code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.compiler.util;
  
  import org.apache.bcel.generic.ACONST_NULL;
  import org.apache.bcel.generic.ALOAD;
  import org.apache.bcel.generic.ASTORE;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.ILOAD;
  import org.apache.bcel.generic.ISTORE;
  import org.apache.bcel.generic.Instruction;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.LocalVariableGen;
  import org.apache.bcel.generic.Type;
  import org.apache.xalan.xsltc.compiler.Constants;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  public final class CompareGenerator extends MethodGenerator {
  
      private static int DOM_INDEX      = 1;
      private static int CURRENT_INDEX  = 2;
      private static int LEVEL_INDEX    = 3;
      private static int TRANSLET_INDEX = 4;
      private static int LAST_INDEX     = 5;
      private int ITERATOR_INDEX = 6;
  
      private final Instruction _iloadCurrent;
      private final Instruction _istoreCurrent;
      private final Instruction _aloadDom;
      private final Instruction _iloadLast;
      private final Instruction _aloadIterator;
      private final Instruction _astoreIterator;
  
      public CompareGenerator(int access_flags, Type return_type,
  			    Type[] arg_types, String[] arg_names,
  			    String method_name, String class_name,
  			    InstructionList il, ConstantPoolGen cp) {
  	super(access_flags, return_type, arg_types, arg_names, method_name, 
  	      class_name, il, cp);
  	
  	_iloadCurrent = new ILOAD(CURRENT_INDEX);
  	_istoreCurrent = new ISTORE(CURRENT_INDEX);
  	_aloadDom = new ALOAD(DOM_INDEX);
  	_iloadLast = new ILOAD(LAST_INDEX);
  
  	LocalVariableGen iterator =
  	    addLocalVariable("iterator",
  			     Util.getJCRefType(Constants.NODE_ITERATOR_SIG),
  			     null, null);
  	ITERATOR_INDEX = iterator.getIndex();
  	_aloadIterator = new ALOAD(ITERATOR_INDEX);
  	_astoreIterator = new ASTORE(ITERATOR_INDEX);
  	il.append(new ACONST_NULL());
  	il.append(storeIterator());
      }
  
      public Instruction loadLastNode() {
  	return _iloadLast;
      }
  
      public Instruction loadCurrentNode() {
  	return _iloadCurrent;
      }
  
      public Instruction storeCurrentNode() {
  	return _istoreCurrent;
      }
  
      public Instruction loadDOM() {
  	return _aloadDom;
      }
  
      public int getHandlerIndex() {
  	return INVALID_INDEX;		// not available
      }
  
      public int getIteratorIndex() {
  	return INVALID_INDEX;
      }
  
      public Instruction storeIterator() {
  	return _astoreIterator;
      }
      
      public Instruction loadIterator() {
  	return _aloadIterator;
      }
  
      //??? may not be used anymore
      public int getLocalIndex(String name) {
  	if (name.equals("current")) {
  	    return CURRENT_INDEX;
  	}
  	return super.getLocalIndex(name);
      }
  }
  