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Telegram/ThirdParty/range-v3/include/range/v3/numeric/partial_sum.hpp

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+/// \file
+// Range v3 library
+//
+//  Copyright Eric Niebler 2013-present
+//  Copyright Gonzalo Brito Gadeschi 2014
+//
+//  Use, modification and distribution is subject to the
+//  Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+// Project home: https://github.com/ericniebler/range-v3
+//
+#ifndef RANGES_V3_NUMERIC_PARTIAL_SUM_HPP
+#define RANGES_V3_NUMERIC_PARTIAL_SUM_HPP
+
+#include <meta/meta.hpp>
+
+#include <range/v3/algorithm/result_types.hpp>
+#include <range/v3/functional/arithmetic.hpp>
+#include <range/v3/functional/compose.hpp>
+#include <range/v3/functional/identity.hpp>
+#include <range/v3/functional/invoke.hpp>
+#include <range/v3/iterator/concepts.hpp>
+#include <range/v3/iterator/traits.hpp>
+#include <range/v3/iterator/unreachable_sentinel.hpp>
+#include <range/v3/range/access.hpp>
+#include <range/v3/range/concepts.hpp>
+#include <range/v3/range/dangling.hpp>
+#include <range/v3/range/traits.hpp>
+#include <range/v3/utility/static_const.hpp>
+
+#include <range/v3/detail/prologue.hpp>
+
+namespace ranges
+{
+    /// \addtogroup group-numerics
+    /// @{
+
+    /// \cond
+    namespace detail
+    {
+        // Only needed for type-checking purposes:
+        struct as_lvalue_fn
+        {
+            template<typename T>
+            constexpr T & operator()(T && t) const noexcept
+            {
+                return t;
+            }
+        };
+        template<typename I>
+        using as_value_type_t = composed<as_lvalue_fn, coerce<iter_value_t<I>>>;
+    } // namespace detail
+      /// \endcond
+
+    // axiom: BOp is associative over values of I.
+    // clang-format off
+    /// \concept indirect_semigroup_
+    /// \brief The \c indirect_semigroup_ concept
+    template(typename I, typename BOp)(
+    concept (indirect_semigroup_)(I, BOp),
+        copyable<iter_value_t<I>> AND
+        indirectly_regular_binary_invocable_<
+            composed<coerce<iter_value_t<I>>, BOp>,
+            iter_value_t<I>*, I>
+    );
+    /// \concept indirect_semigroup
+    /// \brief The \c indirect_semigroup concept
+    template<typename I, typename BOp>
+    CPP_concept indirect_semigroup =
+        indirectly_readable<I> &&
+        CPP_concept_ref(ranges::indirect_semigroup_, I, BOp);
+
+    /// \concept partial_sum_constraints_
+    /// \brief The \c partial_sum_constraints_ concept
+    template(typename I, typename O, typename BOp, typename P)(
+    concept (partial_sum_constraints_)(I, O, BOp, P),
+        indirect_semigroup<
+            projected<projected<I, detail::as_value_type_t<I>>, P>,
+            BOp> AND
+        output_iterator<
+            O,
+            iter_value_t<
+                projected<projected<I, detail::as_value_type_t<I>>, P>> const &>
+    );
+    /// \concept partial_sum_constraints
+    /// \brief The \c partial_sum_constraints concept
+    template<typename I, typename O, typename BOp = plus, typename P = identity>
+    CPP_concept partial_sum_constraints =
+        input_iterator<I> &&
+        CPP_concept_ref(ranges::partial_sum_constraints_, I, O, BOp, P);
+    // clang-format on
+
+    template<typename I, typename O>
+    using partial_sum_result = detail::in_out_result<I, O>;
+
+    struct partial_sum_fn
+    {
+        template(typename I, typename S1, typename O, typename S2, typename BOp = plus,
+                 typename P = identity)(
+            requires sentinel_for<S1, I> AND sentinel_for<S2, O> AND
+                partial_sum_constraints<I, O, BOp, P>)
+        partial_sum_result<I, O> operator()(I first,
+                                            S1 last,
+                                            O result,
+                                            S2 end_result,
+                                            BOp bop = BOp{},
+                                            P proj = P{}) const
+        {
+            using X = projected<projected<I, detail::as_value_type_t<I>>, P>;
+            coerce<iter_value_t<I>> val_i;
+            coerce<iter_value_t<X>> val_x;
+            if(first != last && result != end_result)
+            {
+                auto && cur1 = val_i(*first);
+                iter_value_t<X> t(invoke(proj, cur1));
+                *result = t;
+                for(++first, ++result; first != last && result != end_result;
+                    ++first, ++result)
+                {
+                    auto && cur2 = val_i(*first);
+                    t = val_x(invoke(bop, t, invoke(proj, cur2)));
+                    *result = t;
+                }
+            }
+            return {first, result};
+        }
+
+        template(typename I, typename S, typename O, typename BOp = plus,
+                 typename P = identity)(
+            requires sentinel_for<S, I> AND partial_sum_constraints<I, O, BOp, P>)
+        partial_sum_result<I, O> //
+        operator()(I first, S last, O result, BOp bop = BOp{}, P proj = P{}) const
+        {
+            return (*this)(std::move(first),
+                           std::move(last),
+                           std::move(result),
+                           unreachable,
+                           std::move(bop),
+                           std::move(proj));
+        }
+
+        template(typename Rng, typename ORef, typename BOp = plus, typename P = identity,
+                 typename I = iterator_t<Rng>, typename O = uncvref_t<ORef>)(
+            requires range<Rng> AND partial_sum_constraints<I, O, BOp, P>)
+        partial_sum_result<borrowed_iterator_t<Rng>, O> //
+        operator()(Rng && rng, ORef && result, BOp bop = BOp{}, P proj = P{}) const
+        {
+            return (*this)(begin(rng),
+                           end(rng),
+                           static_cast<ORef &&>(result),
+                           std::move(bop),
+                           std::move(proj));
+        }
+
+        template(typename Rng, typename ORng, typename BOp = plus, typename P = identity,
+                 typename I = iterator_t<Rng>, typename O = iterator_t<ORng>)(
+            requires range<Rng> AND range<ORng> AND partial_sum_constraints<I, O, BOp, P>)
+        partial_sum_result<borrowed_iterator_t<Rng>, borrowed_iterator_t<ORng>> //
+        operator()(Rng && rng, ORng && result, BOp bop = BOp{}, P proj = P{}) const
+        {
+            return (*this)(begin(rng),
+                           end(rng),
+                           begin(result),
+                           end(result),
+                           std::move(bop),
+                           std::move(proj));
+        }
+    };
+
+    RANGES_INLINE_VARIABLE(partial_sum_fn, partial_sum)
+    /// @}
+} // namespace ranges
+
+#include <range/v3/detail/epilogue.hpp>
+
+#endif