src/org/apache/xalan/xsltc/compiler/Copy.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.ALOAD;
import org.apache.bcel.generic.ASTORE;
import org.apache.bcel.generic.BranchHandle;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.IFEQ;
import org.apache.bcel.generic.IFNULL;
import org.apache.bcel.generic.ILOAD;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKEVIRTUAL;
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.ErrorMsg;
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 Copy extends Instruction {
    private UseAttributeSets _useSets;
    
    public void parseContents(Parser parser) {
	final String useSets = getAttribute("use-attribute-sets");
	if (useSets.length() > 0) {
            if (!Util.isValidQNames(useSets)) {
                ErrorMsg err = new ErrorMsg(ErrorMsg.INVALID_QNAME_ERR, useSets, this);
                parser.reportError(Constants.ERROR, err);	
            }		
	    _useSets = new UseAttributeSets(useSets, parser);
	}
	parseChildren(parser);
    }
    
    public void display(int indent) {
	indent(indent);
	Util.println("Copy");
	indent(indent + IndentIncrement);
	displayContents(indent + IndentIncrement);
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	if (_useSets != null) {
	    _useSets.typeCheck(stable);
	}
	typeCheckContents(stable);
	return Type.Void;
    }
	
    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	final LocalVariableGen name =
	    methodGen.addLocalVariable2("name",
					Util.getJCRefType(STRING_SIG),
					null);
	final LocalVariableGen length =
	    methodGen.addLocalVariable2("length",
					Util.getJCRefType("I"),
					null);

	// Get the name of the node to copy and save for later
	il.append(methodGen.loadDOM());
	il.append(methodGen.loadCurrentNode());
	il.append(methodGen.loadHandler());
	final int cpy = cpg.addInterfaceMethodref(DOM_INTF,
						  "shallowCopy",
						  "("
						  + NODE_SIG
						  + TRANSLET_OUTPUT_SIG
						  + ")" + STRING_SIG); 
	il.append(new INVOKEINTERFACE(cpy, 3));
	il.append(DUP);
	name.setStart(il.append(new ASTORE(name.getIndex())));
	final BranchHandle ifBlock1 = il.append(new IFNULL(null));

	// Get the length of the node name and save for later
	il.append(new ALOAD(name.getIndex()));
	final int lengthMethod = cpg.addMethodref(STRING_CLASS,"length","()I");
	il.append(new INVOKEVIRTUAL(lengthMethod));
	length.setStart(il.append(new ISTORE(length.getIndex())));

	// Copy in attribute sets if specified
	if (_useSets != null) {
	    // If the parent of this element will result in an element being
	    // output then we know that it is safe to copy out the attributes
	    final SyntaxTreeNode parent = getParent();
	    if ((parent instanceof LiteralElement) ||
		(parent instanceof LiteralElement)) {
		_useSets.translate(classGen, methodGen);
	    }
	    // If not we have to check to see if the copy will result in an
	    // element being output.
	    else {
		// check if element; if not skip to translate body
		il.append(new ILOAD(length.getIndex()));
		final BranchHandle ifBlock2 = il.append(new IFEQ(null));
		// length != 0 -> element -> do attribute sets
		_useSets.translate(classGen, methodGen);
		// not an element; root
		ifBlock2.setTarget(il.append(NOP));
	    }
	}

	// Instantiate body of xsl:copy
	translateContents(classGen, methodGen);

	// Call the output handler's endElement() if we copied an element
	// (The DOM.shallowCopy() method calls startElement().)
	length.setEnd(il.append(new ILOAD(length.getIndex())));
	final BranchHandle ifBlock3 = il.append(new IFEQ(null));
	il.append(methodGen.loadHandler());
	name.setEnd(il.append(new ALOAD(name.getIndex())));
	il.append(methodGen.endElement());
	
	final InstructionHandle end = il.append(NOP);
	ifBlock1.setTarget(end);
	ifBlock3.setTarget(end);
	methodGen.removeLocalVariable(name);
	methodGen.removeLocalVariable(length);
    }
}