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
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
/*
@file
Defines `boost::hana::experimental::print`.
@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_EXPERIMENTAL_PRINTABLE_HPP
#define BOOST_HANA_EXPERIMENTAL_PRINTABLE_HPP
#include <boost/hana/concept/constant.hpp>
#include <boost/hana/concept/product.hpp>
#include <boost/hana/concept/sequence.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/to.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/first.hpp>
#include <boost/hana/for_each.hpp>
#include <boost/hana/intersperse.hpp>
#include <boost/hana/second.hpp>
#include <boost/hana/transform.hpp>
#include <boost/hana/tuple.hpp>
// models for different containers
#include <boost/hana/fwd/map.hpp>
#include <boost/hana/fwd/optional.hpp>
#include <boost/hana/fwd/set.hpp>
#include <boost/hana/fwd/string.hpp>
#include <boost/hana/fwd/type.hpp>
#include <boost/core/demangle.hpp>
#include <iostream>
#include <regex>
#include <sstream>
#include <string>
#include <typeinfo>
#include <utility>
BOOST_HANA_NAMESPACE_BEGIN namespace experimental {
template <typename T>
struct Printable;
//! @cond
template <typename T, typename = void>
struct print_impl : print_impl<T, hana::when<true>> { };
template <typename T, bool condition>
struct print_impl<T, hana::when<condition>> : hana::default_ {
template <typename ...Args>
static constexpr auto apply(Args&& ...) = delete;
};
//! @endcond
//! @ingroup group-experimental
//! Returns a string representation of the given object.
//!
//! This function is defined for most containers provided by Hana, and
//! also for objects that define an `operator<<` that can be used with
//! a `std::basic_ostream`. It can recursively print containers within
//! containers, but do not expect any kind of proper indentation.
//!
//! This function requires (the rest of) Boost to be available on the
//! system. It also requires RTTI to be enabled.
#ifdef BOOST_HANA_DOXYGEN_INVOKED
auto print = [](auto const& x) -> std::string {
return tag-dispatched;
};
#else
struct print_t {
template <typename T>
std::string operator()(T const& t) const {
using Tag = typename hana::tag_of<T>::type;
using Print = BOOST_HANA_DISPATCH_IF(print_impl<Tag>,
hana::experimental::Printable<Tag>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::experimental::Printable<Tag>::value,
"hana::experimental::print(t) requires 't' to be Printable");
#endif
return Print::apply(t);
}
};
constexpr print_t print{};
#endif
// Define the `Printable` concept
template <typename T>
struct Printable {
using Tag = typename hana::tag_of<T>::type;
static constexpr bool value = !hana::is_default<print_impl<Tag>>::value;
};
namespace print_detail {
std::string strip_type_junk(std::string const& str) {
return std::regex_replace(str, std::regex("^([a-z_]+::)*([a-z_]*)_t<"), "$2<");
}
}
// model for Sequences
template <typename S>
struct print_impl<S, hana::when<hana::Sequence<S>::value>> {
template <typename Xs>
static std::string apply(Xs const& xs) {
std::string result = "(";
auto comma_separated = hana::intersperse(xs, ", ");
hana::for_each(comma_separated, [&result](auto const& x) {
result += hana::experimental::print(x);
});
result += ")";
return result;
}
};
// model for OutputStreamable types
//! @cond
template <typename S>
struct print_impl<S, hana::when_valid<decltype(
std::declval<std::ostringstream&>() << std::declval<S const&>()
)>> {
template <typename T>
static std::string apply(T const& t) {
std::ostringstream os;
os << t;
return os.str();
}
};
//! @endcond
// model for hana::optional
template <>
struct print_impl<hana::optional_tag> {
template <typename O>
static std::string apply(O const& optional) {
return hana::maybe("nothing",
[](auto const& x) {
return "just(" + hana::experimental::print(x) + ")";
}, optional);
}
};
// model for hana::maps
template <>
struct print_impl<hana::map_tag> {
template <typename M>
static std::string apply(M const& map) {
std::string result = "{";
auto pairs = hana::transform(hana::to_tuple(map),
[](auto const& pair) {
return hana::experimental::print(hana::first(pair))
+ " => "
+ hana::experimental::print(hana::second(pair));
});
auto comma_separated = hana::intersperse(pairs, ", ");
hana::for_each(comma_separated, [&result](auto const& element) {
result += element;
});
result += "}";
return result;
}
};
// model for hana::metafunctions
template <template <typename ...> class F>
struct print_impl<hana::metafunction_t<F>> {
template <typename T>
static std::string apply(T const&) {
return print_detail::strip_type_junk(boost::core::demangle(typeid(T).name()));
}
};
// model for hana::metafunction_classes
template <typename F>
struct print_impl<hana::metafunction_class_t<F>> {
template <typename T>
static std::string apply(T const&) {
return print_detail::strip_type_junk(boost::core::demangle(typeid(T).name()));
}
};
// model for Constants holding a `Printable`
template <typename C>
struct print_impl<C, hana::when<
hana::Constant<C>::value &&
Printable<typename C::value_type>::value
>> {
template <typename T>
static std::string apply(T const&) {
constexpr auto value = hana::value<T>();
return hana::experimental::print(value);
}
};
// model for Products
template <typename P>
struct print_impl<P, hana::when<hana::Product<P>::value>> {
template <typename T>
static std::string apply(T const& t) {
return '(' + hana::experimental::print(hana::first(t))
+ ", "
+ hana::experimental::print(hana::second(t)) + ')';
}
};
// model for hana::strings
template <>
struct print_impl<hana::string_tag> {
template <typename S>
static std::string apply(S const& s) {
return '"' + std::string{hana::to<char const*>(s)} + '"';
}
};
// model for hana::sets
template <>
struct print_impl<hana::set_tag> {
template <typename S>
static std::string apply(S const& set) {
std::string result = "{";
auto as_tuple = hana::transform(hana::to_tuple(set),
hana::experimental::print);
auto comma_separated = hana::intersperse(as_tuple, ", ");
hana::for_each(comma_separated, [&result](auto const& element) {
result += element;
});
result += "}";
return result;
}
};
// model for hana::templates
template <template <typename ...> class F>
struct print_impl<template_t<F>> {
template <typename T>
static std::string apply(T const&) {
return print_detail::strip_type_junk(boost::core::demangle(typeid(T).name()));
}
};
// model for hana::types
template <>
struct print_impl<hana::type_tag> {
template <typename T>
static std::string apply(T const&) {
using Type = typename T::type;
return "type<" + boost::core::demangle(typeid(Type).name()) + '>';
}
};
} BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_EXPERIMENTAL_PRINTABLE_HPP
|