src/org/apache/xalan/xsltc/compiler/IdKeyPattern.java

/*
 * 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.GOTO;
import org.apache.bcel.generic.IFNE;
import org.apache.bcel.generic.INVOKEVIRTUAL;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.PUSH;
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;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
abstract class IdKeyPattern extends LocationPathPattern {

    protected RelativePathPattern _left = null;;
    private String _index = null;
    private String _value = null;;

    public IdKeyPattern(String index, String value) {
	_index = index;
	_value = value;
    }

    public String getIndexName() {
	return(_index);
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	return Type.NodeSet;
    }
    
    public boolean isWildcard() {
	return false;
    }
    
    public void setLeft(RelativePathPattern left) {
	_left = left;
    }

    public StepPattern getKernelPattern() {
	return(null);
    }
    
    public void reduceKernelPattern() { }

    public String toString() {
	return "id/keyPattern(" + _index + ", " + _value + ')';
    }

    /**
     * This method is called when the constructor is compiled in
     * Stylesheet.compileConstructor() and not as the syntax tree is traversed.
     */
    public void translate(ClassGenerator classGen,
			  MethodGenerator methodGen) {

	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	// Returns the KeyIndex object of a given name
	final int getKeyIndex = cpg.addMethodref(TRANSLET_CLASS,
						 "getKeyIndex",
						 "(Ljava/lang/String;)"+
						 KEY_INDEX_SIG);
	
	// Initialises a KeyIndex to return nodes with specific values
	final int lookupId = cpg.addMethodref(KEY_INDEX_CLASS,
					      "containsID",
					      "(ILjava/lang/Object;)I");
	final int lookupKey = cpg.addMethodref(KEY_INDEX_CLASS,
					       "containsKey",
					       "(ILjava/lang/Object;)I");
	final int getNodeIdent = cpg.addInterfaceMethodref(DOM_INTF,
							   "getNodeIdent",
							   "(I)"+NODE_SIG);				       

	// Call getKeyIndex in AbstractTranslet with the name of the key
	// to get the index for this key (which is also a node iterator).
	il.append(classGen.loadTranslet());
	il.append(new PUSH(cpg,_index));
	il.append(new INVOKEVIRTUAL(getKeyIndex));
	
	// Now use the value in the second argument to determine what nodes
	// the iterator should return.
	il.append(SWAP);
	il.append(new PUSH(cpg,_value));
	if (this instanceof IdPattern)
	{
	    il.append(new INVOKEVIRTUAL(lookupId));
	}
	else
	{
	    il.append(new INVOKEVIRTUAL(lookupKey));
	}

	_trueList.add(il.append(new IFNE(null)));
	_falseList.add(il.append(new GOTO(null)));
    }

}