greenplumn CHashSetIter 源码
greenplumn CHashSetIter 代码
文件路径：/src/backend/gporca/libgpos/include/gpos/common/CHashSetIter.h
// Greenplum Database
// Copyright (C) 2017 VMware, Inc. or its affiliates
//
// Hash set iterator
#ifndef GPOS_CHashSetIter_H
#define GPOS_CHashSetIter_H
#include "gpos/base.h"
#include "gpos/common/CDynamicPtrArray.h"
#include "gpos/common/CHashSet.h"
#include "gpos/common/CStackObject.h"
namespace gpos
{
// Hash set iterator
template <class T, ULONG (*HashFn)(const T *),
BOOL (*EqFn)(const T *, const T *), void (*CleanupFn)(T *)>
class CHashSetIter : public CStackObject
{
// short hand for hashset type
using TSet = CHashSet<T, HashFn, EqFn, CleanupFn>;
private:
// set to iterate
const TSet *m_set;
// current hashchain
ULONG m_chain_idx;
// current element
ULONG m_elem_idx;
// is initialized?
BOOL m_is_initialized;
public:
CHashSetIter(const CHashSetIter<T, HashFn, EqFn, CleanupFn> &) = delete;
// ctor
CHashSetIter<T, HashFn, EqFn, CleanupFn>(TSet *set)
: m_set(set), m_chain_idx(0), m_elem_idx(0)
{
GPOS_ASSERT(nullptr != set);
}
// dtor
virtual ~CHashSetIter<T, HashFn, EqFn, CleanupFn>() = default;
// advance iterator to next element
BOOL
Advance()
{
if (m_elem_idx < m_set->m_elements->Size())
{
m_elem_idx++;
return true;
}
return false;
}
// current element
const T *
Get() const
{
const typename TSet::CHashSetElem *elem = nullptr;
T *t = (*(m_set->m_elements))[m_elem_idx - 1];
elem = m_set->Lookup(t);
if (nullptr != elem)
{
return elem->Value();
}
return nullptr;
}
}; // class CHashSetIter
} // namespace gpos
#endif // !GPOS_CHashSetIter_H
// EOF
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