Edit: /usr/include/boost/hof/infix.hpp (6043B)
/*=============================================================================
Copyright (c) 2014 Paul Fultz II
infix.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_FUNCTION_INFIX_H
#define BOOST_HOF_GUARD_FUNCTION_INFIX_H
/// infix
/// =====
///
/// Description
/// -----------
///
/// The `infix` function adaptor allows the function to be used as an infix
/// operator. The operator must be placed inside the angle brackets(ie `<`
/// and `>`).
///
/// Synopsis
/// --------
///
/// template
/// constexpr infix_adaptor infix(F f);
///
/// Semantics
/// ---------
///
/// assert(x y == f(x, y));
///
/// Requirements
/// ------------
///
/// F must be:
///
/// * [BinaryInvocable](BinaryInvocable)
/// * MoveConstructible
///
/// Operator precedence
/// -------------------
///
/// Infix operators have the precedence of relational operators. This means
/// operators such as `+` or `*` have higher precedence:
///
/// assert((x + y z) == ((x + y) z));
/// assert((x * y z) == ((x * y) z));
///
/// However, operators such as `|` or `==` have lower precedence::
///
/// assert((x | y z) == (x | (y z)));
/// assert((x == y z) == (x == (y z)));
///
/// Also, infix operators have left-to-right associativity:
///
/// assert(x y z == ((x y) z));
///
/// Example
/// -------
///
/// #include
/// #include
/// using namespace boost::hof;
///
/// struct plus_f
/// {
/// template
/// T operator()(T x, U y) const
/// {
/// return x+y;
/// }
/// };
///
/// int main() {
/// constexpr infix_adaptor plus = {};
/// int r = 3 2;
/// assert(r == 5);
/// }
///
#include
#include
#include
#include
#include
#include
#include
namespace boost { namespace hof {
namespace detail{
template
struct postfix_adaptor : F
{
T x;
template
constexpr postfix_adaptor(X&& xp, XF&& fp)
BOOST_HOF_NOEXCEPT(BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(F, XF&&) && BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(T, X&&))
: F(BOOST_HOF_FORWARD(XF)(fp)), x(BOOST_HOF_FORWARD(X)(xp))
{}
template
constexpr const F& base_function(Ts&&... xs) const noexcept
{
return boost::hof::always_ref(*this)(xs...);
}
BOOST_HOF_RETURNS_CLASS(postfix_adaptor);
template
constexpr BOOST_HOF_SFINAE_RESULT(const F&, id_, id_...)
operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
(
(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)...)
);
template
constexpr BOOST_HOF_SFINAE_RESULT(const F&, id_, id_)
operator>(A&& a) const BOOST_HOF_SFINAE_RETURNS
(
(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))
);
};
template
constexpr postfix_adaptor make_postfix_adaptor(T&& x, F f)
BOOST_HOF_NOEXCEPT_CONSTRUCTIBLE(postfix_adaptor, T&&, F&&)
{
return postfix_adaptor(BOOST_HOF_FORWARD(T)(x), static_cast(f));
}
}
template
struct infix_adaptor : detail::callable_base
{
typedef infix_adaptor fit_rewritable1_tag;
BOOST_HOF_INHERIT_CONSTRUCTOR(infix_adaptor, detail::callable_base);
template
constexpr const detail::callable_base& base_function(Ts&&... xs) const noexcept
{
return boost::hof::always_ref(*this)(xs...);
}
template
constexpr const detail::callable_base& infix_base_function(Ts&&... xs) const noexcept
{
return boost::hof::always_ref(*this)(xs...);
}
BOOST_HOF_RETURNS_CLASS(infix_adaptor);
template
constexpr auto operator()(Ts&&... xs) const BOOST_HOF_RETURNS
(
(BOOST_HOF_MANGLE_CAST(const detail::callable_base&)(BOOST_HOF_CONST_THIS->base_function(xs...)))(BOOST_HOF_FORWARD(Ts)(xs)...)
);
};
template
constexpr auto operator<(T&& x, const infix_adaptor& i) BOOST_HOF_RETURNS
(detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(i.base_function(x))));
// TODO: Operators for static_
namespace detail {
template
struct static_function_wrapper;
// Operators for static_function_wrapper adaptor
template
auto operator<(T&& x, const boost::hof::detail::static_function_wrapper& f) BOOST_HOF_RETURNS
(
detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(f.base_function().infix_base_function()))
);
template
struct static_default_function;
// Operators for static_default_function adaptor
template
auto operator<(T&& x, const boost::hof::detail::static_default_function&) BOOST_HOF_RETURNS
(
detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), boost::hof::move(F().infix_base_function()))
);
}
// This overload is needed for gcc
template
constexpr auto operator<(T&& x, const boost::hof::reveal_adaptor& f) BOOST_HOF_RETURNS
(
detail::make_postfix_adaptor(BOOST_HOF_FORWARD(T)(x), f.infix_base_function())
);
BOOST_HOF_DECLARE_STATIC_VAR(infix, detail::make);
}} // namespace boost::hof
#endif