greenplumn CDrvdProp 源码

greenplumn CDrvdProp 代码

文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CDrvdProp.h

//---------------------------------------------------------------------------
//	Greenplum Database
//	Copyright (C) 2009 - 2011 EMC CORP.
//
//	@filename:
//		CDrvdProp.h
//
//	@doc:
//		Base class for all derived properties
//---------------------------------------------------------------------------
#ifndef GPOPT_CDrvdProp_H
#define GPOPT_CDrvdProp_H

#include "gpos/base.h"
#include "gpos/common/CDynamicPtrArray.h"
#include "gpos/common/CRefCount.h"
#include "gpos/common/DbgPrintMixin.h"


namespace gpopt
{
using namespace gpos;

// fwd declarations
class CExpressionHandle;
class COperator;
class CDrvdProp;
class CDrvdPropCtxt;
class CReqdPropPlan;

// dynamic array for properties
using CDrvdPropArray = CDynamicPtrArray<CDrvdProp, CleanupRelease>;

//---------------------------------------------------------------------------
//	@class:
//		CDrvdProp
//
//	@doc:
//		Abstract base class for all derived properties. Individual property
//		components are added separately. CDrvdProp is memory pool-agnostic.
//
//		All derived property classes implement a pure virtual function
//		CDrvdProp::Derive(). This function is responsible for filling in the
//		different properties in the property container. For example
//		CDrvdPropScalar::Derive() fills in used and defined columns in the
//		current scalar property container.
//
//		Property derivation takes place in a bottom-up fashion. Each operator
//		has to implement virtual derivation functions to be called by the
//		derivation mechanism of each single property. For example,
//		CPhysical::PosDerive() is used to derive sort order of an expression
//		rooted by a given physical operator. Similarly, CScalar::GetUsedColumns() is
//		used to derive the used columns in a scalar expression rooted by a
//		given operator.
//
//		The derivation functions take as argument a CExpressionHandle object,
//		which is an abstraction of the child nodes (which could be Memo groups,
//		or actual operators in stand-alone expression trees). This gives the
//		derivation functions a unified way to access the properties of the
//		children and combine them with local properties.
//
//		The derivation mechanism is kicked off by the function
//		CExpressionHandle::DeriveProps().
//
//---------------------------------------------------------------------------
class CDrvdProp : public CRefCount, public DbgPrintMixin<CDrvdProp>
{
public:
	// types of derived properties
	enum EPropType
	{
		EptRelational,
		EptPlan,
		EptScalar,

		EptInvalid,
		EptSentinel = EptInvalid
	};

private:
public:
	CDrvdProp(const CDrvdProp &) = delete;

	// ctor
	CDrvdProp();

	// dtor
	~CDrvdProp() override = default;

	// type of properties
	virtual EPropType Ept() = 0;

	// derivation function
	virtual void Derive(CMemoryPool *mp, CExpressionHandle &exprhdl,
						CDrvdPropCtxt *pdppropctxt) = 0;

	// check for satisfying required plan properties
	virtual BOOL FSatisfies(const CReqdPropPlan *prpp) const = 0;

	virtual BOOL
	IsComplete() const
	{
		return true;
	}

	virtual gpos::IOstream &OsPrint(gpos::IOstream &os) const = 0;
};	// class CDrvdProp

// shorthand for printing
IOstream &operator<<(IOstream &os, const CDrvdProp &drvdprop);

}  // namespace gpopt


#endif	// !GPOPT_CDrvdProp_H

// EOF

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