1   
//
1   
//
2   
// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
2   
// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
3   
// Copyright (c) 2020 Krystian Stasiowski (sdkrystian@gmail.com)
3   
// Copyright (c) 2020 Krystian Stasiowski (sdkrystian@gmail.com)
4   
// Copyright (c) 2022 Dmitry Arkhipov (grisumbras@gmail.com)
4   
// Copyright (c) 2022 Dmitry Arkhipov (grisumbras@gmail.com)
5   
//
5   
//
6   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
6   
// Distributed under the Boost Software License, Version 1.0. (See accompanying
7   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7   
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8   
//
8   
//
9   
// Official repository: https://github.com/boostorg/json
9   
// Official repository: https://github.com/boostorg/json
10   
//
10   
//
11  
11  
12   
#ifndef BOOST_JSON_DETAIL_VALUE_FROM_HPP
12   
#ifndef BOOST_JSON_DETAIL_VALUE_FROM_HPP
13   
#define BOOST_JSON_DETAIL_VALUE_FROM_HPP
13   
#define BOOST_JSON_DETAIL_VALUE_FROM_HPP
14  
14  
15   
#include <boost/json/conversion.hpp>
15   
#include <boost/json/conversion.hpp>
16   
#include <boost/describe/enum_to_string.hpp>
16   
#include <boost/describe/enum_to_string.hpp>
17   
#include <boost/mp11/algorithm.hpp>
17   
#include <boost/mp11/algorithm.hpp>
18  
18  
19   
#ifndef BOOST_NO_CXX17_HDR_OPTIONAL
19   
#ifndef BOOST_NO_CXX17_HDR_OPTIONAL
20   
# include <optional>
20   
# include <optional>
21   
#endif
21   
#endif
22  
22  
23   
namespace boost {
23   
namespace boost {
24   
namespace json {
24   
namespace json {
25  
25  
26   
namespace detail {
26   
namespace detail {
27  
27  
28   
template< class Ctx, class T >
28   
template< class Ctx, class T >
29   
struct append_tuple_element {
29   
struct append_tuple_element {
30   
    array& arr;
30   
    array& arr;
31   
    Ctx const& ctx;
31   
    Ctx const& ctx;
32   
    T&& t;
32   
    T&& t;
33  
33  
34   
    template<std::size_t I>
34   
    template<std::size_t I>
35   
    void
35   
    void
36   
    operator()(mp11::mp_size_t<I>) const
36   
    operator()(mp11::mp_size_t<I>) const
37   
    {
37   
    {
38   
        using std::get;
38   
        using std::get;
39   
        arr.emplace_back(value_from(
39   
        arr.emplace_back(value_from(
40   
            get<I>(std::forward<T>(t)), ctx, arr.storage() ));
40   
            get<I>(std::forward<T>(t)), ctx, arr.storage() ));
41   
    }
41   
    }
42   
};
42   
};
43  
43  
44   
//----------------------------------------------------------
44   
//----------------------------------------------------------
45   
// User-provided conversion
45   
// User-provided conversion
46  
46  
47   
template< class T, class Ctx >
47   
template< class T, class Ctx >
48   
void
48   
void
49   
value_from_impl( user_conversion_tag, value& jv, T&& from, Ctx const& )
49   
value_from_impl( user_conversion_tag, value& jv, T&& from, Ctx const& )
50   
{
50   
{
51   
    tag_invoke( value_from_tag(), jv, static_cast<T&&>(from) );
51   
    tag_invoke( value_from_tag(), jv, static_cast<T&&>(from) );
52   
}
52   
}
53  
53  
54   
template< class T, class Ctx >
54   
template< class T, class Ctx >
55   
void
55   
void
56   
value_from_impl( context_conversion_tag, value& jv, T&& from, Ctx const& ctx)
56   
value_from_impl( context_conversion_tag, value& jv, T&& from, Ctx const& ctx)
57   
{
57   
{
58   
    using Sup = supported_context<Ctx, T, value_from_conversion>;
58   
    using Sup = supported_context<Ctx, T, value_from_conversion>;
59   
    tag_invoke( value_from_tag(), jv, static_cast<T&&>(from), Sup::get(ctx) );
59   
    tag_invoke( value_from_tag(), jv, static_cast<T&&>(from), Sup::get(ctx) );
60   
}
60   
}
61  
61  
62   
template< class T, class Ctx >
62   
template< class T, class Ctx >
63   
void
63   
void
64   
value_from_impl(
64   
value_from_impl(
65   
    full_context_conversion_tag, value& jv, T&& from, Ctx const& ctx)
65   
    full_context_conversion_tag, value& jv, T&& from, Ctx const& ctx)
66   
{
66   
{
67   
    using Sup = supported_context<Ctx, T, value_from_conversion>;
67   
    using Sup = supported_context<Ctx, T, value_from_conversion>;
68   
    tag_invoke(
68   
    tag_invoke(
69   
        value_from_tag(), jv, static_cast<T&&>(from), Sup::get(ctx), ctx );
69   
        value_from_tag(), jv, static_cast<T&&>(from), Sup::get(ctx), ctx );
70   
}
70   
}
71  
71  
72   
//----------------------------------------------------------
72   
//----------------------------------------------------------
73   
// Native conversion
73   
// Native conversion
74  
74  
75   
template< class T, class Ctx >
75   
template< class T, class Ctx >
76   
void
76   
void
77   
value_from_impl( native_conversion_tag, value& jv, T&& from, Ctx const& )
77   
value_from_impl( native_conversion_tag, value& jv, T&& from, Ctx const& )
78   
{
78   
{
79   
    jv = std::forward<T>(from);
79   
    jv = std::forward<T>(from);
80   
}
80   
}
81  
81  
82   
// null-like types
82   
// null-like types
83   
template< class T, class Ctx >
83   
template< class T, class Ctx >
84   
void
84   
void
85   
value_from_impl( null_like_conversion_tag, value& jv, T&&, Ctx const& )
85   
value_from_impl( null_like_conversion_tag, value& jv, T&&, Ctx const& )
86   
{
86   
{
87   
    // do nothing
87   
    // do nothing
88   
    BOOST_ASSERT(jv.is_null());
88   
    BOOST_ASSERT(jv.is_null());
89   
    (void)jv;
89   
    (void)jv;
90   
}
90   
}
91  
91  
92   
// string-like types
92   
// string-like types
93   
template< class T, class Ctx >
93   
template< class T, class Ctx >
94   
void
94   
void
95   
value_from_impl( string_like_conversion_tag, value& jv, T&& from, Ctx const& )
95   
value_from_impl( string_like_conversion_tag, value& jv, T&& from, Ctx const& )
96   
{
96   
{
97   
    auto sv = static_cast<string_view>(from);
97   
    auto sv = static_cast<string_view>(from);
98   
    jv.emplace_string().assign(sv);
98   
    jv.emplace_string().assign(sv);
99   
}
99   
}
100  
100  
101   
// map-like types
101   
// map-like types
102   
template< class T, class Ctx >
102   
template< class T, class Ctx >
103   
void
103   
void
104   
value_from_impl( map_like_conversion_tag, value& jv, T&& from, Ctx const& ctx )
104   
value_from_impl( map_like_conversion_tag, value& jv, T&& from, Ctx const& ctx )
105   
{
105   
{
106   
    using std::get;
106   
    using std::get;
107   
    object& obj = jv.emplace_object();
107   
    object& obj = jv.emplace_object();
108   
    obj.reserve(detail::try_size(from, size_implementation<T>()));
108   
    obj.reserve(detail::try_size(from, size_implementation<T>()));
109   
    for (auto&& elem : from)
109   
    for (auto&& elem : from)
110   
        obj.emplace(
110   
        obj.emplace(
111   
            get<0>(elem),
111   
            get<0>(elem),
112   
            value_from( get<1>(elem), ctx, obj.storage() ));
112   
            value_from( get<1>(elem), ctx, obj.storage() ));
113   
}
113   
}
114  
114  
115   
// ranges
115   
// ranges
116   
template< class T, class Ctx >
116   
template< class T, class Ctx >
117   
void
117   
void
118   
value_from_impl( sequence_conversion_tag, value& jv, T&& from, Ctx const& ctx )
118   
value_from_impl( sequence_conversion_tag, value& jv, T&& from, Ctx const& ctx )
119   
{
119   
{
120   
    array& result = jv.emplace_array();
120   
    array& result = jv.emplace_array();
121   
    result.reserve(detail::try_size(from, size_implementation<T>()));
121   
    result.reserve(detail::try_size(from, size_implementation<T>()));
122   
    using ForwardedValue = forwarded_value<T&&>;
122   
    using ForwardedValue = forwarded_value<T&&>;
123   
    for (auto&& elem : from)
123   
    for (auto&& elem : from)
124   
        result.emplace_back(
124   
        result.emplace_back(
125   
            value_from(
125   
            value_from(
126   
                // not a static_cast in order to appease clang < 4.0
126   
                // not a static_cast in order to appease clang < 4.0
127   
                ForwardedValue(elem),
127   
                ForwardedValue(elem),
128   
                ctx,
128   
                ctx,
129   
                result.storage() ));
129   
                result.storage() ));
130   
}
130   
}
131  
131  
132   
// tuple-like types
132   
// tuple-like types
133   
template< class T, class Ctx >
133   
template< class T, class Ctx >
134   
void
134   
void
135   
value_from_impl( tuple_conversion_tag, value& jv, T&& from, Ctx const& ctx )
135   
value_from_impl( tuple_conversion_tag, value& jv, T&& from, Ctx const& ctx )
136   
{
136   
{
137   
    constexpr std::size_t n =
137   
    constexpr std::size_t n =
138   
        std::tuple_size<remove_cvref<T>>::value;
138   
        std::tuple_size<remove_cvref<T>>::value;
139   
    array& arr = jv.emplace_array();
139   
    array& arr = jv.emplace_array();
140   
    arr.reserve(n);
140   
    arr.reserve(n);
141   
    mp11::mp_for_each<mp11::mp_iota_c<n>>(
141   
    mp11::mp_for_each<mp11::mp_iota_c<n>>(
142   
        append_tuple_element< Ctx, T >{ arr, ctx, std::forward<T>(from) });
142   
        append_tuple_element< Ctx, T >{ arr, ctx, std::forward<T>(from) });
143   
}
143   
}
144  
144  
145   
// no suitable conversion implementation
145   
// no suitable conversion implementation
146   
template< class T, class Ctx >
146   
template< class T, class Ctx >
147   
void
147   
void
148   
value_from_impl( no_conversion_tag, value&, T&&, Ctx const& )
148   
value_from_impl( no_conversion_tag, value&, T&&, Ctx const& )
149   
{
149   
{
150   
    static_assert(
150   
    static_assert(
151   
        !std::is_same<T, T>::value,
151   
        !std::is_same<T, T>::value,
152   
        "No suitable tag_invoke overload found for the type");
152   
        "No suitable tag_invoke overload found for the type");
153   
}
153   
}
154  
154  
155   
template< class Ctx, class T >
155   
template< class Ctx, class T >
156   
struct from_described_member
156   
struct from_described_member
157   
{
157   
{
158   
    static_assert(
158   
    static_assert(
159   
        uniquely_named_members< remove_cvref<T> >::value,
159   
        uniquely_named_members< remove_cvref<T> >::value,
160   
        "The type has several described members with the same name.");
160   
        "The type has several described members with the same name.");
161  
161  
162   
    using Ds = described_members< remove_cvref<T> >;
162   
    using Ds = described_members< remove_cvref<T> >;
163  
163  
164   
    object& obj;
164   
    object& obj;
165   
    Ctx const& ctx;
165   
    Ctx const& ctx;
166   
    T&& from;
166   
    T&& from;
167  
167  
168   
    template< class I >
168   
    template< class I >
169   
    void
169   
    void
170   
    operator()(I) const
170   
    operator()(I) const
171   
    {
171   
    {
172   
        using D = mp11::mp_at<Ds, I>;
172   
        using D = mp11::mp_at<Ds, I>;
173   
        obj.emplace(
173   
        obj.emplace(
174   
            D::name,
174   
            D::name,
175   
            value_from(
175   
            value_from(
176   
                static_cast<T&&>(from).* D::pointer,
176   
                static_cast<T&&>(from).* D::pointer,
177   
                ctx,
177   
                ctx,
178   
                obj.storage()));
178   
                obj.storage()));
179   
    }
179   
    }
180   
};
180   
};
181  
181  
182   
// described classes
182   
// described classes
183   
template< class T, class Ctx >
183   
template< class T, class Ctx >
184   
void
184   
void
185   
value_from_impl(
185   
value_from_impl(
186   
    described_class_conversion_tag, value& jv, T&& from, Ctx const& ctx )
186   
    described_class_conversion_tag, value& jv, T&& from, Ctx const& ctx )
187   
{
187   
{
188   
    object& obj = jv.emplace_object();
188   
    object& obj = jv.emplace_object();
189   
    from_described_member<Ctx, T> member_converter{
189   
    from_described_member<Ctx, T> member_converter{
190   
        obj, ctx, static_cast<T&&>(from)};
190   
        obj, ctx, static_cast<T&&>(from)};
191  
191  
192   
    using Ds = typename decltype(member_converter)::Ds;
192   
    using Ds = typename decltype(member_converter)::Ds;
193   
    constexpr std::size_t N = mp11::mp_size<Ds>::value;
193   
    constexpr std::size_t N = mp11::mp_size<Ds>::value;
194   
    obj.reserve(N);
194   
    obj.reserve(N);
195   
    mp11::mp_for_each< mp11::mp_iota_c<N> >(member_converter);
195   
    mp11::mp_for_each< mp11::mp_iota_c<N> >(member_converter);
196   
}
196   
}
197  
197  
198   
// described enums
198   
// described enums
199   
template< class T, class Ctx >
199   
template< class T, class Ctx >
200   
void
200   
void
201   
value_from_impl(
201   
value_from_impl(
202   
    described_enum_conversion_tag, value& jv, T from, Ctx const& )
202   
    described_enum_conversion_tag, value& jv, T from, Ctx const& )
203   
{
203   
{
204   
    (void)jv;
204   
    (void)jv;
205   
    (void)from;
205   
    (void)from;
206   
#ifdef BOOST_DESCRIBE_CXX14
206   
#ifdef BOOST_DESCRIBE_CXX14
207   
    char const* const name = describe::enum_to_string(from, nullptr);
207   
    char const* const name = describe::enum_to_string(from, nullptr);
208   
    if( name )
208   
    if( name )
209   
    {
209   
    {
210   
        string& str = jv.emplace_string();
210   
        string& str = jv.emplace_string();
211   
        str.assign(name);
211   
        str.assign(name);
212   
    }
212   
    }
213   
    else
213   
    else
214   
    {
214   
    {
215   
        using Integer = typename std::underlying_type< remove_cvref<T> >::type;
215   
        using Integer = typename std::underlying_type< remove_cvref<T> >::type;
216   
        jv = static_cast<Integer>(from);
216   
        jv = static_cast<Integer>(from);
217   
    }
217   
    }
218   
#endif
218   
#endif
219   
}
219   
}
220  
220  
221   
// optionals
221   
// optionals
222   
template< class T, class Ctx >
222   
template< class T, class Ctx >
223   
void
223   
void
224   
value_from_impl(
224   
value_from_impl(
225   
    optional_conversion_tag, value& jv, T&& from, Ctx const& ctx )
225   
    optional_conversion_tag, value& jv, T&& from, Ctx const& ctx )
226   
{
226   
{
227   
    if( from )
227   
    if( from )
228   
        value_from( *from, ctx, jv );
228   
        value_from( *from, ctx, jv );
229   
    else
229   
    else
230   
        jv = nullptr;
230   
        jv = nullptr;
231   
}
231   
}
232  
232  
233   
// variants
233   
// variants
234   
template< class Ctx >
234   
template< class Ctx >
235   
struct value_from_visitor
235   
struct value_from_visitor
236   
{
236   
{
237   
    value& jv;
237   
    value& jv;
238   
    Ctx const& ctx;
238   
    Ctx const& ctx;
239  
239  
240   
    template<class T>
240   
    template<class T>
241   
    void
241   
    void
242   
    operator()(T&& t)
242   
    operator()(T&& t)
243   
    {
243   
    {
244   
        value_from( static_cast<T&&>(t), ctx, jv );
244   
        value_from( static_cast<T&&>(t), ctx, jv );
245   
    }
245   
    }
246   
};
246   
};
247  
247  
248   
template< class Ctx, class T >
248   
template< class Ctx, class T >
249   
void
249   
void
250   
value_from_impl( variant_conversion_tag, value& jv, T&& from, Ctx const& ctx )
250   
value_from_impl( variant_conversion_tag, value& jv, T&& from, Ctx const& ctx )
251   
{
251   
{
252   
    visit( value_from_visitor<Ctx>{ jv, ctx }, static_cast<T&&>(from) );
252   
    visit( value_from_visitor<Ctx>{ jv, ctx }, static_cast<T&&>(from) );
253   
}
253   
}
254  
254  
255   
template< class Ctx, class T >
255   
template< class Ctx, class T >
256   
void
256   
void
257   
value_from_impl( path_conversion_tag, value& jv, T&& from, Ctx const& )
257   
value_from_impl( path_conversion_tag, value& jv, T&& from, Ctx const& )
258   
{
258   
{
259   
    std::string s = from.generic_string();
259   
    std::string s = from.generic_string();
260   
    string_view sv = s;
260   
    string_view sv = s;
261   
    jv.emplace_string().assign(sv);
261   
    jv.emplace_string().assign(sv);
262   
}
262   
}
263  
263  
264   
//----------------------------------------------------------
264   
//----------------------------------------------------------
265   
// Contextual conversions
265   
// Contextual conversions
266  
266  
267   
template< class Ctx, class T >
267   
template< class Ctx, class T >
268   
using value_from_category = conversion_category<
268   
using value_from_category = conversion_category<
269   
    Ctx, T, value_from_conversion >;
269   
    Ctx, T, value_from_conversion >;
270  
270  
271   
} // detail
271   
} // detail
272  
272  
273   
#ifndef BOOST_NO_CXX17_HDR_OPTIONAL
273   
#ifndef BOOST_NO_CXX17_HDR_OPTIONAL
274   
inline
274   
inline
275   
void
275   
void
276   
tag_invoke(
276   
tag_invoke(
277   
    value_from_tag,
277   
    value_from_tag,
278   
    value& jv,
278   
    value& jv,
279   
    std::nullopt_t)
279   
    std::nullopt_t)
280   
{
280   
{
281   
    // do nothing
281   
    // do nothing
282   
    BOOST_ASSERT(jv.is_null());
282   
    BOOST_ASSERT(jv.is_null());
283   
    (void)jv;
283   
    (void)jv;
284   
}
284   
}
285   
#endif
285   
#endif
286  
286  
287   
} // namespace json
287   
} // namespace json
288   
} // namespace boost
288   
} // namespace boost
289  
289  
290   
#endif
290   
#endif