refactor(irgen): 规范采用visitor生成

include/irgen/IRGen.h

@@ -3,10 +3,12 @@
 
 #pragma once
 
+#include <any>
 #include <memory>
 #include <string>
 #include <unordered_map>
 
+#include "SysYBaseVisitor.h"
 #include "SysYParser.h"
 #include "ir/IR.h"
 #include "sem/Sema.h"
@@ -18,22 +20,31 @@ class IRBuilder;
 class Value;
 }
 
-class IRGenImpl {
+class IRGenImpl final : public SysYBaseVisitor {
  public:
   IRGenImpl(ir::Module& module, const SemanticContext& sema);
 
- void Gen(SysYParser::CompUnitContext& cu);
+  std::any visitCompUnit(SysYParser::CompUnitContext* ctx) override;
+  std::any visitFuncDef(SysYParser::FuncDefContext* ctx) override;
+  std::any visitBlockStmt(SysYParser::BlockStmtContext* ctx) override;
+  std::any visitBlockItem(SysYParser::BlockItemContext* ctx) override;
+  std::any visitDecl(SysYParser::DeclContext* ctx) override;
+  std::any visitStmt(SysYParser::StmtContext* ctx) override;
+  std::any visitVarDef(SysYParser::VarDefContext* ctx) override;
+  std::any visitReturnStmt(SysYParser::ReturnStmtContext* ctx) override;
+  std::any visitParenExp(SysYParser::ParenExpContext* ctx) override;
+  std::any visitNumberExp(SysYParser::NumberExpContext* ctx) override;
+  std::any visitVarExp(SysYParser::VarExpContext* ctx) override;
+  std::any visitAdditiveExp(SysYParser::AdditiveExpContext* ctx) override;
 
  private:
-  void GenFuncDef(SysYParser::FuncDefContext& func);
-  void GenBlock(SysYParser::BlockStmtContext& block);
-  bool GenBlockItem(SysYParser::BlockItemContext& item);
-  void GenDecl(SysYParser::DeclContext& decl);
-  bool GenStmt(SysYParser::StmtContext& stmt);
-  void GenVarDef(SysYParser::VarDefContext& decl);
-  void GenReturnStmt(SysYParser::ReturnStmtContext& ret);
+  enum class BlockFlow {
+    Continue,
+    Terminated,
+  };
 
-  ir::Value* GenExpr(SysYParser::ExpContext& expr);
+  BlockFlow VisitBlockItemResult(SysYParser::BlockItemContext& item);
+  ir::Value* EvalExpr(SysYParser::ExpContext& expr);
 
   ir::Module& module_;
   const SemanticContext& sema_;