greenplumn IConstExprEvaluator 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/eval/IConstExprEvaluator.h
/---------------------------------------------------------------------------
/ Greenplum Database
/ Copyright (C) 2014 VMware, Inc. or its affiliates.
/
/ @filename:
/ IConstExprEvaluator.h
/
/ @doc:
/ Interface for constant expression evaluator in the optimizer
/
/ @owner:
/
/
/ @test:
/
/---------------------------------------------------------------------------
#ifndef GPOPT_IConstExprEvaluator_H
#define GPOPT_IConstExprEvaluator_H
#include "gpos/base.h"
#include "gpos/common/CRefCount.h"
namespace gpopt
{
using namespace gpos;
class CExpression; / forward declaration
/---------------------------------------------------------------------------
/ @class:
/ IConstExprEvaluator
/
/ @doc:
/ Interface to access the underlying evaluator of constant expressions
/ (expressions that can be evaluated independent of the contents of the
/ database)
/
/---------------------------------------------------------------------------
class IConstExprEvaluator : public CRefCount
{
public:
/ dtor
~IConstExprEvaluator() override = default;
/ evaluate the given expression and return the result as a new expression
/ caller takes ownership of returned expression
virtual CExpression *PexprEval(CExpression *pexpr) = 0;
/ returns true iff the evaluator can evaluate constant expressions without
/ subqueries
virtual BOOL FCanEvalExpressions() = 0;
};
} / namespace gpopt
#endif / !GPOPT_IConstExprEvaluator_H
/ EOF
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