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xvector - pod aware container
Raw
xvector.h
/*
* @file xvector.h
* @author David Gallardo Moreno
* @brief POD aware container, uses if constexpr to evaluate the code path to copy/move/destroy the xvector data.
*/
#pragma once
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <type_traits>
namespace nostd
{
template <typename _Type, bool _IsPod = std::is_trivial<_Type>() && std::is_standard_layout<_Type>()>
class xvector
{
public:
using iterator = _Type*;
using const_iterator = _Type const *;
using value_type = _Type;
using reference = _Type &;
using const_reference = _Type const &;
inline static bool const is_pod = _IsPod;
//Constructors / Destructor / Copy / Move
xvector ();
~xvector ();
xvector (xvector<_Type, _IsPod> const & aOther);
xvector (xvector<_Type, _IsPod> && aOther);
xvector (std::initializer_list<_Type> aList);
xvector<_Type, _IsPod> & operator= (xvector<_Type, _IsPod> const & aOther);
xvector<_Type, _IsPod> & operator= (xvector<_Type, _IsPod> && aOther);
//Iterator
iterator begin ();
const_iterator begin () const;
iterator end ();
const_iterator end () const;
//Capacity
uint32_t size32 () const;
size_t size () const;
size_t capacity () const;
bool empty () const;
void reserve (size_t aNumElements);
//Element access
reference operator[] (size_t aIndex);
const_reference operator[] (size_t aIndex) const;
reference front ();
const_reference front () const;
reference back ();
const_reference back () const;
_Type* data () { return reinterpret_cast<_Type* > (mBuffer); }
_Type const * data () const { return reinterpret_cast<_Type const *> (mBuffer); }
//Modifiers
void push_back (const _Type& aElement);
void pop_back ();
void erase (iterator aIterator);
void erase_fast (iterator aIterator);
void clear ();
void swap (xvector<_Type, _IsPod> & aOther);
template <typename... Args>
reference emplace_back (Args... args);
private:
void CopyFrom (const xvector<_Type, _IsPod> & aOther);
void MoveFrom ( xvector<_Type, _IsPod> & aOther);
private:
uint8_t* mBuffer;
size_t mBufferSize;
size_t mElementsCount;
};
//Constructors / Destructor / Copy / Move
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>::xvector()
: mBuffer(nullptr)
, mBufferSize(0)
, mElementsCount(0)
{}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>::~xvector()
{
clear();
if(mBuffer)
{
::free(mBuffer);
mBuffer = nullptr;
mBufferSize = 0;
mElementsCount = 0;
}
}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>::xvector(const xvector<_Type, _IsPod> & aOther)
: mBuffer(nullptr)
, mBufferSize(0)
, mElementsCount(0)
{
CopyFrom(aOther);
}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>::xvector(xvector<_Type, _IsPod> && aOther)
: mBuffer(nullptr)
, mBufferSize(0)
, mElementsCount(0)
{
MoveFrom(aOther);
}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>::xvector(std::initializer_list<_Type> aList)
: mBuffer(nullptr)
, mBufferSize(0)
, mElementsCount(0)
{
for(auto lElement : aList)
{
PushBack(lElement);
}
}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>& xvector<_Type, _IsPod>::operator=(const xvector<_Type, _IsPod> & aOther)
{
CopyFrom(aOther);
return *this;
}
template <typename _Type, bool _IsPod>
xvector<_Type, _IsPod>& xvector<_Type, _IsPod>::operator=(xvector<_Type, _IsPod> && aOther)
{
if constexpr (!_IsPod)
{
clear();
}
::free(mBuffer);
mBuffer = nullptr;
mBufferSize = 0;
MoveFrom(aOther);
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::CopyFrom(const xvector<_Type, _IsPod> & aOther)
{
if constexpr (!_IsPod)
{
clear();
}
reserve(aOther.mElementsCount);
if constexpr (_IsPod)
{
::memcpy(mBuffer, aOther.mBuffer, aOther.mElementsCount * sizeof(_Type));
mElementsCount = aOther.mElementsCount;
}
else
{
for(const _Type& lElement : aOther)
{
push_back(lElement);
}
}
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::MoveFrom(xvector<_Type, _IsPod> & aOther)
{
//TODO: proper way to do a move?
assert(mBuffer == nullptr);
mBuffer = aOther.mBuffer;
mBufferSize = aOther.mBufferSize;
mElementsCount = aOther.mElementsCount;
aOther.mBuffer = nullptr;
aOther.mBufferSize = 0;
aOther.mElementsCount = 0;
}
//Iterator
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::iterator xvector<_Type, _IsPod>::begin ()
{
return data();
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::const_iterator xvector<_Type, _IsPod>::begin () const
{
return data();
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::iterator xvector<_Type, _IsPod>::end ()
{
return data() + mElementsCount;
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::const_iterator xvector<_Type, _IsPod>::end () const
{
return data() + mElementsCount;
}
//Capacity
template <typename _Type, bool _IsPod>
uint32_t xvector<_Type, _IsPod>::size32 () const
{
return mElementsCount & 0xFFFFFFFF;
}
template <typename _Type, bool _IsPod>
size_t xvector<_Type, _IsPod>::size () const
{
return mElementsCount;
}
template <typename _Type, bool _IsPod>
size_t xvector<_Type, _IsPod>::capacity () const
{
return mBufferSize / sizeof(_Type);
}
template <typename _Type, bool _IsPod>
bool xvector<_Type, _IsPod>::empty () const
{
return mElementsCount == 0;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::reserve (size_t aNumElements)
{
if(capacity() < aNumElements)
{
size_t const lNewBufferSize = aNumElements * sizeof(_Type);
_Type* lNewBuffer = reinterpret_cast<_Type*>( ::malloc(lNewBufferSize) );
if constexpr (_IsPod)
{
if(mElementsCount > 0)
{
::memcpy(lNewBuffer, mBuffer, mBufferSize);
}
}
else
{
for(size_t i = 0, l = mElementsCount; i < l; ++i)
{
new (&lNewBuffer[i]) _Type(std::move(data()[i]));
data()[i].~_Type();
}
}
if(mBuffer)
{
::free(mBuffer);
}
mBuffer = reinterpret_cast<uint8_t*>(lNewBuffer);
mBufferSize = lNewBufferSize;
}
}
//Element access
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::reference xvector<_Type, _IsPod>::operator[] (size_t aIndex)
{
assert(aIndex < mElementsCount);
return *(data() + aIndex);
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::const_reference xvector<_Type, _IsPod>::operator[] (size_t aIndex) const
{
assert(aIndex < mElementsCount);
return *(data() + aIndex);
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::reference xvector<_Type, _IsPod>::front ()
{
return *data();
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::const_reference xvector<_Type, _IsPod>::front () const
{
return *data();
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::reference xvector<_Type, _IsPod>::back ()
{
return *(data() + mElementsCount - 1);
}
template <typename _Type, bool _IsPod>
typename xvector<_Type, _IsPod>::const_reference xvector<_Type, _IsPod>::back () const
{
return *(data() + mElementsCount - 1);
}
//Modifiers
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::push_back (const _Type& aElement)
{
if(size() == capacity())
{
reserve(size() + 16);
}
new (end()) _Type(aElement);
++mElementsCount;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::pop_back ()
{
back().~_Type();
--mElementsCount;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::erase (iterator aIterator)
{
assert(aIterator >= begin() && aIterator < end());
if constexpr (!_IsPod)
{
aIterator->~_Type();
for(auto lIt = aIterator; (lIt + 1) != end(); ++lIt)
{
new (lIt) _Type(std::move(*(lIt + 1)));
}
}
--mElementsCount;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::erase_fast (iterator aIterator)
{
assert(aIterator >= begin() && aIterator < end());
if constexpr (!_IsPod)
{
aIterator->~_Type();
}
*aIterator = *reinterpret_cast<_Type*>(end() - 1);
--mElementsCount;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::clear ()
{
if constexpr (!_IsPod)
{
for(auto lIt = begin(); lIt != end(); ++lIt)
{
lIt->~_Type();
}
}
mElementsCount = 0;
}
template <typename _Type, bool _IsPod>
void xvector<_Type, _IsPod>::swap (xvector<_Type, _IsPod> & aOther)
{
xvector<_Type, _IsPod> lTemp(std::move(*this));
MoveFrom(aOther);
aOther.MoveFrom(lTemp);
}
template <typename _Type, bool _IsPod>
template <typename... Args>
typename xvector<_Type, _IsPod>::reference xvector<_Type, _IsPod>::emplace_back (Args... aArgs)
{
if(size() == capacity())
{
reserve(size() + 16);
}
new (end()) _Type(aArgs...);
++mElementsCount;
return back();
}
} // nostd
Raw
xvector_example.cpp
/*
xvector_example.cpp
Expected output:
test start
TPodStruct: 1 1
TNonDefaultLayoutStruct: 1 0
TNonTrivialStruct: 0 1
v0.is_pod: 1
v1.is_pod: 1
v2.is_pod: 0
v3.is_pod: 0
v4.is_pod: 1
v5.is_pod: 0
TNonDefaultLayoutStruct destroyed as an object [40][45]
test end
*/
#include <iostream>
#include "xvector.h"
struct TPodStruct
{
uint32_t a;
uint32_t b;
};
struct TNonDefaultLayoutStruct : public TPodStruct
{
TNonDefaultLayoutStruct(uint32_t pa = 1, uint32_t pb = 1)
: TPodStruct{ pa, pb }
{;}
~TNonDefaultLayoutStruct()
{
std::cout << "TNonDefaultLayoutStruct destroyed as an object [" << a << "][" << b << "]" << std::endl;
}
};
struct TNonTrivialStruct : public TPodStruct
{
uint32_t c;
};
int main()
{
std::cout << "test start" << std::endl;
{
nostd::xvector<uint32_t> v0;
v0.emplace_back(22);
nostd::xvector<TPodStruct> v1;
v1.emplace_back();
nostd::xvector<TNonDefaultLayoutStruct> v2;
v2.emplace_back(40, 45);
nostd::xvector<TNonTrivialStruct> v3;
v3.emplace_back();
//forced pod
nostd::xvector<TNonDefaultLayoutStruct, true> v4;
v4.emplace_back(50, 52);
//forced no-pod
nostd::xvector<TPodStruct, false> v5;
v5.emplace_back();
std::cout << "TPodStruct: " << std::is_standard_layout<TPodStruct>() << " " << std::is_trivial<TPodStruct>() << std::endl;
std::cout << "TNonDefaultLayoutStruct: " << std::is_standard_layout<TNonDefaultLayoutStruct>() << " " << std::is_trivial<TNonDefaultLayoutStruct>() << std::endl;
std::cout << "TNonTrivialStruct: " << std::is_standard_layout<TNonTrivialStruct>() << " " << std::is_trivial<TNonTrivialStruct>() << std::endl;
std::cout << "v0.is_pod: " << v0.is_pod << std::endl;
std::cout << "v1.is_pod: " << v1.is_pod << std::endl;
std::cout << "v2.is_pod: " << v2.is_pod << std::endl;
std::cout << "v3.is_pod: " << v3.is_pod << std::endl;
std::cout << "v4.is_pod: " << v4.is_pod << std::endl;
std::cout << "v5.is_pod: " << v5.is_pod << std::endl;
}
std::cout << "test end" << std::endl;
return 0;
}
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