org.apache.xalan.xsltc.compiler.AncestorPattern Maven / Gradle / Ivy

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Xalan-Java is an XSLT processor for transforming XML documents into HTML, text, or other XML document types. It implements XSL Transformations (XSLT) Version 1.0 and XML Path Language (XPath) Version 1.0 and can be used from the command line, in an applet or a servlet, or as a module in other program.
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/*
 * 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: AncestorPattern.java 468650 2006-10-28 07:03:30Z minchau $
 */

package org.apache.xalan.xsltc.compiler;

import org.apache.bcel.generic.BranchHandle;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.GOTO;
import org.apache.bcel.generic.IFLT;
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
 * @author Erwin Bolwidt 
 */
final class AncestorPattern extends RelativePathPattern {

    private final Pattern _left;	// may be null
    private final RelativePathPattern _right;
    private InstructionHandle _loop;
		
    public AncestorPattern(RelativePathPattern right) {
	this(null, right);
    }

    public AncestorPattern(Pattern left, RelativePathPattern right) {
	_left = left;
	(_right = right).setParent(this);
	if (left != null) {
	    left.setParent(this);
	}
    }
	
    public InstructionHandle getLoopHandle() {
	return _loop;
    }

    public void setParser(Parser parser) {
	super.setParser(parser);
	if (_left != null) {
	    _left.setParser(parser);
	}
	_right.setParser(parser);
    }
    
    public boolean isWildcard() {
	//!!! can be wildcard
	return false;
    }
	
    public StepPattern getKernelPattern() {
	return _right.getKernelPattern();
    }

    public void reduceKernelPattern() {
	_right.reduceKernelPattern();
    }
	
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	if (_left != null) {
	    _left.typeCheck(stable);
	}
	return _right.typeCheck(stable);
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	InstructionHandle parent;
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	/* 
	 * The scope of this local var must be the entire method since
	 * a another pattern may decide to jump back into the loop
	 */
	final LocalVariableGen local =
	    methodGen.addLocalVariable2("app", Util.getJCRefType(NODE_SIG),
					il.getEnd());

	final org.apache.bcel.generic.Instruction loadLocal =
	    new ILOAD(local.getIndex());
	final org.apache.bcel.generic.Instruction storeLocal =
	    new ISTORE(local.getIndex());

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

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

	if (_left != null) {
	    final int getParent = cpg.addInterfaceMethodref(DOM_INTF,
							    GET_PARENT,
							    GET_PARENT_SIG);
	    parent = il.append(new INVOKEINTERFACE(getParent, 2));
	    
	    il.append(DUP);
	    il.append(storeLocal);
	    _falseList.add(il.append(new IFLT(null)));
	    il.append(loadLocal);

	    _left.translate(classGen, methodGen);

	    final SyntaxTreeNode p = getParent();
	    if (p == null || p instanceof Instruction ||
		p instanceof TopLevelElement) 
	    {
		// do nothing
	    }
	    else {
		il.append(loadLocal);
	    }

	    final BranchHandle exit = il.append(new GOTO(null));
	    _loop = il.append(methodGen.loadDOM());
	    il.append(loadLocal);
	    local.setEnd(_loop);
	    il.append(new GOTO(parent));
	    exit.setTarget(il.append(NOP));
	    _left.backPatchFalseList(_loop);

	    _trueList.append(_left._trueList);	
	}
	else {
	    il.append(POP2);
	}
	
	/* 
	 * If _right is an ancestor pattern, backpatch this pattern's false
	 * list to the loop that searches for more ancestors.
	 */
	if (_right instanceof AncestorPattern) {
	    final AncestorPattern ancestor = (AncestorPattern) _right;
	    _falseList.backPatch(ancestor.getLoopHandle());    // clears list
	}

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

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