xpath_rwapi/src2/org/apache/xpath/expression/LetExpr.java

/*
 * The Apache Software License, Version 1.1
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 * ====================================================================
 *
 * 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
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package org.apache.xpath.expression;

import org.apache.xml.QName;
import org.apache.xpath.XPath20Exception;
import org.apache.xpath.datamodel.SequenceType;

/**
 * Represents <code>let</code> expressions.
 * A <code>let</code> expression consists of a list of let clause with binds a variable,
 * eventually typed, to an expression. For example, the following expression:
 * <pre><![CDATA[
 * let $s := (<one/>, <two/>, <three/>)
 * ]>  
 * </pre>
 * contains one let clause which bind the variable <code>s</code> with a sequence
 * of three elements.
 * @author <a href="mailto:villard@us.ibm.com">Lionel Villard</a>
 * @version $Id$
 */
public interface LetExpr extends Expr
{

	/**
	 * Gets the number of let clauses 
	 * @return int
	 */
	int getClauseCount();
	
	/**
	 * Gets the variable name of the ith let clause
	 * @param i
	 * @return QName
	 * @throws XPath20Exception when the specified index is out of bounds
	 */
	QName getVariableName(int i) throws XPath20Exception;
	
	/**
	 * Gets the type of the ith let clause
	 * @param i
	 * @return A {@link SequenceType} or null when no type is specified.
	 * @throws XPath20Exception when the specified index is out of bounds
	 */
	SequenceType getType(int i) throws XPath20Exception;
	
	/**
	 * Gets the expression of the ith let clause
	 * @param i
	 * @return An expression
	 * @throws XPath20Exception when the specified index is out of bounds
	 */
	Expr getExpr(int i) throws XPath20Exception;
	
	/**
	 * Append a clause at the end of the clause list
	 * @param varName
	 * @param type
	 * @param expr
	 * @throws XPath20Exception when the specified expression is not a single expression
	 */
	void appendClause(QName varName, SequenceType type, Expr expr)  throws XPath20Exception;
	
	/**
	 * Insert a clause before the ith position.
	 * @param i
	 * @param varName
	 * @param type
	 * @param expr
	 * @throws XPath20Exception when the specified expression is not a single expression
	 * or when the specified index is out of bounds
	 */
	void insertClause(int i, QName varName, SequenceType type, Expr expr) throws XPath20Exception;
	
	/**
	 * Remove the clause at the ith position
	 * @param i
	 * @throws XPath20Exception when the specified index is out of bounds
	 */
	void removeClause(int i) throws XPath20Exception;
}