unicodeconstant.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 137 行

/*
 * @(#)UnicodeConstant.java	1.13 06/10/21
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package components;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import consts.Const;
import util.ValidationException;
import jcc.Util;


// Class that represents a CONSTANT_UTF8 in a classfile's
// constant pool

public
class UnicodeConstant extends ConstantObject
{
    public String string;
    private String UTFstring;
    public int	  stringTableOffset;	// used by in-core output writers
    public boolean isSuffix = false;    // used by in-core output writers

    public UnicodeConstant(String s) {
        super(Const.CONSTANT_UTF8);
	string = s;
    }

    /**
     * Factory method to construct a UnicodeConstant instance from the
     * constant pool data stream.  This method is only called from the
     * ConstantObject.readObject() factory.
     */
    static ConstantObject read(DataInput i) throws IOException {
	return new UnicodeConstant(i.readUTF());
    }

    public void write( DataOutput o ) throws IOException{
	o.writeByte( tag );
	o.writeUTF( string );
    }


    public int hashCode() {
	return string.hashCode();
    }

    public void incReference() {
	Throwable t;
        super.incReference();
	t = new Error();
	System.err.println("UnicodeConstant.incReference() at ");
	t.printStackTrace();
	System.err.println();
    }

    public boolean equals(Object o) {
	if (o instanceof UnicodeConstant) {
	    UnicodeConstant a = (UnicodeConstant) o;
	    return string.equals(a.string);
	} else {
	    return false;
	}
    }

    /*
     * This method can only be called at the very end of processing,
     * just before output writing. Unlike all other constants,
     * UnicodeConstants still exist, but are not expected to be found
     * in any constant pool. Their reference counts must all be 0.
     * Their index must be -1, and they must not appear in a shared ConstantPool.
     * Because of these different requirements, we cannot call super.validate() here.
     * (Note: even if the above is wrong, their ldcReferences must always
     * be zero, as no instructions are allowed to refer to them directly!)
     * If any constraint is violated, throw a ValidationException.
     * This should stop processing and print a backtrace to the offender.
     */
    public void validate(){
	if ((getReferences() != 0) || (getLdcReferences() != 0)) {
	    throw new ValidationException("Referenced UnicodeConstant", this);
	}
	if (index != -1){
	    throw new ValidationException("UnicodeConstant with index not -1", this);
	}
	if (shared){
	    throw new ValidationException("UnicodeConstant marked shared", this);
	}
    }

    public String toString() {
	return string;
    }

    public void createUTF() {
        if (UTFstring == null ){
           UTFstring = Util.unicodeToUTF( string );
        }
    }

    public String toUTF() {
        if (UTFstring == null ){
           UTFstring = Util.unicodeToUTF( string );
        }
        return UTFstring;
    }

    public String getUTF() {
        return UTFstring;
    }

    public boolean isResolved(){ return true; }
}