diff --git a/grammar/MXParser.g4 b/grammar/MXParser.g4
index ce26d09..768249e 100644
--- a/grammar/MXParser.g4
+++ b/grammar/MXParser.g4
@@ -52,12 +52,12 @@ expr
     ;
 
 basic_expr
-    : THIS
-    | LPAREN expr RPAREN
-    | ID
-    | ID LPAREN (expr (COMMA expr)*)? RPAREN
-    | formatted_string
-    | constant
+    : THIS #this_expr
+    | LPAREN expr RPAREN #paren_expr
+    | ID #id_expr
+    | ID LPAREN (expr (COMMA expr)*)? RPAREN #function_call_expr
+    | formatted_string #formatted_string_expr
+    | constant #constant_expr
     ;
 
 formatted_string : FORMAT_STRING_WHOLE | (FORMAT_STRING_HEAD expr (FORMAT_STRING_BODY expr)*? FORMAT_STRING_TAIL);
diff --git a/include/ast/ast.h b/include/ast/ast.h
new file mode 100644
index 0000000..5997c1a
--- /dev/null
+++ b/include/ast/ast.h
@@ -0,0 +1,8 @@
+#ifndef AST_H
+#define AST_H
+#include "astnode.h"
+#include "astnode_visitor.h"
+#include "expr_astnode.h"
+#include "statement_astnode.h"
+#include "structural_astnode.h"
+#endif  // AST_H
\ No newline at end of file
diff --git a/include/ast/astnode.h b/include/ast/astnode.h
new file mode 100644
index 0000000..57ac448
--- /dev/null
+++ b/include/ast/astnode.h
@@ -0,0 +1,31 @@
+#ifndef ASTNODE_H
+#define ASTNODE_H
+#include <memory>
+#include <variant>
+#include <vector>
+using IdentifierType = std::string;
+struct ArrayType {
+  bool has_base_type;
+  IdentifierType basetype;
+  size_t level;
+};
+using ExprTypeInfo = std::variant<IdentifierType, ArrayType>;
+class ASTNodeVisitorBase {
+ public:
+  virtual ~ASTNodeVisitorBase() = default;
+  virtual void visit(class ASTNodeBase *context) = 0;
+};
+enum class ASTNodeType {
+
+};
+
+class ASTNodeBase {
+  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;
+};
+#endif
\ No newline at end of file
diff --git a/include/ast/astnode_visitor.h b/include/ast/astnode_visitor.h
new file mode 100644
index 0000000..14145fa
--- /dev/null
+++ b/include/ast/astnode_visitor.h
@@ -0,0 +1,6 @@
+#ifndef ASTNODE_VISITOR_H
+#define ASTNODE_VISITOR_H
+#include "astnode.h"
+#include "expr_astnode.h"
+class ASTNodeVisitor : public ASTNodeVisitorBase {};
+#endif
\ No newline at end of file
diff --git a/include/ast/expr_astnode.h b/include/ast/expr_astnode.h
new file mode 100644
index 0000000..0b5da73
--- /dev/null
+++ b/include/ast/expr_astnode.h
@@ -0,0 +1,126 @@
+#ifndef EXPR_ASTNODE_H
+#define EXPR_ASTNODE_H
+#include <cstdint>
+#include <string>
+#include <variant>
+#include "astnode.h"
+
+class Expr_ASTNode : public ASTNodeBase {
+  ExprTypeInfo expr_type_info;
+
+ public:
+  virtual ~Expr_ASTNode() = default;
+};
+
+class BasicExpr_ASTNode : public Expr_ASTNode {};  // This is a virtual class
+class NewArrayExpr_ASTNode : public Expr_ASTNode {
+  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 AccessExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> base;
+  IdentifierType member;
+};
+class MemberVariableAccessExpr_ASTNode : public AccessExpr_ASTNode {};
+class MemberFunctionAccessExpr_ASTNode : public AccessExpr_ASTNode {
+  std::vector<std::shared_ptr<Expr_ASTNode>> arguments;
+};
+class IndexExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> base;
+  std::vector<std::shared_ptr<Expr_ASTNode>> indices;
+};
+class SuffixExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> base;
+};
+class PrefixExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> base;
+};
+class OppositeExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> base;
+};
+class LNotExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class BNotExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class MDMExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class PMExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class RLExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class GGLLExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class NEExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class BAndExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class BXorExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class BOrExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class LAndExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class LOrExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> left;
+  std::shared_ptr<Expr_ASTNode> right;
+};
+class TernaryExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> condition;
+  std::shared_ptr<Expr_ASTNode> src1;
+  std::shared_ptr<Expr_ASTNode> src2;
+};
+class AssignExpr_ASTNode : public Expr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> dest;
+  std::shared_ptr<Expr_ASTNode> src;
+};
+
+class ThisExpr_ASTNode : public BasicExpr_ASTNode {};
+class ParenExpr_ASTNode : public BasicExpr_ASTNode {
+  std::shared_ptr<Expr_ASTNode> expr;
+};
+class IDExpr_ASTNode : public BasicExpr_ASTNode {
+  IdentifierType id;
+};
+class FunctionCallExpr_ASTNode : public BasicExpr_ASTNode {
+  IdentifierType func_name;
+  std::vector<std::shared_ptr<Expr_ASTNode>> arguments;
+};
+class FormattedStringExpr_ASTNode : public BasicExpr_ASTNode {
+  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 {
+  std::vector<std::variant<std::shared_ptr<ArrayConstantType>, NullType, AtomicConstantType>> elements;
+  size_t level;
+};
+class ConstantExpr_ASTNode : public BasicExpr_ASTNode {
+  std::variant<AtomicConstantType, ArrayConstantType> value;
+};
+
+#endif  // EXPR_ASTNODE_H
\ No newline at end of file
diff --git a/include/ast/statement_astnode.h b/include/ast/statement_astnode.h
new file mode 100644
index 0000000..858dc7b
--- /dev/null
+++ b/include/ast/statement_astnode.h
@@ -0,0 +1,42 @@
+#ifndef STATEMENT_ASTNODE_H
+#define STATEMENT_ASTNODE_H
+#include <vector>
+#include "astnode.h"
+#include "expr_astnode.h"
+class Statement_ASTNode : public ASTNodeBase {
+ public:
+  virtual ~Statement_ASTNode() = default;
+};
+
+class EmptyStatement_ASTNode : public Statement_ASTNode {};
+class DefinitionStatement_ASTNode : public Statement_ASTNode {
+  ExprTypeInfo type;
+  std::vector<std::pair<IdentifierType, std::shared_ptr<Expr_ASTNode>>> vars;
+};
+class ExprStatement_ASTNode : public Statement_ASTNode {
+  std::shared_ptr<Expr_ASTNode> expr;
+};
+class IfStatement_ASTNode : public Statement_ASTNode {
+  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 {
+  std::shared_ptr<Expr_ASTNode> condition;
+  std::shared_ptr<Statement_ASTNode> loop_body;
+};
+class ForStatement_ASTNode : public Statement_ASTNode {
+  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 {
+  std::shared_ptr<Expr_ASTNode> return_value;
+};
+class SuiteStatement_ASTNode : public Statement_ASTNode {
+  std::vector<std::shared_ptr<Statement_ASTNode>> statements;
+};
+
+#endif  // STATEMENT_ASTNODE_H
\ No newline at end of file
diff --git a/include/ast/structural_astnode.h b/include/ast/structural_astnode.h
new file mode 100644
index 0000000..99d7fb0
--- /dev/null
+++ b/include/ast/structural_astnode.h
@@ -0,0 +1,27 @@
+#ifndef STRUCTURAL_ASTNODE_H
+#define STRUCTURAL_ASTNODE_H
+#include <memory>
+#include <variant>
+#include <vector>
+#include "astnode.h"
+#include "expr_astnode.h"
+#include "statement_astnode.h"
+class FuncDef_ASTNode : public ASTNodeBase {
+  IdentifierType func_name;
+  std::vector<std::pair<IdentifierType, ExprTypeInfo>> params;
+  std::shared_ptr<SuiteStatement_ASTNode> func_body;
+};
+class Constructor_ASTNode : public FuncDef_ASTNode {};
+class ClassVariable_ASTNode : public DefinitionStatement_ASTNode {};
+class ClassDef_ASTNode : public ASTNodeBase {
+ private:
+  using ClassElement = std::variant<std::shared_ptr<Constructor_ASTNode>, std::shared_ptr<ClassVariable_ASTNode>,
+                                    std::shared_ptr<FuncDef_ASTNode>>;
+  std::vector<ClassElement> elements;
+};
+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;
+};
+#endif
\ No newline at end of file
diff --git a/include/semantic/semantic.h b/include/semantic/semantic.h
index a549e60..6c45d2d 100644
--- a/include/semantic/semantic.h
+++ b/include/semantic/semantic.h
@@ -1,5 +1,18 @@
 #ifndef SEMANTIC_H
 #define SEMANTIC_H
 #include <ios>
-int SemanticCheck(std::istream &fin);
+#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 b2a3129..e22511e 100644
--- a/include/semantic/visitor.h
+++ b/include/semantic/visitor.h
@@ -1,15 +1,57 @@
 #ifndef VISITOR_H
 #define VISITOR_H
+
 #include "MXParserVisitor.h"
+
 class Visitor : public MXParserVisitor {
  public:
-  virtual std::any visitMxprog(MXParser::MxprogContext *context);
-  virtual std::any visitFunction(MXParser::FunctionContext *context);
-  virtual std::any visitType(MXParser::TypeContext *context);
-  virtual std::any visitBlock(MXParser::BlockContext *context);
-  virtual std::any visitStatement(MXParser::StatementContext *context);
-  virtual std::any visitExpression(MXParser::ExpressionContext *context);
-  virtual std::any visitReturnStmt(MXParser::ReturnStmtContext *context);
-  virtual std::any visitIfStmt(MXParser::IfStmtContext *context);
+  std::any visitMxprog(MXParser::MxprogContext *context) override;
+  std::any visitFunction_def(MXParser::Function_defContext *context) override;
+  std::any visitClass_def(MXParser::Class_defContext *context) override;
+  std::any visitClass_var_def(MXParser::Class_var_defContext *context) override;
+  std::any visitClass_constructor(MXParser::Class_constructorContext *context) override;
+  std::any visitSuite(MXParser::SuiteContext *context) override;
+  std::any visitEmpty_statement(MXParser::Empty_statementContext *context) override;
+  std::any visitDefinition_statement(MXParser::Definition_statementContext *context) override;
+  std::any visitExpr_statement(MXParser::Expr_statementContext *context) override;
+  std::any visitIf_statement(MXParser::If_statementContext *context) override;
+  std::any visitWhile_statement(MXParser::While_statementContext *context) override;
+  std::any visitFor_statement(MXParser::For_statementContext *context) override;
+  std::any visitJmp_statement(MXParser::Jmp_statementContext *context) override;
+  std::any visitSuite_statement(MXParser::Suite_statementContext *context) override;
+  std::any visitDefine_statement(MXParser::Define_statementContext *context) override;
+  std::any visitGgll_expression(MXParser::Ggll_expressionContext *context) override;
+  std::any visitBxor_expression(MXParser::Bxor_expressionContext *context) override;
+  std::any visitSuffix_expression(MXParser::Suffix_expressionContext *context) override;
+  std::any visitLand_expression(MXParser::Land_expressionContext *context) override;
+  std::any visitPm_expression(MXParser::Pm_expressionContext *context) override;
+  std::any visitIndex_expression(MXParser::Index_expressionContext *context) override;
+  std::any visitOpposite_expression(MXParser::Opposite_expressionContext *context) override;
+  std::any visitNew_array_expression(MXParser::New_array_expressionContext *context) override;
+  std::any visitBasic_expression(MXParser::Basic_expressionContext *context) override;
+  std::any visitAccess_expression(MXParser::Access_expressionContext *context) override;
+  std::any visitBand_expression(MXParser::Band_expressionContext *context) override;
+  std::any visitNew_construct_expression(MXParser::New_construct_expressionContext *context) override;
+  std::any visitTernary_expression(MXParser::Ternary_expressionContext *context) override;
+  std::any visitBnot_expression(MXParser::Bnot_expressionContext *context) override;
+  std::any visitLnot_expression(MXParser::Lnot_expressionContext *context) override;
+  std::any visitPrefix_expression(MXParser::Prefix_expressionContext *context) override;
+  std::any visitRl_expression(MXParser::Rl_expressionContext *context) override;
+  std::any visitAssign_expression(MXParser::Assign_expressionContext *context) override;
+  std::any visitMdm_expression(MXParser::Mdm_expressionContext *context) override;
+  std::any visitNew_expression(MXParser::New_expressionContext *context) override;
+  std::any visitNe_expression(MXParser::Ne_expressionContext *context) override;
+  std::any visitBor_expression(MXParser::Bor_expressionContext *context) override;
+  std::any visitLor_expression(MXParser::Lor_expressionContext *context) override;
+  std::any visitThis_expr(MXParser::This_exprContext *context) override;
+  std::any visitParen_expr(MXParser::Paren_exprContext *context) override;
+  std::any visitId_expr(MXParser::Id_exprContext *context) override;
+  std::any visitFunction_call_expr(MXParser::Function_call_exprContext *context) override;
+  std::any visitFormatted_string_expr(MXParser::Formatted_string_exprContext *context) override;
+  std::any visitConstant_expr(MXParser::Constant_exprContext *context) override;
+  std::any visitFormatted_string(MXParser::Formatted_stringContext *context) override;
+  std::any visitConstant(MXParser::ConstantContext *context) override;
+  std::any visitType(MXParser::TypeContext *context) override;
 };
-#endif
\ No newline at end of file
+
+#endif  // VISITOR_H
\ No newline at end of file
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index b2879d9..11a7386 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,3 +1,4 @@
+add_subdirectory(ast)
 add_subdirectory(semantic)
 add_executable(code main.cpp)
 target_link_libraries(code semantic argparse)
diff --git a/src/ast/CMakeLists.txt b/src/ast/CMakeLists.txt
new file mode 100644
index 0000000..2513fe2
--- /dev/null
+++ b/src/ast/CMakeLists.txt
@@ -0,0 +1,3 @@
+include_directories(${CMAKE_SOURCE_DIR}/include/ast)
+file(GLOB AST_SOURCES "*.cpp")
+add_library(ast STATIC ${AST_SOURCES})
\ No newline at end of file
diff --git a/src/ast/astnode.cpp b/src/ast/astnode.cpp
new file mode 100644
index 0000000..df9f623
--- /dev/null
+++ b/src/ast/astnode.cpp
@@ -0,0 +1,2 @@
+#include "astnode.h"
+#include "astnode_visitor.h"
\ No newline at end of file
diff --git a/src/ast/astnode_visitor.cpp b/src/ast/astnode_visitor.cpp
new file mode 100644
index 0000000..e69de29
diff --git a/src/ast/expr_astnode.cpp b/src/ast/expr_astnode.cpp
new file mode 100644
index 0000000..71824f6
--- /dev/null
+++ b/src/ast/expr_astnode.cpp
@@ -0,0 +1 @@
+#include "expr_astnode.h"
\ No newline at end of file
diff --git a/src/ast/statement_astnode.cpp b/src/ast/statement_astnode.cpp
new file mode 100644
index 0000000..7d84b2b
--- /dev/null
+++ b/src/ast/statement_astnode.cpp
@@ -0,0 +1 @@
+#include "statement_astnode.h"
\ No newline at end of file
diff --git a/src/ast/structural_astnode.cpp b/src/ast/structural_astnode.cpp
new file mode 100644
index 0000000..9864b72
--- /dev/null
+++ b/src/ast/structural_astnode.cpp
@@ -0,0 +1 @@
+#include "structural_astnode.h"
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index bb38701..75343db 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -21,8 +21,18 @@ int main(int argc, char **argv) {
   auto input_file = program.get<std::string>("input");
   auto output_file = program.get<std::string>("output");
   std::ifstream fin(input_file);
-  int err_code = SemanticCheck(fin);
-  if (err_code != 0) return err_code;
-
+  std::shared_ptr<ASTNodeBase> ast;
+  try {
+    SemanticCheck(fin, ast);
+  } catch (const SemanticError &err) {
+    std::cout << err.what() << std::endl;
+    return err.GetErrorCode();
+  } catch (const std::exception &err) {
+    std::cout << "Unknown error: " << err.what() << std::endl;
+    return 254;
+  } catch (...) {
+    std::cout << "Unknown error without message" << std::endl;
+    return 255;
+  }
   return 0;
 }
\ No newline at end of file
diff --git a/src/semantic/CMakeLists.txt b/src/semantic/CMakeLists.txt
index 94b9fd1..a2630c7 100644
--- a/src/semantic/CMakeLists.txt
+++ b/src/semantic/CMakeLists.txt
@@ -1,9 +1,10 @@
 include_directories(/usr/include/antlr4-runtime/)
 include_directories(${CMAKE_SOURCE_DIR}/include/semantic)
-include_directories(${CMAKE_CURRENT_SOURCE_DIR}/antlr-generated)
 file(GLOB ANLTR_SOURCES "antlr-generated/*.cpp")
 file(GLOB SEMANTIC_SOURCES "*.cpp")
 add_library(mx-antlr STATIC ${ANLTR_SOURCES})
 add_library(semantic STATIC ${SEMANTIC_SOURCES})
+target_include_directories(semantic PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/antlr-generated)
+target_include_directories(semantic PUBLIC /usr/include/antlr4-runtime/)
 target_link_libraries(mx-antlr PUBLIC antlr4-runtime)
-target_link_libraries(semantic PUBLIC antlr4-runtime mx-antlr)
\ No newline at end of file
+target_link_libraries(semantic PUBLIC antlr4-runtime mx-antlr ast)
\ No newline at end of file
diff --git a/src/semantic/antlr-generated/MXParser.cpp b/src/semantic/antlr-generated/MXParser.cpp
index eacfbf0..7e5c8a6 100644
--- a/src/semantic/antlr-generated/MXParser.cpp
+++ b/src/semantic/antlr-generated/MXParser.cpp
@@ -2660,59 +2660,137 @@ MXParser::Basic_exprContext::Basic_exprContext(ParserRuleContext *parent, size_t
   : ParserRuleContext(parent, invokingState) {
 }
 
-tree::TerminalNode* MXParser::Basic_exprContext::THIS() {
-  return getToken(MXParser::THIS, 0);
-}
-
-tree::TerminalNode* MXParser::Basic_exprContext::LPAREN() {
-  return getToken(MXParser::LPAREN, 0);
-}
-
-std::vector<MXParser::ExprContext *> MXParser::Basic_exprContext::expr() {
-  return getRuleContexts<MXParser::ExprContext>();
-}
-
-MXParser::ExprContext* MXParser::Basic_exprContext::expr(size_t i) {
-  return getRuleContext<MXParser::ExprContext>(i);
-}
-
-tree::TerminalNode* MXParser::Basic_exprContext::RPAREN() {
-  return getToken(MXParser::RPAREN, 0);
-}
-
-tree::TerminalNode* MXParser::Basic_exprContext::ID() {
-  return getToken(MXParser::ID, 0);
-}
-
-std::vector<tree::TerminalNode *> MXParser::Basic_exprContext::COMMA() {
-  return getTokens(MXParser::COMMA);
-}
-
-tree::TerminalNode* MXParser::Basic_exprContext::COMMA(size_t i) {
-  return getToken(MXParser::COMMA, i);
-}
-
-MXParser::Formatted_stringContext* MXParser::Basic_exprContext::formatted_string() {
-  return getRuleContext<MXParser::Formatted_stringContext>(0);
-}
-
-MXParser::ConstantContext* MXParser::Basic_exprContext::constant() {
-  return getRuleContext<MXParser::ConstantContext>(0);
-}
-
 
 size_t MXParser::Basic_exprContext::getRuleIndex() const {
   return MXParser::RuleBasic_expr;
 }
 
+void MXParser::Basic_exprContext::copyFrom(Basic_exprContext *ctx) {
+  ParserRuleContext::copyFrom(ctx);
+}
 
-std::any MXParser::Basic_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+//----------------- Paren_exprContext ------------------------------------------------------------------
+
+tree::TerminalNode* MXParser::Paren_exprContext::LPAREN() {
+  return getToken(MXParser::LPAREN, 0);
+}
+
+MXParser::ExprContext* MXParser::Paren_exprContext::expr() {
+  return getRuleContext<MXParser::ExprContext>(0);
+}
+
+tree::TerminalNode* MXParser::Paren_exprContext::RPAREN() {
+  return getToken(MXParser::RPAREN, 0);
+}
+
+MXParser::Paren_exprContext::Paren_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::Paren_exprContext::accept(tree::ParseTreeVisitor *visitor) {
   if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
-    return parserVisitor->visitBasic_expr(this);
+    return parserVisitor->visitParen_expr(this);
   else
     return visitor->visitChildren(this);
 }
+//----------------- Constant_exprContext ------------------------------------------------------------------
 
+MXParser::ConstantContext* MXParser::Constant_exprContext::constant() {
+  return getRuleContext<MXParser::ConstantContext>(0);
+}
+
+MXParser::Constant_exprContext::Constant_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::Constant_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+  if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
+    return parserVisitor->visitConstant_expr(this);
+  else
+    return visitor->visitChildren(this);
+}
+//----------------- This_exprContext ------------------------------------------------------------------
+
+tree::TerminalNode* MXParser::This_exprContext::THIS() {
+  return getToken(MXParser::THIS, 0);
+}
+
+MXParser::This_exprContext::This_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::This_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+  if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
+    return parserVisitor->visitThis_expr(this);
+  else
+    return visitor->visitChildren(this);
+}
+//----------------- Id_exprContext ------------------------------------------------------------------
+
+tree::TerminalNode* MXParser::Id_exprContext::ID() {
+  return getToken(MXParser::ID, 0);
+}
+
+MXParser::Id_exprContext::Id_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::Id_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+  if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
+    return parserVisitor->visitId_expr(this);
+  else
+    return visitor->visitChildren(this);
+}
+//----------------- Formatted_string_exprContext ------------------------------------------------------------------
+
+MXParser::Formatted_stringContext* MXParser::Formatted_string_exprContext::formatted_string() {
+  return getRuleContext<MXParser::Formatted_stringContext>(0);
+}
+
+MXParser::Formatted_string_exprContext::Formatted_string_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::Formatted_string_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+  if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
+    return parserVisitor->visitFormatted_string_expr(this);
+  else
+    return visitor->visitChildren(this);
+}
+//----------------- Function_call_exprContext ------------------------------------------------------------------
+
+tree::TerminalNode* MXParser::Function_call_exprContext::ID() {
+  return getToken(MXParser::ID, 0);
+}
+
+tree::TerminalNode* MXParser::Function_call_exprContext::LPAREN() {
+  return getToken(MXParser::LPAREN, 0);
+}
+
+tree::TerminalNode* MXParser::Function_call_exprContext::RPAREN() {
+  return getToken(MXParser::RPAREN, 0);
+}
+
+std::vector<MXParser::ExprContext *> MXParser::Function_call_exprContext::expr() {
+  return getRuleContexts<MXParser::ExprContext>();
+}
+
+MXParser::ExprContext* MXParser::Function_call_exprContext::expr(size_t i) {
+  return getRuleContext<MXParser::ExprContext>(i);
+}
+
+std::vector<tree::TerminalNode *> MXParser::Function_call_exprContext::COMMA() {
+  return getTokens(MXParser::COMMA);
+}
+
+tree::TerminalNode* MXParser::Function_call_exprContext::COMMA(size_t i) {
+  return getToken(MXParser::COMMA, i);
+}
+
+MXParser::Function_call_exprContext::Function_call_exprContext(Basic_exprContext *ctx) { copyFrom(ctx); }
+
+
+std::any MXParser::Function_call_exprContext::accept(tree::ParseTreeVisitor *visitor) {
+  if (auto parserVisitor = dynamic_cast<MXParserVisitor*>(visitor))
+    return parserVisitor->visitFunction_call_expr(this);
+  else
+    return visitor->visitChildren(this);
+}
 MXParser::Basic_exprContext* MXParser::basic_expr() {
   Basic_exprContext *_localctx = _tracker.createInstance<Basic_exprContext>(_ctx, getState());
   enterRule(_localctx, 18, MXParser::RuleBasic_expr);
@@ -2730,6 +2808,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     _errHandler->sync(this);
     switch (getInterpreter<atn::ParserATNSimulator>()->adaptivePredict(_input, 35, _ctx)) {
     case 1: {
+      _localctx = _tracker.createInstance<MXParser::This_exprContext>(_localctx);
       enterOuterAlt(_localctx, 1);
       setState(306);
       match(MXParser::THIS);
@@ -2737,6 +2816,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     }
 
     case 2: {
+      _localctx = _tracker.createInstance<MXParser::Paren_exprContext>(_localctx);
       enterOuterAlt(_localctx, 2);
       setState(307);
       match(MXParser::LPAREN);
@@ -2748,6 +2828,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     }
 
     case 3: {
+      _localctx = _tracker.createInstance<MXParser::Id_exprContext>(_localctx);
       enterOuterAlt(_localctx, 3);
       setState(311);
       match(MXParser::ID);
@@ -2755,6 +2836,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     }
 
     case 4: {
+      _localctx = _tracker.createInstance<MXParser::Function_call_exprContext>(_localctx);
       enterOuterAlt(_localctx, 4);
       setState(312);
       match(MXParser::ID);
@@ -2787,6 +2869,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     }
 
     case 5: {
+      _localctx = _tracker.createInstance<MXParser::Formatted_string_exprContext>(_localctx);
       enterOuterAlt(_localctx, 5);
       setState(325);
       formatted_string();
@@ -2794,6 +2877,7 @@ MXParser::Basic_exprContext* MXParser::basic_expr() {
     }
 
     case 6: {
+      _localctx = _tracker.createInstance<MXParser::Constant_exprContext>(_localctx);
       enterOuterAlt(_localctx, 6);
       setState(326);
       constant();
diff --git a/src/semantic/antlr-generated/MXParser.h b/src/semantic/antlr-generated/MXParser.h
index 1c96faa..9ca14f7 100644
--- a/src/semantic/antlr-generated/MXParser.h
+++ b/src/semantic/antlr-generated/MXParser.h
@@ -610,21 +610,76 @@ public:
   class  Basic_exprContext : public antlr4::ParserRuleContext {
   public:
     Basic_exprContext(antlr4::ParserRuleContext *parent, size_t invokingState);
-    virtual size_t getRuleIndex() const override;
-    antlr4::tree::TerminalNode *THIS();
-    antlr4::tree::TerminalNode *LPAREN();
-    std::vector<ExprContext *> expr();
-    ExprContext* expr(size_t i);
-    antlr4::tree::TerminalNode *RPAREN();
-    antlr4::tree::TerminalNode *ID();
-    std::vector<antlr4::tree::TerminalNode *> COMMA();
-    antlr4::tree::TerminalNode* COMMA(size_t i);
-    Formatted_stringContext *formatted_string();
-    ConstantContext *constant();
+   
+    Basic_exprContext() = default;
+    void copyFrom(Basic_exprContext *context);
+    using antlr4::ParserRuleContext::copyFrom;
 
+    virtual size_t getRuleIndex() const override;
+
+   
+  };
+
+  class  Paren_exprContext : public Basic_exprContext {
+  public:
+    Paren_exprContext(Basic_exprContext *ctx);
+
+    antlr4::tree::TerminalNode *LPAREN();
+    ExprContext *expr();
+    antlr4::tree::TerminalNode *RPAREN();
+
+    virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
+  };
+
+  class  Constant_exprContext : public Basic_exprContext {
+  public:
+    Constant_exprContext(Basic_exprContext *ctx);
+
+    ConstantContext *constant();
+
+    virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
+  };
+
+  class  This_exprContext : public Basic_exprContext {
+  public:
+    This_exprContext(Basic_exprContext *ctx);
+
+    antlr4::tree::TerminalNode *THIS();
+
+    virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
+  };
+
+  class  Id_exprContext : public Basic_exprContext {
+  public:
+    Id_exprContext(Basic_exprContext *ctx);
+
+    antlr4::tree::TerminalNode *ID();
+
+    virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
+  };
+
+  class  Formatted_string_exprContext : public Basic_exprContext {
+  public:
+    Formatted_string_exprContext(Basic_exprContext *ctx);
+
+    Formatted_stringContext *formatted_string();
+
+    virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
+  };
+
+  class  Function_call_exprContext : public Basic_exprContext {
+  public:
+    Function_call_exprContext(Basic_exprContext *ctx);
+
+    antlr4::tree::TerminalNode *ID();
+    antlr4::tree::TerminalNode *LPAREN();
+    antlr4::tree::TerminalNode *RPAREN();
+    std::vector<ExprContext *> expr();
+    ExprContext* expr(size_t i);
+    std::vector<antlr4::tree::TerminalNode *> COMMA();
+    antlr4::tree::TerminalNode* COMMA(size_t i);
 
     virtual std::any accept(antlr4::tree::ParseTreeVisitor *visitor) override;
-   
   };
 
   Basic_exprContext* basic_expr();
diff --git a/src/semantic/antlr-generated/MXParserVisitor.h b/src/semantic/antlr-generated/MXParserVisitor.h
index 1381949..f2908df 100644
--- a/src/semantic/antlr-generated/MXParserVisitor.h
+++ b/src/semantic/antlr-generated/MXParserVisitor.h
@@ -95,7 +95,17 @@ public:
 
     virtual std::any visitLor_expression(MXParser::Lor_expressionContext *context) = 0;
 
-    virtual std::any visitBasic_expr(MXParser::Basic_exprContext *context) = 0;
+    virtual std::any visitThis_expr(MXParser::This_exprContext *context) = 0;
+
+    virtual std::any visitParen_expr(MXParser::Paren_exprContext *context) = 0;
+
+    virtual std::any visitId_expr(MXParser::Id_exprContext *context) = 0;
+
+    virtual std::any visitFunction_call_expr(MXParser::Function_call_exprContext *context) = 0;
+
+    virtual std::any visitFormatted_string_expr(MXParser::Formatted_string_exprContext *context) = 0;
+
+    virtual std::any visitConstant_expr(MXParser::Constant_exprContext *context) = 0;
 
     virtual std::any visitFormatted_string(MXParser::Formatted_stringContext *context) = 0;
 
diff --git a/src/semantic/semantic.cpp b/src/semantic/semantic.cpp
index 530fa12..9cf2ad0 100644
--- a/src/semantic/semantic.cpp
+++ b/src/semantic/semantic.cpp
@@ -3,15 +3,37 @@
 #include "MXLexer.h"
 #include "MXParser.h"
 #include "antlr4-runtime.h"
+#include "ast/ast.h"
 #include "visitor.h"
-int SemanticCheck(std::istream &fin) {
+
+class MXErrorListener : public antlr4::BaseErrorListener {
+  bool no_problem;
+
+ public:
+  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;
+    no_problem = false;
+  }
+  bool IsOk() { return no_problem; }
+};
+std::shared_ptr<ASTNodeBase> BuildAST(Visitor *visitor, antlr4::tree::ParseTree *tree) { ; }
+std::shared_ptr<ASTNodeBase> CheckAndDecorate(std::shared_ptr<ASTNodeBase> src) { ; }
+
+void SemanticCheck(std::istream &fin, std::shared_ptr<ASTNodeBase> &ast_out) {
   antlr4::ANTLRInputStream input(fin);
   MXLexer lexer(&input);
   antlr4::CommonTokenStream tokens(&lexer);
   tokens.fill();
   MXParser parser(&tokens);
+  parser.removeErrorListeners();
+  MXErrorListener error_listener;
+  parser.addErrorListener(&error_listener);
   antlr4::tree::ParseTree *tree = parser.mxprog();
+  if (!error_listener.IsOk()) throw SemanticError("Fatal error: syntax error", 1);
   Visitor visitor;
-  visitor.visit(tree);
-  return 0;
+  std::shared_ptr<ASTNodeBase> ast = BuildAST(&visitor, tree);
+  ast_out = CheckAndDecorate(ast);
 }
\ No newline at end of file
diff --git a/src/semantic/visitor.cpp b/src/semantic/visitor.cpp
index 42fb7c9..4369d97 100644
--- a/src/semantic/visitor.cpp
+++ b/src/semantic/visitor.cpp
@@ -1,41 +1,128 @@
 #include "visitor.h"
+#include <stdexcept>
 
-std::any Visitor::visitMxprog(MXParser::MxprogContext *context) {
-  // 空的函数体
-  return {};
+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::visitFunction(MXParser::FunctionContext *context) {
-  // 空的函数体
-  return {};
+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");
 }
-
-std::any Visitor::visitType(MXParser::TypeContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitClass_constructor(MXParser::Class_constructorContext *context) {
+  throw std::runtime_error("Not implemented");
 }
-
-std::any Visitor::visitBlock(MXParser::BlockContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitSuite(MXParser::SuiteContext *context) { throw std::runtime_error("Not implemented"); }
+std::any Visitor::visitEmpty_statement(MXParser::Empty_statementContext *context) {
+  throw std::runtime_error("Not implemented");
 }
-
-std::any Visitor::visitStatement(MXParser::StatementContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitDefinition_statement(MXParser::Definition_statementContext *context) {
+  throw std::runtime_error("Not implemented");
 }
-
-std::any Visitor::visitExpression(MXParser::ExpressionContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitExpr_statement(MXParser::Expr_statementContext *context) {
+  throw std::runtime_error("Not implemented");
 }
-
-std::any Visitor::visitReturnStmt(MXParser::ReturnStmtContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitIf_statement(MXParser::If_statementContext *context) {
+  throw std::runtime_error("Not implemented");
 }
-
-std::any Visitor::visitIfStmt(MXParser::IfStmtContext *context) {
-  // 空的函数体
-  return {};
+std::any Visitor::visitWhile_statement(MXParser::While_statementContext *context) {
+  throw std::runtime_error("Not implemented");
 }
+std::any Visitor::visitFor_statement(MXParser::For_statementContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitJmp_statement(MXParser::Jmp_statementContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitSuite_statement(MXParser::Suite_statementContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitDefine_statement(MXParser::Define_statementContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitGgll_expression(MXParser::Ggll_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitBxor_expression(MXParser::Bxor_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitSuffix_expression(MXParser::Suffix_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitLand_expression(MXParser::Land_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitPm_expression(MXParser::Pm_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitIndex_expression(MXParser::Index_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitOpposite_expression(MXParser::Opposite_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitNew_array_expression(MXParser::New_array_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitBasic_expression(MXParser::Basic_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitAccess_expression(MXParser::Access_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitBand_expression(MXParser::Band_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitNew_construct_expression(MXParser::New_construct_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitTernary_expression(MXParser::Ternary_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitBnot_expression(MXParser::Bnot_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitLnot_expression(MXParser::Lnot_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitPrefix_expression(MXParser::Prefix_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitRl_expression(MXParser::Rl_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitAssign_expression(MXParser::Assign_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitMdm_expression(MXParser::Mdm_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitNew_expression(MXParser::New_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitNe_expression(MXParser::Ne_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitBor_expression(MXParser::Bor_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitLor_expression(MXParser::Lor_expressionContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitThis_expr(MXParser::This_exprContext *context) { throw std::runtime_error("Not implemented"); }
+std::any Visitor::visitParen_expr(MXParser::Paren_exprContext *context) { throw std::runtime_error("Not implemented"); }
+std::any Visitor::visitId_expr(MXParser::Id_exprContext *context) { throw std::runtime_error("Not implemented"); }
+std::any Visitor::visitFunction_call_expr(MXParser::Function_call_exprContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitFormatted_string_expr(MXParser::Formatted_string_exprContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitConstant_expr(MXParser::Constant_exprContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitFormatted_string(MXParser::Formatted_stringContext *context) {
+  throw std::runtime_error("Not implemented");
+}
+std::any Visitor::visitConstant(MXParser::ConstantContext *context) { throw std::runtime_error("Not implemented"); }
+std::any Visitor::visitType(MXParser::TypeContext *context) { throw std::runtime_error("Not implemented"); }