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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
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 * originally based on software copyright (c) 2002, International
 * Business Machines Corporation., http://www.ibm.com.  For more
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package org.apache.xpath.expression;

/**
 * Represents <em>conditional</em> expressions. 
 * <quote>XPath supports a conditional expression based on the keywords 
 * <code>if</code>, <code>then</code>, and <code>else</code>.</quote>
 * @author <a href="mailto:villard@us.ibm.com>Lionel Villard</a>
 * @version $Id$
 * @see <a target="_top" href="http://www.w3.org/TR/xpath20/#id-conditionals">XPath 2.0 Specification</a>
 */
public interface ConditionalExpr extends Expr
{
    /**
     * Gets the test expression.
     * @return The test expression
     */
    Expr getTestExpr();

    /**
     * Gets the then-expression
     * @return The then-expression
     */
    Expr getThenExpr();

    /**
     * Gets the else-expression
     * @return The else-expression
     */
    Expr getElseExpr();

    /**
     * Replaces the test expression by the specified one.
     * <p>If the specified
     * expression belongs to another expression, it is duplicated by following
     * the same rules as {@link Expr#cloneExpression()} before its insertion.</p>
     * @param expr The test expression
     * @return The expression that has just been added or a clone.
     */
    Expr replaceTestExpr(Expr expr);

    /**
     * Replaces the then-expression by the specified one.
     * <p>If the specified
     * expression belongs to another expression, it is duplicated by following
     * the same rules as {@link Expr#cloneExpression()} before its insertion.</p>
     * @param expr The then-expression
     * @return The expression that has just been added or a clone.
     */
	Expr replaceThenExpr(Expr expr);

    /**
     * Replaces the else-expression by the specified one.
     * <p>If the specified
     * expression belongs to another expression, it is duplicated by following
     * the same rules as {@link Expr#cloneExpression()} before its insertion.</p>
     * @param expr The else-expression
     * @return The expression that has just been added or a clone.
     */
	Expr replaceElseExpr(Expr expr);
}