ExecutorEngine.java

package com.donaldy.jvm.engine;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import com.donaldy.jvm.attr.CodeAttr;
import com.donaldy.jvm.clz.ClassFile;
import com.donaldy.jvm.cmd.ByteCodeCommand;
import com.donaldy.jvm.constant.MethodRefInfo;
import com.donaldy.jvm.method.Method;

public class ExecutorEngine {

	private Stack<StackFrame> stack = new Stack<StackFrame>();
	
	public ExecutorEngine() {
		
	}
	
	public void execute(Method mainMethod){

		StackFrame mainFrame = StackFrame.create(mainMethod);

		stack.push(mainFrame);

		while (!stack.empty()) {

			StackFrame frame = stack.peek();

			ExecutionResult result = frame.execute();

			//函数栈帧来了。。。
			if (result.isPauseAndRunNewFrame()) {

				Method nextMethod = result.getNextMethod();

				StackFrame nextFrame = StackFrame.create(nextMethod);

				nextFrame.setCallerFrame(frame);

				setupFunctionCallParams(frame, nextFrame);

				stack.push(nextFrame);
			} else {

				//认为其执行完了
				stack.pop();

			}
		}


	}



	private void setupFunctionCallParams(StackFrame currentFrame,StackFrame nextFrame) {

		Method nextMethod = nextFrame.getMethod();


		List<String> paramList = nextMethod.getParameterList();

		//加上1 是因为要把this也传递过去

		int paramNum = paramList.size() + 1;


		List<JavaObject> values = new ArrayList<JavaObject>();

		//数据结构知识：  从栈中取出栈顶的x个元素
		while(paramNum>0){
			values.add(currentFrame.getOprandStack().pop());
			paramNum --;
		}
		//数据结构知识：  把一个列表倒序排列
		List<JavaObject> params = new ArrayList<JavaObject>();

		for(int i=values.size()-1; i>=0 ;i--){
			params.add(values.get(i));
		}


		nextFrame.setLocalVariableTable(params);

	}
	
}