//%/////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000, 2001 BMC Software, Hewlett-Packard Company, IBM, 
// The Open Group, Tivoli Systems
//
// 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_WQLSelectStatement_h
#define Pegasus_WQLSelectStatement_h

#include <Pegasus/Common/Config.h>
#include <Pegasus/Common/Array.h>
#include <Pegasus/Common/String.h>
#include <Pegasus/WQL/WQLOperation.h>
#include <Pegasus/WQL/WQLOperand.h>
#include <Pegasus/WQL/WQLPropertySource.h>

PEGASUS_NAMESPACE_BEGIN

/** This class represents a compiled WQL1 select statement. 

    An instance of WQLSelectStatement is passed to WQLParser::parse() which
    parses the WQL1 SELECT statement and initializes the WQLSelectStatement
    instance. A WQL1 SELECT statement has the following form:

    <pre>
	SELECT &lt;property&gt;...
	FROM &lt;class name&gt;
	WHERE &lt;where clause&gt;
    </pre>

    There are methods for obtaining the various elements of the select
    statement.
    
    The components of the where clause are stored in two arrays: one for
    operands and one for operators (these are placed in proper order by the
    YACC parser). Evaluation is performed using a Boolean stack. See the
    implementation of evaluateWhereClause() for details.
*/
class PEGASUS_WQL_LINKAGE WQLSelectStatement
{
public:

    /** Default constructor. 
    */
    WQLSelectStatement();

    /** Destructor.
    */
    ~WQLSelectStatement();

    /** Clears all data members of this object.
    */
    void clear();

    /** Accessor.
    */
    const String& getClassName() const
    {
	return _className;
    }

    /** Modifier. This method should not be called by the user (only by the
	parser).
    */
    void setClassName(const String& className)
    {
	_className = className;
    }

    /** Returns the number of property names which were indicated in the
	selection list.
    */
    Uint32 getSelectPropertyNameCount() const
    {
	return _selectPropertyNames.size();
    }

    /** Gets the i-th selected property name in the list.
    */
    const String& getSelectPropertyName(Uint32 i) const
    {
	return _selectPropertyNames[i];
    }

    /** Appends a property name to the property name list. This user should
	not call this method; it should only be called by the parser.
    */
    void appendSelectPropertyName(const String& x)
    {
	_selectPropertyNames.append(x);
    }

    /** Returns the number of unique property names from the where clause.
    */
    Uint32 getWherePropertyNameCount() const
    {
	return _wherePropertyNames.size();
    }

    /** Gets the i-th unique property appearing in the where clause.
    */
    const String& getWherePropertyName(Uint32 i) const
    {
	return _wherePropertyNames[i];
    }

    /** Appends a property name to the where property name list. This user 
	should not call this method; it should only be called by the parser.

	@param x name of the property.
	@return false if a property with that name already exists.
    */
    Boolean appendWherePropertyName(const String& x);

    /** Appends an operation to the operation array. This method should only
	be called by the parser itself.
    */
    void appendOperation(WQLOperation x)
    {
	_operations.append(x);
    }

    /** Appends an operand to the operation array. This method should only
	be called by the parser itself.
    */
    void appendOperand(const WQLOperand& x)
    {
	_operands.append(x);
    }

    /** Returns true if this class has a where clause.
    */
    Boolean hasWhereClause() const
    {
	return _operations.size() != 0;
    }

    /** Evalautes the where clause using the symbol table to resolve symbols.
    */
    Boolean evaluateWhereClause(const WQLPropertySource* source) const;

    /** Prints out the members of this class.
    */
    void print() const;

private:

    //
    // The name of the target class. For example:
    //
    //     SELECT * 
    //     FROM TargetClass
    //     WHERE ...
    //

    String _className;

    //
    // The list of property names being selected. For example, see "firstName",
    // and "lastName" below.
    //
    //     SELECT firstName, lastName 
    //     FROM TargetClass
    //     WHERE ...
    //

    Array<String> _selectPropertyNames;

    //
    // The unique list of property names appearing in the WHERE clause.
    // Although a property may occur many times in the WHERE clause, it will
    // only appear once in this list.
    //

    Array<String> _wherePropertyNames;

    //
    // The list of operations encountered while parsing the WHERE clause.
    // Consider this query:
    //
    //     SELECT *
    //     FROM TargetClass
    //     WHERE count > 10 OR peak < 20 AND state = "OKAY"
    //
    // This would generate the following stream of WQLOperations:
    //
    //     WQL_GT
    //     WQL_LT
    //     WQL_EQ
    //     WQL_AND
    //     WQL_OR
    //

    Array<WQLOperation> _operations;

    // 
    // The list of operands encountered while parsing the WHERE clause. They
    // query just above would generate the following stream of operands:
    //
    //     count, 10, peak, 20, state, "OKAY"
    //

    Array<WQLOperand> _operands;

    void f() const { }
};

PEGASUS_NAMESPACE_END

#endif /* Pegasus_WQLSelectStatement_h */