
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else:
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self.HandleExprLlvm(Node.value)
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elif isinstance(Node, ast.Return):
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self.Trans.ReturnHandler._HandleReturnLlvm(Node)
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elif isinstance(Node, ast.Assign):
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@@ -79,6 +85,15 @@ class BodyHandle(BaseHandle):
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if Gen.builder and not Gen.builder.block.is_terminated:
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Gen._EmitTempFrees()
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@staticmethod
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def _IsNoBreakMarkerStmt(Node: ast.stmt) -> bool:
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"""是否 `c.NoBreak()` 标记语句（`fallthrough` 软关键字的脱糖形态）"""
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if not isinstance(Node, ast.Expr) or not isinstance(Node.value, ast.Call):
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return False
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Fn: ast.expr = Node.value.func
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return (isinstance(Fn, ast.Attribute) and isinstance(Fn.value, ast.Name)
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and Fn.value.id == 'c' and Fn.attr == 'NoBreak')
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def HandleExprLlvm(self, Node: ast.expr, VarType: ir.Type | None = None,
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ConstWidthHint: int | None = None) -> ir.Value | None:
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return self.Trans.ExprHandler.HandleExprLlvm(Node, VarType, ConstWidthHint)
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@@ -239,43 +239,53 @@ class MatchHandle(BaseHandle):
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for j in range(NumSubCases):
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if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
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Gen.builder.position_at_start(CaseBBs[CaseIdx])
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, (ast.MatchValue, ast.MatchSingleton)):
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if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
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Gen.builder.position_at_start(CaseBBs[CaseIdx])
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchAs):
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if pattern.pattern is None:
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Gen.builder.position_at_start(DefaultBB)
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchSequence):
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Gen.builder.position_at_start(DefaultBB)
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchClass):
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# 兜底处理：MatchClass 在非 REnum 路径的 case body 生成
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# case 收集阶段已创建 CaseBB，此处生成 body
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if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
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Gen.builder.position_at_start(CaseBBs[CaseIdx])
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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if not HasDefault:
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Gen.builder.position_at_start(DefaultBB)
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@@ -285,6 +295,32 @@ class MatchHandle(BaseHandle):
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Gen.builder.branch(AfterBB)
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Gen.builder.position_at_start(AfterBB)
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def _HandleMatchCaseBody(self, Gen: "Translator.LlvmGen",
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Body: list[ast.stmt], AfterBB: ir.Block) -> None:
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"""翻译 match case 体：case 体内的 break 目标是 match 的 AfterBB
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C switch 语义——case 内 break 跳出 **match**（而非外层循环）。故翻译前把
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AfterBB 压入 loop_break_targets，翻译完弹出（外层循环目标不受影响）。
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"""
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Targets: list = Gen.loop_break_targets
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Targets.append(AfterBB)
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try:
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self.HandleBodyLlvm(Body)
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finally:
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Targets.pop()
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@staticmethod
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def _FallThroughTarget(CaseBBs: list[ir.Block], CaseIdx: int, AfterBB: ir.Block) -> ir.Block:
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"""fallthrough 的落点：下一个 case 的 body（无后继槽位时落到 AfterBB）
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`fallthrough`（vast 软关键字，脱糖为 c.NoBreak()）表示"本 case 不自动
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break"，直接落到下一个 case 的 body（对齐 C 的 [[fallthrough]]）。
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"""
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NextIdx: int = CaseIdx + 1
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if 0 <= NextIdx < len(CaseBBs):
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return CaseBBs[NextIdx]
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return AfterBB
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def _HandleRenumMatchLlvm(self, Node: ast.Match, RenumName: str, SubjectPtr: ir.Value) -> None:
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Gen: "Translator.LlvmGen" = self.Trans.LlvmGen
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if isinstance(SubjectPtr.type, ir.PointerType) and isinstance(SubjectPtr.type.pointee, ir.PointerType):
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@@ -455,36 +491,44 @@ class MatchHandle(BaseHandle):
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if isinstance(elem_ptr.type, ir.PointerType) and elem_ptr.type.pointee != member_type:
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elem_ptr = Gen.builder.bitcast(elem_ptr, ir.PointerType(member_type), name=f"match_{bind_name}_cast")
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Gen.variables[bind_name] = elem_ptr
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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for bind_name, _, _, _ in bindings:
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if bind_name in Gen.variables:
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del Gen.variables[bind_name]
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchValue):
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if CaseIdx < len(CaseBBs) and CaseBBs[CaseIdx] != DefaultBB:
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Gen.builder.position_at_start(CaseBBs[CaseIdx])
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchAs):
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if pattern.pattern is None:
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Gen.builder.position_at_start(DefaultBB)
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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elif isinstance(pattern, ast.MatchSequence):
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Gen.builder.position_at_start(DefaultBB)
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self.HandleBodyLlvm(case.body)
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self._HandleMatchCaseBody(Gen, case.body, AfterBB)
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if not Gen.builder.block.is_terminated:
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if not HasNoBreak[i]:
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Gen.builder.branch(AfterBB)
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else:
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Gen.builder.branch(self._FallThroughTarget(CaseBBs, CaseIdx, AfterBB))
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CaseIdx += 1
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if not HasDefault:
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Gen.builder.position_at_start(DefaultBB)
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@@ -82,6 +82,11 @@ _STRUCT_EXAMPLE: str = (
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'struct Node(Base): value: int'
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)
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# fallthrough 软关键字（语句级）：仅当整条语句就是 `fallthrough` 时命中，
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# 脱糖为 `c.NoBreak()` 标记调用（match 生成侧据此让 case 体不自动 break，
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# 落到下一个 case）。作标识符/属性的写法逐字不变。
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_FALLTHROUGH_KEYWORD: str = 'fallthrough'
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class Parser(ExprParserMixin):
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"""Viper/Python 完整语法分析器。"""
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@@ -186,6 +191,13 @@ class Parser(ExprParserMixin):
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return self._ParseMatch()
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except SyntaxError:
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self.Idx = save
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# fallthrough 软关键字（语句级）：仅当整条语句就是 `fallthrough`
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# （后随 NEWLINE / ';' / ENDMARKER）时命中，脱糖为 `c.NoBreak()`
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# 标记调用，由 match 生成侧消费（case 体因此不自动 break）。
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# 作标识符/属性的写法（fallthrough = 1 / fallthrough(x) /
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# d.fallthrough）不命中，逐字不变。
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if v == _FALLTHROUGH_KEYWORD and self._IsFallThroughStmt():
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return self._ParseFallThrough()
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if v == 'return':
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return self._ParseReturn()
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if v == 'raise':
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@@ -224,6 +236,32 @@ class Parser(ExprParserMixin):
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return self._ParseDecorated()
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return self._ParseSimpleStmt()
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# ==================================================================
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# fallthrough 软关键字（语句级）
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# ==================================================================
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def _IsFallThroughStmt(self) -> bool:
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"""当前语句是否为软关键字 `fallthrough`（后随 NEWLINE / ';' / ENDMARKER）
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只在"整条语句就是 fallthrough"时命中；`fallthrough = 1`（赋值）、
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`fallthrough(x)`（调用）、`d.fallthrough`（属性）都不命中。
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"""
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nxt: Token = self._Peek(1)
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if nxt.Type == NEWLINE or nxt.Type == ENDMARKER:
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return True
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return nxt.Type == OP and nxt.Value == ';'
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def _ParseFallThrough(self) -> N.stmt:
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"""`fallthrough` 脱糖为 `c.NoBreak()`（match 生成侧识别的 fallthrough 标记）"""
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tok: Token = self._Peek()
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self._Next()
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marker: N.Call = N.Call(
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func=N.Attribute(value=N.Name(id='c', ctx=N.Load()),
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attr='NoBreak', ctx=N.Load()),
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args=[], keywords=[])
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node: N.Expr = N.Expr(value=marker)
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self._FixLoc(node, tok)
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return node
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# ==================================================================
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# 简单语句
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# ==================================================================
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