feat():initial version

install/boost_1_75_0/include/boost/hof/capture.hpp

@@ -0,0 +1,189 @@
+/*=============================================================================
+    Copyright (c) 2015 Paul Fultz II
+    capture.h
+    Distributed under 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)
+==============================================================================*/
+
+#ifndef BOOST_HOF_GUARD_CAPTURE_H
+#define BOOST_HOF_GUARD_CAPTURE_H
+
+#include <boost/hof/detail/callable_base.hpp>
+#include <boost/hof/detail/compressed_pair.hpp>
+#include <boost/hof/reveal.hpp>
+#include <boost/hof/pack.hpp>
+#include <boost/hof/always.hpp>
+#include <boost/hof/detail/move.hpp>
+#include <boost/hof/detail/result_type.hpp>
+
+/// capture
+/// =======
+/// 
+/// Description
+/// -----------
+/// 
+/// The `capture` function decorator is used to capture values in a function.
+/// It provides more flexibility in capturing than the lambda capture list in
+/// C++. It provides a way to do move and perfect capturing. The values
+/// captured are prepended to the argument list of the function that will be
+/// called.
+/// 
+/// Synopsis
+/// --------
+/// 
+///     // Capture by decaying each value
+///     template<class... Ts>
+///     constexpr auto capture(Ts&&... xs);
+/// 
+///     // Capture lvalues by reference and rvalue reference by reference
+///     template<class... Ts>
+///     constexpr auto capture_forward(Ts&&... xs);
+/// 
+///     // Capture lvalues by reference and rvalues by value.
+///     template<class... Ts>
+///     constexpr auto capture_basic(Ts&&... xs);
+/// 
+/// Semantics
+/// ---------
+/// 
+///     assert(capture(xs...)(f)(ys...) == f(xs..., ys...));
+/// 
+/// 
+/// Example
+/// -------
+/// 
+///     #include <boost/hof.hpp>
+///     #include <cassert>
+/// 
+///     struct sum_f
+///     {
+///         template<class T, class U>
+///         T operator()(T x, U y) const
+///         {
+///             return x+y;
+///         }
+///     };
+/// 
+///     int main() {
+///         auto add_one = boost::hof::capture(1)(sum_f());
+///         assert(add_one(2) == 3);
+///     }
+/// 
+
+namespace boost { namespace hof {
+
+namespace detail {
+
+template<class F, class Pack>
+struct capture_invoke : detail::compressed_pair<detail::callable_base<F>, Pack>, detail::function_result_type<F>
+{
+    typedef capture_invoke fit_rewritable1_tag;
+    typedef detail::compressed_pair<detail::callable_base<F>, Pack> base;
+    BOOST_HOF_INHERIT_CONSTRUCTOR(capture_invoke, base)
+    template<class... Ts>
+    constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const noexcept
+    {
+        return this->first(xs...);
+    }
+
+    template<class... Ts>
+    constexpr const Pack& get_pack(Ts&&...xs) const noexcept
+    {
+        return this->second(xs...);
+    }
+
+    template<class Failure, class... Ts>
+    struct unpack_capture_failure
+    {
+        template<class... Us>
+        struct apply
+        {
+            typedef typename Failure::template of<Us..., Ts...> type;
+        };
+    };
+
+    struct capture_failure
+    {
+        template<class Failure>
+        struct apply
+        {
+            template<class... Ts>
+            struct of
+            : Pack::template apply<unpack_capture_failure<Failure, Ts...>>::type
+            {};
+        };
+    };
+
+    struct failure
+    : failure_map<capture_failure, detail::callable_base<F>>
+    {};
+
+    BOOST_HOF_RETURNS_CLASS(capture_invoke);
+
+    template<class... Ts>
+    constexpr BOOST_HOF_SFINAE_RESULT
+    (
+        typename result_of<decltype(boost::hof::pack_join), 
+            id_<const Pack&>, 
+            result_of<decltype(boost::hof::pack_forward), id_<Ts>...> 
+        >::type,
+        id_<detail::callable_base<F>&&>
+    ) 
+    operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
+    (
+        boost::hof::pack_join
+        (
+            BOOST_HOF_MANGLE_CAST(const Pack&)(BOOST_HOF_CONST_THIS->get_pack(xs...)), 
+            boost::hof::pack_forward(BOOST_HOF_FORWARD(Ts)(xs)...)
+        )
+        (BOOST_HOF_RETURNS_C_CAST(detail::callable_base<F>&&)(BOOST_HOF_CONST_THIS->base_function(xs...)))
+    );
+};
+
+template<class Pack>
+struct capture_pack : Pack
+{
+    BOOST_HOF_INHERIT_CONSTRUCTOR(capture_pack, Pack);
+
+    BOOST_HOF_RETURNS_CLASS(capture_pack);
+
+    // TODO: Should use rvalue ref qualifier
+    template<class F>
+    constexpr auto operator()(F f) const BOOST_HOF_SFINAE_RETURNS
+    (
+        capture_invoke<F, Pack>(BOOST_HOF_RETURNS_STATIC_CAST(F&&)(f), 
+            BOOST_HOF_RETURNS_C_CAST(Pack&&)(
+                BOOST_HOF_RETURNS_STATIC_CAST(const Pack&)(*boost::hof::always(BOOST_HOF_CONST_THIS)(f))
+            )
+        )
+    );
+};
+
+struct make_capture_pack_f
+{
+    template<class Pack>
+    constexpr capture_pack<Pack> operator()(Pack p) const
+    BOOST_HOF_NOEXCEPT_CONSTRUCTIBLE(capture_pack<Pack>, Pack&&)
+    {
+        return capture_pack<Pack>(static_cast<Pack&&>(p));
+    }
+};
+
+template<class F>
+struct capture_f
+{
+    template<class... Ts>
+    constexpr auto operator()(Ts&&... xs) const BOOST_HOF_RETURNS
+    (
+        BOOST_HOF_RETURNS_CONSTRUCT(make_capture_pack_f)()(BOOST_HOF_RETURNS_CONSTRUCT(F)()(BOOST_HOF_FORWARD(Ts)(xs)...))
+    );
+};
+}
+
+BOOST_HOF_DECLARE_STATIC_VAR(capture_basic, detail::capture_f<detail::pack_basic_f>);
+BOOST_HOF_DECLARE_STATIC_VAR(capture_forward, detail::capture_f<detail::pack_forward_f>);
+BOOST_HOF_DECLARE_STATIC_VAR(capture, detail::capture_f<detail::pack_f>);
+
+}} // namespace boost::hof
+
+#endif