From b469814281b063c8ea6a752c28de7b2fdcca2cac Mon Sep 17 00:00:00 2001
From: jeff
Date: Mon, 25 Aug 2014 16:49:41 -0400
Subject: wrote CheckCastIterator to try to do generic type inference. It's too
 hard to do at the bytecode level though, so I'm tabling that problem for now.

---
 src/cuchaz/enigma/bytecode/CheckCastIterator.java | 150 ++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 src/cuchaz/enigma/bytecode/CheckCastIterator.java

diff --git a/src/cuchaz/enigma/bytecode/CheckCastIterator.java b/src/cuchaz/enigma/bytecode/CheckCastIterator.java
new file mode 100644
index 0000000..7ed5d7f
--- /dev/null
+++ b/src/cuchaz/enigma/bytecode/CheckCastIterator.java
@@ -0,0 +1,150 @@
+/*******************************************************************************
+ * 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.CodeAttribute;
+import javassist.bytecode.CodeIterator;
+import javassist.bytecode.ConstPool;
+import javassist.bytecode.Descriptor;
+import javassist.bytecode.Opcode;
+import cuchaz.enigma.bytecode.CheckCastIterator.CheckCast;
+import cuchaz.enigma.mapping.ClassEntry;
+import cuchaz.enigma.mapping.MethodEntry;
+
+public class CheckCastIterator implements Iterator<CheckCast>
+{
+	public static class CheckCast
+	{
+		public String className;
+		public MethodEntry prevMethodEntry;
+		
+		public CheckCast( String className, MethodEntry prevMethodEntry )
+		{
+			this.className = className;
+			this.prevMethodEntry = prevMethodEntry;
+		}
+	}
+	
+	private ConstPool m_constants;
+	private CodeAttribute m_attribute;
+	private CodeIterator m_iter;
+	private CheckCast m_next;
+	
+	public CheckCastIterator( CodeAttribute codeAttribute )
+	throws BadBytecode
+	{
+		m_constants = codeAttribute.getConstPool();
+		m_attribute = codeAttribute;
+		m_iter = m_attribute.iterator();
+		
+		m_next = getNext();
+	}
+	
+	@Override
+	public boolean hasNext( )
+	{
+		return m_next != null;
+	}
+
+	@Override
+	public CheckCast next( )
+	{
+		CheckCast out = m_next;
+		try
+		{
+			m_next = getNext();
+		}
+		catch( BadBytecode ex )
+		{
+			throw new Error( ex );
+		}
+		return out;
+	}
+
+	@Override
+	public void remove( )
+	{
+		throw new UnsupportedOperationException();
+	}
+	
+	private CheckCast getNext( )
+	throws BadBytecode
+	{
+		int prevPos = 0;
+		while( m_iter.hasNext() )
+		{
+			int pos = m_iter.next();
+			int opcode = m_iter.byteAt( pos );
+			switch( opcode )
+			{
+				case Opcode.CHECKCAST:
+					
+					// get the type of this op code (next two bytes are a classinfo index)
+					MethodEntry prevMethodEntry = getMethodEntry( prevPos );
+					if( prevMethodEntry != null )
+					{
+						return new CheckCast(
+							m_constants.getClassInfo( m_iter.s16bitAt( pos + 1 ) ),
+							prevMethodEntry
+						);
+					}
+				break;
+			}
+			prevPos = pos;
+		}
+		return null;
+	}
+	
+	private MethodEntry getMethodEntry( int pos )
+	{
+		switch( m_iter.byteAt( pos ) )
+		{
+			case Opcode.INVOKEVIRTUAL:
+			case Opcode.INVOKESTATIC:
+			case Opcode.INVOKEDYNAMIC:
+			case Opcode.INVOKESPECIAL:
+			{
+				int index = m_iter.s16bitAt( pos + 1 );
+				return new MethodEntry(
+					new ClassEntry( Descriptor.toJvmName( m_constants.getMethodrefClassName( index ) ) ),
+					m_constants.getMethodrefName( index ),
+					m_constants.getMethodrefType( index )
+				);
+			}
+			
+			case Opcode.INVOKEINTERFACE:
+			{
+				int index = m_iter.s16bitAt( pos + 1 );
+				return new MethodEntry(
+					new ClassEntry( Descriptor.toJvmName( m_constants.getInterfaceMethodrefClassName( index ) ) ),
+					m_constants.getInterfaceMethodrefName( index ),
+					m_constants.getInterfaceMethodrefType( index )
+				);
+			}
+		}
+		return null;
+	}
+
+	public Iterable<CheckCast> casts( )
+	{
+		return new Iterable<CheckCast>( )
+		{
+			@Override
+			public Iterator<CheckCast> iterator( )
+			{
+				return CheckCastIterator.this;
+			}
+		};
+	}
+}
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