/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  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 acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
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 *
 * 5. Products derived from this software may not be called "Apache",
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 *
 * 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
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * 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 Apache Software Foundation and was
 * originally based on software copyright (c) 2002, International
 * Business Machines Corporation., http://www.ibm.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xpath.expression;

import java.math.BigDecimal;
import java.math.BigInteger;

import org.apache.xpath.XPath20Exception;


/**
 * Represents <em>literal</em> expressions.
 * Use {@link #getLiteralType()} to get the type of literal, as following
 * <ul>
 * <li>{@link #INTEGER_LITERAL}: xs:integer datatype</li>
 * <li>{@link #DOUBLE_LITERAL}: xs:double datatype</li>
 * <li>{@link #DECIMAL_LITERAL}: xs:decimal datatype</li>
 * <li>{@link #STRING_LITERAL}: xs:string datatype</li>
 * </ul>
 * @author <a href="mailto:villard@us.ibm.com">Lionel Villard</a>
 * @version $Id$
 * @see <a href="http://www.w3.org/TR/xpath20#id-literals">XPath 2.0 Specification</a>
 */
public interface Literal extends Expr
{
    /**
     * This expression is an integer literal
     */
    short INTEGER_LITERAL = 0;

    /**
     * This expression is a decimal literal
     */
    short DECIMAL_LITERAL = 1;

    /**
     * This expression is an string literal
     */
    short STRING_LITERAL = 2;

    /**
     * This expression is an double literal
     */
    short DOUBLE_LITERAL = 3;

    /**
     * Gets the literal type
     * @return short One of the four following literal type:
     *         {@link #INTEGER_LITERAL}, {@link #DECIMAL_LITERAL},
     *         {@link #STRING_LITERAL}, {@link #DOUBLE_LITERAL}.
     */
    short getLiteralType();

    /**
     * Gets the integer literal as primitive Java int type. 
     * @return int
     * @throws XPath20Exception when the literal isn't an integer or when it cannot be
     *         represented as a primitive int type without approximations
     */
    int getIntegerLiteralAsInt() throws XPath20Exception;

    /**
     * Gets the integer literal.
     * @return BigInteger
     * @throws XPath20Exception when the literal isn't an integer
     */
    BigInteger getIntegerLiteral() throws XPath20Exception;

    /**
     * Gets the decimal literal
     * @return BigDecimal
     * @throws XPath20Exception when the literal isn't a decimal
     */
    BigDecimal getDecimalLiteral() throws XPath20Exception;

    /**
     * Gets the decimal literal as a double
     * @return double
     * @throws XPath20Exception when the literal isn't a decimal or
     * when it cannot be represented as a double without approximations
     */
    double getDecimalLiteralAsDouble() throws XPath20Exception;

    /**
     * Gets the double literal
     * @return double
     * @throws XPath20Exception when the literal isn't a double
     */
    double getDoubleLiteral() throws XPath20Exception;

    /**
     * Gets the string literal
     * @return String
     * @throws XPath20Exception when the literal isn't a string
     */
    String getStringLiteral() throws XPath20Exception;
}