/*
 * @(#)TextSyntax.java	1.4 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */


package javax.print.attribute;

import java.io.Serializable;
import java.util.Locale;

/**
 * Class TextSyntax is an abstract base class providing the common 
 * implementation of all attributes whose value is a string. The text attribute 
 * includes a locale to indicate the natural language. Thus, a text attribute 
 * always represents a localized string. Once constructed, a text attribute's 
 * value is immutable. 
 * <P>
 *
 * @author  David Mendenhall
 * @author  Alan Kaminsky
 */
public abstract class TextSyntax implements Serializable, Cloneable {


    /**
     * String value of this text attribute.
     * @serial
     */
    private String value;

    /**
     * Locale of this text attribute. 
     * @serial
     */
    private Locale locale;

    /**
     * Constructs a TextAttribute with the specified string and locale. 
     *
     * @param  value   Text string.
     * @param  locale  Natural language of the text string. null
     * is interpreted to mean the default locale for as returned
     * by <code>Locale.getDefault()</code>
     *
     * @exception  NullPointerException
     *     (unchecked exception) Thrown if <CODE>value</CODE> is null.
     */
    protected TextSyntax(String value, Locale locale) {
	this.value = verify (value);
	this.locale = verify (locale);
    }

    private static String verify(String value) {
	if (value == null) {
	    throw new NullPointerException(" value is null");
	}
	return value;
    }

    private static Locale verify(Locale locale) {
	if (locale == null) {
	    return Locale.getDefault();
	}
	return locale;
    }

    /**
     * Returns this text attribute's text string.
     * @return the text string.
     */
    public String getValue() {
	return value;
    }

    /**
     * Returns this text attribute's text string's natural language (locale). 
     * @return the locale
     */
    public Locale getLocale() {
	return locale;
    } 

    /**
     * Returns a hashcode for this text attribute.
     *
     * @return  A hashcode value for this object.
     */
    public int hashCode() {
	return value.hashCode() ^ locale.hashCode();
    }

    /**
     * Returns whether this text attribute is equivalent to the passed in 
     * object. To be equivalent, all of the following conditions must be true: 
     * <OL TYPE=1>
     * <LI>
     * <CODE>object</CODE> is not null.
     * <LI>
     * <CODE>object</CODE> is an instance of class TextSyntax.
     * <LI>
     * This text attribute's underlying string and <CODE>object</CODE>'s 
     * underlying string are equal. 
     * <LI>
     * This text attribute's locale and <CODE>object</CODE>'s locale are 
     * equal. 
     * </OL>
     *
     * @param  object  Object to compare to.
     *
     * @return  True if <CODE>object</CODE> is equivalent to this text
     *          attribute, false otherwise. 
     */
    public boolean equals(Object object) {
	return(object != null &&
	       object instanceof TextSyntax &&
	       this.value.equals (((TextSyntax) object).value) &&
	       this.locale.equals (((TextSyntax) object).locale));
    }

    /**
     * Returns a String identifying this text attribute. The String is
     * the attribute's underlying text string.
     *
     * @return  A String identifying this object.
     */
    public String toString(){
	return value;
    }
    
}
