mirror of https://github.com/axmolengine/axmol.git
124 lines
3.5 KiB
C++
124 lines
3.5 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Casey Carter 2017
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// Copyright Gonzalo Brito Gadeschi 2017
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Project home: https://github.com/ericniebler/range-v3
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//
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#ifndef RANGES_V3_VIEW_LINEAR_DISTRIBUTE_HPP
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#define RANGES_V3_VIEW_LINEAR_DISTRIBUTE_HPP
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#include <type_traits>
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#include <meta/meta.hpp>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/iterator/default_sentinel.hpp>
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#include <range/v3/utility/static_const.hpp>
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#include <range/v3/view/facade.hpp>
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#include <range/v3/detail/prologue.hpp>
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namespace ranges
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{
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namespace views
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{
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/// \addtogroup group-views
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/// @{
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template<typename T>
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struct linear_distribute_view : view_facade<linear_distribute_view<T>, finite>
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{
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CPP_assert(std::is_arithmetic<T>());
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private:
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friend range_access;
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using Calc = meta::conditional_t<std::is_floating_point<T>::value, T, double>;
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T from_, to_;
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Calc delta_;
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std::ptrdiff_t n_;
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constexpr T read() const noexcept
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{
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return from_;
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}
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constexpr bool equal(default_sentinel_t) const noexcept
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{
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return n_ == 0;
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}
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constexpr bool equal(linear_distribute_view const & other) const noexcept
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{
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bool const eq = n_ == other.n_;
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RANGES_DIAGNOSTIC_PUSH
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RANGES_DIAGNOSTIC_IGNORE_FLOAT_EQUAL
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RANGES_EXPECT(to_ == other.to_);
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RANGES_EXPECT(!eq || from_ == other.from_);
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RANGES_DIAGNOSTIC_POP
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return eq;
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}
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constexpr void next() noexcept
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{
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RANGES_EXPECT(n_ > 0);
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--n_;
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if(n_ == 0)
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{
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from_ = to_;
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}
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else
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{
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from_ = T(to_ - (delta_ * Calc(n_ - 1)));
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}
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}
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public:
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constexpr linear_distribute_view() = default;
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constexpr linear_distribute_view(T from, T to, std::ptrdiff_t n) noexcept
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: from_(from)
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, to_(to)
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, delta_(n > 1 ? (to - from) / Calc(n - 1) : 0)
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, n_(n)
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{
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RANGES_EXPECT(n_ > 0);
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RANGES_EXPECT(to_ >= from_);
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}
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constexpr std::size_t size() const noexcept
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{
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return static_cast<std::size_t>(n_);
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}
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};
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/// Distributes `n` values linearly in the closed interval [`from`, `to`].
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///
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/// \pre `from <= to && n > 0`
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///
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/// If `from == to`, returns n-times `to`.
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/// If `n == 1` returns `to`.
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struct linear_distribute_fn
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{
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template(typename T)(
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requires std::is_arithmetic<T>::value)
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constexpr auto operator()(T from, T to, std::ptrdiff_t n) const
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{
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return linear_distribute_view<T>{from, to, n};
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}
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};
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/// \relates linear_distribute_fn
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/// \ingroup group-views
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RANGES_INLINE_VARIABLE(linear_distribute_fn, linear_distribute)
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} // namespace views
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#endif
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