//%2003////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000, 2001, 2002  BMC Software, Hewlett-Packard Development
// Company, L. P., IBM Corp., The Open Group, Tivoli Systems.
// Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L. P.;
// IBM Corp.; EMC Corporation, The Open Group.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
// ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
// "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//==============================================================================
//
// Author: Mike Brasher (mbrasher@bmc.com)
//
// Modified By:
//
//%/////////////////////////////////////////////////////////////////////////////

#ifndef Pegasus_WQLOperation_h
#define Pegasus_WQLOperation_h

#include <Pegasus/Common/Config.h>
#include <Pegasus/WQL/Linkage.h>

PEGASUS_NAMESPACE_BEGIN

/** Represents SQL where clause operators.

    These operators include the following:

    <ul>
	<li>OR</li>
	<li>AND</li>
	<li>NOT</li>
	<li>=</li>
	<li>&lt;&gt;</li>
	<li>&lt;</li>
	<li>&le;</li>
	<li>&gt;</li>
	<li>&ge;</li>
	<li>IS NULL</li>
	<li>IS NOT NULL</li>
	<li>IS TRUE</li>
	<li>IS NOT TRUE</li>
	<li>IS FALSE</li>
	<li>IS NOT FALSE</li>
    </ul>

    Here's an example of a SQL query that uses some of these operations.

    <pre>
	SELECT *
	FROM MyClass
	WHERE (x &gt; 10 OR y &le; 1.5) OR z = 19 AND name IS NOT NULL
    </pre>

    As the parser recognizes these operations, it adds the corresponding
    WQLOperation enumeration tag to the WQLSelectStatement by calling
    WQLSelectStatement::appendOperation().

    Operators may be converted to string by calling WQLOperationToString().

    Note that in expressions like this one:

    <pre>
	count IS TRUE
    </pre>

    The IS operator is NOT treated as a binary operator (which would take
    count and TRUE as its operands). Instead, the IS operator and TRUE operand
    are combined to form a single unary operation called "IS_TRUE". In this 
    way, evaluation may be implemented by more efficiently (the TRUE operand
    is eliminated and therefore need not be handled). Conceptually, the above
    expression is equivalent to the following psuedo expression:

    <pre>
    	IS_TRUE(count)
    </pre>

    Note that this technique is applied the following operations (also 
    combined to be unary operations).

    <ul>
	<li>WQL_IS_NULL</li>
	<li>WQL_IS_NOT_NULL</li>
	<li>WQL_IS_TRUE</li>
	<li>WQL_IS_NOT_TRUE</li>
	<li>WQL_IS_FALSE</li>
	<li>WQL_IS_NOT_FALSE</li>
    </ul>
*/
enum WQLOperation
{
    WQL_OR,
    WQL_AND,
    WQL_NOT,
    WQL_EQ,
    WQL_NE,
    WQL_LT,
    WQL_LE,
    WQL_GT,
    WQL_GE,
    WQL_IS_NULL,
    WQL_IS_NOT_NULL,
    WQL_IS_TRUE,
    WQL_IS_NOT_TRUE,
    WQL_IS_FALSE,
    WQL_IS_NOT_FALSE
};

PEGASUS_WQL_LINKAGE const char* WQLOperationToString(WQLOperation x);

PEGASUS_NAMESPACE_END

#endif /* Pegasus_WQLOperation_h */
