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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_CONTAINERS_EXTEND_H_
#define BASE_CONTAINERS_EXTEND_H_
#include <algorithm>
#include <iterator>
#include <ranges>
#include <type_traits>
#include <vector>
namespace base {
// Append to |dst| all elements of |src| by std::move-ing them out of |src|.
// After this operation, |src| will be empty.
template <typename T>
void Extend(std::vector<T>& dst, std::vector<T>&& src) {
dst.insert(dst.end(), std::make_move_iterator(src.begin()),
std::make_move_iterator(src.end()));
src.clear();
}
// Appends `range` to `dst`, copying them out of `range`.
template <typename T, typename Range, typename Proj = std::identity>
requires std::ranges::range<Range> &&
std::indirectly_unary_invocable<Proj, std::ranges::iterator_t<Range>>
void Extend(std::vector<T>& dst, Range&& range, Proj proj = {}) {
if constexpr (std::ranges::sized_range<Range>) {
dst.reserve(dst.size() + std::ranges::size(range));
}
std::ranges::transform(std::forward<Range>(range), std::back_inserter(dst),
std::move(proj));
}
} // namespace base
#endif // BASE_CONTAINERS_EXTEND_H_
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