ExecutorEngine.java

package com.coderising.jvm.engine;

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

import com.coderising.jvm.attr.CodeAttr;
import com.coderising.jvm.clz.ClassFile;
import com.coderising.jvm.cmd.ByteCodeCommand;
import com.coderising.jvm.constant.MethodRefInfo;
import com.coderising.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.isEmpty()) {
			
			StackFrame frame = stack.peek();
			
			ExecutionResult result = frame.execute();
			
			if (result.isPauseAndRunNewFrame()) {
				
				Method nextMethod = result.getNextMethod();
				StackFrame nextFrame = StackFrame.create(nextMethod);
				nextFrame.setCallerFrame(frame);
				setupFunctionCallParams(frame,nextFrame);
				
				stack.push(nextFrame);	
				
			} else {
				
				stack.pop();
			}
			
		}
	}
	
	
	
	private void setupFunctionCallParams(StackFrame currentFrame,StackFrame nextFrame) {
		
		Method nextMethod = nextFrame.getMethod();
		
		List<String> paramList = nextMethod.getParameterList();
		
		int paramNum = paramList.size() + 1;
		
		List<JavaObject> params = new ArrayList<JavaObject>();
		
		while(paramNum > 0) {
			params.add(currentFrame.getOprandStack().pop());
			paramNum--;
		}
		
		Collections.reverse(params);
		
		nextFrame.setLocalVariableTable(params);
		
	}
	
}