diff --git a/include/ast/astnode.h b/include/ast/astnode.h
index 57ac448..fbd9e97 100644
--- a/include/ast/astnode.h
+++ b/include/ast/astnode.h
@@ -3,6 +3,8 @@
 #include <memory>
 #include <variant>
 #include <vector>
+#include "../semantic/visitor.h"
+#include "tools.h"
 using IdentifierType = std::string;
 struct ArrayType {
   bool has_base_type;
@@ -15,17 +17,15 @@ class ASTNodeVisitorBase {
   virtual ~ASTNodeVisitorBase() = default;
   virtual void visit(class ASTNodeBase *context) = 0;
 };
-enum class ASTNodeType {
-
-};
 
 class ASTNodeBase {
+  friend Visitor;
   ASTNodeType type;
   // std::vector<std::shared_ptr<ASTNodeBase>> children;
   size_t start_line, start_char_pos, end_line, end_char_pos;
 
  public:
   virtual ~ASTNodeBase() = default;
-  virtual void accept(class ASTNodeVisitorBase *visitor) = 0;
+  // virtual void accept(class ASTNodeVisitorBase *visitor) = 0;
 };
 #endif
\ No newline at end of file
diff --git a/include/ast/expr_astnode.h b/include/ast/expr_astnode.h
index 0b5da73..71922b6 100644
--- a/include/ast/expr_astnode.h
+++ b/include/ast/expr_astnode.h
@@ -14,112 +14,147 @@ class Expr_ASTNode : public ASTNodeBase {
 
 class BasicExpr_ASTNode : public Expr_ASTNode {};  // This is a virtual class
 class NewArrayExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   bool has_initial_value;
   std::shared_ptr<class ConstantExpr_ASTNode> initial_value;
 };
-class NewConstructExpr_ASTNode : public Expr_ASTNode {};
-class NewExpr_ASTNode : public Expr_ASTNode {};
+class NewConstructExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
+};
+class NewExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
+};
 class AccessExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> base;
   IdentifierType member;
 };
-class MemberVariableAccessExpr_ASTNode : public AccessExpr_ASTNode {};
+class MemberVariableAccessExpr_ASTNode : public AccessExpr_ASTNode {
+  friend Visitor;
+};
 class MemberFunctionAccessExpr_ASTNode : public AccessExpr_ASTNode {
+  friend Visitor;
   std::vector<std::shared_ptr<Expr_ASTNode>> arguments;
 };
 class IndexExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> base;
   std::vector<std::shared_ptr<Expr_ASTNode>> indices;
 };
 class SuffixExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> base;
 };
 class PrefixExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> base;
 };
 class OppositeExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> base;
 };
 class LNotExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class BNotExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class MDMExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class PMExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class RLExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class GGLLExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class NEExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class BAndExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class BXorExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class BOrExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class LAndExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class LOrExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> left;
   std::shared_ptr<Expr_ASTNode> right;
 };
 class TernaryExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> condition;
   std::shared_ptr<Expr_ASTNode> src1;
   std::shared_ptr<Expr_ASTNode> src2;
 };
 class AssignExpr_ASTNode : public Expr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> dest;
   std::shared_ptr<Expr_ASTNode> src;
 };
 
-class ThisExpr_ASTNode : public BasicExpr_ASTNode {};
+class ThisExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
+};
 class ParenExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> expr;
 };
 class IDExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
   IdentifierType id;
 };
 class FunctionCallExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
   IdentifierType func_name;
   std::vector<std::shared_ptr<Expr_ASTNode>> arguments;
 };
 class FormattedStringExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
   using SegmentType = std::variant<std::string, std::shared_ptr<Expr_ASTNode>>;
   std::vector<SegmentType> segments;
 };
 struct NullType {};
 using AtomicConstantType = std::variant<uint32_t, bool, std::string, NullType>;
 struct ArrayConstantType {
+  friend Visitor;
   std::vector<std::variant<std::shared_ptr<ArrayConstantType>, NullType, AtomicConstantType>> elements;
   size_t level;
 };
 class ConstantExpr_ASTNode : public BasicExpr_ASTNode {
+  friend Visitor;
   std::variant<AtomicConstantType, ArrayConstantType> value;
 };
 
diff --git a/include/ast/statement_astnode.h b/include/ast/statement_astnode.h
index 858dc7b..0b7e48c 100644
--- a/include/ast/statement_astnode.h
+++ b/include/ast/statement_astnode.h
@@ -8,34 +8,43 @@ class Statement_ASTNode : public ASTNodeBase {
   virtual ~Statement_ASTNode() = default;
 };
 
-class EmptyStatement_ASTNode : public Statement_ASTNode {};
+class EmptyStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
+};
 class DefinitionStatement_ASTNode : public Statement_ASTNode {
-  ExprTypeInfo type;
+  friend Visitor;
+  ExprTypeInfo var_type;
   std::vector<std::pair<IdentifierType, std::shared_ptr<Expr_ASTNode>>> vars;
 };
 class ExprStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> expr;
 };
 class IfStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   bool has_else_clause;
   std::shared_ptr<Expr_ASTNode> condition;
   std::shared_ptr<Statement_ASTNode> if_clause;
   std::shared_ptr<Statement_ASTNode> else_clause;
 };
 class WhileStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> condition;
   std::shared_ptr<Statement_ASTNode> loop_body;
 };
 class ForStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   std::shared_ptr<Statement_ASTNode> initial;
   std::shared_ptr<Expr_ASTNode> condition;
   std::shared_ptr<Statement_ASTNode> update;
   std::shared_ptr<Statement_ASTNode> loop_body;
 };
 class JmpStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   std::shared_ptr<Expr_ASTNode> return_value;
 };
 class SuiteStatement_ASTNode : public Statement_ASTNode {
+  friend Visitor;
   std::vector<std::shared_ptr<Statement_ASTNode>> statements;
 };
 
diff --git a/include/ast/structural_astnode.h b/include/ast/structural_astnode.h
index 99d7fb0..5c2d3bf 100644
--- a/include/ast/structural_astnode.h
+++ b/include/ast/structural_astnode.h
@@ -7,21 +7,35 @@
 #include "expr_astnode.h"
 #include "statement_astnode.h"
 class FuncDef_ASTNode : public ASTNodeBase {
+  friend Visitor;
+  bool is_constructor;
   IdentifierType func_name;
+  ExprTypeInfo return_type;
   std::vector<std::pair<IdentifierType, ExprTypeInfo>> params;
   std::shared_ptr<SuiteStatement_ASTNode> func_body;
+
+ public:
+  FuncDef_ASTNode() = default;
 };
-class Constructor_ASTNode : public FuncDef_ASTNode {};
-class ClassVariable_ASTNode : public DefinitionStatement_ASTNode {};
 class ClassDef_ASTNode : public ASTNodeBase {
+  friend Visitor;
+
  private:
-  using ClassElement = std::variant<std::shared_ptr<Constructor_ASTNode>, std::shared_ptr<ClassVariable_ASTNode>,
-                                    std::shared_ptr<FuncDef_ASTNode>>;
-  std::vector<ClassElement> elements;
+  std::string class_name;
+  std::vector<std::shared_ptr<DefinitionStatement_ASTNode>> member_variables;
+  std::vector<std::shared_ptr<FuncDef_ASTNode>> member_functions;
+  std::shared_ptr<FuncDef_ASTNode> constructor;
+
+ public:
+  ClassDef_ASTNode() = default;
 };
 class Program_ASTNode : public ASTNodeBase {
-  using ProgramElement = std::variant<std::shared_ptr<FuncDef_ASTNode>, std::shared_ptr<ClassDef_ASTNode>,
-                                      std::shared_ptr<DefinitionStatement_ASTNode>>;
-  std::vector<ProgramElement> elements;
+  friend Visitor;
+  std::vector<std::shared_ptr<DefinitionStatement_ASTNode>> global_variables;
+  std::vector<std::shared_ptr<ClassDef_ASTNode>> classes;
+  std::vector<std::shared_ptr<FuncDef_ASTNode>> functions;
+
+ public:
+  Program_ASTNode() = default;
 };
 #endif
\ No newline at end of file
diff --git a/include/semantic/semantic.h b/include/semantic/semantic.h
index 6c45d2d..0bd3290 100644
--- a/include/semantic/semantic.h
+++ b/include/semantic/semantic.h
@@ -4,15 +4,6 @@
 #include "ast/ast.h"
 #include "visitor.h"
 
-class SemanticError : public std::exception {
-  std::string msg;
-  int error_code;
-
- public:
-  SemanticError(const std::string &msg, int error_code) : msg(msg), error_code(error_code) {}
-  const char *what() const noexcept override { return msg.c_str(); }
-  int GetErrorCode() const { return error_code; }
-};
 std::shared_ptr<ASTNodeBase> BuildAST(Visitor *visitor, antlr4::tree::ParseTree *tree);
 void SemanticCheck(std::istream &fin, std::shared_ptr<ASTNodeBase> &ast);
 #endif
\ No newline at end of file
diff --git a/include/semantic/visitor.h b/include/semantic/visitor.h
index e22511e..0ccfe3f 100644
--- a/include/semantic/visitor.h
+++ b/include/semantic/visitor.h
@@ -1,9 +1,13 @@
 #ifndef VISITOR_H
 #define VISITOR_H
 
+#include <stack>
+#include <vector>
 #include "MXParserVisitor.h"
-
+#include "tools.h"
 class Visitor : public MXParserVisitor {
+  std::vector<ASTNodeType> nodetype_stk;
+
  public:
   std::any visitMxprog(MXParser::MxprogContext *context) override;
   std::any visitFunction_def(MXParser::Function_defContext *context) override;
diff --git a/include/tools.h b/include/tools.h
new file mode 100644
index 0000000..60ac182
--- /dev/null
+++ b/include/tools.h
@@ -0,0 +1,61 @@
+#pragma once
+#include <stdexcept>
+enum class ASTNodeType {
+  // Expression nodes
+  NewArrayExpr,
+  NewConstructExpr,
+  NewExpr,
+  MemberVariableAccessExpr,
+  MemberFunctionAccessExpr,
+  IndexExpr,
+  SuffixExpr,
+  PrefixExpr,
+  OppositeExpr,
+  LNotExpr,
+  BNotExpr,
+  MDMExpr,
+  PMExpr,
+  RLExpr,
+  GGLLExpr,
+  NEExpr,
+  BAndExpr,
+  BXorExpr,
+  BOrExpr,
+  LAndExpr,
+  LOrExpr,
+  TernaryExpr,
+  AssignExpr,
+  ThisExpr,
+  ParenExpr,
+  IDExpr,
+  FunctionCallExpr,
+  FormattedStringExpr,
+  ConstantExpr,
+
+  // Statement nodes
+  EmptyStatement,
+  DefinitionStatement,
+  ExprStatement,
+  IfStatement,
+  WhileStatement,
+  ForStatement,
+  JmpStatement,
+  SuiteStatement,
+
+  // Structural nodes
+  FuncDef,
+  Constructor,
+  ClassVariable,
+  ClassDef,
+  Program
+};
+
+class SemanticError : public std::exception {
+  std::string msg;
+  int error_code;
+
+ public:
+  SemanticError(const std::string &msg, int error_code) : msg(msg), error_code(error_code) {}
+  const char *what() const noexcept override { return msg.c_str(); }
+  int GetErrorCode() const { return error_code; }
+};
\ No newline at end of file
diff --git a/src/ast/CMakeLists.txt b/src/ast/CMakeLists.txt
index 2513fe2..d901faa 100644
--- a/src/ast/CMakeLists.txt
+++ b/src/ast/CMakeLists.txt
@@ -1,3 +1,6 @@
 include_directories(${CMAKE_SOURCE_DIR}/include/ast)
 file(GLOB AST_SOURCES "*.cpp")
-add_library(ast STATIC ${AST_SOURCES})
\ No newline at end of file
+add_library(ast STATIC ${AST_SOURCES})
+target_include_directories(ast PUBLIC /usr/include/antlr4-runtime/)
+target_include_directories(ast PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../semantic/antlr-generated)
+target_link_libraries(ast PUBLIC antlr4-runtime)
\ No newline at end of file
diff --git a/src/semantic/semantic.cpp b/src/semantic/semantic.cpp
index 9cf2ad0..884f373 100644
--- a/src/semantic/semantic.cpp
+++ b/src/semantic/semantic.cpp
@@ -13,13 +13,15 @@ class MXErrorListener : public antlr4::BaseErrorListener {
   MXErrorListener() : no_problem(true) {}
   void syntaxError(antlr4::Recognizer *recognizer, antlr4::Token *offendingSymbol, size_t line,
                    size_t charPositionInLine, const std::string &msg, std::exception_ptr e) override {
-    std::cout << "line " << line << ":" << charPositionInLine << " AT "
-              << offendingSymbol->getText() << ": " << msg << std::endl;
+    std::cout << "line " << line << ":" << charPositionInLine << " AT " << offendingSymbol->getText() << ": " << msg
+              << std::endl;
     no_problem = false;
   }
   bool IsOk() { return no_problem; }
 };
-std::shared_ptr<ASTNodeBase> BuildAST(Visitor *visitor, antlr4::tree::ParseTree *tree) { ; }
+std::shared_ptr<ASTNodeBase> BuildAST(Visitor *visitor, antlr4::tree::ParseTree *tree) {
+  return std::any_cast<std::shared_ptr<Program_ASTNode>>(visitor->visit(tree));
+}
 std::shared_ptr<ASTNodeBase> CheckAndDecorate(std::shared_ptr<ASTNodeBase> src) { ; }
 
 void SemanticCheck(std::istream &fin, std::shared_ptr<ASTNodeBase> &ast_out) {
diff --git a/src/semantic/visitor.cpp b/src/semantic/visitor.cpp
index 4369d97..40c24f4 100644
--- a/src/semantic/visitor.cpp
+++ b/src/semantic/visitor.cpp
@@ -1,16 +1,205 @@
 #include "visitor.h"
 #include <stdexcept>
+#include <type_traits>
+#include "MXParser.h"
+#include "MXParserVisitor.h"
+#include "ast/ast.h"
 
-std::any Visitor::visitMxprog(MXParser::MxprogContext *context) { throw std::runtime_error("Not implemented"); }
-std::any Visitor::visitFunction_def(MXParser::Function_defContext *context) {
-  throw std::runtime_error("Not implemented");
+std::any Visitor::visitMxprog(MXParser::MxprogContext *context) {
+  auto program = std::make_shared<Program_ASTNode>();
+  program->type = ASTNodeType::Program;
+  program->start_line = context->getStart()->getLine();
+  program->start_char_pos = context->getStart()->getCharPositionInLine();
+  program->end_line = context->getStop()->getLine();
+  program->end_char_pos = context->getStop()->getCharPositionInLine();
+  nodetype_stk.push_back(ASTNodeType::Program);
+
+  for (auto def : context->children) {
+    if (auto classDefContext = dynamic_cast<MXParser::Class_defContext *>(def)) {
+      auto classNode = std::any_cast<std::shared_ptr<ClassDef_ASTNode>>(visit(classDefContext));
+      program->classes.push_back(classNode);
+    } else if (auto defineStmtContext = dynamic_cast<MXParser::Define_statementContext *>(def)) {
+      auto defineNode = std::any_cast<std::shared_ptr<DefinitionStatement_ASTNode>>(visit(defineStmtContext));
+      program->global_variables.push_back(defineNode);
+    } else if (auto funcDefContext = dynamic_cast<MXParser::Function_defContext *>(def)) {
+      auto funcNode = std::any_cast<std::shared_ptr<FuncDef_ASTNode>>(visit(funcDefContext));
+      program->functions.push_back(funcNode);
+    } else if (auto EOFToken = dynamic_cast<antlr4::tree::TerminalNode *>(def)) {
+      if (EOFToken == context->EOF()) break;
+      throw std::runtime_error("unknown subnode occurred in visitMxprog");
+    } else {
+      throw std::runtime_error("unknown subnode occurred in visitMxprog");
+    }
+  }
+  nodetype_stk.pop_back();
+
+  return program;
+}
+
+std::any Visitor::visitFunction_def(MXParser::Function_defContext *context) {
+  auto func = std::make_shared<FuncDef_ASTNode>();
+  func->type = ASTNodeType::FuncDef;
+  func->is_constructor = false;
+  func->start_line = context->getStart()->getLine();
+  func->start_char_pos = context->getStart()->getCharPositionInLine();
+  func->end_line = context->getStop()->getLine();
+  func->end_char_pos = context->getStop()->getCharPositionInLine();
+  nodetype_stk.push_back(ASTNodeType::FuncDef);
+  std::string return_type_str;
+
+  if (auto type_context = dynamic_cast<MXParser::TypeContext *>(context->children[0])) {
+    // return type
+    return_type_str = type_context->getText();
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "return_type_str=" << return_type_str << std::endl;
+  } else
+    throw std::runtime_error("unknown subnode occurred in visitFunction_def");
+  int return_dimensions = 0;
+  for (size_t i = 1; i < context->children.size(); i++) {
+    if (dynamic_cast<antlr4::tree::TerminalNode *>(context->children[i]) != nullptr &&
+        dynamic_cast<antlr4::tree::TerminalNode *>(context->children[i])->getSymbol()->getType() == MXParser::ID) {
+      break;
+    }
+    return_dimensions++;
+  }
+  return_dimensions >>= 1;
+  if (return_dimensions == 0) {
+    func->return_type = return_type_str;
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded return type is [none-array]" << return_type_str
+              << std::endl;
+  } else {
+    func->return_type = ArrayType{true, return_type_str, static_cast<size_t>(return_dimensions)};
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded return type is [array]" << return_type_str
+              << " with dimensions=" << return_dimensions << std::endl;
+  }
+  func->func_name = context->children[1 + 2 * return_dimensions]->getText();
+  std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "func_name=" << func->func_name << std::endl;
+  size_t cur = 3 + 2 * return_dimensions;
+  bool is_first_para = true;
+  while (true) {
+    if (cur >= context->children.size()) throw std::runtime_error("something strange happened in visitFunction_def");
+    auto ptr = dynamic_cast<antlr4::tree::TerminalNode *>(context->children[cur]);
+    if (ptr != nullptr && ptr->getSymbol()->getType() == MXParser::RPAREN) break;
+    if (is_first_para) goto cancel_first;
+    if (ptr->getSymbol()->getType() != MXParser::COMMA)
+      throw std::runtime_error("something strange happened in visitFunction_def");
+    cur++;
+  cancel_first:
+    is_first_para = false;
+    std::string cur_para_type_base_str = context->children[cur]->getText();
+    int cur_para_dimensions = 0;
+    while (dynamic_cast<antlr4::tree::TerminalNode *>(context->children[cur + 1]) != nullptr &&
+           (dynamic_cast<antlr4::tree::TerminalNode *>(context->children[cur + 1])->getSymbol()->getType() ==
+                MXParser::LBRACKET ||
+            dynamic_cast<antlr4::tree::TerminalNode *>(context->children[cur + 1])->getSymbol()->getType() ==
+                MXParser::RBRACKET)) {
+      cur_para_dimensions++;
+      cur++;
+    }
+    cur++;
+    cur_para_dimensions >>= 1;
+    std::string cur_para_name = context->children[cur]->getText();
+    ExprTypeInfo cur_para_type;
+    if (cur_para_dimensions == 0) {
+      cur_para_type = cur_para_type_base_str;
+      std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded parameter type is [none-array]"
+                << cur_para_type_base_str << std::endl;
+      std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded parameter name is " << cur_para_name
+                << std::endl;
+    } else {
+      cur_para_type = ArrayType{true, cur_para_type_base_str, static_cast<size_t>(cur_para_dimensions)};
+      std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded parameter type is [array]"
+                << cur_para_type_base_str << " with dimensions=" << cur_para_dimensions << std::endl;
+      std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded parameter name is " << cur_para_name
+                << std::endl;
+    }
+    func->params.push_back(std::make_pair(cur_para_name, cur_para_type));
+    cur++;
+  }
+  func->func_body = std::any_cast<std::shared_ptr<SuiteStatement_ASTNode>>(visit(context->suite()));
+  nodetype_stk.pop_back();
+  return func;
+}
+std::any Visitor::visitClass_def(MXParser::Class_defContext *context) {
+  auto class_def = std::make_shared<ClassDef_ASTNode>();
+  class_def->type = ASTNodeType::ClassDef;
+  class_def->start_line = context->getStart()->getLine();
+  class_def->start_char_pos = context->getStart()->getCharPositionInLine();
+  class_def->end_line = context->getStop()->getLine();
+  class_def->end_char_pos = context->getStop()->getCharPositionInLine();
+  nodetype_stk.push_back(ASTNodeType::ClassDef);
+
+  class_def->class_name = context->ID()->getText();
+  std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "building a class named " << class_def->class_name
+            << std::endl;
+  std::vector<MXParser::Class_constructorContext *> constructors = context->class_constructor();
+  if (constructors.size() > 1) throw SemanticError("Multiple constructor found for class " + class_def->class_name, 2);
+  if (constructors.size() > 0)
+    class_def->constructor = std::any_cast<std::shared_ptr<FuncDef_ASTNode>>(visit(constructors[0]));
+  std::vector<MXParser::Function_defContext *> functions = context->function_def();
+  for (auto func : functions) {
+    auto func_node = std::any_cast<std::shared_ptr<FuncDef_ASTNode>>(visit(func));
+    class_def->member_functions.push_back(func_node);
+  }
+
+  nodetype_stk.pop_back();
+  return class_def;
 }
-std::any Visitor::visitClass_def(MXParser::Class_defContext *context) { throw std::runtime_error("Not implemented"); }
 std::any Visitor::visitClass_var_def(MXParser::Class_var_defContext *context) {
-  throw std::runtime_error("Not implemented");
+  auto member_var_def = std::make_shared<DefinitionStatement_ASTNode>();
+  member_var_def->type = ASTNodeType::ClassVariable;
+  member_var_def->start_line = context->getStart()->getLine();
+  member_var_def->start_char_pos = context->getStart()->getCharPositionInLine();
+  member_var_def->end_line = context->getStop()->getLine();
+  member_var_def->end_char_pos = context->getStop()->getCharPositionInLine();
+  nodetype_stk.push_back(ASTNodeType::ClassVariable);
+
+  std::string define_type_base;
+  if (auto type_context = dynamic_cast<MXParser::TypeContext *>(context->children[0])) {
+    define_type_base = type_context->getText();
+  } else
+    throw std::runtime_error("unknown subnode occurred in visitClass_var_def");
+  int define_dimensions = 0;
+  for (size_t i = 1; i < context->children.size(); i++) {
+    if (dynamic_cast<antlr4::tree::TerminalNode *>(context->children[i]) != nullptr &&
+        dynamic_cast<antlr4::tree::TerminalNode *>(context->children[i])->getSymbol()->getType() == MXParser::ID) {
+      break;
+    }
+    define_dimensions++;
+  }
+  define_dimensions >>= 1;
+  if (define_dimensions == 0) {
+    member_var_def->var_type = define_type_base;
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded member variable type is [none-array]"
+              << define_type_base << std::endl;
+  } else {
+    member_var_def->var_type = ArrayType{true, define_type_base, static_cast<size_t>(define_dimensions)};
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded member variable type is [array]"
+              << define_type_base << " with dimensions=" << define_dimensions << std::endl;
+  }
+  auto identifiers = context->ID();
+  for (auto id : identifiers) {
+    member_var_def->vars.push_back(std::make_pair(id->getText(), nullptr));
+    std::cerr << std::string(nodetype_stk.size() * 2, ' ') << "recorded member variable name is " << id->getText()
+              << std::endl;
+  }
+
+  nodetype_stk.pop_back();
+  return member_var_def;
 }
 std::any Visitor::visitClass_constructor(MXParser::Class_constructorContext *context) {
-  throw std::runtime_error("Not implemented");
+  auto construct_func = std::make_shared<FuncDef_ASTNode>();
+  construct_func->type = ASTNodeType::Constructor;
+  construct_func->is_constructor = false;
+  construct_func->start_line = context->getStart()->getLine();
+  construct_func->start_char_pos = context->getStart()->getCharPositionInLine();
+  construct_func->end_line = context->getStop()->getLine();
+  construct_func->end_char_pos = context->getStop()->getCharPositionInLine();
+  nodetype_stk.push_back(ASTNodeType::Constructor);
+
+  construct_func->func_body = std::any_cast<std::shared_ptr<SuiteStatement_ASTNode>>(visit(context->suite()));
+
+  nodetype_stk.pop_back();
+  return construct_func;
 }
 std::any Visitor::visitSuite(MXParser::SuiteContext *context) { throw std::runtime_error("Not implemented"); }
 std::any Visitor::visitEmpty_statement(MXParser::Empty_statementContext *context) {