package com.coderising.jvm.loader;
import java.io.UnsupportedEncodingException;
import com.coderising.jvm.clz.AccessFlag;
import com.coderising.jvm.clz.ClassFile;
import com.coderising.jvm.clz.ClassIndex;
import com.coderising.jvm.constant.ClassInfo;
import com.coderising.jvm.constant.ConstantPool;
import com.coderising.jvm.constant.FieldRefInfo;
import com.coderising.jvm.constant.MethodRefInfo;
import com.coderising.jvm.constant.NameAndTypeInfo;
import com.coderising.jvm.constant.NullConstantInfo;
import com.coderising.jvm.constant.StringInfo;
import com.coderising.jvm.constant.UTF8Info;
public class ClassFileParser {
public ClassFile parse(byte[] codes) {
ClassFile clzFile = new ClassFile();
ByteCodeIterator iterator = new ByteCodeIterator(codes);
// Magic Number
String magicNumber = iterator.next4BytesToString();
clzFile.setMagicNumer(magicNumber);
// Version Number
int minorVersion = iterator.next2BytesToInt();
int majorVersion = iterator.next2BytesToInt();
clzFile.setMinorVersion(minorVersion);
clzFile.setMajorVersion(majorVersion);
clzFile.setPool(parseConstantPool(iterator));
clzFile.setAccessFlag(parseAccessFlag(iterator));
clzFile.setClassIndex(parseClassIndex(iterator));
return clzFile;
}
private AccessFlag parseAccessFlag(ByteCodeIterator iterator) {
int flagValue = iterator.next2BytesToInt();
AccessFlag accessFlag = new AccessFlag(flagValue);
return accessFlag;
}
private ClassIndex parseClassIndex(ByteCodeIterator iterator) {
ClassIndex classIndex = new ClassIndex();
int thisClassIndex = iterator.next2BytesToInt();
int superClassIndex = iterator.next2BytesToInt();
classIndex.setThisClassIndex(thisClassIndex);
classIndex.setSuperClassIndex(superClassIndex);
return classIndex;
}
private ConstantPool parseConstantPool(ByteCodeIterator iterator) {
ConstantPool pool = new ConstantPool();
int ConstantNumber = iterator.next2BytesToInt();
pool.addConstantInfo(new NullConstantInfo());
for (int i = 1; i <= ConstantNumber - 1; i++) {
int tag = iterator.nextByteToInt();
if (tag == 7) {
ClassInfo clzInfo = new ClassInfo(pool);
int utf8Index = iterator.next2BytesToInt();
clzInfo.setUtf8Index(utf8Index);
pool.addConstantInfo(clzInfo);
}
else if(tag == 1){
UTF8Info utf8Info = new UTF8Info(pool);
int length = iterator.next2BytesToInt();
utf8Info.setLength(length);
byte[] utf8Bytes = iterator.getBytes(length);
String value = null;
try {
value = new String(utf8Bytes, "UTF-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
utf8Info.setValue(value);
pool.addConstantInfo(utf8Info);
}
else if(tag == 12){
NameAndTypeInfo nameAndTypeInfo = new NameAndTypeInfo(pool);
int index_Name = iterator.next2BytesToInt();
int index_Describe = iterator.next2BytesToInt();
nameAndTypeInfo.setIndex_Name(index_Name);
nameAndTypeInfo.setIndex_Describe(index_Describe);
pool.addConstantInfo(nameAndTypeInfo);
}
else if(tag == 10){
MethodRefInfo methofInfo = new MethodRefInfo(pool);
int index_ClassInfo = iterator.next2BytesToInt();
int index_NameAndType = iterator.next2BytesToInt();
methofInfo.setClassInfoIndex(index_ClassInfo);
methofInfo.setNameAndTypeIndex(index_NameAndType);
pool.addConstantInfo(methofInfo);
}
else if (tag == 9) {
FieldRefInfo fieldRefInfo = new FieldRefInfo(pool);
int index_ClassInfo = iterator.next2BytesToInt();
int index_NameAndType = iterator.next2BytesToInt();
fieldRefInfo.setClassInfoIndex(index_ClassInfo);
fieldRefInfo.setNameAndTypeIndex(index_NameAndType);
pool.addConstantInfo(fieldRefInfo);
}
else if (tag == 8) {
StringInfo stringInfo = new StringInfo(pool);
int index = iterator.next2BytesToInt();
stringInfo.setIndex(index);
pool.addConstantInfo(stringInfo);
}
}
return pool;
}
}