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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 * 
 * http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.olingo.odata2.core.uri.expression;

import org.apache.olingo.odata2.api.exception.ODataMessageException;
import org.apache.olingo.odata2.api.uri.expression.ExpressionParserException;
import org.apache.olingo.odata2.api.uri.expression.OrderByExpression;

/**
 * Interface which defines a method for parsing a $orderby expression to allow different parser implementations
 * <p>
 * The current expression parser supports expressions as defined in the OData specification 2.0 with the following
 * restrictions
 * - the methods "cast", "isof" and "replace" are not supported
 * 
 * The expression parser can be used with providing an Entity Data Model (EDM) an without providing it.
 * <p>When a EDM is provided the expression parser will be as strict as possible. That means:
 * <li>All properties used in the expression must be defined inside the EDM</li>
 * <li>The types of EDM properties will be checked against the lists of allowed type per method, binary- and unary
 * operator</li>
 * </p>
 * <p>If no EDM is provided the expression parser performs a lax validation
 * <li>The properties used in the expression are not looked up inside the EDM and the type of the expression node
 * representing the
 * property will be "null"</li>
 * <li>Expression node with EDM-types which are "null" are not considered during the parameter type validation, to the
 * return type of the parent expression node will
 * also become "null"</li>
 * 
 * 
 */
public interface OrderByParser {
  /**
   * Parses a $orderby expression string and creates an $orderby expression tree
   * @param orderByExpression
   * The $orderby expression string ( for example "name asc" ) to be parsed
   * @return
   * The $orderby expression tree
   * @throws ExpressionParserException
   * Exception thrown due to errors while parsing the $orderby expression string
   * @throws ODataMessageException
   * Used for extensibility
   */
  abstract OrderByExpression parseOrderByString(String orderByExpression) throws ExpressionParserException,
      ODataMessageException;
}
