c1bc70b711
A lot of files were missing copyright field in the header and
the Blender Foundation contributed to them in a sense of bug
fixing and general maintenance.
This change makes it explicit that those files are at least
partially copyrighted by the Blender Foundation.
Note that this does not make it so the Blender Foundation is
the only holder of the copyright in those files, and developers
who do not have a signed contract with the foundation still
hold the copyright as well.
Another aspect of this change is using SPDX format for the
header. We already used it for the license specification,
and now we state it for the copyright as well, following the
FAQ:
https://reuse.software/faq/
123 lines
2.5 KiB
C++
123 lines
2.5 KiB
C++
/* SPDX-FileCopyrightText: 2023 Blender Foundation
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#pragma once
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#include <algorithm>
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#include "BLI_vector.hh"
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namespace blender {
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/**
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* A VectorList is a vector of vectors.
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*
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* VectorList can be used when:
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*
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* 1) Don't know up front the number of elements that will be added to the list. Use array or
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* vector.reserve when known up front.
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*
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* 2) Number of reads/writes doesn't require sequential access
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* of the whole list. A vector ensures memory is sequential which is fast when reading, writing can
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* have overhead when the reserved memory is full.
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*
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* When a VectorList reserved memory is full it will allocate memory for the new items, breaking
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* the sequential access. Within each allocated memory block the elements are ordered sequentially.
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*/
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template<typename T, int64_t CapacityStart = 32, int64_t CapacitySoftLimit = 4096>
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class VectorList {
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public:
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using UsedVector = Vector<T, 0>;
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private:
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/**
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* Contains the individual vectors. There must always be at least one vector
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*/
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Vector<UsedVector> vectors_;
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public:
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VectorList()
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{
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this->append_vector();
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}
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void append(const T &value)
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{
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this->append_as(value);
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}
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void append(T &&value)
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{
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this->append_as(std::move(value));
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}
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template<typename ForwardT> void append_as(ForwardT &&value)
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{
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UsedVector &vector = this->ensure_space_for_one();
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vector.append_unchecked_as(std::forward<ForwardT>(value));
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}
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UsedVector *begin()
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{
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return vectors_.begin();
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}
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UsedVector *end()
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{
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return vectors_.end();
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}
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const UsedVector *begin() const
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{
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return vectors_.begin();
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}
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const UsedVector *end() const
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{
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return vectors_.end();
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}
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T &last()
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{
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return vectors_.last().last();
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}
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int64_t size() const
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{
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int64_t result = 0;
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for (const UsedVector &vector : *this) {
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result += vector.size();
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}
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return result;
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}
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private:
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UsedVector &ensure_space_for_one()
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{
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UsedVector &vector = vectors_.last();
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if (LIKELY(!vector.is_at_capacity())) {
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return vector;
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}
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this->append_vector();
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return vectors_.last();
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}
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void append_vector()
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{
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const int64_t new_vector_capacity = this->get_next_vector_capacity();
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vectors_.append({});
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vectors_.last().reserve(new_vector_capacity);
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}
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int64_t get_next_vector_capacity()
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{
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if (vectors_.is_empty()) {
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return CapacityStart;
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}
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return std::min(vectors_.last().capacity() * 2, CapacitySoftLimit);
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}
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};
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} // namespace blender
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