insert.md

jsoncons::basic_json::insert

template <class T>
array_iterator insert(const_array_iterator pos, T&& val); (1)

template <class InputIt>
array_iterator insert(const_array_iterator pos, InputIt first, InputIt last); (2)

(1) Adds a new json element at the specified position of a json array, shifting all elements currently at or above that position to the right. The argument val is forwarded to the json constructor as std::forward<T>(val). Returns an array_iterator that points to the new value Throws std::domain_error if not an array.

(2) Inserts elements from range [first, last) before pos.

template <class InputIt>
void insert(InputIt first, InputIt last); (3)

(3) Inserts elements from range [first, last) into a json object. If multiple elements in the range have the same key, the first element in the range is inserted. The function template parameter InputIt represents an input iterator type that iterates over elements of type key_value_type, or alternatively over elements of type std::pair<T1,T2> where T1 is convertible to key_type and T2 is convertible to basic_json.

Examples

Creating an array of elements

json cities(json_array_arg);       // an empty array
std::cout << cities << std::endl;  // output is "[]"

cities.push_back("Toronto");  
cities.push_back("Vancouver");
// Insert "Montreal" at beginning of array
cities.insert(cities.array_range().begin(),"Montreal");  

std::cout << cities << std::endl;

Output:

[]
["Montreal","Toronto","Vancouver"]

Creating an array of elements with reserved storage

json cities(json_array_arg);  
cities.reserve(10);  // storage is reserved
std::cout << "capacity=" << cities.capacity() 
          << ", size=" << cities.size() << std::endl;

cities.push_back("Toronto");  
cities.push_back("Vancouver");
cities.insert(cities.array_range().begin(),"Montreal");
std::cout << "capacity=" << cities.capacity() 
          << ", size=" << cities.size() << std::endl;

std::cout << cities << std::endl;

Output:

capacity=10, size=0
capacity=10, size=3
["Montreal","Toronto","Vancouver"]

Copy two std::map's into a json

std::map<std::string,double> m1 = {{"f",4},{"e",5},{"d",6}};
std::map<std::string,double> m2 = {{"c",1},{"b",2},{"a",3}};

json j;
j.insert(m1.begin(),m1.end());
j.insert(m2.begin(),m2.end());

std::cout << j << "\n";

Output:

{"a":3.0,"b":2.0,"c":1.0,"d":6.0,"e":5.0,"f":4.0}

Copy two std::map's into an ojson

std::map<std::string,double> m1 = {{"f",4},{"e",5},{"d",6}};
std::map<std::string,double> m2 = {{"c",1},{"b",2},{"a",3}};

ojson j;
j.insert(m1.begin(),m1.end());
j.insert(m2.begin(),m2.end());

std::cout << j << "\n";

Output:

{"d":6.0,"e":5.0,"f":4.0,"a":3.0,"b":2.0,"c":1.0}

Move two std::map's into a json

std::map<std::string,double> m1 = {{"a",1},{"b",2},{"c",3}};
std::map<std::string,double> m2 = {{"d",4},{"e",5},{"f",6}};

json j;
j.insert(std::make_move_iterator(m1.begin()),std::make_move_iterator(m1.end()));
j.insert(std::make_move_iterator(m2.begin()),std::make_move_iterator(m2.end()));

std::cout << j << "\n";

Output:

{"a":1.0,"b":2.0,"c":3.0,"d":4.0,"e":5.0,"f":6.0}

See also

push_back