greenplumn CConstExprEvaluatorProxy 源码
greenplumn CConstExprEvaluatorProxy 代码
文件路径：/src/backend/gpopt/utils/CConstExprEvaluatorProxy.cpp
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2014 VMware, Inc. or its affiliates.
//
// @filename:
// CConstExprEvaluatorProxy.cpp
//
// @doc:
// Wrapper over GPDB's expression evaluator that takes a constant expression,
// given as DXL, evaluates it and returns the result as DXL. In case the expression
// has variables, an exception is raised
//
// @test:
//
//---------------------------------------------------------------------------
extern "C" {
#include "postgres.h"
#include "executor/executor.h"
}
#include "gpopt/gpdbwrappers.h"
#include "gpopt/translate/CTranslatorScalarToDXL.h"
#include "gpopt/utils/CConstExprEvaluatorProxy.h"
#include "naucrates/dxl/operators/CDXLNode.h"
#include "naucrates/exception.h"
using namespace gpdxl;
using namespace gpmd;
using namespace gpos;
//---------------------------------------------------------------------------
// @function:
// CConstExprEvaluatorProxy::EmptyMappingColIdVar::PvarFromDXLNodeScId
//
// @doc:
// Raises an exception in case someone looks up a variable
//
//---------------------------------------------------------------------------
Var *
CConstExprEvaluatorProxy::CEmptyMappingColIdVar::VarFromDXLNodeScId(
const CDXLScalarIdent * /*scalar_ident*/
)
{
elog(LOG,
"Expression passed to CConstExprEvaluatorProxy contains variables. "
"Evaluation will fail and an exception will be thrown.");
GPOS_RAISE(gpdxl::ExmaGPDB, gpdxl::ExmiGPDBError);
return nullptr;
}
//---------------------------------------------------------------------------
// @function:
// CConstExprEvaluatorProxy::EvaluateExpr
//
// @doc:
// Evaluate 'expr', assumed to be a constant expression, and return the DXL representation
// of the result. Caller keeps ownership of 'expr' and takes ownership of the returned pointer.
//
//---------------------------------------------------------------------------
CDXLNode *
CConstExprEvaluatorProxy::EvaluateExpr(const CDXLNode *dxl_expr)
{
// Translate DXL -> GPDB Expr
Expr *expr = m_dxl2scalar_translator.TranslateDXLToScalar(
dxl_expr, &m_emptymapcidvar);
GPOS_ASSERT(nullptr != expr);
// Evaluate the expression
Expr *result = gpdb::EvaluateExpr(expr, gpdb::ExprType((Node *) expr),
gpdb::ExprTypeMod((Node *) expr));
if (!IsA(result, Const))
{
#ifdef GPOS_DEBUG
elog(
NOTICE,
"Expression did not evaluate to Const, but to an expression of type %d",
result->type);
#endif
GPOS_RAISE(gpdxl::ExmaConstExprEval, gpdxl::ExmiConstExprEvalNonConst);
}
Const *const_result = (Const *) result;
CDXLDatum *datum_dxl = CTranslatorScalarToDXL::TranslateConstToDXL(
m_mp, m_md_accessor, const_result);
CDXLNode *dxl_result = GPOS_NEW(m_mp)
CDXLNode(m_mp, GPOS_NEW(m_mp) CDXLScalarConstValue(m_mp, datum_dxl));
gpdb::GPDBFree(result);
gpdb::GPDBFree(expr);
return dxl_result;
}
// EOF
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