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// Copyright Louis Dionne 2013-2017
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#ifndef TEST_SUPPORT_IDENTITY_HPP
#define TEST_SUPPORT_IDENTITY_HPP
#include <boost/hana/chain.hpp>
#include <boost/hana/eval_if.hpp>
#include <boost/hana/functional/compose.hpp>
#include <boost/hana/functional/partial.hpp>
#include <boost/hana/fwd/adjust_if.hpp>
#include <boost/hana/fwd/ap.hpp>
#include <boost/hana/fwd/equal.hpp>
#include <boost/hana/fwd/flatten.hpp>
#include <boost/hana/fwd/less.hpp>
#include <boost/hana/fwd/lift.hpp>
#include <boost/hana/lazy.hpp>
#include <boost/hana/transform.hpp>
#include <type_traits>
struct Identity;
template <typename T>
struct identity_t {
T value;
using hana_tag = Identity;
};
struct make_identity {
template <typename T>
constexpr identity_t<typename std::decay<T>::type> operator()(T&& t) const {
return {static_cast<T&&>(t)};
}
};
constexpr make_identity identity{};
namespace boost { namespace hana {
//////////////////////////////////////////////////////////////////////////
// Comparable
//////////////////////////////////////////////////////////////////////////
template <>
struct equal_impl<Identity, Identity> {
template <typename Id1, typename Id2>
static constexpr auto apply(Id1 x, Id2 y)
{ return hana::equal(x.value, y.value); }
};
//////////////////////////////////////////////////////////////////////////
// Orderable
//////////////////////////////////////////////////////////////////////////
template <>
struct less_impl<Identity, Identity> {
template <typename Id1, typename Id2>
static constexpr auto apply(Id1 x, Id2 y)
{ return hana::less(x.value, y.value); }
};
//////////////////////////////////////////////////////////////////////////
// Functor
//
// Define either one to select which MCD is used:
// BOOST_HANA_TEST_FUNCTOR_TRANSFORM_MCD
// BOOST_HANA_TEST_FUNCTOR_ADJUST_MCD_MCD
//
// If neither is defined, the MCD used is unspecified.
//////////////////////////////////////////////////////////////////////////
#ifdef BOOST_HANA_TEST_FUNCTOR_TRANSFORM_MCD
template <>
struct transform_impl<Identity> {
template <typename Id, typename F>
static constexpr auto apply(Id self, F f)
{ return ::identity(f(self.value)); }
};
#else
template <>
struct adjust_if_impl<Identity> {
struct get_value {
template <typename T>
constexpr auto operator()(T t) const { return t.value; }
};
template <typename Id, typename P, typename F>
static constexpr auto apply(Id self, P p, F f) {
auto x = hana::eval_if(p(self.value),
hana::make_lazy(hana::compose(f, get_value{}))(self),
hana::make_lazy(get_value{})(self)
);
return ::identity(x);
}
};
#endif
//////////////////////////////////////////////////////////////////////////
// Applicative
//
// Define either one to select which MCD is used:
// BOOST_HANA_TEST_APPLICATIVE_FULL_MCD
// BOOST_HANA_TEST_APPLICATIVE_MONAD_MCD
//
// If neither is defined, the MCD used is unspecified.
//////////////////////////////////////////////////////////////////////////
template <>
struct lift_impl<Identity> {
template <typename X>
static constexpr auto apply(X x)
{ return ::identity(x); }
};
#ifdef BOOST_HANA_TEST_APPLICATIVE_FULL_MCD
template <>
struct ap_impl<Identity> {
template <typename F, typename X>
static constexpr auto apply(F f, X x)
{ return ::identity(f.value(x.value)); }
};
#else
template <>
struct ap_impl<Identity> {
template <typename F, typename X>
static constexpr decltype(auto) apply(F&& f, X&& x) {
return hana::chain(
static_cast<F&&>(f),
hana::partial(hana::transform, static_cast<X&&>(x))
);
}
};
#endif
//////////////////////////////////////////////////////////////////////////
// Monad
//
// Define either one to select which MCD is used:
// BOOST_HANA_TEST_MONAD_FLATTEN_MCD
// BOOST_HANA_TEST_MONAD_CHAIN_MCD
//
// If neither is defined, the MCD used is unspecified.
//////////////////////////////////////////////////////////////////////////
#ifdef BOOST_HANA_TEST_MONAD_FLATTEN_MCD
template <>
struct flatten_impl<Identity> {
template <typename Id>
static constexpr auto apply(Id self)
{ return self.value; }
};
#else
template <>
struct chain_impl<Identity> {
template <typename X, typename F>
static constexpr auto apply(X x, F f)
{ return f(x.value); }
};
#endif
}} // end namespace boost::hana
#endif // !TEST_SUPPORT_IDENTITY_HPP
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