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Add utility::is_sorted[_until]
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‎docs/Miscellaneous-utilities.md‎

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This buffer provider allocates on the heap a number of elements depending on a given *size policy* (a class whose `operator()` takes the size of the collection and returns another size). You can use the function objects from `utility/functional.h` as basic size policies. The buffer construction may throw an instance of [`std::bad_alloc`][std-bad-alloc] if it fails to allocate the required memory.
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### `is_sorted` and `is_sorted_until`
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```cpp
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#include <cpp-sort/utility/is_sorted.h>
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#include <cpp-sort/utility/is_sorted_until.h>
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```
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Simple reimplementations of the standard library algorithms [`std::is_sorted`][std-is-sorted] and [`std::is_sorted_until`][std-is-sorted-until], reimplemented as function objects that follow the library's *unified sorting interface*.
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*New in version 2.1.0*
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### Miscellaneous function objects
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```cpp
@@ -543,6 +554,8 @@ assert(not cppsort::utility::check_strict_weak_ordering(vec, std::less{});)
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[std-invoke]: https://en.cppreference.com/w/cpp/utility/functional/invoke
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[std-is-arithmetic]: https://en.cppreference.com/w/cpp/types/is_arithmetic
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[std-is-member-function-pointer]: https://en.cppreference.com/w/cpp/types/is_member_function_pointer
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[std-is-sorted]: https://en.cppreference.com/w/cpp/algorithm/is_sorted.html
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[std-is-sorted-until]: https://en.cppreference.com/w/cpp/algorithm/is_sorted_until.html
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[std-less]: https://en.cppreference.com/w/cpp/utility/functional/less
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[std-less-void]: https://en.cppreference.com/w/cpp/utility/functional/less_void
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[std-mem-fn]: https://en.cppreference.com/w/cpp/utility/functional/mem_fn

‎include/cpp-sort/utility/is_sorted.h‎

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/*
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* Copyright (c) 2026 Morwenn
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* SPDX-License-Identifier: MIT
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*/
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#ifndef CPPSORT_UTILITY_CHECK_IS_SORTED_H_
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#define CPPSORT_UTILITY_CHECK_IS_SORTED_H_
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////////////////////////////////////////////////////////////
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// Headers
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////////////////////////////////////////////////////////////
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#include <functional>
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#include <iterator>
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#include <utility>
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#include <cpp-sort/sorter_facade.h>
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#include <cpp-sort/sorter_traits.h>
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#include <cpp-sort/utility/functional.h>
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#include "../detail/is_sorted_until.h"
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#include "../detail/type_traits.h"
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namespace cppsort::utility
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{
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namespace detail
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{
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struct is_sorted_impl
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{
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template<
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typename ForwardIterator,
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typename Compare = std::less<>,
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typename Projection = utility::identity,
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typename = cppsort::detail::enable_if_t<
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is_projection_iterator_v<Projection, ForwardIterator, Compare>
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>
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>
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constexpr auto operator()(ForwardIterator first, ForwardIterator last,
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Compare compare={}, Projection projection={}) const
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-> bool
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{
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return cppsort::detail::is_sorted(
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first, last,
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std::move(compare), std::move(projection)
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);
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}
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////////////////////////////////////////////////////////////
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// Sorter traits
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using iterator_category = std::forward_iterator_tag;
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};
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}
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struct is_sorted_t:
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sorter_facade<detail::is_sorted_impl>
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{};
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inline constexpr is_sorted_t is_sorted{};
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}
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#endif // CPPSORT_UTILITY_CHECK_IS_SORTED_H_

‎include/cpp-sort/utility/is_sorted_until.h‎

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/*
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* Copyright (c) 2026 Morwenn
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* SPDX-License-Identifier: MIT
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*/
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#ifndef CPPSORT_UTILITY_CHECK_IS_SORTED_UNTIL_H_
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#define CPPSORT_UTILITY_CHECK_IS_SORTED_UNTIL_H_
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////////////////////////////////////////////////////////////
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// Headers
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////////////////////////////////////////////////////////////
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#include <functional>
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#include <iterator>
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#include <utility>
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#include <cpp-sort/sorter_facade.h>
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#include <cpp-sort/sorter_traits.h>
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#include <cpp-sort/utility/functional.h>
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#include "../detail/is_sorted_until.h"
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#include "../detail/type_traits.h"
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namespace cppsort::utility
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{
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namespace detail
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{
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struct is_sorted_until_impl
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{
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template<
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typename ForwardIterator,
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typename Compare = std::less<>,
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typename Projection = utility::identity,
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typename = cppsort::detail::enable_if_t<
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is_projection_iterator_v<Projection, ForwardIterator, Compare>
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>
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>
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constexpr auto operator()(ForwardIterator first, ForwardIterator last,
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Compare compare={}, Projection projection={}) const
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-> ForwardIterator
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{
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return cppsort::detail::is_sorted_until(
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first, last,
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std::move(compare), std::move(projection)
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);
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}
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////////////////////////////////////////////////////////////
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// Sorter traits
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using iterator_category = std::forward_iterator_tag;
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};
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}
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struct is_sorted_until_t:
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sorter_facade<detail::is_sorted_until_impl>
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{};
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inline constexpr is_sorted_until_t is_sorted_until{};
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}
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#endif // CPPSORT_UTILITY_CHECK_IS_SORTED_UNTIL_H_

‎tests/CMakeLists.txt‎

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utility/buffer.cpp
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utility/chainable_projections.cpp
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utility/check_strict_weak_ordering.cpp
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utility/is_sorted.cpp
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utility/iter_swap.cpp
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utility/metric_tools.cpp
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utility/quicksort_adversary.cpp

‎tests/utility/is_sorted.cpp‎

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/*
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* Copyright (c) 2026 Morwenn
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* SPDX-License-Identifier: MIT
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*/
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#include <iterator>
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#include <vector>
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#include <catch2/catch_test_macros.hpp>
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#include <cpp-sort/utility/is_sorted.h>
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#include <cpp-sort/utility/is_sorted_until.h>
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#include <testing-tools/distributions.h>
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namespace utility = cppsort::utility;
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TEST_CASE( "is_sorted and is_sorted_until test", "[utility][is_sorted]" )
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{
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SECTION( "empty collection" )
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{
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std::vector<int> vec = {};
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CHECK( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == vec.end() );
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}
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SECTION( "collection with one element" )
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{
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std::vector<int> vec = {5};
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CHECK( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == vec.end() );
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}
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SECTION( "collection with two elements" )
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{
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std::vector<int> vec1 = {0, 0};
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CHECK( utility::is_sorted(vec1) );
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CHECK( utility::is_sorted_until(vec1) == vec1.end() );
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std::vector<int> vec2 = {0, 5};
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CHECK( utility::is_sorted(vec2) );
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CHECK( utility::is_sorted_until(vec2) == vec2.end() );
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std::vector<int> vec3 = {5, 0};
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CHECK_FALSE( utility::is_sorted(vec3) );
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CHECK( utility::is_sorted_until(vec3) == std::next(vec3.begin()) );
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}
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SECTION( "distribution: ascending" )
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{
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std::vector<int> vec;
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vec.reserve(250);
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auto distribution = dist::ascending{};
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distribution(std::back_inserter(vec), 250);
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CHECK( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == vec.end() );
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}
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SECTION( "distribution: ascending_duplicates" )
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{
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std::vector<int> vec;
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vec.reserve(250);
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auto distribution = dist::ascending_duplicates{};
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distribution(std::back_inserter(vec), 250);
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CHECK( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == vec.end() );
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}
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SECTION( "distribution: all_equal" )
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{
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std::vector<int> vec;
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vec.reserve(250);
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auto distribution = dist::all_equal{};
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distribution(std::back_inserter(vec), 250);
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CHECK( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == vec.end() );
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}
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SECTION( "distribution: descending" )
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{
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std::vector<int> vec;
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vec.reserve(250);
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auto distribution = dist::descending{};
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distribution(std::back_inserter(vec), 250);
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CHECK_FALSE( utility::is_sorted(vec) );
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CHECK( utility::is_sorted_until(vec) == std::next(vec.begin()) );
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}
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}

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