greenplumn CMaxCard 源码
greenplumn CMaxCard 代码
文件路径：/src/backend/gporca/libgpopt/include/gpopt/base/CMaxCard.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2009 - 2012 EMC Corp.
//
// @filename:
// CMaxCard.h
//
// @doc:
// Data type to carry maximal card information;
//
// This numeric is NOT an estimate but a guaranteed upper bound
// on the cardinality, ie., plans can be pruned based on this information
//---------------------------------------------------------------------------
#ifndef GPOPT_CMaxCard_H
#define GPOPT_CMaxCard_H
#include "gpos/base.h"
// use gpos::ulong_max instead of gpos::ullong_max to make sure arithmetic does not cause overflows
#define GPOPT_MAX_CARD ((ULLONG)(gpos::ulong_max))
namespace gpopt
{
using namespace gpos;
//---------------------------------------------------------------------------
// @class:
// CMaxCard
//
// @doc:
// Maximum Cardinality, including basic operators
//
//---------------------------------------------------------------------------
class CMaxCard
{
// friends that enforce 'literal == variable' order
friend BOOL operator==(ULLONG, const CMaxCard &);
friend BOOL operator==(const CMaxCard &, const CMaxCard &);
private:
// actual (cropped) value
ULLONG m_ull;
// equality
BOOL
operator==(ULLONG ull) const
{
GPOS_ASSERT(ull <= GPOPT_MAX_CARD);
return m_ull == ull;
}
public:
// ctor
explicit CMaxCard(ULLONG ull = GPOPT_MAX_CARD) : m_ull(ull)
{
GPOS_ASSERT(m_ull <= GPOPT_MAX_CARD);
m_ull = std::min(m_ull, GPOPT_MAX_CARD);
}
// copy ctor
CMaxCard(const CMaxCard &mc)
{
*this = mc;
}
// accessor
ULLONG
Ull() const
{
return m_ull;
}
// assignment
void
operator=(const CMaxCard &mc)
{
m_ull = mc.m_ull;
}
// arithmetic operators
void
operator*=(const CMaxCard &mc)
{
m_ull = std::min(mc.m_ull * m_ull, GPOPT_MAX_CARD);
}
// arithmetic operators
void
operator+=(const CMaxCard &mc)
{
m_ull = std::min(mc.m_ull + m_ull, GPOPT_MAX_CARD);
}
// print
IOstream &
OsPrint(IOstream &os) const
{
if (GPOPT_MAX_CARD == m_ull)
{
return os << "unbounded";
}
return os << m_ull;
}
}; // class CMaxCard
// shorthand for printing
inline IOstream &
operator<<(IOstream &os, const CMaxCard &mc)
{
return mc.OsPrint(os);
}
// shorthand for less-than equal
inline BOOL
operator<=(const CMaxCard &mcLHS, const CMaxCard &mcRHS)
{
if (mcLHS.Ull() <= mcRHS.Ull())
{
return true;
}
return false;
}
// shorthand for equality
inline BOOL
operator==(const CMaxCard &mcLHS, const CMaxCard &mcRHS)
{
return mcLHS.operator==(mcRHS.Ull());
}
// shorthand for equality
inline BOOL
operator==(ULLONG ull, const CMaxCard &mc)
{
return mc.operator==(ull);
}
} // namespace gpopt
#endif // !GPOPT_CMaxCard_H
// EOF
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