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Java example source code file (ValueOf.java)

This example Java source code file (ValueOf.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, charactersw, charactersw_sig, expression, indentincrement, instructionlist, invokeinterface, invokevirtual, methodgenerator, push, string, type, valueof

The ValueOf.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: ValueOf.java,v 1.2.4.1 2005/09/05 09:30:04 pvedula Exp $
 */

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

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.INVOKEVIRTUAL;
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.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
 * @author Morten Jorgensen
 */
final class ValueOf extends Instruction {
    private Expression _select;
    private boolean _escaping = true;
    private boolean _isString = false;

    public void display(int indent) {
        indent(indent);
        Util.println("ValueOf");
        indent(indent + IndentIncrement);
        Util.println("select " + _select.toString());
    }

    public void parseContents(Parser parser) {
        _select = parser.parseExpression(this, "select", null);

        // make sure required attribute(s) have been set
        if (_select.isDummy()) {
            reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "select");
            return;
        }
        final String str = getAttribute("disable-output-escaping");
        if ((str != null) && (str.equals("yes"))) _escaping = false;
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
        Type type = _select.typeCheck(stable);

        // Prefer to handle the value as a node; fall back to String, otherwise
        if (type != null && !type.identicalTo(Type.Node)) {
            /***
             *** %HZ% Would like to treat result-tree fragments in the same
             *** %HZ% way as node sets for value-of, but that's running into
             *** %HZ% some snags.  Instead, they'll be converted to String
            if (type.identicalTo(Type.ResultTree)) {
                _select = new CastExpr(new CastExpr(_select, Type.NodeSet),
                                       Type.Node);
            } else
            ***/
            if (type.identicalTo(Type.NodeSet)) {
                _select = new CastExpr(_select, Type.Node);
            } else {
                _isString = true;
                if (!type.identicalTo(Type.String)) {
                    _select = new CastExpr(_select, Type.String);
                }
                _isString = true;
            }
        }
        return Type.Void;
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();
        final int setEscaping = cpg.addInterfaceMethodref(OUTPUT_HANDLER,
                                                          "setEscaping","(Z)Z");

        // Turn off character escaping if so is wanted.
        if (!_escaping) {
            il.append(methodGen.loadHandler());
            il.append(new PUSH(cpg,false));
            il.append(new INVOKEINTERFACE(setEscaping,2));
        }

        // Translate the contents.  If the value is a string, use the
        // translet.characters(String, TranslatOutputHandler) method.
        // Otherwise, the value is a node, and the
        // dom.characters(int node, TransletOutputHandler) method can dispatch
        // the string value of the node to the output handler more efficiently.
        if (_isString) {
            final int characters = cpg.addMethodref(TRANSLET_CLASS,
                                                    CHARACTERSW,
                                                    CHARACTERSW_SIG);

            il.append(classGen.loadTranslet());
            _select.translate(classGen, methodGen);
            il.append(methodGen.loadHandler());
            il.append(new INVOKEVIRTUAL(characters));
        } else {
            final int characters = cpg.addInterfaceMethodref(DOM_INTF,
                                                             CHARACTERS,
                                                             CHARACTERS_SIG);

            il.append(methodGen.loadDOM());
            _select.translate(classGen, methodGen);
            il.append(methodGen.loadHandler());
            il.append(new INVOKEINTERFACE(characters, 3));
        }

        // Restore character escaping setting to whatever it was.
        if (!_escaping) {
            il.append(methodGen.loadHandler());
            il.append(SWAP);
            il.append(new INVOKEINTERFACE(setEscaping,2));
            il.append(POP);
        }
    }
}

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