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Java example source code file (ObjectType.java)

This example Java source code file (ObjectType.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

aload, astore, branchhandle, class, classnotfoundexception, errormsg, instruction, instructionlist, methodgenerator, objecttype, string, string_sig, stringbuffer, stringtype

The ObjectType.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: ObjectType.java,v 1.2.4.1 2005/09/12 11:45:54 pvedula Exp $
 */

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

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.GOTO;
import com.sun.org.apache.bcel.internal.generic.IFNULL;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.Instruction;
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.Constants;
import com.sun.org.apache.xalan.internal.utils.ObjectFactory;

/**
 * @author Todd Miller
 * @author Santiago Pericas-Geertsen
 */
public final class ObjectType extends Type {

    private String _javaClassName = "java.lang.Object";
    private Class  _clazz = java.lang.Object.class;

    /**
     * Used to represent a Java Class type such is required to support
     * non-static java functions.
     * @param javaClassName name of the class such as 'com.foo.Processor'
     */
    protected ObjectType(String javaClassName) {
        _javaClassName = javaClassName;

        try {
          _clazz = ObjectFactory.findProviderClass(javaClassName, true);
        }
        catch (ClassNotFoundException e) {
          _clazz = null;
        }
    }

    protected ObjectType(Class clazz) {
        _clazz = clazz;
        _javaClassName = clazz.getName();
    }

    /**
     * Must return the same value for all ObjectType instances. This is
     * needed in CastExpr to ensure the mapping table is used correctly.
     */
    public int hashCode() {
        return java.lang.Object.class.hashCode();
    }

    public boolean equals(Object obj) {
        return (obj instanceof ObjectType);
    }

    public String getJavaClassName() {
        return _javaClassName;
    }

    public Class getJavaClass() {
        return _clazz;
    }

    public String toString() {
        return _javaClassName;
    }

    public boolean identicalTo(Type other) {
        return this == other;
    }

    public String toSignature() {
        final StringBuffer result = new StringBuffer("L");
        result.append(_javaClassName.replace('.', '/')).append(';');
        return result.toString();
    }

    public com.sun.org.apache.bcel.internal.generic.Type toJCType() {
        return Util.getJCRefType(toSignature());
    }

    /**
     * Translates a void into an object of internal type <code>type.
     * This translation is needed when calling external functions
     * that return void.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            Type type) {
        if (type == Type.String) {
            translateTo(classGen, methodGen, (StringType) type);
        }
        else {
            ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
                                        toString(), type.toString());
            classGen.getParser().reportError(Constants.FATAL, err);
        }
    }

    /**
     * Expects an integer on the stack and pushes its string value by calling
     * <code>Integer.toString(int i).
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            StringType type) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();

        il.append(DUP);
        final BranchHandle ifNull = il.append(new IFNULL(null));
        il.append(new INVOKEVIRTUAL(cpg.addMethodref(_javaClassName,
                                                    "toString",
                                                    "()" + STRING_SIG)));
        final BranchHandle gotobh = il.append(new GOTO(null));
        ifNull.setTarget(il.append(POP));
        il.append(new PUSH(cpg, ""));
        gotobh.setTarget(il.append(NOP));
    }

    /**
     * Translates an object of this type to the external (Java) type denoted
     * by <code>clazz. This method is used to translate parameters
     * when external functions are called.
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            Class clazz) {
        if (clazz.isAssignableFrom(_clazz))
            methodGen.getInstructionList().append(NOP);
        else {
            ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
                               toString(), clazz.getClass().toString());
            classGen.getParser().reportError(Constants.FATAL, err);
        }
    }

    /**
     * Translates an external Java type into an Object type
     */
    public void translateFrom(ClassGenerator classGen,
                              MethodGenerator methodGen, Class clazz) {
        methodGen.getInstructionList().append(NOP);
    }

    public Instruction LOAD(int slot) {
        return new ALOAD(slot);
    }

    public Instruction STORE(int slot) {
        return new ASTORE(slot);
    }
}

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