/*=============================================================================
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Copyright (c) 2014 Paul Fultz II
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infix.h
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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==============================================================================*/
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#ifndef BOOST_HOF_GUARD_FUNCTION_INFIX_H
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#define BOOST_HOF_GUARD_FUNCTION_INFIX_H
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/// infix
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/// =====
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///
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/// Description
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/// -----------
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///
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/// The `infix` function adaptor allows the function to be used as an infix
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/// operator. The operator must be placed inside the angle brackets(ie `<`
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/// and `>`).
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///
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/// Synopsis
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/// --------
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///
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/// template<class F>
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/// constexpr infix_adaptor<F> infix(F f);
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///
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/// Semantics
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/// ---------
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///
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/// assert(x <infix(f)> y == f(x, y));
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///
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/// Requirements
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/// ------------
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///
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/// F must be:
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///
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/// * [BinaryInvocable](BinaryInvocable)
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/// * MoveConstructible
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///
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/// Operator precedence
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/// -------------------
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///
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/// Infix operators have the precedence of relational operators. This means
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/// operators such as `+` or `*` have higher precedence:
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///
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/// assert((x + y <infix(f)> z) == ((x + y) <infix(f)> z));
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/// assert((x * y <infix(f)> z) == ((x * y) <infix(f)> z));
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///
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/// However, operators such as `|` or `==` have lower precedence::
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///
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/// assert((x | y <infix(f)> z) == (x | (y <infix(f)> z)));
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/// assert((x == y <infix(f)> z) == (x == (y <infix(f)> z)));
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///
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/// Also, infix operators have left-to-right associativity:
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///
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/// assert(x <infix(f)> y <infix(g)> z == ((x <infix(f)> y) <infix(g)> z));
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///
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/// Example
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/// -------
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///
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/// #include <boost/hof.hpp>
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/// #include <cassert>
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/// using namespace boost::hof;
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///
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/// struct plus_f
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/// {
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/// template<class T, class U>
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/// T operator()(T x, U y) const
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/// {
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/// return x+y;
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/// }
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/// };
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///
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/// int main() {
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/// constexpr infix_adaptor<plus_f> plus = {};
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/// int r = 3 <plus> 2;
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/// assert(r == 5);
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/// }
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///
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#include <boost/hof/detail/delegate.hpp>
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#include <boost/hof/detail/callable_base.hpp>
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#include <boost/hof/always.hpp>
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#include <boost/hof/reveal.hpp>
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#include <boost/hof/detail/move.hpp>
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#include <boost/hof/detail/make.hpp>
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#include <boost/hof/detail/static_const_var.hpp>
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namespace boost { namespace hof {
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namespace detail{
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template<class T, class F>
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struct postfix_adaptor : F
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{
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T x;
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template<class X, class XF>
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constexpr postfix_adaptor(X&& xp, XF&& fp)
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BOOST_HOF_NOEXCEPT(BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(F, XF&&) && BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(T, X&&))
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: F(BOOST_HOF_FORWARD(XF)(fp)), x(BOOST_HOF_FORWARD(X)(xp))
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{}
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template<class... Ts>
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constexpr const F& base_function(Ts&&... xs) const noexcept
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{
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return boost::hof::always_ref(*this)(xs...);
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}
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BOOST_HOF_RETURNS_CLASS(postfix_adaptor);
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template<class... Ts>
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constexpr BOOST_HOF_SFINAE_RESULT(const F&, id_<T&&>, id_<Ts>...)
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operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
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(
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(BOOST_HOF_MANGLE_CAST(const F&)(BOOST_HOF_CONST_THIS->base_function(xs...)))(BOOST_HOF_RETURNS_C_CAST(T&&)(BOOST_HOF_CONST_THIS->x), BOOST_HOF_FORWARD(Ts)(xs)...)
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);
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template<class A>
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constexpr BOOST_HOF_SFINAE_RESULT(const F&, id_<T&&>, id_<A>)
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operator>(A&& a) const BOOST_HOF_SFINAE_RETURNS
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(
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(BOOST_HOF_MANGLE_CAST(const F&)(BOOST_HOF_CONST_THIS->base_function(a)))(BOOST_HOF_RETURNS_C_CAST(T&&)(BOOST_HOF_CONST_THIS->x), BOOST_HOF_FORWARD(A)(a))
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);
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};
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template<class T, class F>
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constexpr postfix_adaptor<T, F> make_postfix_adaptor(T&& x, F f)
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BOOST_HOF_NOEXCEPT_CONSTRUCTIBLE(postfix_adaptor<T, F>, T&&, F&&)
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{
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return postfix_adaptor<T, F>(BOOST_HOF_FORWARD(T)(x), static_cast<F&&>(f));
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}
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}
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template<class F>
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struct infix_adaptor : detail::callable_base<F>
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{
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typedef infix_adaptor fit_rewritable1_tag;
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BOOST_HOF_INHERIT_CONSTRUCTOR(infix_adaptor, detail::callable_base<F>);
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template<class... Ts>
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constexpr const detail::callable_base<F>& base_function(Ts&&... xs) const noexcept
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{
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return boost::hof::always_ref(*this)(xs...);
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}
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template<class... Ts>
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constexpr const detail::callable_base<F>& infix_base_function(Ts&&... xs) const noexcept
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{
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return boost::hof::always_ref(*this)(xs...);
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}
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BOOST_HOF_RETURNS_CLASS(infix_adaptor);
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template<class... Ts>
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constexpr auto operator()(Ts&&... xs) const BOOST_HOF_RETURNS
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(
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(BOOST_HOF_MANGLE_CAST(const detail::callable_base<F>&)(BOOST_HOF_CONST_THIS->base_function(xs...)))(BOOST_HOF_FORWARD(Ts)(xs)...)
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);
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};
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template<class T, class F>
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constexpr auto operator<(T&& x, const infix_adaptor<F>& i) BOOST_HOF_RETURNS
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(detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(i.base_function(x))));
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// TODO: Operators for static_
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namespace detail {
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template<class F>
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struct static_function_wrapper;
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// Operators for static_function_wrapper adaptor
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template<class T, class F>
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auto operator<(T&& x, const boost::hof::detail::static_function_wrapper<F>& f) BOOST_HOF_RETURNS
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(
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detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(f.base_function().infix_base_function()))
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);
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template<class F>
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struct static_default_function;
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// Operators for static_default_function adaptor
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template<class T, class F>
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auto operator<(T&& x, const boost::hof::detail::static_default_function<F>&) BOOST_HOF_RETURNS
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(
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detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(F().infix_base_function()))
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);
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}
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// This overload is needed for gcc
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template<class T, class F>
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constexpr auto operator<(T&& x, const boost::hof::reveal_adaptor<F>& f) BOOST_HOF_RETURNS
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(
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detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), f.infix_base_function())
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);
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BOOST_HOF_DECLARE_STATIC_VAR(infix, detail::make<infix_adaptor>);
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}} // namespace boost::hof
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#endif
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