diff --git a/src/json.hpp b/src/json.hpp
index d5fad77b..307fddb3 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -575,6 +575,14 @@ struct external_constructor<value_t::string>
j.m_value = s;
j.assert_invariant();
}
+
+ template<typename BasicJsonType>
+ static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
+ {
+ j.m_type = value_t::string;
+ j.m_value = std::move(s);
+ j.assert_invariant();
+ }
};
template<>
@@ -624,6 +632,14 @@ struct external_constructor<value_t::array>
j.assert_invariant();
}
+ template<typename BasicJsonType>
+ static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
+ {
+ j.m_type = value_t::array;
+ j.m_value = std::move(arr);
+ j.assert_invariant();
+ }
+
template<typename BasicJsonType, typename CompatibleArrayType,
enable_if_t<not std::is_same<CompatibleArrayType,
typename BasicJsonType::array_t>::value,
@@ -662,6 +678,14 @@ struct external_constructor<value_t::object>
j.assert_invariant();
}
+ template<typename BasicJsonType>
+ static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
+ {
+ j.m_type = value_t::object;
+ j.m_value = std::move(obj);
+ j.assert_invariant();
+ }
+
template<typename BasicJsonType, typename CompatibleObjectType,
enable_if_t<not std::is_same<CompatibleObjectType,
typename BasicJsonType::object_t>::value, int> = 0>
@@ -850,6 +874,12 @@ void to_json(BasicJsonType& j, const CompatibleString& s)
external_constructor<value_t::string>::construct(j, s);
}
+template <typename BasicJsonType>
+void to_json(BasicJsonType& j, typename BasicJsonType::string_t&& s)
+{
+ external_constructor<value_t::string>::construct(j, std::move(s));
+}
+
template<typename BasicJsonType, typename FloatType,
enable_if_t<std::is_floating_point<FloatType>::value, int> = 0>
void to_json(BasicJsonType& j, FloatType val) noexcept
@@ -900,13 +930,25 @@ void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
external_constructor<value_t::array>::construct(j, arr);
}
+template <typename BasicJsonType>
+void to_json(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
+{
+ external_constructor<value_t::array>::construct(j, std::move(arr));
+}
+
template <
typename BasicJsonType, typename CompatibleObjectType,
enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value,
int> = 0 >
-void to_json(BasicJsonType& j, const CompatibleObjectType& arr)
+void to_json(BasicJsonType& j, const CompatibleObjectType& obj)
{
- external_constructor<value_t::object>::construct(j, arr);
+ external_constructor<value_t::object>::construct(j, obj);
+}
+
+template <typename BasicJsonType>
+void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
+{
+ external_constructor<value_t::object>::construct(j, std::move(obj));
}
template<typename BasicJsonType, typename T, std::size_t N,
@@ -6799,6 +6841,67 @@ class serializer
/// the indentation string
string_t indent_string;
};
+
+template<typename BasicJsonType>
+struct json_ref
+{
+ typedef BasicJsonType value_type;
+
+ json_ref(value_type&& value)
+ : owned_value_(std::move(value))
+ , is_rvalue_(true)
+ {
+ value_ref_ = &owned_value_;
+ }
+
+ json_ref(const value_type& value)
+ : value_ref_(const_cast<value_type*>(&value))
+ , is_rvalue_(false)
+ {}
+
+ json_ref(std::initializer_list<json_ref> init)
+ : owned_value_(init)
+ , is_rvalue_(true)
+ {
+ value_ref_ = &owned_value_;
+ }
+
+ template <class... Args>
+ json_ref(Args... args)
+ : owned_value_(std::forward<Args>(args)...)
+ , is_rvalue_(true)
+ {
+ value_ref_ = &owned_value_;
+ }
+
+ value_type moved_or_copied() const
+ {
+ if (is_rvalue_)
+ {
+ return std::move(*value_ref_);
+ }
+ else
+ {
+ return *value_ref_;
+ }
+ }
+
+ value_type const& operator*() const
+ {
+ return *static_cast<value_type const*>(value_ref_);
+ }
+
+ value_type const* operator->() const
+ {
+ return static_cast<value_type const*>(value_ref_);
+ }
+
+ private:
+ value_type * value_ref_;
+ mutable value_type owned_value_;
+ bool is_rvalue_;
+};
+
} // namespace detail
/// namespace to hold default `to_json` / `from_json` functions
@@ -7297,6 +7400,7 @@ class basic_json
template<typename T, typename SFINAE>
using json_serializer = JSONSerializer<T, SFINAE>;
+ using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;
////////////////
// exceptions //
@@ -8025,18 +8129,36 @@ class basic_json
string = create<string_t>(value);
}
+ /// constructor for rvalue strings
+ json_value(string_t&& value)
+ {
+ string = create<string_t>(std::move(value));
+ }
+
/// constructor for objects
json_value(const object_t& value)
{
object = create<object_t>(value);
}
+ /// constructor for rvalue objects
+ json_value(object_t&& value)
+ {
+ object = create<object_t>(std::move(value));
+ }
+
/// constructor for arrays
json_value(const array_t& value)
{
array = create<array_t>(value);
}
+ /// constructor for rvalue arrays
+ json_value(array_t&& value)
+ {
+ array = create<array_t>(std::move(value));
+ }
+
void destroy(value_t t)
{
switch (t)
@@ -8310,10 +8432,10 @@ class basic_json
With the rules described above, the following JSON values cannot be
expressed by an initializer list:
- - the empty array (`[]`): use @ref array(std::initializer_list<basic_json>)
+ - the empty array (`[]`): use @ref array(initializer_list_t)
with an empty initializer list in this case
- arrays whose elements satisfy rule 2: use @ref
- array(std::initializer_list<basic_json>) with the same initializer list
+ array(initializer_list_t) with the same initializer list
in this case
@note When used without parentheses around an empty initializer list, @ref
@@ -8325,8 +8447,8 @@ class basic_json
@param[in] type_deduction internal parameter; when set to `true`, the type
of the JSON value is deducted from the initializer list @a init; when set
to `false`, the type provided via @a manual_type is forced. This mode is
- used by the functions @ref array(std::initializer_list<basic_json>) and
- @ref object(std::initializer_list<basic_json>).
+ used by the functions @ref array(initializer_list_t) and
+ @ref object(initializer_list_t).
@param[in] manual_type internal parameter; when @a type_deduction is set
to `false`, the created JSON value will use the provided type (only @ref
@@ -8337,7 +8459,7 @@ class basic_json
`value_t::object`, but @a init contains an element which is not a pair
whose first element is a string. In this case, the constructor could not
create an object. If @a type_deduction would have be `true`, an array
- would have been created. See @ref object(std::initializer_list<basic_json>)
+ would have been created. See @ref object(initializer_list_t)
for an example.
@complexity Linear in the size of the initializer list @a init.
@@ -8345,23 +8467,23 @@ class basic_json
@liveexample{The example below shows how JSON values are created from
initializer lists.,basic_json__list_init_t}
- @sa @ref array(std::initializer_list<basic_json>) -- create a JSON array
+ @sa @ref array(initializer_list_t) -- create a JSON array
value from an initializer list
- @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+ @sa @ref object(initializer_list_t) -- create a JSON object
value from an initializer list
@since version 1.0.0
*/
- basic_json(std::initializer_list<basic_json> init,
+ basic_json(initializer_list_t init,
bool type_deduction = true,
value_t manual_type = value_t::array)
{
// check if each element is an array with two elements whose first
// element is a string
bool is_an_object = std::all_of(init.begin(), init.end(),
- [](const basic_json & element)
+ [](const detail::json_ref<basic_json>& element_ref)
{
- return (element.is_array() and element.size() == 2 and element[0].is_string());
+ return (element_ref->is_array() and element_ref->size() == 2 and (*element_ref)[0].is_string());
});
// adjust type if type deduction is not wanted
@@ -8386,16 +8508,19 @@ class basic_json
m_type = value_t::object;
m_value = value_t::object;
- std::for_each(init.begin(), init.end(), [this](const basic_json & element)
+ std::for_each(init.begin(), init.end(), [this](const detail::json_ref<basic_json>& element_ref)
{
- m_value.object->emplace(*(element[0].m_value.string), element[1]);
+ basic_json element = element_ref.moved_or_copied();
+ m_value.object->emplace(
+ std::move(*((*element.m_value.array)[0].m_value.string)),
+ std::move((*element.m_value.array)[1]));
});
}
else
{
// the initializer list describes an array -> create array
m_type = value_t::array;
- m_value.array = create<array_t>(init);
+ m_value.array = create<array_t>(init.begin(), init.end());
}
assert_invariant();
@@ -8410,7 +8535,7 @@ class basic_json
@note This function is only needed to express two edge cases that cannot
be realized with the initializer list constructor (@ref
- basic_json(std::initializer_list<basic_json>, bool, value_t)). These cases
+ basic_json(initializer_list_t, bool, value_t)). These cases
are:
1. creating an array whose elements are all pairs whose first element is a
string -- in this case, the initializer list constructor would create an
@@ -8428,15 +8553,14 @@ class basic_json
@liveexample{The following code shows an example for the `array`
function.,array}
- @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+ @sa @ref basic_json(initializer_list_t, bool, value_t) --
create a JSON value from an initializer list
- @sa @ref object(std::initializer_list<basic_json>) -- create a JSON object
+ @sa @ref object(initializer_list_t) -- create a JSON object
value from an initializer list
@since version 1.0.0
*/
- static basic_json array(std::initializer_list<basic_json> init =
- std::initializer_list<basic_json>())
+ static basic_json array(initializer_list_t init = {})
{
return basic_json(init, false, value_t::array);
}
@@ -8449,10 +8573,10 @@ class basic_json
the initializer list is empty, the empty object `{}` is created.
@note This function is only added for symmetry reasons. In contrast to the
- related function @ref array(std::initializer_list<basic_json>), there are
+ related function @ref array(initializer_list_t), there are
no cases which can only be expressed by this function. That is, any
initializer list @a init can also be passed to the initializer list
- constructor @ref basic_json(std::initializer_list<basic_json>, bool, value_t).
+ constructor @ref basic_json(initializer_list_t, bool, value_t).
@param[in] init initializer list to create an object from (optional)
@@ -8460,7 +8584,7 @@ class basic_json
@throw type_error.301 if @a init is not a list of pairs whose first
elements are strings. In this case, no object can be created. When such a
- value is passed to @ref basic_json(std::initializer_list<basic_json>, bool, value_t),
+ value is passed to @ref basic_json(initializer_list_t, bool, value_t),
an array would have been created from the passed initializer list @a init.
See example below.
@@ -8469,15 +8593,14 @@ class basic_json
@liveexample{The following code shows an example for the `object`
function.,object}
- @sa @ref basic_json(std::initializer_list<basic_json>, bool, value_t) --
+ @sa @ref basic_json(initializer_list_t, bool, value_t) --
create a JSON value from an initializer list
- @sa @ref array(std::initializer_list<basic_json>) -- create a JSON array
+ @sa @ref array(initializer_list_t) -- create a JSON array
value from an initializer list
@since version 1.0.0
*/
- static basic_json object(std::initializer_list<basic_json> init =
- std::initializer_list<basic_json>())
+ static basic_json object(initializer_list_t init = {})
{
return basic_json(init, false, value_t::object);
}
@@ -8650,6 +8773,11 @@ class basic_json
// other constructors and destructor //
///////////////////////////////////////
+ basic_json(const detail::json_ref<basic_json>& ref)
+ : basic_json(ref.moved_or_copied())
+ {
+ }
+
/*!
@brief copy constructor
@@ -11450,7 +11578,7 @@ class basic_json
@brief add an object to an array
@copydoc push_back(basic_json&&)
*/
- reference operator+=(basic_json&& val)
+ reference operator+=(basic_json && val)
{
push_back(std::move(val));
return *this;
@@ -11565,12 +11693,13 @@ class basic_json
@liveexample{The example shows how initializer lists are treated as
objects when possible.,push_back__initializer_list}
*/
- void push_back(std::initializer_list<basic_json> init)
+ void push_back(initializer_list_t init)
{
- if (is_object() and init.size() == 2 and init.begin()->is_string())
+ if (is_object() and init.size() == 2 and (*init.begin())->is_string())
{
- const string_t key = *init.begin();
- push_back(typename object_t::value_type(key, *(init.begin() + 1)));
+ basic_json&& key = init.begin()->moved_or_copied();
+ push_back(typename object_t::value_type(
+ std::move(key.get_ref<string_t&>()), (init.begin() + 1)->moved_or_copied()));
}
else
{
@@ -11580,9 +11709,9 @@ class basic_json
/*!
@brief add an object to an object
- @copydoc push_back(std::initializer_list<basic_json>)
+ @copydoc push_back(initializer_list_t)
*/
- reference operator+=(std::initializer_list<basic_json> init)
+ reference operator+=(initializer_list_t init)
{
push_back(init);
return *this;
@@ -11867,7 +11996,7 @@ class basic_json
@since version 1.0.0
*/
- iterator insert(const_iterator pos, std::initializer_list<basic_json> ilist)
+ iterator insert(const_iterator pos, initializer_list_t ilist)
{
// insert only works for arrays
if (JSON_UNLIKELY(not is_array()))
@@ -11883,7 +12012,7 @@ class basic_json
// insert to array and return iterator
iterator result(this);
- result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, ilist);
+ result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, ilist.begin(), ilist.end());
return result;
}
diff --git a/test/src/unit-constructor1.cpp b/test/src/unit-constructor1.cpp
index 7822b634..5130e505 100644
--- a/test/src/unit-constructor1.cpp
+++ b/test/src/unit-constructor1.cpp
@@ -842,8 +842,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l;
- json j(l);
+ json j(json::initializer_list_t {});
CHECK(j.type() == json::value_t::object);
}
@@ -860,8 +859,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(json::array_t())};
- json j(l);
+ json j(json::initializer_list_t {json(json::array_t())});
CHECK(j.type() == json::value_t::array);
}
@@ -876,8 +874,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(json::object_t())};
- json j(l);
+ json j(json::initializer_list_t {json(json::object_t())});
CHECK(j.type() == json::value_t::array);
}
@@ -892,8 +889,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json("Hello world")};
- json j(l);
+ json j(json::initializer_list_t {json("Hello world")});
CHECK(j.type() == json::value_t::array);
}
@@ -908,8 +904,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(true)};
- json j(l);
+ json j(json::initializer_list_t {json(true)});
CHECK(j.type() == json::value_t::array);
}
@@ -924,8 +919,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(1)};
- json j(l);
+ json j(json::initializer_list_t {json(1)});
CHECK(j.type() == json::value_t::array);
}
@@ -940,8 +934,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(1u)};
- json j(l);
+ json j(json::initializer_list_t {json(1u)});
CHECK(j.type() == json::value_t::array);
}
@@ -956,8 +949,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {json(42.23)};
- json j(l);
+ json j(json::initializer_list_t {json(42.23)});
CHECK(j.type() == json::value_t::array);
}
@@ -973,8 +965,7 @@ TEST_CASE("constructors")
{
SECTION("explicit")
{
- std::initializer_list<json> l = {1, 1u, 42.23, true, nullptr, json::object_t(), json::array_t()};
- json j(l);
+ json j(json::initializer_list_t {1, 1u, 42.23, true, nullptr, json::object_t(), json::array_t()});
CHECK(j.type() == json::value_t::array);
}
@@ -1034,6 +1025,125 @@ TEST_CASE("constructors")
CHECK(j.type() == json::value_t::array);
}
}
+
+ SECTION("move from initializer_list")
+ {
+ SECTION("string")
+ {
+ // This should break through any short string optimization in std::string
+ std::string source(1024, '!');
+ const char* source_addr = source.data();
+
+ SECTION("constructor with implicit types (array)")
+ {
+ json j = {std::move(source)};
+ CHECK(j[0].get_ref<std::string const&>().data() == source_addr);
+ }
+
+ SECTION("constructor with implicit types (object)")
+ {
+ json j = {{"key", std::move(source)}};
+ CHECK(j["key"].get_ref<std::string const&>().data() == source_addr);
+ }
+
+ SECTION("constructor with implicit types (object key)")
+ {
+ json j = {{std::move(source), 42}};
+ CHECK(j.get_ref<json::object_t&>().begin()->first.data() == source_addr);
+ }
+ }
+
+ SECTION("array")
+ {
+ json::array_t source = {1, 2, 3};
+ const json* source_addr = source.data();
+
+ SECTION("constructor with implicit types (array)")
+ {
+ json j {std::move(source)};
+ CHECK(j[0].get_ref<json::array_t const&>().data() == source_addr);
+ }
+
+ SECTION("constructor with implicit types (object)")
+ {
+ json j {{"key", std::move(source)}};
+ CHECK(j["key"].get_ref<json::array_t const&>().data() == source_addr);
+ }
+
+ SECTION("assignment with implicit types (array)")
+ {
+ json j = {std::move(source)};
+ CHECK(j[0].get_ref<json::array_t const&>().data() == source_addr);
+ }
+
+ SECTION("assignment with implicit types (object)")
+ {
+ json j = {{"key", std::move(source)}};
+ CHECK(j["key"].get_ref<json::array_t const&>().data() == source_addr);
+ }
+ }
+
+ SECTION("object")
+ {
+ json::object_t source = {{"hello", "world"}};
+ const json* source_addr = &source.at("hello");
+
+ SECTION("constructor with implicit types (array)")
+ {
+ json j {std::move(source)};
+ CHECK(&(j[0].get_ref<json::object_t const&>().at("hello")) == source_addr);
+ }
+
+ SECTION("constructor with implicit types (object)")
+ {
+ json j {{"key", std::move(source)}};
+ CHECK(&(j["key"].get_ref<json::object_t const&>().at("hello")) == source_addr);
+ }
+
+ SECTION("assignment with implicit types (array)")
+ {
+ json j = {std::move(source)};
+ CHECK(&(j[0].get_ref<json::object_t const&>().at("hello")) == source_addr);
+ }
+
+ SECTION("assignment with implicit types (object)")
+ {
+ json j = {{"key", std::move(source)}};
+ CHECK(&(j["key"].get_ref<json::object_t const&>().at("hello")) == source_addr);
+ }
+ }
+
+ SECTION("json")
+ {
+ json source {1, 2, 3};
+ const json* source_addr = &source[0];
+
+ SECTION("constructor with implicit types (array)")
+ {
+ json j {std::move(source), {}};
+ CHECK(&j[0][0] == source_addr);
+ }
+
+ SECTION("constructor with implicit types (object)")
+ {
+ json j {{"key", std::move(source)}};
+ CHECK(&j["key"][0] == source_addr);
+ }
+
+ SECTION("assignment with implicit types (array)")
+ {
+ json j = {std::move(source), {}};
+ CHECK(&j[0][0] == source_addr);
+ }
+
+ SECTION("assignment with implicit types (object)")
+ {
+ json j = {{"key", std::move(source)}};
+ CHECK(&j["key"][0] == source_addr);
+ }
+ }
+
+ }
}
SECTION("create an array of n copies of a given value")