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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