greenplumn CScalarIf 源码
greenplumn CScalarIf 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/operators/CScalarIf.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2011 EMC Corp.
//
// @filename:
// CScalarIf.h
//
// @doc:
// Scalar if operator
//---------------------------------------------------------------------------
#ifndef GPOPT_CScalarIf_H
#define GPOPT_CScalarIf_H
#include "gpos/base.h"
#include "gpopt/base/CDrvdProp.h"
#include "gpopt/operators/CScalar.h"
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CScalarIf
//
// @doc:
// Scalar if operator. A case statement in SQL is represented as as
// cascaded if statements. The format of if statement is:
// if ------ condition
// |-------- true value
// |-------- false value
// For example: (case when r.a < r.b then 10 when r.a > r.b then 20 else 15 end)
// Is represented as if ---- r.a < r.b
// |----- 10
// |----- if ----- r.a > r.b
// |------- 20
// |------- 15
//
//---------------------------------------------------------------------------
class CScalarIf : public CScalar
{
private:
// metadata id in the catalog
IMDId *m_mdid_type;
// is operator return type BOOL?
BOOL m_fBoolReturnType;
public:
CScalarIf(const CScalarIf &) = delete;
// ctor
CScalarIf(CMemoryPool *mp, IMDId *mdid);
// dtor
~CScalarIf() override
{
m_mdid_type->Release();
}
// ident accessors
EOperatorId
Eopid() const override
{
return EopScalarIf;
}
// return a string for operator name
const CHAR *
SzId() const override
{
return "CScalarIf";
}
// the type of the scalar expression
IMDId *
MdidType() const override
{
return m_mdid_type;
}
// operator specific hash function
ULONG HashValue() const override;
// match function
BOOL Matches(COperator *) const override;
// sensitivity to order of inputs
BOOL
FInputOrderSensitive() const override
{
return true;
}
// return a copy of the operator with remapped columns
COperator *
PopCopyWithRemappedColumns(CMemoryPool *, //mp,
UlongToColRefMap *, //colref_mapping,
BOOL //must_exist
) override
{
return PopCopyDefault();
}
// boolean expression evaluation
EBoolEvalResult
Eber(ULongPtrArray *pdrgpulChildren) const override
{
return EberNullOnAllNullChildren(pdrgpulChildren);
}
// conversion function
static CScalarIf *
PopConvert(COperator *pop)
{
GPOS_ASSERT(nullptr != pop);
GPOS_ASSERT(EopScalarIf == pop->Eopid());
return dynamic_cast<CScalarIf *>(pop);
}
}; // class CScalarIf
} // namespace gpopt
#endif // !GPOPT_CScalarIf_H
// EOF
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