alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (StringType.java)

This example Java source code file (StringType.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

booleantype, branchhandle, class, constantpoolgen, errormsg, flowlist, goto, instructionlist, ljava\/lang\/string, methodgenerator, realtype, referencetype, string, stringtype

The StringType.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: StringType.java,v 1.2.4.1 2005/09/05 11:35:57 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.IFEQ;
import com.sun.org.apache.bcel.internal.generic.IFNONNULL;
import com.sun.org.apache.bcel.internal.generic.INVOKESTATIC;
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.xsltc.compiler.FlowList;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
public class StringType extends Type {
    protected StringType() {}

    public String toString() {
        return "string";
    }

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

    public String toSignature() {
        return "Ljava/lang/String;";
    }

    public boolean isSimple() {
        return true;
    }

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

    /**
     * Translates a string into an object of internal type <code>type.
     * The translation to int is undefined since strings are always converted
     * to reals in arithmetic expressions.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            Type type) {
        if (type == Type.Boolean) {
            translateTo(classGen, methodGen, (BooleanType) type);
        }
        else if (type == Type.Real) {
            translateTo(classGen, methodGen, (RealType) type);
        }
        else if (type == Type.Reference) {
            translateTo(classGen, methodGen, (ReferenceType) type);
        }
        else if (type == Type.ObjectString) {
            // NOP -> same representation
        }
        else {
            ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
                                        toString(), type.toString());
            classGen.getParser().reportError(Constants.FATAL, err);
        }
    }

    /**
     * Translates a string into a synthesized boolean.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            BooleanType type) {
        final InstructionList il = methodGen.getInstructionList();
        FlowList falsel = translateToDesynthesized(classGen, methodGen, type);
        il.append(ICONST_1);
        final BranchHandle truec = il.append(new GOTO(null));
        falsel.backPatch(il.append(ICONST_0));
        truec.setTarget(il.append(NOP));
    }

    /**
     * Translates a string into a real by calling stringToReal() from the
     * basis library.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            RealType type) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();
        il.append(new INVOKESTATIC(cpg.addMethodref(BASIS_LIBRARY_CLASS,
                                                    STRING_TO_REAL,
                                                    STRING_TO_REAL_SIG)));
    }

    /**
     * Translates a string into a non-synthesized boolean. It does not push a
     * 0 or a 1 but instead returns branchhandle list to be appended to the
     * false list.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateToDesynthesized
     */
    public FlowList translateToDesynthesized(ClassGenerator classGen,
                                             MethodGenerator methodGen,
                                             BooleanType type) {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();

        il.append(new INVOKEVIRTUAL(cpg.addMethodref(STRING_CLASS,
                                                     "length", "()I")));
        return new FlowList(il.append(new IFEQ(null)));
    }

    /**
     * Expects a string on the stack and pushes a boxed string.
     * Strings are already boxed so the translation is just a NOP.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            ReferenceType type) {
        methodGen.getInstructionList().append(NOP);
    }

    /**
     * Translates a internal string into an external (Java) string.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateFrom
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen,
                            Class clazz)
    {
        // Is String <: clazz? I.e. clazz in { String, Object }
        if (clazz.isAssignableFrom(java.lang.String.class)) {
            methodGen.getInstructionList().append(NOP);
        }
        else {
            ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
                                        toString(), clazz.getName());
            classGen.getParser().reportError(Constants.FATAL, err);
        }
    }

    /**
     * Translates an external (primitive) Java type into a string.
     *
     * @see     com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateFrom
     */
    public void translateFrom(ClassGenerator classGen,
        MethodGenerator methodGen, Class clazz)
    {
        final ConstantPoolGen cpg = classGen.getConstantPool();
        final InstructionList il = methodGen.getInstructionList();

        if (clazz.getName().equals("java.lang.String")) {
            // same internal representation, convert null to ""
            il.append(DUP);
            final BranchHandle ifNonNull = il.append(new IFNONNULL(null));
            il.append(POP);
            il.append(new PUSH(cpg, ""));
            ifNonNull.setTarget(il.append(NOP));
        }
        else {
            ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
                                        toString(), clazz.getName());
            classGen.getParser().reportError(Constants.FATAL, err);
        }
    }

    /**
     * Translates an object of this type to its boxed representation.
     */
    public void translateBox(ClassGenerator classGen,
                             MethodGenerator methodGen) {
        translateTo(classGen, methodGen, Type.Reference);
    }

    /**
     * Translates an object of this type to its unboxed representation.
     */
    public void translateUnBox(ClassGenerator classGen,
                               MethodGenerator methodGen) {
        methodGen.getInstructionList().append(NOP);
    }

    /**
     * Returns the class name of an internal type's external representation.
     */
    public String getClassName() {
        return(STRING_CLASS);
    }


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

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

Other Java examples (source code examples)

Here is a short list of links related to this Java StringType.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.