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authorRichard <q@1bpm.net>2022-09-04 00:32:56 +0100
committerRichard <q@1bpm.net>2022-09-04 00:32:56 +0100
commit1d055261b4144dbf86b2658437015b15d4dd9bff (patch)
tree6049b19d1bf953a650383de1a5e438b8b82679f6 /include/jsoncons/decode_traits.hpp
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diff --git a/include/jsoncons/decode_traits.hpp b/include/jsoncons/decode_traits.hpp
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+// Copyright 2017 Daniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_DECODE_TRAITS_HPP
+#define JSONCONS_DECODE_TRAITS_HPP
+
+#include <string>
+#include <tuple>
+#include <array>
+#include <memory>
+#include <type_traits> // std::enable_if, std::true_type, std::false_type
+#include <jsoncons/json_visitor.hpp>
+#include <jsoncons/json_decoder.hpp>
+#include <jsoncons/json_type_traits.hpp>
+#include <jsoncons/staj_cursor.hpp>
+#include <jsoncons/conv_error.hpp>
+#include <jsoncons/more_type_traits.hpp>
+
+namespace jsoncons {
+
+ // decode_traits
+
+ template <class T, class CharT, class Enable = void>
+ struct decode_traits
+ {
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ decoder.reset();
+ cursor.read_to(decoder, ec);
+ if (ec)
+ {
+ JSONCONS_THROW(ser_error(ec, cursor.context().line(), cursor.context().column()));
+ }
+ else if (!decoder.is_valid())
+ {
+ JSONCONS_THROW(ser_error(conv_errc::conversion_failed, cursor.context().line(), cursor.context().column()));
+ }
+ return decoder.get_result().template as<T>();
+ }
+ };
+
+ // specializations
+
+ // primitive
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<type_traits::is_primitive<T>::value
+ >::type>
+ {
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>&,
+ std::error_code& ec)
+ {
+ T v = cursor.current().template get<T>(ec);
+ return v;
+ }
+ };
+
+ // string
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<type_traits::is_basic_string<T>::value &&
+ std::is_same<typename T::value_type,CharT>::value
+ >::type>
+ {
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>&,
+ std::error_code& ec)
+ {
+ T v = cursor.current().template get<T>(ec);
+ return v;
+ }
+ };
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<type_traits::is_basic_string<T>::value &&
+ !std::is_same<typename T::value_type,CharT>::value
+ >::type>
+ {
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>&,
+ std::error_code& ec)
+ {
+ auto val = cursor.current().template get<std::basic_string<CharT>>(ec);
+ T s;
+ if (!ec)
+ {
+ unicode_traits::convert(val.data(), val.size(), s);
+ }
+ return s;
+ }
+ };
+
+ // std::pair
+
+ template <class T1, class T2, class CharT>
+ struct decode_traits<std::pair<T1, T2>, CharT>
+ {
+ template <class Json, class TempAllocator>
+ static std::pair<T1, T2> decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json, TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ using value_type = std::pair<T1, T2>;
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ return value_type{};
+ }
+ if (cursor.current().event_type() != staj_event_type::begin_array)
+ {
+ ec = conv_errc::not_pair;
+ return value_type();
+ }
+ cursor.next(ec); // skip past array
+ if (ec)
+ {
+ return value_type();
+ }
+
+ T1 v1 = decode_traits<T1,CharT>::decode(cursor, decoder, ec);
+ if (ec) {return value_type();}
+ cursor.next(ec);
+ if (ec) {return value_type();}
+ T2 v2 = decode_traits<T2, CharT>::decode(cursor, decoder, ec);
+ if (ec) {return value_type();}
+ cursor.next(ec);
+
+ if (cursor.current().event_type() != staj_event_type::end_array)
+ {
+ ec = conv_errc::not_pair;
+ return value_type();
+ }
+ return std::make_pair(v1, v2);
+ }
+ };
+
+ // vector like
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_list_like<T>::value &&
+ type_traits::is_back_insertable<T>::value &&
+ !type_traits::is_typed_array<T>::value
+ >::type>
+ {
+ using value_type = typename T::value_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ T v;
+
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ return T{};
+ }
+ if (cursor.current().event_type() != staj_event_type::begin_array)
+ {
+ ec = conv_errc::not_vector;
+ return v;
+ }
+ cursor.next(ec);
+ while (cursor.current().event_type() != staj_event_type::end_array && !ec)
+ {
+ v.push_back(decode_traits<value_type,CharT>::decode(cursor, decoder, ec));
+ if (ec) {return T{};}
+ cursor.next(ec);
+ }
+ return v;
+ }
+ };
+
+ template <class T>
+ struct typed_array_visitor : public default_json_visitor
+ {
+ T& v_;
+ int level_;
+ public:
+ using value_type = typename T::value_type;
+
+ typed_array_visitor(T& v)
+ : default_json_visitor(false,conv_errc::not_vector), v_(v), level_(0)
+ {
+ }
+ private:
+ bool visit_begin_array(semantic_tag,
+ const ser_context&,
+ std::error_code& ec) override
+ {
+ if (++level_ != 1)
+ {
+ ec = conv_errc::not_vector;
+ return false;
+ }
+ return true;
+ }
+
+ bool visit_begin_array(std::size_t size,
+ semantic_tag,
+ const ser_context&,
+ std::error_code& ec) override
+ {
+ if (++level_ != 1)
+ {
+ ec = conv_errc::not_vector;
+ return false;
+ }
+ if (size > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), v_, size);
+ }
+ return true;
+ }
+
+ bool visit_end_array(const ser_context&,
+ std::error_code& ec) override
+ {
+ if (level_ != 1)
+ {
+ ec = conv_errc::not_vector;
+ return false;
+ }
+ return false;
+ }
+
+ bool visit_uint64(uint64_t value,
+ semantic_tag,
+ const ser_context&,
+ std::error_code&) override
+ {
+ v_.push_back(static_cast<value_type>(value));
+ return true;
+ }
+
+ bool visit_int64(int64_t value,
+ semantic_tag,
+ const ser_context&,
+ std::error_code&) override
+ {
+ v_.push_back(static_cast<value_type>(value));
+ return true;
+ }
+
+ bool visit_half(uint16_t value,
+ semantic_tag,
+ const ser_context&,
+ std::error_code&) override
+ {
+ return visit_half_(typename std::integral_constant<bool, std::is_integral<value_type>::value>::type(), value);
+ }
+
+ bool visit_half_(std::true_type, uint16_t value)
+ {
+ v_.push_back(static_cast<value_type>(value));
+ return true;
+ }
+
+ bool visit_half_(std::false_type, uint16_t value)
+ {
+ v_.push_back(static_cast<value_type>(binary::decode_half(value)));
+ return true;
+ }
+
+ bool visit_double(double value,
+ semantic_tag,
+ const ser_context&,
+ std::error_code&) override
+ {
+ v_.push_back(static_cast<value_type>(value));
+ return true;
+ }
+
+ bool visit_typed_array(const jsoncons::span<const value_type>& data,
+ semantic_tag,
+ const ser_context&,
+ std::error_code&) override
+ {
+ v_ = std::vector<value_type>(data.begin(),data.end());
+ return false;
+ }
+
+ static
+ void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static
+ void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_list_like<T>::value &&
+ type_traits::is_back_insertable_byte_container<T>::value &&
+ type_traits::is_typed_array<T>::value
+ >::type>
+ {
+ using value_type = typename T::value_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>&,
+ std::error_code& ec)
+ {
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ return T{};
+ }
+ switch (cursor.current().event_type())
+ {
+ case staj_event_type::byte_string_value:
+ {
+ auto bytes = cursor.current().template get<byte_string_view>(ec);
+ if (!ec)
+ {
+ T v;
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), v, cursor.current().size());
+ }
+ for (auto ch : bytes)
+ {
+ v.push_back(static_cast<value_type>(ch));
+ }
+ cursor.next(ec);
+ return v;
+ }
+ else
+ {
+ return T{};
+ }
+ }
+ case staj_event_type::begin_array:
+ {
+ T v;
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), v, cursor.current().size());
+ }
+ typed_array_visitor<T> visitor(v);
+ cursor.read_to(visitor, ec);
+ return v;
+ }
+ default:
+ {
+ ec = conv_errc::not_vector;
+ return T{};
+ }
+ }
+ }
+
+ static void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_list_like<T>::value &&
+ type_traits::is_back_insertable<T>::value &&
+ !type_traits::is_back_insertable_byte_container<T>::value &&
+ type_traits::is_typed_array<T>::value
+ >::type>
+ {
+ using value_type = typename T::value_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>&,
+ std::error_code& ec)
+ {
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ return T{};
+ }
+ switch (cursor.current().event_type())
+ {
+ case staj_event_type::begin_array:
+ {
+ T v;
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), v, cursor.current().size());
+ }
+ typed_array_visitor<T> visitor(v);
+ cursor.read_to(visitor, ec);
+ return v;
+ }
+ default:
+ {
+ ec = conv_errc::not_vector;
+ return T{};
+ }
+ }
+ }
+
+ static void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+ // set like
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_list_like<T>::value &&
+ !type_traits::is_back_insertable<T>::value &&
+ type_traits::is_insertable<T>::value
+ >::type>
+ {
+ using value_type = typename T::value_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ T v;
+
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ return T{};
+ }
+ if (cursor.current().event_type() != staj_event_type::begin_array)
+ {
+ ec = conv_errc::not_vector;
+ return v;
+ }
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), v, cursor.current().size());
+ }
+ cursor.next(ec);
+ while (cursor.current().event_type() != staj_event_type::end_array && !ec)
+ {
+ v.insert(decode_traits<value_type,CharT>::decode(cursor, decoder, ec));
+ if (ec) {return T{};}
+ cursor.next(ec);
+ if (ec) {return T{};}
+ }
+ return v;
+ }
+
+ static void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+ // std::array
+
+ template <class T, class CharT, std::size_t N>
+ struct decode_traits<std::array<T,N>,CharT>
+ {
+ using value_type = typename std::array<T,N>::value_type;
+
+ template <class Json,class TempAllocator>
+ static std::array<T, N> decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ std::array<T,N> v;
+ cursor.array_expected(ec);
+ if (ec)
+ {
+ v.fill(T());
+ return v;
+ }
+ v.fill(T{});
+ if (cursor.current().event_type() != staj_event_type::begin_array)
+ {
+ ec = conv_errc::not_vector;
+ return v;
+ }
+ cursor.next(ec);
+ for (std::size_t i = 0; i < N && cursor.current().event_type() != staj_event_type::end_array && !ec; ++i)
+ {
+ v[i] = decode_traits<value_type,CharT>::decode(cursor, decoder, ec);
+ if (ec) {return v;}
+ cursor.next(ec);
+ if (ec) {return v;}
+ }
+ return v;
+ }
+ };
+
+ // map like
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_map_like<T>::value &&
+ type_traits::is_constructible_from_const_pointer_and_size<typename T::key_type>::value
+ >::type>
+ {
+ using mapped_type = typename T::mapped_type;
+ using value_type = typename T::value_type;
+ using key_type = typename T::key_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ T val;
+ if (cursor.current().event_type() != staj_event_type::begin_object)
+ {
+ ec = conv_errc::not_map;
+ return val;
+ }
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), val, cursor.current().size());
+ }
+ cursor.next(ec);
+
+ while (cursor.current().event_type() != staj_event_type::end_object && !ec)
+ {
+ if (cursor.current().event_type() != staj_event_type::key)
+ {
+ ec = json_errc::expected_key;
+ return val;
+ }
+ auto key = cursor.current().template get<key_type>(ec);
+ if (ec) return val;
+ cursor.next(ec);
+ if (ec) return val;
+ val.emplace(std::move(key),decode_traits<mapped_type,CharT>::decode(cursor, decoder, ec));
+ if (ec) {return val;}
+ cursor.next(ec);
+ if (ec) {return val;}
+ }
+ return val;
+ }
+
+ static void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+ template <class T, class CharT>
+ struct decode_traits<T,CharT,
+ typename std::enable_if<!is_json_type_traits_declared<T>::value &&
+ type_traits::is_map_like<T>::value &&
+ std::is_integral<typename T::key_type>::value
+ >::type>
+ {
+ using mapped_type = typename T::mapped_type;
+ using value_type = typename T::value_type;
+ using key_type = typename T::key_type;
+
+ template <class Json,class TempAllocator>
+ static T decode(basic_staj_cursor<CharT>& cursor,
+ json_decoder<Json,TempAllocator>& decoder,
+ std::error_code& ec)
+ {
+ T val;
+ if (cursor.current().event_type() != staj_event_type::begin_object)
+ {
+ ec = conv_errc::not_map;
+ return val;
+ }
+ if (cursor.current().size() > 0)
+ {
+ reserve_storage(typename std::integral_constant<bool, type_traits::has_reserve<T>::value>::type(), val, cursor.current().size());
+ }
+ cursor.next(ec);
+
+ while (cursor.current().event_type() != staj_event_type::end_object && !ec)
+ {
+ if (cursor.current().event_type() != staj_event_type::key)
+ {
+ ec = json_errc::expected_key;
+ return val;
+ }
+ auto s = cursor.current().template get<jsoncons::basic_string_view<typename Json::char_type>>(ec);
+ if (ec) return val;
+ key_type n{0};
+ auto r = jsoncons::detail::to_integer(s.data(), s.size(), n);
+ if (r.ec != jsoncons::detail::to_integer_errc())
+ {
+ ec = json_errc::invalid_number;
+ return val;
+ }
+ cursor.next(ec);
+ if (ec) return val;
+ val.emplace(n, decode_traits<mapped_type,CharT>::decode(cursor, decoder, ec));
+ if (ec) {return val;}
+ cursor.next(ec);
+ if (ec) {return val;}
+ }
+ return val;
+ }
+
+ static void reserve_storage(std::true_type, T& v, std::size_t new_cap)
+ {
+ v.reserve(new_cap);
+ }
+
+ static void reserve_storage(std::false_type, T&, std::size_t)
+ {
+ }
+ };
+
+} // jsoncons
+
+#endif
+