FM / hof

/usr/include/boost/hof

Name	Size	Mode	Actions
detail/	-	0755	rm
alias.hpp	5552	0644	edit dl rm
always.hpp	4261	0644	edit dl rm
apply.hpp	8363	0644	edit dl rm
apply_eval.hpp	4428	0644	edit dl rm
arg.hpp	3148	0644	edit dl rm
capture.hpp	5419	0644	edit dl rm
combine.hpp	3877	0644	edit dl rm
compose.hpp	5042	0644	edit dl rm
config.hpp	6149	0644	edit dl rm
construct.hpp	8774	0644	edit dl rm
decay.hpp	1790	0644	edit dl rm
decorate.hpp	6329	0644	edit dl rm
eval.hpp	2400	0644	edit dl rm
first_of.hpp	7100	0644	edit dl rm
fix.hpp	6314	0644	edit dl rm
flip.hpp	2690	0644	edit dl rm
flow.hpp	5060	0644	edit dl rm
fold.hpp	5000	0644	edit dl rm
function.hpp	3129	0644	edit dl rm
function_param_limit.hpp	1658	0644	edit dl rm
identity.hpp	1884	0644	edit dl rm
if.hpp	3314	0644	edit dl rm
implicit.hpp	4041	0644	edit dl rm
indirect.hpp	3268	0644	edit dl rm
infix.hpp	6043	0644	edit dl rm
is_invocable.hpp	1706	0644	edit dl rm
is_unpackable.hpp	3341	0644	edit dl rm
lambda.hpp	6458	0644	edit dl rm
lazy.hpp	8729	0644	edit dl rm
lift.hpp	3752	0644	edit dl rm
limit.hpp	3817	0644	edit dl rm
match.hpp	3331	0644	edit dl rm
mutable.hpp	1988	0644	edit dl rm
pack.hpp	12747	0644	edit dl rm
partial.hpp	8307	0644	edit dl rm
pipable.hpp	6227	0644	edit dl rm
placeholders.hpp	13799	0644	edit dl rm
proj.hpp	7517	0644	edit dl rm
protect.hpp	2145	0644	edit dl rm
repeat.hpp	4184	0644	edit dl rm
repeat_while.hpp	5154	0644	edit dl rm
result.hpp	3644	0644	edit dl rm
returns.hpp	8607	0644	edit dl rm
reveal.hpp	12187	0644	edit dl rm
reverse_fold.hpp	5271	0644	edit dl rm
rotate.hpp	2576	0644	edit dl rm
static.hpp	2395	0644	edit dl rm
tap.hpp	2118	0644	edit dl rm
unpack.hpp	5588	0644	edit dl rm
unpack_sequence.hpp	1810	0644	edit dl rm
version.hpp	679	0644	edit dl rm

Edit: /usr/include/boost/hof/fix.hpp (6314B)

/*=============================================================================
    Copyright (c) 2014 Paul Fultz II
    fix.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_FIX_H
#define BOOST_HOF_GUARD_FUNCTION_FIX_H

/// fix
/// ===
/// 
/// Description
/// -----------
/// 
/// The `fix` function adaptor implements a fixed-point combinator. This can be
/// used to write recursive functions. 
/// 
/// When using `constexpr`, a function can recurse to a depth that is defined by
/// `BOOST_HOF_RECURSIVE_CONSTEXPR_DEPTH`(default is 16). There is no limitiation on
/// recursion depth for non-constexpr functions. In addition, due to the
/// eagerness of `constexpr` to instantiation templates, in some cases, an
/// explicit return type must be specified in order to avoid reaching the
/// recursion limits of the compiler. This can be accomplished using
/// [`boost::hof::result`](/include/boost/hof/result):
/// 
///     int r = boost::hof::result<int>(factorial)(5);
/// 
/// Synopsis
/// --------
/// 
///     template<class F>
///     constexpr fix_adaptor<F> fix(F f);
/// 
/// Semantics
/// ---------
/// 
///     assert(fix(f)(xs...) == f(fix(f), xs...));
/// 
/// Requirements
/// ------------
/// 
/// F must be:
/// 
/// * [ConstFunctionObject](ConstFunctionObject)
/// * MoveConstructible
/// 
/// Example
/// -------
/// 
///     #include <boost/hof.hpp>
///     #include <cassert>
/// 
///     int main() {
///         auto factorial = boost::hof::fix(
///             [](auto recurse, auto x) -> decltype(x) { 
///                 return x == 0 ? 1 : x * recurse(x-1); 
///             }
///         );
///         int r = boost::hof::result<int>(factorial)(5);
///         assert(r == 5*4*3*2*1);
///     }
/// 
/// References
/// ----------
/// 
/// * [Fixed-point combinator](https://en.wikipedia.org/wiki/Fixed-point_combinator)
/// * [Recursive](Recursive)
///

#include <boost/hof/always.hpp>
#include <boost/hof/detail/callable_base.hpp>
#include <boost/hof/reveal.hpp>
#include <boost/hof/detail/delegate.hpp>
#include <boost/hof/detail/move.hpp>
#include <boost/hof/detail/make.hpp>
#include <boost/hof/detail/static_const_var.hpp>
#include <boost/hof/indirect.hpp>
#include <boost/hof/result.hpp>
#include <boost/hof/detail/recursive_constexpr_depth.hpp>

namespace boost { namespace hof {

namespace detail{

template<class F>
struct compute_indirect_ref
{ typedef indirect_adaptor<const F*> type; };

template<class F>
struct compute_indirect_ref<indirect_adaptor<F*>>
{ typedef indirect_adaptor<F*> type; };

template<class F>
constexpr indirect_adaptor<const F*> make_indirect_ref(const F& f) noexcept
{
    return indirect_adaptor<const F*>(&f);
}

template<class F>
constexpr indirect_adaptor<const F*> make_indirect_ref(const indirect_adaptor<F*>& f) noexcept
{
    return f;
}

template<class F, class=void>
struct fix_result
{
    template<class... Ts>
    struct apply
    { 
        typedef decltype(std::declval<F>()(std::declval<Ts>()...)) type; 
    };
};

template<class F>
struct fix_result<F, typename holder<
    typename F::result_type
>::type>
{
    template<class...>
    struct apply
    { 
        typedef typename F::result_type type; 
    };
    
};

template<class F, class Result, int N>
struct fix_adaptor_base : F
{
    BOOST_HOF_INHERIT_CONSTRUCTOR(fix_adaptor_base, F);

typedef typename compute_indirect_ref<F>::type base_ref_type;
    typedef fix_adaptor_base<base_ref_type, Result, N-1> derived;

template<class... Ts>
    constexpr const F& base_function(Ts&&... xs) const noexcept
    {
        return boost::hof::always_ref(*this)(xs...);
    }

template<class... Ts>
    constexpr derived derived_function(Ts&&... xs) const noexcept
    {
        return derived(boost::hof::detail::make_indirect_ref(this->base_function(xs...)));
    }

struct fix_failure
    {
        template<class Failure>
        struct apply
        {
            template<class... Ts>
            struct of
            : Failure::template of<derived, Ts...>
            {};
        };
    };

struct failure
    : failure_map<fix_failure, F>
    {};

BOOST_HOF_RETURNS_CLASS(fix_adaptor_base);

template<class... Ts>
    constexpr BOOST_HOF_SFINAE_RESULT(const F&, id_<derived>, id_<Ts>...) 
    operator()(Ts&&... xs) const BOOST_HOF_SFINAE_RETURNS
    (
        BOOST_HOF_MANGLE_CAST(const F&)(BOOST_HOF_CONST_THIS->base_function(xs...))
            (
                BOOST_HOF_MANGLE_CAST(derived)(BOOST_HOF_CONST_THIS->derived_function(xs...)), 
                BOOST_HOF_FORWARD(Ts)(xs)...
            )
    );
};

template<class F, class Result>
struct fix_adaptor_base<F, Result, 0> : F
{
    BOOST_HOF_INHERIT_CONSTRUCTOR(fix_adaptor_base, F);

template<class... Ts>
    const F& base_function(Ts&&...) const noexcept
    {
        return *this;
    }

struct fix_failure
    {
        template<class Failure>
        struct apply
        {
            template<class... Ts>
            struct of
            : Failure::template of<fix_adaptor_base, Ts...>
            {};
        };
    };

struct failure
    : failure_map<fix_failure, F>
    {};

BOOST_HOF_RETURNS_CLASS(fix_adaptor_base);

template<class... Ts>
    typename Result::template apply<fix_adaptor_base, Ts...>::type
    operator()(Ts&&... xs) const
    {
        return this->base_function(xs...)(*this, BOOST_HOF_FORWARD(Ts)(xs)...);
    }
};
}

template<class F>
struct fix_adaptor : detail::fix_adaptor_base<F, detail::fix_result<F>, BOOST_HOF_RECURSIVE_CONSTEXPR_DEPTH>
{
    typedef fix_adaptor fit_rewritable1_tag;
    typedef detail::fix_adaptor_base<F, detail::fix_result<F>, BOOST_HOF_RECURSIVE_CONSTEXPR_DEPTH> base;
    BOOST_HOF_INHERIT_CONSTRUCTOR(fix_adaptor, base);
};

template<class Result, class F>
struct result_adaptor<Result, fix_adaptor<F>>
: fix_adaptor<result_adaptor<Result, F>>
{
    typedef fix_adaptor<result_adaptor<Result, F>> base;
    BOOST_HOF_INHERIT_CONSTRUCTOR(result_adaptor, base)
};

BOOST_HOF_DECLARE_STATIC_VAR(fix, detail::make<fix_adaptor>);

}} // namespace boost::hof

#endif

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