greenplumn CDXLScalarProjElem 源码
greenplumn CDXLScalarProjElem 代码
文件路径：/src/backend/gporca/libnaucrates/include/naucrates/dxl/operators/CDXLScalarProjElem.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2010 Greenplum, Inc.
//
// @filename:
// CDXLScalarProjElem.h
//
// @doc:
// Class for representing DXL projection lists.
//---------------------------------------------------------------------------
#ifndef GPDXL_CDXLScalarProjElem_H
#define GPDXL_CDXLScalarProjElem_H
#include "gpos/base.h"
#include "naucrates/dxl/operators/CDXLScalar.h"
#include "naucrates/md/CMDName.h"
namespace gpdxl
{
using namespace gpmd;
//---------------------------------------------------------------------------
// @class:
// CDXLScalarProjElem
//
// @doc:
// Container for projection list elements, storing the expression and the alias
//
//---------------------------------------------------------------------------
class CDXLScalarProjElem : public CDXLScalar
{
private:
// id of column defined by this project element:
// for computed columns this is a new id, for colrefs: id of the original column
ULONG m_id;
// alias
const CMDName *m_mdname;
public:
CDXLScalarProjElem(CDXLScalarProjElem &) = delete;
// ctor/dtor
CDXLScalarProjElem(CMemoryPool *mp, ULONG id, const CMDName *mdname);
~CDXLScalarProjElem() override;
// ident accessors
Edxlopid GetDXLOperator() const override;
// name of the operator
const CWStringConst *GetOpNameStr() const override;
// id of the proj element
ULONG Id() const;
// alias of the proj elem
const CMDName *GetMdNameAlias() const;
// serialize operator in DXL format
void SerializeToDXL(CXMLSerializer *, const CDXLNode *) const override;
// check if given column is defined by operator
BOOL
IsColDefined(ULONG colid) const override
{
return (Id() == colid);
}
// conversion function
static CDXLScalarProjElem *
Cast(CDXLOperator *dxl_op)
{
GPOS_ASSERT(nullptr != dxl_op);
GPOS_ASSERT(EdxlopScalarProjectElem == dxl_op->GetDXLOperator());
return dynamic_cast<CDXLScalarProjElem *>(dxl_op);
}
// does the operator return a boolean result
BOOL
HasBoolResult(CMDAccessor * //md_accessor
) const override
{
GPOS_ASSERT(!"Invalid function call on a container operator");
return false;
}
#ifdef GPOS_DEBUG
// checks whether the operator has valid structure
void AssertValid(const CDXLNode *dxlnode,
BOOL validate_children) const override;
#endif // GPOS_DEBUG
};
} // namespace gpdxl
#endif // !GPDXL_CDXLScalarProjElem_H
// EOF
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