greenplumn CStack 源码
greenplumn CStack 代码
文件路径：/src/backend/gporca/libgpos/include/gpos/common/CStack.h
//---------------------------------------------------------------------------
// Greenplum Database
// Copyright (C) 2009 Greenplum, Inc.
//
// @filename:
// CStack.h
//
// @doc:
// Create stack of objects
//
// @owner:
// Siva
//
// @test:
//
//
//---------------------------------------------------------------------------
#ifndef GPOPT_CStack_H
#define GPOPT_CStack_H
#include "gpos/base.h"
#include "gpos/common/CDynamicPtrArray.h"
#include "gpos/common/CRefCount.h"
namespace gpos
{
template <class T>
class CStack
{
private:
// backing dynamic array store
CDynamicPtrArray<T, CleanupNULL> *m_dynamic_ptr_array;
// top of stack index
ULONG m_size;
public:
CStack(CStack &) = delete;
// c'tor
CStack<T>(CMemoryPool *mp, ULONG min_size = 4) : m_size(0)
{
m_dynamic_ptr_array =
GPOS_NEW(mp) CDynamicPtrArray<T, CleanupNULL>(mp, min_size, 10);
}
// destructor
virtual ~CStack()
{
m_dynamic_ptr_array->Release();
}
// push element onto stack
void
Push(T *obj)
{
GPOS_ASSERT(m_dynamic_ptr_array != nullptr && "Dynamic array missing");
GPOS_ASSERT(m_size <= m_dynamic_ptr_array->Size() &&
"The top of stack cannot be beyond the underlying array");
// if the stack was Popped before, reuse that space by replacing the element
if (m_size < m_dynamic_ptr_array->Size())
{
m_dynamic_ptr_array->Replace(m_size, obj);
}
else
{
m_dynamic_ptr_array->Append(obj);
}
m_size++;
}
// pop top element
T *
Pop()
{
GPOS_ASSERT(!this->IsEmpty() && "Cannot pop from empty stack");
T *obj = (*m_dynamic_ptr_array)[m_size - 1];
m_size--;
return obj;
}
// peek at top element
const T *
Peek() const
{
GPOS_ASSERT(!this->IsEmpty() && "Cannot peek into empty stack");
const T *obj = (*m_dynamic_ptr_array)[m_size - 1];
return obj;
}
// is stack empty?
BOOL
IsEmpty() const
{
return (m_size == 0);
}
};
} // namespace gpos
#endif // !GPOPT_CStack_H
// EOF
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