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✨ add recursive update function for iterator range

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Niels Lohmann 2021-10-10 10:40:30 +02:00
parent 685327f48e
commit 9fba12704d
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GPG Key ID: 7F3CEA63AE251B69
5 changed files with 62 additions and 80 deletions
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13
doc/examples/update__range.cpp
View File

@ -7,12 +7,17 @@ using json = nlohmann::json;
int main()
{
// create two JSON objects
json o1 = R"( {"color": "red", "price": 17.99} )"_json;
json o2 = R"( {"color": "blue", "speed": 100} )"_json;
json o1 = R"( {"color": "red", "price": 17.99, "names": {"de": "Flugzeug"}} )"_json;
json o2 = R"( {"color": "blue", "speed": 100, "names": {"en": "plane"}} )"_json;
json o3 = o1;
// add all keys from o2 to o1 (updating "color")
// add all keys from o2 to o1 (updating "color", replacing "names")
o1.update(o2.begin(), o2.end());
// output updated object o1
// add all keys from o2 to o1 (updating "color", merging "names")
o3.update(o2.begin(), o2.end(), true);
// output updated object o1 and o3
std::cout << std::setw(2) << o1 << '\n';
std::cout << std::setw(2) << o3 << '\n';
}

12
doc/examples/update__range.output
View File

@ -1,5 +1,17 @@
{
"color": "blue",
"names": {
"en": "plane"
},
"price": 17.99,
"speed": 100
}
{
"color": "blue",
"names": {
"de": "Flugzeug",
"en": "plane"
},
"price": 17.99,
"speed": 100
}

10
doc/mkdocs/docs/api/basic_json/update.md
View File

@ -5,12 +5,14 @@
void update(const_reference j, bool merge_objects = false);
// (2)
void update(const_iterator first, const_iterator last);
void update(const_iterator first, const_iterator last, bool merge_objects = false);
```
1. Inserts all values from JSON object `j`. and overwrites existing keys. When `merge_objects` is `#!c false` (default),
existing keys are overwritten. When `merge_objects` is `#!c true`, recursively merges objects with common keys.
2. Inserts all values from from range `[first, last)` and overwrites existing keys.
1. Inserts all values from JSON object `j`.
2. Inserts all values from from range `[first, last)`
When `merge_objects` is `#!c false` (default), existing keys are overwritten. When `merge_objects` is `#!c true`,
recursively merges objects with common keys.
The function is motivated by Python's [dict.update](https://docs.python.org/3.6/library/stdtypes.html#dict.update)
function.

50
include/nlohmann/json.hpp
View File

@ -6002,39 +6002,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
*/
void update(const_reference j, bool merge_objects = false)
{
// implicitly convert null value to an empty object
if (is_null())
{
m_type = value_t::object;
m_value.object = create<object_t>();
assert_invariant();
}
if (JSON_HEDLEY_UNLIKELY(!is_object()))
{
JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()), *this));
}
if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
{
JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(j.type_name()), *this));
}
for (auto it = j.cbegin(); it != j.cend(); ++it)
{
if (merge_objects && it.value().is_object())
{
auto it2 = m_value.object->find(it.key());
if (it2 != m_value.object->end())
{
it2->second.update(it.value(), true);
continue;
}
}
m_value.object->operator[](it.key()) = it.value();
#if JSON_DIAGNOSTICS
m_value.object->operator[](it.key()).m_parent = this;
#endif
}
update(j.begin(), j.end(), merge_objects);
}
/*!
@ -6045,6 +6013,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@param[in] first begin of the range of elements to insert
@param[in] last end of the range of elements to insert
@param[in] merge_objects when true, existing keys are not overwritten, but
contents of objects are merged recursively
(default: false)
@throw type_error.312 if called on JSON values other than objects; example:
`"cannot use update() with string"`
@ -6061,9 +6032,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@sa https://docs.python.org/3.6/library/stdtypes.html#dict.update
@since version 3.0.0
@since version 3.0.0, `merge_objects` parameter added in 3.10.4.
*/
void update(const_iterator first, const_iterator last)
void update(const_iterator first, const_iterator last, bool merge_objects = false)
{
// implicitly convert null value to an empty object
if (is_null())
@ -6093,6 +6064,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
for (auto it = first; it != last; ++it)
{
if (merge_objects && it.value().is_object())
{
auto it2 = m_value.object->find(it.key());
if (it2 != m_value.object->end())
{
it2->second.update(it.value(), true);
continue;
}
}
m_value.object->operator[](it.key()) = it.value();
#if JSON_DIAGNOSTICS
m_value.object->operator[](it.key()).m_parent = this;

57
single_include/nlohmann/json.hpp
View File

@ -23471,6 +23471,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
Inserts all values from JSON object @a j and overwrites existing keys.
@param[in] j JSON object to read values from
@param[in] merge_objects when true, existing keys are not overwritten, but
contents of objects are merged recursively
(default: false)
@throw type_error.312 if called on JSON values other than objects; example:
`"cannot use update() with string"`
@ -23482,43 +23485,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@sa https://docs.python.org/3.6/library/stdtypes.html#dict.update
@since version 3.0.0
@since version 3.0.0, `merge_objects` parameter added in 3.10.4.
*/
void update(const_reference j, bool recursive = false)
void update(const_reference j, bool merge_objects = false)
{
// implicitly convert null value to an empty object
if (is_null())
{
m_type = value_t::object;
m_value.object = create<object_t>();
assert_invariant();
}
if (JSON_HEDLEY_UNLIKELY(!is_object()))
{
JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()), *this));
}
if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
{
JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(j.type_name()), *this));
}
for (auto it = j.cbegin(); it != j.cend(); ++it)
{
if (recursive && it.value().is_object())
{
auto it2 = m_value.object->find(it.key());
if (it2 != m_value.object->end())
{
it2->second.update(it.value(), recursive);
continue;
}
}
m_value.object->operator[](it.key()) = it.value();
#if JSON_DIAGNOSTICS
m_value.object->operator[](it.key()).m_parent = this;
#endif
}
update(j.begin(), j.end(), merge_objects);
}
/*!
@ -23529,6 +23500,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@param[in] first begin of the range of elements to insert
@param[in] last end of the range of elements to insert
@param[in] merge_objects when true, existing keys are not overwritten, but
contents of objects are merged recursively
(default: false)
@throw type_error.312 if called on JSON values other than objects; example:
`"cannot use update() with string"`
@ -23545,9 +23519,9 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
@sa https://docs.python.org/3.6/library/stdtypes.html#dict.update
@since version 3.0.0
@since version 3.0.0, `merge_objects` parameter added in 3.10.4.
*/
void update(const_iterator first, const_iterator last)
void update(const_iterator first, const_iterator last, bool merge_objects = false)
{
// implicitly convert null value to an empty object
if (is_null())
@ -23577,6 +23551,15 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
for (auto it = first; it != last; ++it)
{
if (merge_objects && it.value().is_object())
{
auto it2 = m_value.object->find(it.key());
if (it2 != m_value.object->end())
{
it2->second.update(it.value(), true);
continue;
}
}
m_value.object->operator[](it.key()) = it.value();
#if JSON_DIAGNOSTICS
m_value.object->operator[](it.key()).m_parent = this;