Java example source code file (Copy.java)

This example Java source code file (Copy.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

branchhandle, constantpoolgen, copy, errormsg, ifeq, ifnull, indentincrement, literalelement, localvariablegen, node_sig, translet_output_sig, type, useattributesets

The Copy.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * 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: Copy.java,v 1.2.4.1 2005/09/01 12:14:32 pvedula Exp $
 */

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

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.BranchHandle;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.IFNULL;
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.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.ISTORE;
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.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import com.sun.org.apache.xalan.internal.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));
        il.append(DUP);
        length.setStart(il.append(new ISTORE(length.getIndex())));

        // Ignore attribute sets if current node is ROOT. DOM.shallowCopy()
        // returns "" for ROOT, so skip attribute sets if length == 0
        final BranchHandle ifBlock4 = il.append(new IFEQ(null));

        // 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
        ifBlock4.setTarget(il.append(NOP));
        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);
    }
}