/*
* $Header$
* $Revision: 624 $
* $Date: 2006-06-24 21:02:12 +1000 (Sat, 24 Jun 2006) $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003 The JRDF Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* the JRDF Project (http://jrdf.sf.net/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The JRDF Project" and "JRDF" must not be used to endorse
* or promote products derived from this software without prior written
* permission. For written permission, please contact
* newmana@users.sourceforge.net.
*
* 5. Products derived from this software may not be called "JRDF"
* nor may "JRDF" appear in their names without prior written
* permission of the JRDF Project.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the JRDF Project. For more
* information on JRDF, please see <http://jrdf.sourceforge.net/>.
*/
package org.jrdf.graph;
// Java 2 standard
import java.net.URI;
/**
* RDF literal node.
*
* @author <a href="http://staff.pisoftware.com/raboczi">Simon Raboczi</a>
* @author Andrew Newman
*
* @version $Revision: 624 $
*/
public interface Literal extends ObjectNode, TypedNodeVisitable, org.openrdf.model.Literal {
/**
* Obtain the text of this literal.
*
* @return the text of the literal, never <code>null</code>
*/
String getLexicalForm();
/**
* Returns the language code of the literal, or <code>null</code> if no
* language specified.
*
* @return the language code of the literal, or <code>null</code> if no
* language specified.
*/
String getLanguage();
/**
* Whether the literal is well formed XML.
*
* @return whether the literal is wll formed XML.
*/
boolean isWellFormedXML();
/**
* Returns the URI of the RDF datatype of this resource, or <code>null</code>
* for an untyped node.
*
* @return the URI of the RDF datatype of this resource, or <code>null</code>
* for an untyped node.
*/
URI getDatatypeURI();
/**
* Indicates whether some other object is "equal to" this one.
*
* A literal is equal to another literal if:
* <ul>
* <li> The strings of the two lexical forms compare equal, character by
* character.
* <li> Either both or neither have language tags.
* <li> The language tags, if any, compare equal.
* <li> Either both or neither have datatype URIs.
* <li> The two datatype URIs, if any, compare equal, character by character.
* </ul>
*
* @param obj the reference object with which to compare.
* @return true if this object is the same as the obj argument; false otherwise.
*/
boolean equals(Object obj);
/**
* Returns a hash-code value for this literal. The hash code is based upon
* XORing all of the literal's components hash codes including the
* lexical form, datatype, and language.
*
* @return a hash-code value for this literal.
*/
int hashCode();
/**
* Provide a legible representation of a literal, following the N-Triples
* format defined in
* <a href="http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/#ntrip_strings">§3.2</a>
* of the <a href="http://www.w3.org/">W3C</a>'s (World Wide Web Consortium)
* <a href="http://www.w3.org/TR/2004/REC-rdf-testcases-20040210">RDF Test Cases</a> Recommendation.
*
* Well-formed Unicode surrogate pairs in the lexical form are escaped as a
* single 8-digit hexadecimal <code>\U</code> escape sequence rather than a
* pair of 4-digit <code>&x5C;u</code> sequences representing the surrogates.
*
* @return this instance in N-Triples format
*/
String getEscapedForm();
/**
* Returns an escaped lexical form where double quotes and backslashes are
* escaped.
*
* @return String the lexical form.
*/
String getEscapedLexicalForm();
/**
* Returns the lexical form.
*
* @return the lexical form.
*/
String toString();
}