/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed 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: MethodGenerator.java,v 1.15 2004/02/16 22:26:44 minchau Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler.util;

import com.sun.org.apache.bcel.internal.generic.ALOAD;
import com.sun.org.apache.bcel.internal.generic.ASTORE;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.ICONST;
import com.sun.org.apache.bcel.internal.generic.ILOAD;
import com.sun.org.apache.bcel.internal.generic.INVOKEINTERFACE;
import com.sun.org.apache.bcel.internal.generic.ISTORE;
import com.sun.org.apache.bcel.internal.generic.Instruction;
import com.sun.org.apache.bcel.internal.generic.InstructionHandle;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.LocalVariableGen;
import com.sun.org.apache.bcel.internal.generic.MethodGen;
import com.sun.org.apache.bcel.internal.generic.Type;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
public class MethodGenerator extends MethodGen
    implements com.sun.org.apache.xalan.internal.xsltc.compiler.Constants {
    protected static final int INVALID_INDEX   = -1;
    
    private static final String START_ELEMENT_SIG   
	= "(" + STRING_SIG + ")V";
    private static final String END_ELEMENT_SIG     
	= START_ELEMENT_SIG;
    
    private InstructionList _mapTypeSub;
	
    private static final int DOM_INDEX       = 1;
    private static final int ITERATOR_INDEX  = 2;
    private static final int HANDLER_INDEX   = 3;

    private Instruction       _iloadCurrent;
    private Instruction       _istoreCurrent;
    private final Instruction _astoreHandler;
    private final Instruction _aloadHandler;
    private final Instruction _astoreIterator;
    private final Instruction _aloadIterator;
    private final Instruction _aloadDom;
    private final Instruction _astoreDom;
    
    private final Instruction _startElement;
    private final Instruction _endElement;
    private final Instruction _startDocument;
    private final Instruction _endDocument;
    private final Instruction _attribute;
    private final Instruction _uniqueAttribute;
    private final Instruction _namespace;

    private final Instruction _setStartNode;
    private final Instruction _reset;
    private final Instruction _nextNode;

    private SlotAllocator _slotAllocator;
    private boolean _allocatorInit = false;
    
    public MethodGenerator(int access_flags, Type return_type,
			   Type[] arg_types, String[] arg_names,
			   String method_name, String class_name,
			   InstructionList il, ConstantPoolGen cpg) {
	super(access_flags, return_type, arg_types, arg_names, method_name, 
	      class_name, il, cpg);
	
	_astoreHandler  = new ASTORE(HANDLER_INDEX);
	_aloadHandler   = new ALOAD(HANDLER_INDEX);
	_astoreIterator = new ASTORE(ITERATOR_INDEX);
	_aloadIterator  = new ALOAD(ITERATOR_INDEX);
	_aloadDom       = new ALOAD(DOM_INDEX);
	_astoreDom      = new ASTORE(DOM_INDEX);
	
	final int startElement =
	    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
				      "startElement",
				      START_ELEMENT_SIG);
	_startElement = new INVOKEINTERFACE(startElement, 2);
	
	final int endElement =
	    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
				      "endElement",
				      END_ELEMENT_SIG);
	_endElement = new INVOKEINTERFACE(endElement, 2);

	final int attribute =
	    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
				      "addAttribute", 
				      "("
				      + STRING_SIG
				      + STRING_SIG
				      + ")V");
	_attribute = new INVOKEINTERFACE(attribute, 3);

	final int uniqueAttribute =
	    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
				      "addUniqueAttribute", 
				      "("
				      + STRING_SIG
				      + STRING_SIG
				      + "I)V");
	_uniqueAttribute = new INVOKEINTERFACE(uniqueAttribute, 4);

	final int namespace =
	    cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
				      "namespaceAfterStartElement", 
				      "("
				      + STRING_SIG
				      + STRING_SIG
				      + ")V");
	_namespace = new INVOKEINTERFACE(namespace, 3);
	
	int index = cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
					      "startDocument",
					      "()V");
	_startDocument = new INVOKEINTERFACE(index, 1);
	
	index = cpg.addInterfaceMethodref(TRANSLET_OUTPUT_INTERFACE,
					  "endDocument",
					  "()V");
	_endDocument = new INVOKEINTERFACE(index, 1);
	
	
	index = cpg.addInterfaceMethodref(NODE_ITERATOR,
					  SET_START_NODE,
					  SET_START_NODE_SIG);
	_setStartNode = new INVOKEINTERFACE(index, 2);

	index = cpg.addInterfaceMethodref(NODE_ITERATOR,
					  "reset", "()"+NODE_ITERATOR_SIG);
	_reset = new INVOKEINTERFACE(index, 1);
	
	index = cpg.addInterfaceMethodref(NODE_ITERATOR, NEXT, NEXT_SIG);
	_nextNode = new INVOKEINTERFACE(index, 1);
	
	_slotAllocator = new SlotAllocator();
	_slotAllocator.initialize(getLocalVariables());
	_allocatorInit = true;
    }

    /**
     * Allocates a local variable. If the slot allocator has already been
     * initialized, then call addLocalVariable2() so that the new variable
     * is known to the allocator. Failing to do this may cause the allocator 
     * to return a slot that is already in use.
     */
    public LocalVariableGen addLocalVariable(String name, Type type,
					     InstructionHandle start,
					     InstructionHandle end) 
    {
	return (_allocatorInit) ? addLocalVariable2(name, type, start) 
	    : super.addLocalVariable(name, type, start, end);
    }
    
    public LocalVariableGen addLocalVariable2(String name, Type type,
					      InstructionHandle start) 
    {
	return super.addLocalVariable(name, type,
				      _slotAllocator.allocateSlot(type),
				      start, null);
    }

    public void removeLocalVariable(LocalVariableGen lvg) {
	_slotAllocator.releaseSlot(lvg);
	super.removeLocalVariable(lvg);
    }

    public Instruction loadDOM() {
	return _aloadDom;
    }

    public Instruction storeDOM() {
	return _astoreDom;
    }
    
    public Instruction storeHandler() {
	return _astoreHandler;
    }

    public Instruction loadHandler() {
	return _aloadHandler;
    }

    public Instruction storeIterator() {
	return _astoreIterator;
    }
    
    public Instruction loadIterator() {
	return _aloadIterator;
    }
    
    public final Instruction setStartNode() {
	return _setStartNode;
    }

    public final Instruction reset() {
	return _reset;
    }
    
    public final Instruction nextNode() {
	return _nextNode;
    }

    public final Instruction startElement() {
	return _startElement;
    }

    public final Instruction endElement() {
	return _endElement;
    }

    public final Instruction startDocument() {
	return _startDocument;
    }

    public final Instruction endDocument() {
	return _endDocument;
    }

    public final Instruction attribute() {
	return _attribute;
    }

    public final Instruction uniqueAttribute() {
    	return _uniqueAttribute;
    }

    public final Instruction namespace() {
	return _namespace;
    }

    public Instruction loadCurrentNode() {
	if (_iloadCurrent == null) {
	    int idx = getLocalIndex("current");
	    if (idx > 0)
		_iloadCurrent = new ILOAD(idx);
	    else
		_iloadCurrent = new ICONST(0);
	}
	return _iloadCurrent;
    }

    public Instruction storeCurrentNode() {
	return _istoreCurrent != null
	    ? _istoreCurrent
	    : (_istoreCurrent = new ISTORE(getLocalIndex("current")));
    }

    /** by default context node is the same as current node. MK437 */
    public Instruction loadContextNode() {
	return loadCurrentNode();
    }

    public Instruction storeContextNode() {
	return storeCurrentNode();
    }

    public int getLocalIndex(String name) {
	return getLocalVariable(name).getIndex();
    }

    public LocalVariableGen getLocalVariable(String name) {
	final LocalVariableGen[] vars = getLocalVariables();
	for (int i = 0; i < vars.length; i++)
	    if (vars[i].getName().equals(name))
		return vars[i];
	return null;	
    }

    public void setMaxLocals() {
	
	// Get the current number of local variable slots
	int maxLocals = super.getMaxLocals();
	int prevLocals = maxLocals;

	// Get numer of actual variables
	final LocalVariableGen[] localVars = super.getLocalVariables();
	if (localVars != null) {
	    if (localVars.length > maxLocals)
		maxLocals = localVars.length;
	}

	// We want at least 5 local variable slots (for parameters)
	if (maxLocals < 5) maxLocals = 5;

	super.setMaxLocals(maxLocals);
    }

}