fix(frontend): 修复部分实现

src/sem/Sema.cpp

@@ -1,58 +1,75 @@
-// 极简语义分析：只检查变量是否先声明再使用。
-// 如需扩展，可在此基础上加入：
-// - 常量折叠/类型检查
-// - 函数签名/参数数量校验
-// - 控制流相关检查（return 覆盖、break/continue 合法性等）
 #include "sem/Sema.h"
 
 #include <stdexcept>
 #include <string>
-#include <unordered_set>
 
-#include "ast/AstNodes.h"
 #include "sem/SymbolTable.h"
 
 namespace {
 
-class SemaVisitor {
- public:
-  explicit SemaVisitor(SymbolTable& table) : table_(table) {}
+void CheckExpr(SysYParser::ExpContext& exp, const SymbolTable& table);
 
-  void CheckBlock(const ast::Block& block) {
-    for (const auto& item : block.items) {
-      if (auto decl = dynamic_cast<ast::VarDecl*>(item.get())) {
-        table_.Add(decl->name);
-        if (decl->init) CheckExpr(*decl->init);
-        continue;
-      }
-      if (auto ret = dynamic_cast<ast::ReturnStmt*>(item.get())) {
-        CheckExpr(*ret->value);
-      }
-    }
+void CheckPrimary(SysYParser::PrimaryContext& primary,
+                  const SymbolTable& table) {
+  if (primary.Number()) {
+    return;
   }
 
-  void CheckExpr(const ast::Expr& expr) {
-    if (auto var = dynamic_cast<const ast::VarExpr*>(&expr)) {
-      if (!table_.Contains(var->name)) {
-        throw std::runtime_error("[sema] 使用了未定义的变量: " + var->name);
-      }
-    } else if (auto bin = dynamic_cast<const ast::BinaryExpr*>(&expr)) {
-      CheckExpr(*bin->lhs);
-      CheckExpr(*bin->rhs);
-      
+  if (primary.Ident()) {
+    const std::string name = primary.Ident()->getText();
+    if (!table.Contains(name)) {
+      throw std::runtime_error("[sema] 使用了未定义的变量: " + name);
     }
+    return;
   }
 
- private:
-  SymbolTable& table_;
-};
+  if (primary.exp()) {
+    CheckExpr(*primary.exp(), table);
+    return;
+  }
+
+  throw std::runtime_error("[sema] 暂不支持的 primary 形式");
+}
+
+void CheckExpr(SysYParser::ExpContext& exp, const SymbolTable& table) {
+  if (!exp.addExp()) {
+    throw std::runtime_error("[sema] 非法表达式");
+  }
+  const auto& terms = exp.addExp()->primary();
+  for (auto* term : terms) {
+    CheckPrimary(*term, table);
+  }
+}
 
 }  // namespace
 
-std::shared_ptr<ast::CompUnit> RunSema(std::shared_ptr<ast::CompUnit> ast) {
-  if (!ast || !ast->func || !ast->func->body) return ast;
+void RunSema(SysYParser::CompUnitContext& comp_unit) {
+  auto* func = comp_unit.funcDef();
+  if (!func || !func->block()) {
+    throw std::runtime_error("[sema] 缺少 main 函数定义");
+  }
+
   SymbolTable table;
-  SemaVisitor visitor(table);
-  visitor.CheckBlock(*ast->func->body);
-  return ast;
+
+  for (auto* stmt : func->block()->stmt()) {
+    if (!stmt) {
+      continue;
+    }
+    if (auto* decl = stmt->varDecl()) {
+      const std::string name = decl->Ident()->getText();
+      if (table.Contains(name)) {
+        throw std::runtime_error("[sema] 重复定义变量: " + name);
+      }
+      if (decl->exp()) {
+        CheckExpr(*decl->exp(), table);
+      }
+      table.Add(name);
+      continue;
+    }
+    if (auto* ret = stmt->returnStmt()) {
+      CheckExpr(*ret->exp(), table);
+      break;
+    }
+    throw std::runtime_error("[sema] 暂不支持的语句类型");
+  }
 }