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Java example source code file (ProcessingInstructionPattern.java)

This example Java source code file (ProcessingInstructionPattern.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, goto, if_icmpeq, instructionhandle, instructionlist, invokeinterface, invokevirtual, methodgenerator, predicate, processinginstructionpattern, push, steppattern, string, type

The ProcessingInstructionPattern.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: ProcessingInstructionPattern.java,v 1.2.4.1 2005/09/12 11:04:08 pvedula Exp $
 */

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

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.GOTO;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPEQ;
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.InstructionHandle;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
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.xml.internal.dtm.Axis;
import com.sun.org.apache.xml.internal.dtm.DTM;

/**
 * @author Morten Jorgensen
 */
final class ProcessingInstructionPattern extends StepPattern {

    private String _name = null;
    private boolean _typeChecked = false;

    /**
     * Handles calls with no parameter (current node is implicit parameter).
     */
    public ProcessingInstructionPattern(String name) {
        super(Axis.CHILD, DTM.PROCESSING_INSTRUCTION_NODE, null);
        _name = name;
        //if (_name.equals("*")) _typeChecked = true; no wildcard allowed!
    }

    /**
     *
     */
     public double getDefaultPriority() {
        return (_name != null) ? 0.0 : -0.5;
     }
    public String toString() {
        if (_predicates == null)
            return "processing-instruction("+_name+")";
        else
            return "processing-instruction("+_name+")"+_predicates;
    }

    public void reduceKernelPattern() {
        _typeChecked = true;
    }

    public boolean isWildcard() {
        return false;
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
        if (hasPredicates()) {
            // Type check all the predicates (e -> position() = e)
            final int n = _predicates.size();
            for (int i = 0; i < n; i++) {
                final Predicate pred = (Predicate)_predicates.elementAt(i);
                pred.typeCheck(stable);
            }
        }
        return Type.NodeSet;
    }

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

        // context node is on the stack
        int gname = cpg.addInterfaceMethodref(DOM_INTF,
                                              "getNodeName",
                                              "(I)Ljava/lang/String;");
        int cmp = cpg.addMethodref(STRING_CLASS,
                                   "equals", "(Ljava/lang/Object;)Z");

        // Push current node on the stack
        il.append(methodGen.loadCurrentNode());
        il.append(SWAP);

        // Overwrite current node with matching node
        il.append(methodGen.storeCurrentNode());

        // If pattern not reduced then check kernel
        if (!_typeChecked) {
            il.append(methodGen.loadCurrentNode());
            final int getType = cpg.addInterfaceMethodref(DOM_INTF,
                                                          "getExpandedTypeID",
                                                          "(I)I");
            il.append(methodGen.loadDOM());
            il.append(methodGen.loadCurrentNode());
            il.append(new INVOKEINTERFACE(getType, 2));
            il.append(new PUSH(cpg, DTM.PROCESSING_INSTRUCTION_NODE));
            _falseList.add(il.append(new IF_ICMPEQ(null)));
        }

        // Load the requested processing instruction name
        il.append(new PUSH(cpg, _name));
        // Load the current processing instruction's name
        il.append(methodGen.loadDOM());
        il.append(methodGen.loadCurrentNode());
        il.append(new INVOKEINTERFACE(gname, 2));
        // Compare the two strings
        il.append(new INVOKEVIRTUAL(cmp));
        _falseList.add(il.append(new IFEQ(null)));

        // Compile the expressions within the predicates
        if (hasPredicates()) {
            final int n = _predicates.size();
            for (int i = 0; i < n; i++) {
                Predicate pred = (Predicate)_predicates.elementAt(i);
                Expression exp = pred.getExpr();
                exp.translateDesynthesized(classGen, methodGen);
                _trueList.append(exp._trueList);
                _falseList.append(exp._falseList);
            }
        }

        // Backpatch true list and restore current iterator/node
        InstructionHandle restore;
        restore = il.append(methodGen.storeCurrentNode());
        backPatchTrueList(restore);
        BranchHandle skipFalse = il.append(new GOTO(null));

        // Backpatch false list and restore current iterator/node
        restore = il.append(methodGen.storeCurrentNode());
        backPatchFalseList(restore);
        _falseList.add(il.append(new GOTO(null)));

        // True list falls through
        skipFalse.setTarget(il.append(NOP));
    }
}

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