vector_reserve.h

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#pragma once
 
#include "di/container/algorithm/uninitialized_relocate.h"
#include "di/container/vector/mutable_vector.h"
#include "di/container/vector/vector_begin.h"
#include "di/container/vector/vector_data.h"
#include "di/container/vector/vector_end.h"
#include "di/container/vector/vector_size.h"
#include "di/types/prelude.h"
#include "di/util/create.h"
#include "di/util/swap.h"
#include "di/vocab/expected/prelude.h"
 
namespace di::container::vector {
template<concepts::detail::MutableVector Vec, typename R = meta::detail::VectorAllocResult<Vec>>
constexpr auto reserve(Vec& vector, size_t capacity) -> R {
    if (capacity <= vector.capacity()) {
        return util::create<R>();
    }
 
    auto size = vector::size(vector);
    auto temp = Vec();
    return invoke_as_fallible([&] {
               return temp.reserve_from_nothing(capacity);
           }) % [&] {
        auto new_buffer = vector::data(temp);
        container::uninitialized_relocate(vector::begin(vector), vector::end(vector), new_buffer,
                                          new_buffer + capacity);
        temp.assume_size(size);
        vector.assume_size(0);
        util::swap(vector, temp);
    } | try_infallible;
}
}