assimp/include/assimp/SmallVector.h

165 lines
4.9 KiB
C++

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------
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All rights reserved.
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following disclaimer.
* Redistributions in binary form must reproduce the above
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* Neither the name of the assimp team, nor the names of its
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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*/
/** @file Defines small vector with inplace storage.
Based on CppCon 2016: Chandler Carruth "High Performance Code 201: Hybrid Data Structures" */
#pragma once
#ifndef AI_SMALLVECTOR_H_INC
#define AI_SMALLVECTOR_H_INC
#ifdef __GNUC__
# pragma GCC system_header
#endif
namespace Assimp {
// --------------------------------------------------------------------------------------------
/// @brief Small vector with inplace storage.
///
/// Reduces heap allocations when list is shorter. It uses a small array for a dedicated size.
/// When the growing gets bigger than this small cache a dynamic growing algorithm will be
/// used.
// --------------------------------------------------------------------------------------------
template<typename T, unsigned int Capacity>
class SmallVector {
public:
/// @brief The default class constructor.
SmallVector() :
mStorage(mInplaceStorage),
mSize(0),
mCapacity(Capacity) {
// empty
}
/// @brief The class destructor.
~SmallVector() {
if (mStorage != mInplaceStorage) {
delete [] mStorage;
}
}
/// @brief Will push a new item. The capacity will grow in case of a too small capacity.
/// @param item [in] The item to push at the end of the vector.
void push_back(const T& item) {
if (mSize < mCapacity) {
mStorage[mSize++] = item;
return;
}
push_back_and_grow(item);
}
/// @brief Will resize the vector.
/// @param newSize [in] The new size.
void resize(size_t newSize) {
if (newSize > mCapacity) {
grow(newSize);
}
mSize = newSize;
}
/// @brief Returns the current size of the vector.
/// @return The current size.
size_t size() const {
return mSize;
}
/// @brief Returns a pointer to the first item.
/// @return The first item as a pointer.
T* begin() {
return mStorage;
}
/// @brief Returns a pointer to the end.
/// @return The end as a pointer.
T* end() {
return &mStorage[mSize];
}
/// @brief Returns a const pointer to the first item.
/// @return The first item as a const pointer.
T* begin() const {
return mStorage;
}
/// @brief Returns a const pointer to the end.
/// @return The end as a const pointer.
T* end() const {
return &mStorage[mSize];
}
SmallVector(const SmallVector &) = delete;
SmallVector(SmallVector &&) = delete;
SmallVector &operator = (const SmallVector &) = delete;
SmallVector &operator = (SmallVector &&) = delete;
private:
void grow( size_t newCapacity) {
T* oldStorage = mStorage;
T* newStorage = new T[newCapacity];
std::memcpy(newStorage, oldStorage, mSize * sizeof(T));
mStorage = newStorage;
mCapacity = newCapacity;
if (oldStorage != mInplaceStorage) {
delete [] oldStorage;
}
}
void push_back_and_grow(const T& item) {
grow(mCapacity + Capacity);
mStorage[mSize++] = item;
}
T* mStorage;
size_t mSize;
size_t mCapacity;
T mInplaceStorage[Capacity];
};
} // end namespace Assimp
#endif // !! AI_SMALLVECTOR_H_INC