遍历AST过程中解释执行代码--java实现

本人博客内编译原理文章的配套资源jar包，包括词法分析，语法分析，中间代码生成，静态语义检查，代码解释执行以及抽象语法树的手动生成：https://download.csdn.net/download/as1072966956/10448935

转载请注明出处。

Lab5Main.java

package sch.cauc.edu.token;

import java.io.File;
import java.util.LinkedList;
import java.util.Stack;

import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.Assignment;
import org.eclipse.jdt.core.dom.Block;
import org.eclipse.jdt.core.dom.ExpressionStatement;
import org.eclipse.jdt.core.dom.InfixExpression;
import org.eclipse.jdt.core.dom.WhileStatement;

import edu.ustc.cs.compile.platform.interfaces.InterRepresent;
import edu.ustc.cs.compile.platform.interfaces.InterpreterException;

/**
 * 
 * 
 * Lab5Main
 * 创建人:xrzhang 
 * 时间：2018年5月31日-上午8:42:30 
 * @version 1.0.0
 *
 */
public class Lab5Main {
	public static void main(String[] args) throws InterpreterException {		
        String srcFileName = "test/expr5.txt"; 
        StaticCheck checker=new StaticCheck();
        InterRepresent ir =checker.doParse(srcFileName);
         ir.showIR();
        Interpreter it = new Interpreter();
        it.interpret(ir);            	   
    }
}

Interpreter.java

package sch.cauc.edu.token;

import java.util.Hashtable;
import java.util.Stack;

import org.eclipse.jdt.core.dom.*;
import edu.ustc.cs.compile.platform.interfaces.InterpreterInterface;
import edu.ustc.cs.compile.platform.interfaces.InterpreterException;
import edu.ustc.cs.compile.platform.interfaces.InterRepresent;


/**
 * 
 * SimpleMiniJOOL程序的解释器类。
 * Interpreter
 * 创建人:xrzhang 
 * 时间：2018年5月31日-上午8:44:21 
 * @version 1.0.0
 *
 */
public class Interpreter implements InterpreterInterface {
    public void interpret(InterRepresent ir) throws InterpreterException {
        InterpVisitor visitor = new InterpVisitor();
        try {
            // 调用实际解释执行SimpleMiniJOOL程序的代码

        	((Block)ir.getIR()).accept(visitor);
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
            throw new InterpreterException();
        } 
    }
}
/**
 * 
 * 封装实际解释执行SimpleMiniJOOL程序的代码。
 * InterpVisitor
 * 创建人:xrzhang 
 * 时间：2018年5月31日-上午8:46:06 
 * @version 1.0.0
 *
 */
class InterpVisitor extends ASTVisitor {
	Hashtable symTable = new Hashtable();
	Stack stack = new Stack(); 
    public boolean visit(IfStatement n) { 
    	n.getExpression().accept(this);
    	Statement thenstatement = n.getThenStatement();
    	Statement elsestatement = n.getElseStatement();
    	int result = stack.pop();
        if(result == 1){
        	 thenstatement.accept(this);
        }
        else{
        	if(null != elsestatement) elsestatement.accept(this);
        }
        return false;
    }
 
    public boolean visit(WhileStatement n) {
    	n.getExpression().accept(this);
    	int result = stack.pop();
    	while(result == 1){
    		n.getBody().accept(this);
    		n.getExpression().accept(this);
    		result = stack.pop();
    	}
        return false;
    }
   
    public void endVisit(Assignment n) {
         
        Assignment.Operator operator = n.getOperator();
        String varName = n.getLeftHandSide().toString();
        int value = stack.pop();
        stack.pop();
        if (operator == Assignment.Operator.ASSIGN) {
            symTable.put(varName, value);
        } /*else if (operator == Assignment.Operator.PLUS_ASSIGN) {
        
        } else if (operator == Assignment.Operator.MINUS_ASSIGN) {
        
        } else if (operator == Assignment.Operator.TIMES_ASSIGN) {
        
        } else if (operator == Assignment.Operator.DIVIDE_ASSIGN) {
         
        } else if (operator == Assignment.Operator.REMAINDER_ASSIGN) {
          
        } */
        System.out.println(varName + "=" + value);

    }
  
    public  void endVisit(InfixExpression n) {

        InfixExpression.Operator operator = n.getOperator();
        int leftValue,rightValue;
        rightValue = stack.pop();
        leftValue = stack.pop();        
        
        if (operator == InfixExpression.Operator.PLUS) {        	
        	stack.push(leftValue + rightValue);
        } else if (operator == InfixExpression.Operator.MINUS) {
        	stack.push(leftValue - rightValue);
        } else if (operator == InfixExpression.Operator.TIMES) {
        	stack.push(leftValue * rightValue);
        } else if (operator == InfixExpression.Operator.DIVIDE) {
        	if(rightValue == 0){
        		System.out.println("divided by zero");
        		System.exit(1);
        	}else{
        		stack.push(leftValue / rightValue);
        	}
        } else if (operator == InfixExpression.Operator.REMAINDER) {
        	if(rightValue == 0){
        		System.out.println("divided by zero");
        		System.exit(1);
        	}else{
        		stack.push(leftValue % rightValue);
        	}
        } else if (operator == InfixExpression.Operator.GREATER){
        	stack.push(leftValue > rightValue?1:0) ;
        	
        } else if (operator == InfixExpression.Operator.GREATER_EQUALS){
        	stack.push(leftValue >= rightValue?1:0) ;
        } else if (operator == InfixExpression.Operator.LESS){
        	stack.push(leftValue < rightValue?1:0) ;
        	
        } else if (operator == InfixExpression.Operator.LESS_EQUALS){
        	stack.push(leftValue <= rightValue?1:0) ;
        } else if (operator == InfixExpression.Operator.EQUALS){
        	stack.push(leftValue == rightValue?1:0) ;
        } else if (operator == InfixExpression.Operator.NOT_EQUALS){
        	stack.push(leftValue != rightValue?1:0) ;       	
        }
    }

    public  void endVisit(SimpleName n) {
    	String name = n.getIdentifier();
    	if (!symTable.containsKey(name)){
    		symTable.put(name, 0);    		
    	}
    	stack.push(symTable.get(name));
    }
    public  void endVisit(NumberLiteral n){
    	stack.push(Integer.parseInt(n.getToken()));
    }
   
}

expr.java

{
	int m,n,r;
	m=12;n=21;
	if(m