1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/*!
@file
Defines `boost::hana::find_if`.
@copyright Louis Dionne 2013-2016
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 BOOST_HANA_FIND_IF_HPP
#define BOOST_HANA_FIND_IF_HPP
#include <boost/hana/fwd/find_if.hpp>
#include <boost/hana/accessors.hpp>
#include <boost/hana/at.hpp>
#include <boost/hana/bool.hpp>
#include <boost/hana/concept/iterable.hpp>
#include <boost/hana/concept/searchable.hpp>
#include <boost/hana/concept/sequence.hpp>
#include <boost/hana/concept/struct.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/detail/decay.hpp>
#include <boost/hana/drop_while.hpp>
#include <boost/hana/first.hpp>
#include <boost/hana/front.hpp>
#include <boost/hana/functional/compose.hpp>
#include <boost/hana/is_empty.hpp>
#include <boost/hana/length.hpp>
#include <boost/hana/not.hpp>
#include <boost/hana/optional.hpp>
#include <boost/hana/second.hpp>
#include <boost/hana/transform.hpp>
#include <cstddef>
#include <utility>
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template <typename Xs, typename Pred>
constexpr auto find_if_t::operator()(Xs&& xs, Pred&& pred) const {
using S = typename hana::tag_of<Xs>::type;
using FindIf = BOOST_HANA_DISPATCH_IF(find_if_impl<S>,
hana::Searchable<S>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Searchable<S>::value,
"hana::find_if(xs, pred) requires 'xs' to be a Searchable");
#endif
return FindIf::apply(static_cast<Xs&&>(xs), static_cast<Pred&&>(pred));
}
//! @endcond
template <typename S, bool condition>
struct find_if_impl<S, when<condition>> : default_ {
template <typename ...Args>
static constexpr auto apply(Args&& ...) = delete;
};
namespace detail {
template <typename Xs, typename Pred, std::size_t i, std::size_t N, bool Done>
struct advance_until;
template <typename Xs, typename Pred, std::size_t i, std::size_t N>
struct advance_until<Xs, Pred, i, N, false>
: advance_until<Xs, Pred, i + 1, N, static_cast<bool>(detail::decay<decltype(
std::declval<Pred>()(hana::at_c<i>(std::declval<Xs>()))
)>::type::value)>
{ };
template <typename Xs, typename Pred, std::size_t N>
struct advance_until<Xs, Pred, N, N, false> {
template <typename Ys>
static constexpr auto apply(Ys&&) {
return hana::nothing;
}
};
template <typename Xs, typename Pred, std::size_t i, std::size_t N>
struct advance_until<Xs, Pred, i, N, true> {
template <typename Ys>
static constexpr auto apply(Ys&& ys) {
return hana::just(hana::at_c<i - 1>(static_cast<Ys&&>(ys)));
}
};
}
template <typename S>
struct find_if_impl<S, when<Sequence<S>::value>> {
template <typename Xs, typename Pred>
static constexpr auto apply(Xs&& xs, Pred&&) {
constexpr std::size_t N = decltype(hana::length(xs))::value;
return detail::advance_until<Xs&&, Pred&&, 0, N, false>::apply(
static_cast<Xs&&>(xs)
);
}
};
template <typename It>
struct find_if_impl<It, when<hana::Iterable<It>::value && !Sequence<It>::value>> {
template <typename Xs, typename Pred>
static constexpr auto find_if_helper(Xs&& xs, Pred&& pred, hana::true_) {
return hana::just(hana::front(
hana::drop_while(static_cast<Xs&&>(xs),
hana::compose(hana::not_, static_cast<Pred&&>(pred)))
));
}
template <typename Xs, typename Pred>
static constexpr auto find_if_helper(Xs&&, Pred&&, hana::false_) {
return hana::nothing;
}
template <typename Xs, typename Pred>
static constexpr auto apply(Xs&& xs, Pred&& pred) {
constexpr bool found = !decltype(
hana::is_empty(hana::drop_while(static_cast<Xs&&>(xs),
hana::compose(hana::not_, static_cast<Pred&&>(pred))))
)::value;
return find_if_impl::find_if_helper(static_cast<Xs&&>(xs),
static_cast<Pred&&>(pred),
hana::bool_<found>{});
}
};
template <typename T, std::size_t N>
struct find_if_impl<T[N]> {
template <typename Xs>
static constexpr auto find_if_helper(Xs&&, hana::false_)
{ return hana::nothing; }
template <typename Xs>
static constexpr auto find_if_helper(Xs&& xs, hana::true_)
{ return hana::just(static_cast<Xs&&>(xs)[0]); }
template <typename Xs, typename Pred>
static constexpr auto apply(Xs&& xs, Pred&& pred) {
return find_if_helper(static_cast<Xs&&>(xs),
hana::bool_c<decltype(
static_cast<Pred&&>(pred)(static_cast<Xs&&>(xs)[0])
)::value>
);
}
};
namespace struct_detail {
template <typename X>
struct get_member {
X x;
template <typename Member>
constexpr decltype(auto) operator()(Member&& member) && {
return hana::second(static_cast<Member&&>(member))(
static_cast<X&&>(x)
);
}
};
}
template <typename S>
struct find_if_impl<S, when<hana::Struct<S>::value>> {
template <typename X, typename Pred>
static constexpr decltype(auto) apply(X&& x, Pred&& pred) {
return hana::transform(
hana::find_if(hana::accessors<S>(),
hana::compose(static_cast<Pred&&>(pred), hana::first)
),
struct_detail::get_member<X>{static_cast<X&&>(x)}
);
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_FIND_IF_HPP
|
