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/*******************************************************************************
* Copyright (c) 2014 Jeff Martin.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the GNU Public License v3.0
* which accompanies this distribution, and is available at
* http://www.gnu.org/licenses/gpl.html
*
* Contributors:
* Jeff Martin - initial API and implementation
******************************************************************************/
package cuchaz.enigma.bytecode;
import java.util.Iterator;
import javassist.bytecode.BadBytecode;
import javassist.bytecode.Bytecode;
import javassist.bytecode.CodeAttribute;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.Opcode;
public class BytecodeIndexIterator implements Iterator<BytecodeIndexIterator.Index>
{
public static class Index
{
private CodeIterator m_iter;
private int m_pos;
private boolean m_isWide;
protected Index( CodeIterator iter, int pos, boolean isWide )
{
m_iter = iter;
m_pos = pos;
m_isWide = isWide;
}
public int getIndex( )
{
if( m_isWide )
{
return m_iter.s16bitAt( m_pos );
}
else
{
return m_iter.byteAt( m_pos );
}
}
public void setIndex( int val )
throws BadBytecode
{
if( m_isWide )
{
m_iter.write16bit( val, m_pos );
}
else
{
if( val < 256 )
{
// we can write the byte
m_iter.writeByte( val, m_pos );
}
else
{
// we need to upgrade this instruction to LDC_W
assert( m_iter.byteAt( m_pos - 1 ) == Opcode.LDC );
m_iter.insertGap( m_pos - 1, 1 );
m_iter.writeByte( Opcode.LDC_W, m_pos - 1 );
m_iter.write16bit( val, m_pos );
m_isWide = true;
// move the iterator to the next opcode
m_iter.move( m_pos + 2 );
}
}
// sanity check
assert( val == getIndex() );
}
public boolean isValid( Bytecode bytecode )
{
return getIndex() >= 0 && getIndex() < bytecode.getConstPool().getSize();
}
}
private Bytecode m_bytecode;
private CodeAttribute m_attribute;
private CodeIterator m_iter;
private Index m_next;
public BytecodeIndexIterator( Bytecode bytecode )
throws BadBytecode
{
m_bytecode = bytecode;
m_attribute = bytecode.toCodeAttribute();
m_iter = m_attribute.iterator();
m_next = getNext();
}
@Override
public boolean hasNext( )
{
return m_next != null;
}
@Override
public Index next( )
{
Index out = m_next;
try
{
m_next = getNext();
}
catch( BadBytecode ex )
{
throw new Error( ex );
}
return out;
}
@Override
public void remove( )
{
throw new UnsupportedOperationException();
}
private Index getNext( )
throws BadBytecode
{
while( m_iter.hasNext() )
{
int pos = m_iter.next();
int opcode = m_iter.byteAt( pos );
switch( opcode )
{
// for only these opcodes, the next two bytes are a const pool reference
case Opcode.ANEWARRAY:
case Opcode.CHECKCAST:
case Opcode.INSTANCEOF:
case Opcode.INVOKEDYNAMIC:
case Opcode.INVOKEINTERFACE:
case Opcode.INVOKESPECIAL:
case Opcode.INVOKESTATIC:
case Opcode.INVOKEVIRTUAL:
case Opcode.LDC_W:
case Opcode.LDC2_W:
case Opcode.MULTIANEWARRAY:
case Opcode.NEW:
case Opcode.PUTFIELD:
case Opcode.PUTSTATIC:
case Opcode.GETFIELD:
case Opcode.GETSTATIC:
return new Index( m_iter, pos + 1, true );
case Opcode.LDC:
return new Index( m_iter, pos + 1, false );
}
}
return null;
}
public Iterable<Index> indices( )
{
return new Iterable<Index>( )
{
@Override
public Iterator<Index> iterator( )
{
return BytecodeIndexIterator.this;
}
};
}
public void saveChangesToBytecode( )
{
BytecodeTools.setBytecode( m_bytecode, m_attribute.getCode() );
}
}
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