json/impl/value_ref.ipp

0001 //
0002 // Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
0003 //
0004 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0005 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // Official repository: https://github.com/boostorg/json
0008 //
0009
0010 #ifndef BOOST_JSON_IMPL_VALUE_REF_IPP
0011 #define BOOST_JSON_IMPL_VALUE_REF_IPP
0012
0013 #include <boost/json/value_ref.hpp>
0014 #include <boost/json/array.hpp>
0015 #include <boost/json/value.hpp>
0016
0017 namespace boost {
0018 namespace json {
0019
0020 value_ref::
0021 operator
0022 value() const
0023 {
0024     return make_value({});
0025 }
0026
0027 value
0028 value_ref::
0029 from_init_list(
0030     void const* p,
0031     storage_ptr sp)
0032 {
0033     return make_value(
0034         *reinterpret_cast<
0035             init_list const*>(p),
0036         std::move(sp));
0037 }
0038
0039 bool
0040 value_ref::
0041 is_key_value_pair() const noexcept
0042 {
0043     if(what_ != what::ini)
0044         return false;
0045     if(arg_.init_list_.size() != 2)
0046         return false;
0047     auto const& e =
0048         *arg_.init_list_.begin();
0049     if( e.what_ != what::str &&
0050         e.what_ != what::strfunc)
0051         return false;
0052     return true;
0053 }
0054
0055 bool
0056 value_ref::
0057 maybe_object(
0058     std::initializer_list<
0059         value_ref> init) noexcept
0060 {
0061     for(auto const& e : init)
0062         if(! e.is_key_value_pair())
0063             return false;
0064     return true;
0065 }
0066
0067 string_view
0068 value_ref::
0069 get_string() const noexcept
0070 {
0071     BOOST_ASSERT(
0072         what_ == what::str ||
0073         what_ == what::strfunc);
0074     if (what_ == what::strfunc)
0075         return *static_cast<const string*>(f_.p);
0076     return arg_.str_;
0077 }
0078
0079 value
0080 value_ref::
0081 make_value(
0082     storage_ptr sp) const
0083 {
0084     switch(what_)
0085     {
0086     default:
0087     case what::str:
0088         return string(
0089             arg_.str_,
0090             std::move(sp));
0091
0092     case what::ini:
0093         return make_value(
0094             arg_.init_list_,
0095             std::move(sp));
0096
0097     case what::func:
0098         return f_.f(f_.p,
0099             std::move(sp));
0100
0101     case what::strfunc:
0102         return f_.f(f_.p,
0103             std::move(sp));
0104
0105     case what::cfunc:
0106         return cf_.f(cf_.p,
0107             std::move(sp));
0108     }
0109 }
0110
0111 value
0112 value_ref::
0113 make_value(
0114     std::initializer_list<
0115         value_ref> init,
0116     storage_ptr sp)
0117 {
0118     if(maybe_object(init))
0119         return make_object(
0120             init, std::move(sp));
0121     return make_array(
0122         init, std::move(sp));
0123 }
0124
0125 object
0126 value_ref::
0127 make_object(
0128     std::initializer_list<value_ref> init,
0129     storage_ptr sp)
0130 {
0131     object obj(std::move(sp));
0132     obj.reserve(init.size());
0133     for(auto const& e : init)
0134         obj.emplace(
0135             e.arg_.init_list_.begin()[0].get_string(),
0136             e.arg_.init_list_.begin()[1].make_value(
0137                 obj.storage()));
0138     return obj;
0139 }
0140
0141 array
0142 value_ref::
0143 make_array(
0144     std::initializer_list<
0145         value_ref> init,
0146     storage_ptr sp)
0147 {
0148     array arr(std::move(sp));
0149     arr.reserve(init.size());
0150     for(auto const& e : init)
0151         arr.emplace_back(
0152             e.make_value(
0153                 arr.storage()));
0154     return arr;
0155 }
0156
0157 void
0158 value_ref::
0159 write_array(
0160     value* dest,
0161     std::initializer_list<
0162         value_ref> init,
0163     storage_ptr const& sp)
0164 {
0165     struct undo
0166     {
0167         value* const base;
0168         value* pos;
0169         ~undo()
0170         {
0171             if(pos)
0172                 while(pos > base)
0173                     (--pos)->~value();
0174         }
0175     };
0176     undo u{dest, dest};
0177     for(auto const& e : init)
0178     {
0179         ::new(u.pos) value(
0180             e.make_value(sp));
0181         ++u.pos;
0182     }
0183     u.pos = nullptr;
0184 }
0185
0186 } // namespace json
0187 } // namespace boost
0188
0189 #endif