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added a constructor from an input stream
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104c4b5286
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55
doc/examples/basic_json__istream.cpp
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55
doc/examples/basic_json__istream.cpp
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#include <json.hpp>
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using json = nlohmann::json;
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int main()
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{
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// a JSON text
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auto text = R"(
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{
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"Image": {
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"Width": 800,
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"Height": 600,
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"Title": "View from 15th Floor",
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"Thumbnail": {
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"Url": "http://www.example.com/image/481989943",
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"Height": 125,
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"Width": 100
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},
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"Animated" : false,
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"IDs": [116, 943, 234, 38793]
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}
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}
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)";
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// fill a stream with JSON text
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std::stringstream ss;
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ss << text;
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// create JSON from stream
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json j_complete(ss);
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std::cout << std::setw(4) << j_complete << "\n\n";
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// define parser callback
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json::parser_callback_t cb = [](int depth, json::parse_event_t event, json & parsed)
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{
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// skip object elements with key "Thumbnail"
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if (event == json::parse_event_t::key and parsed == json("Thumbnail"))
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{
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return false;
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}
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else
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{
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return true;
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}
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};
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// fill a stream with JSON text
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ss.clear();
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ss << text;
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// create JSON from stream (with callback)
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json j_filtered(ss, cb);
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std::cout << std::setw(4) << j_filtered << '\n';
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}
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1
doc/examples/basic_json__istream.link
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1
doc/examples/basic_json__istream.link
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@ -0,0 +1 @@
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<a target="_blank" href="http://melpon.org/wandbox/permlink/lUltfC5TlmxeUq5X"><b>online</b></a>
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34
doc/examples/basic_json__istream.output
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34
doc/examples/basic_json__istream.output
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{
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"Image": {
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"Animated": false,
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"Height": 600,
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"IDs": [
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116,
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943,
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234,
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38793
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],
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"Thumbnail": {
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"Height": 125,
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"Url": "http://www.example.com/image/481989943",
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"Width": 100
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},
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"Title": "View from 15th Floor",
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"Width": 800
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}
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}
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{
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"Image": {
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"Animated": false,
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"Height": 600,
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"IDs": [
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116,
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943,
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234,
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38793
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],
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"Title": "View from 15th Floor",
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"Width": 800
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}
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}
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25
src/json.hpp
25
src/json.hpp
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@ -1806,6 +1806,31 @@ class basic_json
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}
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}
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}
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}
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/*!
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@brief construct a JSON value given an input stream
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@param[in,out] i stream to read a serialized JSON value from
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@param[in] cb a parser callback function of type @ref parser_callback_t
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which is used to control the deserialization by filtering unwanted values
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(optional)
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@complexity Linear in the length of the input. The parser is a predictive
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LL(1) parser. The complexity can be higher if the parser callback function
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@a cb has a super-linear complexity.
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@note A UTF-8 byte order mark is silently ignored.
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@liveexample{The example below demonstrates constructing a JSON value from
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a `std::stringstream` with and without callback
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function.,basic_json__istream}
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@since version 2.0.0
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*/
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basic_json(std::istream& i, parser_callback_t cb = nullptr)
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{
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*this = parser(i, cb).parse();
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}
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///////////////////////////////////////
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///////////////////////////////////////
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// other constructors and destructor //
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// other constructors and destructor //
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///////////////////////////////////////
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///////////////////////////////////////
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@ -1806,6 +1806,31 @@ class basic_json
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}
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}
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}
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}
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/*!
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@brief construct a JSON value given an input stream
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@param[in,out] i stream to read a serialized JSON value from
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@param[in] cb a parser callback function of type @ref parser_callback_t
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which is used to control the deserialization by filtering unwanted values
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(optional)
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@complexity Linear in the length of the input. The parser is a predictive
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LL(1) parser. The complexity can be higher if the parser callback function
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@a cb has a super-linear complexity.
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@note A UTF-8 byte order mark is silently ignored.
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@liveexample{The example below demonstrates constructing a JSON value from
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a `std::stringstream` with and without callback
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function.,basic_json__istream}
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@since version 2.0.0
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*/
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basic_json(std::istream& i, parser_callback_t cb = nullptr)
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{
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*this = parser(i, cb).parse();
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}
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///////////////////////////////////////
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///////////////////////////////////////
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// other constructors and destructor //
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// other constructors and destructor //
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///////////////////////////////////////
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///////////////////////////////////////
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@ -1264,6 +1264,42 @@ TEST_CASE("constructors")
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}
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}
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}
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}
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}
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}
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SECTION("create a JSON value from an input stream")
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{
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SECTION("sts::stringstream")
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{
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std::stringstream ss;
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ss << "[\"foo\",1,2,3,false,{\"one\":1}]";
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json j(ss);
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CHECK(j == json({"foo", 1, 2, 3, false, {{"one", 1}}}));
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}
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SECTION("with callback function")
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{
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std::stringstream ss;
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ss << "[\"foo\",1,2,3,false,{\"one\":1}]";
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json j(ss, [](int, json::parse_event_t, const json & val)
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{
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// filter all number(2) elements
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if (val == json(2))
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{
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return false;
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}
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else
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{
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return true;
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}
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});
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CHECK(j == json({"foo", 1, 3, false, {{"one", 1}}}));
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}
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SECTION("std::ifstream")
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{
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std::ifstream f("test/json_tests/pass1.json");
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json j(f);
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}
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}
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}
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}
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TEST_CASE("other constructors and destructor")
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TEST_CASE("other constructors and destructor")
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