//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2014 VMware, Inc. or its affiliates.
//
//	@filename:
//		CDefaultComparator.h
//
//	@doc:
//		Default comparator for IDatum instances
//
//	@owner:
//
//
//	@test:
//
//---------------------------------------------------------------------------

#ifndef GPOPT_CDefaultComparator_H
#define GPOPT_CDefaultComparator_H

#include "gpos/base.h"

#include "gpopt/base/IComparator.h"
#include "naucrates/md/IMDType.h"
#include "naucrates/traceflags/traceflags.h"

namespace gpmd
{
// fwd declarations
class IMDId;
}  // namespace gpmd

namespace gpnaucrates
{
// fwd declarations
class IDatum;
}  // namespace gpnaucrates

namespace gpopt
{
using namespace gpmd;
using namespace gpnaucrates;
using namespace gpos;

// fwd declarations
class IConstExprEvaluator;

//---------------------------------------------------------------------------
//	@class:
//		CDefaultComparator
//
//	@doc:
//		Default comparator for IDatum instances. It is a singleton accessed
//		via CompGetInstance.
//
//---------------------------------------------------------------------------
class CDefaultComparator : public IComparator
{
private:
	// constant expression evaluator
	IConstExprEvaluator *m_pceeval;

	// construct a comparison expression from the given components and evaluate it
	BOOL FEvalComparison(CMemoryPool *mp, const IDatum *datum1,
						 const IDatum *datum2,
						 IMDType::ECmpType cmp_type) const;

	// return true iff we should use the internal (stats-based) evaluation
	static BOOL FUseInternalEvaluator(const IDatum *datum1,
									  const IDatum *datum2,
									  BOOL *can_use_external_evaluator);

public:
	CDefaultComparator(const CDefaultComparator &) = delete;

	// ctor
	CDefaultComparator(IConstExprEvaluator *pceeval);

	// dtor
	~CDefaultComparator() override = default;

	// tests if the two arguments are equal
	BOOL Equals(const IDatum *datum1, const IDatum *datum2) const override;

	// tests if the first argument is less than the second
	BOOL IsLessThan(const IDatum *datum1, const IDatum *datum2) const override;

	// tests if the first argument is less or equal to the second
	BOOL IsLessThanOrEqual(const IDatum *datum1,
						   const IDatum *datum2) const override;

	// tests if the first argument is greater than the second
	BOOL IsGreaterThan(const IDatum *datum1,
					   const IDatum *datum2) const override;

	// tests if the first argument is greater or equal to the second
	BOOL IsGreaterThanOrEqual(const IDatum *datum1,
							  const IDatum *datum2) const override;

};	// CDefaultComparator
}  // namespace gpopt

#endif	// !CDefaultComparator_H

// EOF