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Allow to add metadata to json nodes

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* by default no metadata is allowed and the library behaves as it already did
* if a user explicitly adds metadata (last template parameter) each node has a data member of this type and access functions for this member
* add test for this feature
This commit is contained in:
Raphael Grimm 2021-09-24 23:32:20 +02:00
parent 0b345b20c8
commit 1b11773cd6
6 changed files with 278 additions and 12 deletions
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30
include/nlohmann/detail/json_metadata.hpp Normal file
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@ -0,0 +1,30 @@
#pragma once
namespace nlohmann
{
namespace detail
{
template<class MetaDataType>
class json_metadata
{
public:
using metadata_t = MetaDataType;
metadata_t& metadata()
{
return m_metadata;
}
const metadata_t& metadata() const
{
return m_metadata;
}
private:
metadata_t m_metadata;
};
template<>
class json_metadata<void>
{
//no metadata
};
} // namespace detail
} // namespace nlohmann

5
include/nlohmann/detail/macro_scope.hpp
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@ -131,12 +131,13 @@
class NumberUnsignedType, class NumberFloatType, \
template<typename> class AllocatorType, \
template<typename, typename = void> class JSONSerializer, \
class BinaryType>
class BinaryType, \
class MetaDataType>
#define NLOHMANN_BASIC_JSON_TPL \
basic_json<ObjectType, ArrayType, StringType, BooleanType, \
NumberIntegerType, NumberUnsignedType, NumberFloatType, \
AllocatorType, JSONSerializer, BinaryType>
AllocatorType, JSONSerializer, BinaryType, MetaDataType>
// Macros to simplify conversion from/to types

14
include/nlohmann/json.hpp
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@ -63,6 +63,7 @@ SOFTWARE.
#include <nlohmann/detail/iterators/iteration_proxy.hpp>
#include <nlohmann/detail/iterators/json_reverse_iterator.hpp>
#include <nlohmann/detail/iterators/primitive_iterator.hpp>
#include <nlohmann/detail/json_metadata.hpp>
#include <nlohmann/detail/json_pointer.hpp>
#include <nlohmann/detail/json_ref.hpp>
#include <nlohmann/detail/macro_scope.hpp>
@ -174,6 +175,7 @@ Format](https://tools.ietf.org/html/rfc8259)
*/
NLOHMANN_BASIC_JSON_TPL_DECLARATION
class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-special-member-functions)
: public ::nlohmann::detail::json_metadata<MetaDataType>
{
private:
template<detail::value_t> friend struct detail::external_constructor;
@ -196,6 +198,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
/// workaround type for MSVC
using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
using json_metadata_t = ::nlohmann::detail::json_metadata<MetaDataType>;
JSON_PRIVATE_UNLESS_TESTED:
// convenience aliases for types residing in namespace detail;
@ -2188,7 +2191,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 1.0.0
*/
basic_json(const basic_json& other)
: m_type(other.m_type)
: json_metadata_t(other),
m_type(other.m_type)
{
// check of passed value is valid
other.assert_invariant();
@ -2280,7 +2284,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 1.0.0
*/
basic_json(basic_json&& other) noexcept
: m_type(std::move(other.m_type)),
: json_metadata_t(std::move(other)),
m_type(std::move(other.m_type)),
m_value(std::move(other.m_value))
{
// check that passed value is valid
@ -2321,12 +2326,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
std::is_nothrow_move_constructible<value_t>::value&&
std::is_nothrow_move_assignable<value_t>::value&&
std::is_nothrow_move_constructible<json_value>::value&&
std::is_nothrow_move_assignable<json_value>::value
std::is_nothrow_move_assignable<json_value>::value&&
std::is_nothrow_move_assignable<json_metadata_t>::value
)
{
// check that passed value is valid
other.assert_invariant();
json_metadata_t::operator=(std::move(other));
using std::swap;
swap(m_type, other.m_type);
swap(m_value, other.m_value);

3
include/nlohmann/json_fwd.hpp
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@ -34,7 +34,8 @@ template<template<typename U, typename V, typename... Args> class ObjectType =
template<typename U> class AllocatorType = std::allocator,
template<typename T, typename SFINAE = void> class JSONSerializer =
adl_serializer,
class BinaryType = std::vector<std::uint8_t>>
class BinaryType = std::vector<std::uint8_t>,
class MetaDataType = void>
class basic_json;
/*!

53
single_include/nlohmann/json.hpp
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@ -2343,12 +2343,13 @@ JSON_HEDLEY_DIAGNOSTIC_POP
class NumberUnsignedType, class NumberFloatType, \
template<typename> class AllocatorType, \
template<typename, typename = void> class JSONSerializer, \
class BinaryType>
class BinaryType, \
class MetaDataType>
#define NLOHMANN_BASIC_JSON_TPL \
basic_json<ObjectType, ArrayType, StringType, BooleanType, \
NumberIntegerType, NumberUnsignedType, NumberFloatType, \
AllocatorType, JSONSerializer, BinaryType>
AllocatorType, JSONSerializer, BinaryType, MetaDataType>
// Macros to simplify conversion from/to types
@ -3380,7 +3381,8 @@ template<template<typename U, typename V, typename... Args> class ObjectType =
template<typename U> class AllocatorType = std::allocator,
template<typename T, typename SFINAE = void> class JSONSerializer =
adl_serializer,
class BinaryType = std::vector<std::uint8_t>>
class BinaryType = std::vector<std::uint8_t>,
class MetaDataType = void>
class basic_json;
/*!
@ -12354,6 +12356,38 @@ class json_reverse_iterator : public std::reverse_iterator<Base>
// #include <nlohmann/detail/iterators/primitive_iterator.hpp>
// #include <nlohmann/detail/json_metadata.hpp>
namespace nlohmann
{
namespace detail
{
template<class MetaDataType>
class json_metadata
{
public:
using metadata_t = MetaDataType;
metadata_t& metadata()
{
return m_metadata;
}
const metadata_t& metadata() const
{
return m_metadata;
}
private:
metadata_t m_metadata;
};
template<>
class json_metadata<void>
{
//no metadata
};
} // namespace detail
} // namespace nlohmann
// #include <nlohmann/detail/json_pointer.hpp>
@ -17580,6 +17614,7 @@ Format](https://tools.ietf.org/html/rfc8259)
*/
NLOHMANN_BASIC_JSON_TPL_DECLARATION
class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-special-member-functions)
: public ::nlohmann::detail::json_metadata<MetaDataType>
{
private:
template<detail::value_t> friend struct detail::external_constructor;
@ -17602,6 +17637,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
/// workaround type for MSVC
using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
using json_metadata_t = ::nlohmann::detail::json_metadata<MetaDataType>;
JSON_PRIVATE_UNLESS_TESTED:
// convenience aliases for types residing in namespace detail;
@ -19594,7 +19630,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 1.0.0
*/
basic_json(const basic_json& other)
: m_type(other.m_type)
: json_metadata_t(other),
m_type(other.m_type)
{
// check of passed value is valid
other.assert_invariant();
@ -19686,7 +19723,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@since version 1.0.0
*/
basic_json(basic_json&& other) noexcept
: m_type(std::move(other.m_type)),
: json_metadata_t(std::move(other)),
m_type(std::move(other.m_type)),
m_value(std::move(other.m_value))
{
// check that passed value is valid
@ -19727,12 +19765,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
std::is_nothrow_move_constructible<value_t>::value&&
std::is_nothrow_move_assignable<value_t>::value&&
std::is_nothrow_move_constructible<json_value>::value&&
std::is_nothrow_move_assignable<json_value>::value
std::is_nothrow_move_assignable<json_value>::value&&
std::is_nothrow_move_assignable<json_metadata_t>::value
)
{
// check that passed value is valid
other.assert_invariant();
json_metadata_t::operator=(std::move(other));
using std::swap;
swap(m_type, other.m_type);
swap(m_value, other.m_value);

185
test/src/unit-metadata.cpp Normal file
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@ -0,0 +1,185 @@
/*
__ _____ _____ _____
__| | __| | | | JSON for Modern C++ (test suite)
| | |__ | | | | | | version 3.10.2
|_____|_____|_____|_|___| https://github.com/nlohmann/json
Licensed under the MIT License <http://opensource.org/licenses/MIT>.
SPDX-License-Identifier: MIT
Copyright (c) 2013-2019 Niels Lohmann <http://nlohmann.me>.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "doctest_compatibility.h"
#include <nlohmann/json.hpp>
template<class T>
using json_with_metadata =
nlohmann::basic_json <
std::map,
std::vector,
std::string,
bool,
std::int64_t,
std::uint64_t,
double,
std::allocator,
nlohmann::adl_serializer,
std::vector<std::uint8_t>,
T
>;
TEST_CASE("JSON Node Metadata")
{
SECTION("type int")
{
using json = json_with_metadata<int>;
json null;
auto obj = json::object();
auto array = json::array();
null.metadata() = 1;
obj.metadata() = 2;
array.metadata() = 3;
auto copy = array;
CHECK(null.metadata() == 1);
CHECK(obj.metadata() == 2);
CHECK(array.metadata() == 3);
CHECK(copy.metadata() == 3);
}
SECTION("type vector<int>")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
auto copy = value;
value.metadata().emplace_back(2);
CHECK(copy.metadata().size() == 1);
CHECK(copy.metadata().at(0) == 1);
CHECK(value.metadata().size() == 2);
CHECK(value.metadata().at(0) == 1);
CHECK(value.metadata().at(1) == 2);
}
SECTION("copy ctor")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
value.metadata().emplace_back(2);
json copy = value;
CHECK(copy.metadata().size() == 2);
CHECK(copy.metadata().at(0) == 1);
CHECK(copy.metadata().at(1) == 2);
CHECK(value.metadata().size() == 2);
CHECK(value.metadata().at(0) == 1);
CHECK(value.metadata().at(1) == 2);
value.metadata().clear();
CHECK(copy.metadata().size() == 2);
CHECK(value.metadata().size() == 0);
}
SECTION("move ctor")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
value.metadata().emplace_back(2);
const json moved = std::move(value);
CHECK(moved.metadata().size() == 2);
CHECK(moved.metadata().at(0) == 1);
CHECK(moved.metadata().at(1) == 2);
CHECK(value.metadata().size() == 0);
}
SECTION("move assign")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
value.metadata().emplace_back(2);
json moved;
moved = std::move(value);
CHECK(moved.metadata().size() == 2);
CHECK(moved.metadata().at(0) == 1);
CHECK(moved.metadata().at(1) == 2);
CHECK(value.metadata().size() == 0);
}
SECTION("copy assign")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
value.metadata().emplace_back(2);
json copy;
copy = value;
CHECK(copy.metadata().size() == 2);
CHECK(copy.metadata().at(0) == 1);
CHECK(copy.metadata().at(1) == 2);
CHECK(value.metadata().size() == 2);
CHECK(value.metadata().at(0) == 1);
CHECK(value.metadata().at(1) == 2);
value.metadata().clear();
CHECK(copy.metadata().size() == 2);
CHECK(value.metadata().size() == 0);
}
SECTION("type unique_ptr<int>")
{
using json = json_with_metadata<std::unique_ptr<int>>;
json value;
value.metadata().reset(new int);
(*value.metadata()) = 42;
auto moved = std::move(value);
CHECK(value.metadata() == nullptr);
CHECK(moved.metadata() != nullptr);
CHECK(*moved.metadata() == 42);
}
SECTION("type vector<int> in json array")
{
using json = json_with_metadata<std::vector<int>>;
json value;
value.metadata().emplace_back(1);
value.metadata().emplace_back(2);
json array(10, value);
CHECK(value.metadata().size() == 2);
CHECK(value.metadata().at(0) == 1);
CHECK(value.metadata().at(1) == 2);
for (const auto& val : array)
{
CHECK(val.metadata().size() == 2);
CHECK(val.metadata().at(0) == 1);
CHECK(val.metadata().at(1) == 2);
}
}
}