/*
 * 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;

import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.ILOAD;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.ISTORE;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.LocalVariableGen;
import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
import org.apache.xalan.xsltc.compiler.util.Type;
import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
import org.apache.xalan.xsltc.compiler.util.Util;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
final class ParentPattern extends RelativePathPattern {
    private final Pattern _left;
    private final RelativePathPattern _right;
		
    public ParentPattern(Pattern left, RelativePathPattern right) {
	(_left = left).setParent(this);
	(_right = right).setParent(this);
    }

    public void setParser(Parser parser) {
	super.setParser(parser);
	_left.setParser(parser);
	_right.setParser(parser);
    }
    
    public boolean isWildcard() {
	return false;
    }
	
    public StepPattern getKernelPattern() {
	return _right.getKernelPattern();
    }
	
    public void reduceKernelPattern() {
	_right.reduceKernelPattern();
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	_left.typeCheck(stable);
	return _right.typeCheck(stable);
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();
	final LocalVariableGen local =
	    methodGen.addLocalVariable2("ppt", 
					Util.getJCRefType(NODE_SIG),
					null);
	
	final org.apache.bcel.generic.Instruction loadLocal =
	    new ILOAD(local.getIndex());
	final org.apache.bcel.generic.Instruction storeLocal =
	    new ISTORE(local.getIndex());

	if (_right.isWildcard()) {
	    il.append(methodGen.loadDOM());
	    il.append(SWAP);
	}
	else if (_right instanceof StepPattern) {
	    il.append(DUP);
	    local.setStart(il.append(storeLocal));
	    
	    _right.translate(classGen, methodGen);
	    
	    il.append(methodGen.loadDOM());
	    local.setEnd(il.append(loadLocal));
	}
	else {
	    _right.translate(classGen, methodGen);

	    if (_right instanceof AncestorPattern) {
		il.append(methodGen.loadDOM());
		il.append(SWAP);
	    }
	}

	final int getParent = cpg.addInterfaceMethodref(DOM_INTF,
							GET_PARENT,
							GET_PARENT_SIG);
	il.append(new INVOKEINTERFACE(getParent, 2));

	final SyntaxTreeNode p = getParent();
	if (p == null || p instanceof Instruction || 
	    p instanceof TopLevelElement) 
	{
	    _left.translate(classGen, methodGen);
	}
	else {
	    il.append(DUP);
	    InstructionHandle storeInst = il.append(storeLocal);

            if (local.getStart() == null) {
                local.setStart(storeInst);
            }
	    _left.translate(classGen, methodGen);

	    il.append(methodGen.loadDOM());
	    local.setEnd(il.append(loadLocal));
	}

	methodGen.removeLocalVariable(local);
	
	/*
	 * If _right is an ancestor pattern, backpatch _left false
	 * list to the loop that searches for more ancestors.
	 */
	if (_right instanceof AncestorPattern) {
	    final AncestorPattern ancestor = (AncestorPattern) _right;
	    _left.backPatchFalseList(ancestor.getLoopHandle());    // clears list
	}

	_trueList.append(_right._trueList.append(_left._trueList));
	_falseList.append(_right._falseList.append(_left._falseList));
    }

    public String toString() {
	return "Parent(" + _left + ", " + _right + ')';
    }
}