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Java example source code file (FilterParentPath.java)

This example Java source code file (FilterParentPath.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

castexpr, expression, filterparentpath, instructionlist, invokeinterface, invokespecial, localvariablegen, node_iterator_sig, nodesettype, referencetype, string, syntaxtreenode, type, typecheckerror

The FilterParentPath.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 2001-2005 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: FilterParentPath.java,v 1.2.4.1 2005/09/12 10:24:55 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.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.INVOKEINTERFACE;
import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.LocalVariableGen;
import com.sun.org.apache.bcel.internal.generic.NEW;
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.NodeSetType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ReferenceType;
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 FilterParentPath extends Expression {

    private Expression _filterExpr;
    private Expression _path;
    private boolean _hasDescendantAxis = false;

    public FilterParentPath(Expression filterExpr, Expression path) {
        (_path = path).setParent(this);
        (_filterExpr = filterExpr).setParent(this);
    }

    public void setParser(Parser parser) {
        super.setParser(parser);
        _filterExpr.setParser(parser);
        _path.setParser(parser);
    }

    public String toString() {
        return "FilterParentPath(" + _filterExpr + ", " + _path + ')';
    }

    public void setDescendantAxis() {
        _hasDescendantAxis = true;
    }

    /**
     * Type check a FilterParentPath. If the filter is not a node-set add a
     * cast to node-set only if it is of reference type. This type coercion is
     * needed for expressions like $x/LINE where $x is a parameter reference.
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
        final Type ftype = _filterExpr.typeCheck(stable);
        if (ftype instanceof NodeSetType == false) {
            if (ftype instanceof ReferenceType)  {
                _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
            }
            /*
            else if (ftype instanceof ResultTreeType)  {
                _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
            }
            */
            else if (ftype instanceof NodeType)  {
                _filterExpr = new CastExpr(_filterExpr, Type.NodeSet);
            }
            else {
                throw new TypeCheckError(this);
            }
        }

        // Wrap single node path in a node set
        final Type ptype = _path.typeCheck(stable);
        if (!(ptype instanceof NodeSetType)) {
            _path = new CastExpr(_path, Type.NodeSet);
        }

        return _type = Type.NodeSet;
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();
        // Create new StepIterator
        final int initSI = cpg.addMethodref(STEP_ITERATOR_CLASS,
                                            "<init>",
                                            "("
                                            +NODE_ITERATOR_SIG
                                            +NODE_ITERATOR_SIG
                                            +")V");

        // Backwards branches are prohibited if an uninitialized object is
        // on the stack by section 4.9.4 of the JVM Specification, 2nd Ed.
        // We don't know whether this code might contain backwards branches,
        // so we mustn't create the new object until after we've created
        // the suspect arguments to its constructor.  Instead we calculate
        // the values of the arguments to the constructor first, store them
        // in temporary variables, create the object and reload the
        // arguments from the temporaries to avoid the problem.

        // Recursively compile 2 iterators
        _filterExpr.translate(classGen, methodGen);
        LocalVariableGen filterTemp =
                methodGen.addLocalVariable("filter_parent_path_tmp1",
                                           Util.getJCRefType(NODE_ITERATOR_SIG),
                                           null, null);
        filterTemp.setStart(il.append(new ASTORE(filterTemp.getIndex())));

        _path.translate(classGen, methodGen);
        LocalVariableGen pathTemp =
                methodGen.addLocalVariable("filter_parent_path_tmp2",
                                           Util.getJCRefType(NODE_ITERATOR_SIG),
                                           null, null);
        pathTemp.setStart(il.append(new ASTORE(pathTemp.getIndex())));

        il.append(new NEW(cpg.addClass(STEP_ITERATOR_CLASS)));
        il.append(DUP);
        filterTemp.setEnd(il.append(new ALOAD(filterTemp.getIndex())));
        pathTemp.setEnd(il.append(new ALOAD(pathTemp.getIndex())));

        // Initialize StepIterator with iterators from the stack
        il.append(new INVOKESPECIAL(initSI));

        // This is a special case for the //* path with or without predicates
        if (_hasDescendantAxis) {
            final int incl = cpg.addMethodref(NODE_ITERATOR_BASE,
                                              "includeSelf",
                                              "()" + NODE_ITERATOR_SIG);
            il.append(new INVOKEVIRTUAL(incl));
        }

        SyntaxTreeNode parent = getParent();

        boolean parentAlreadyOrdered =
            (parent instanceof RelativeLocationPath)
                || (parent instanceof FilterParentPath)
                || (parent instanceof KeyCall)
                || (parent instanceof CurrentCall)
                || (parent instanceof DocumentCall);

        if (!parentAlreadyOrdered) {
            final int order = cpg.addInterfaceMethodref(DOM_INTF,
                                                        ORDER_ITERATOR,
                                                        ORDER_ITERATOR_SIG);
            il.append(methodGen.loadDOM());
            il.append(SWAP);
            il.append(methodGen.loadContextNode());
            il.append(new INVOKEINTERFACE(order, 3));
        }
    }
}

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