Method.java

package com.donaldy.jvm.method;

import com.donaldy.jvm.attr.*;
import com.donaldy.jvm.clz.ClassFile;
import com.donaldy.jvm.cmd.ByteCodeCommand;
import com.donaldy.jvm.constant.ConstantPool;
import com.donaldy.jvm.constant.UTF8Info;
import com.donaldy.jvm.loader.ByteCodeIterator;

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


public class Method {
	
	private int accessFlag;
	private int nameIndex;
	private int descriptorIndex;
	
	private CodeAttr codeAttr;
	
	private ClassFile clzFile;
	
	
	public ClassFile getClzFile() {
		return clzFile;
	}

	public int getNameIndex() {
		return nameIndex;
	}
	public int getDescriptorIndex() {
		return descriptorIndex;
	}
	
	public CodeAttr getCodeAttr() {
		return codeAttr;
	}

	public void setCodeAttr(CodeAttr code) {
		this.codeAttr = code;
	}

	public Method(ClassFile clzFile,int accessFlag, int nameIndex, int descriptorIndex) {
		this.clzFile = clzFile;
		this.accessFlag = accessFlag;
		this.nameIndex = nameIndex;
		this.descriptorIndex = descriptorIndex;
	}
	
	
	public static Method parse(ClassFile clzFile, ByteCodeIterator iter){


		int accessFlag = iter.nextU2ToInt();
		int nameIndex = iter.nextU2ToInt();
		int descIndex = iter.nextU2ToInt();
		int attribCount = iter.nextU2ToInt();


		Method m = new Method(clzFile, accessFlag, nameIndex, descIndex);

		for( int j = 1; j <= attribCount; j++){

			int attrNameIndex = iter.nextU2ToInt();

			String attrName = clzFile.getConstantPool().getUTF8String(attrNameIndex);

			iter.back(2);

			if(AttributeInfo.CODE.equalsIgnoreCase(attrName)){

				CodeAttr codeAttr = CodeAttr.parse(clzFile, iter);
				m.setCodeAttr(codeAttr);
			} else{
				throw new RuntimeException("only CODE attribute is implemented , please implement the "+ attrName);
			}

		}

		return m ;

		//////////////////////Backup///////////////////////
		/*int accessFlag = iter.nextU2ToInt();
		int nameIndex = iter.nextU2ToInt();
		int descriptorIndex = iter.nextU2ToInt();

		int attributeCount = iter.nextU2ToInt();
		System.out.println("attributeCount : " + attributeCount);

		int attrNameIndex = iter.nextU2ToInt();
		if (!"Code".equals(clzFile.getConstantPool().getUTF8String(attrNameIndex)))
			throw new RuntimeException("attributeInfo : " + attrNameIndex);

		//CodeAttr.parse
		int attrLen = iter.nextU4ToInt();
		int maxStack = iter.nextU2ToInt();
		int maxLocals = iter.nextU2ToInt();
		int codeLen = iter.nextU4ToInt();
		String code = iter.nextUxToHexString(codeLen);

		CodeAttr codeAttr = new CodeAttr(attrNameIndex, attrLen, maxStack, maxLocals, codeLen, code);

		int exceptionLen = iter.nextU2ToInt();
		System.out.println("execptionLen : " + exceptionLen);

		int attributesCount = iter.nextU2ToInt();
		System.out.println("attributeCount : " + attributesCount);

		LineNumberTable lnTable = LineNumberTable.parse(iter);
		codeAttr.setLineNumberTable(lnTable);

		LocalVariableTable lvTable = LocalVariableTable.parse(iter);
		codeAttr.setLocalVariableTable(lvTable);


		Method method = new Method(clzFile, accessFlag, nameIndex, descriptorIndex);

		method.setCodeAttr(codeAttr);
		return method;*/
		
	}

	public String toString() {

		ConstantPool pool = this.clzFile.getConstantPool();
		StringBuilder buffer = new StringBuilder();

		String name = ((UTF8Info)pool.getConstantInfo(this.nameIndex)).getValue();

		String desc = ((UTF8Info)pool.getConstantInfo(this.descriptorIndex)).getValue();

		buffer.append(name).append(":").append(desc).append("\n");

		buffer.append(this.codeAttr.toString(pool));

		return buffer.toString();
	}

	public ByteCodeCommand[] getCmds() {

		return this.getCodeAttr().getCmds();

	}

	private String getParamAndReturnType() {
		UTF8Info nameAndTypeInfo = (UTF8Info) this.getClzFile()
			.getConstantPool().getConstantInfo(this.getDescriptorIndex());
		return nameAndTypeInfo.getValue();
	}

	public List<String> getParameterList() {

		//e.g. (Ljava/util/List;Ljava/lang/String;II)V
		String paramAndType = getParamAndReturnType();

		int first = paramAndType.indexOf("(");
		int last = paramAndType.lastIndexOf(")");

		//e.g. Ljava/util/List;Ljava/lang/String;II
		String param = paramAndType.substring(first + 1, last);

		List<String> paramList = new ArrayList<>();

		if ((null == param) || "".equals(param)) {
			return paramList;
		}

		while (!param.equals("")) {
			int pos = 0;

			//这是一个对象类型
			if (param.charAt(pos) == 'L') {
				int end = param.indexOf(";");

				if (end == -1) {
					throw new RuntimeException("can't find the ; fro a object type");
				}

				paramList.add(param.substring(pos+ 1, end));

				pos = end + 1;
			}
			else if (param.charAt(pos) == 'I') {
				//int
				paramList.add("I");
				pos ++;
			}
			else if (param.charAt(pos) == 'F') {
				//float
				paramList.add("F");
				pos ++;
			} else {
				throw new RuntimeException("the param has unsupported type : " + param);
			}

			param = param.substring(pos);
		}

		return paramList;
	}
}