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template<template< typename U, typename V, typename...Args > class ObjectType = std::map, template< typename U, typename...Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = int64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>
- Parameters
-
[in] | s | string to read a serialized JSON value from |
[in] | cb | a parser callback function of type parser_callback_t which is used to control the deserialization by filtering unwanted values (optional) |
- Returns
- result of the deserialization
- Complexity
- Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the parser callback function cb has a super-linear complexity.
- Example
- The example below demonstrates the parse function with and without callback function.
13 "Title": "View from 15th Floor",
15 "Url": "http://www.example.com/image/481989943",
20 "IDs": [116, 943, 234, 38793]
27 std::cout << std::setw(4) << j_complete << "\n\n";
46 std::cout << std::setw(4) << j_filtered << '\n';
basic_json<> json default JSON class Definition: json.hpp:6097
a class to store JSON values Definition: json.hpp:121
static basic_json parse(const string_t &s, parser_callback_t cb=nullptr) deserialize from string Definition: json.hpp:3594
std::function< bool(int depth, parse_event_t event, basic_json &parsed)> parser_callback_t per-element parser callback type Definition: json.hpp:415
namespace for Niels Lohmann Definition: json.hpp:56
the parser read a key of a value in an object
parse_event_t JSON callback events. Definition: json.hpp:351
Output: {
"Image": {
"Animated": false,
"Height": 600,
"IDs": [
116,
943,
234,
38793
],
"Thumbnail": {
"Height": 125,
"Url": "http://www.example.com/image/481989943",
"Width": 100
},
"Title": "View from 15th Floor",
"Width": 800
}
}
{
"Image": {
"Animated": false,
"Height": 600,
"IDs": [
116,
943,
234,
38793
],
"Title": "View from 15th Floor",
"Width": 800
}
}
The example code above can be translated withg++ -std=c++11 -Isrc doc/examples/parse__string__parser_callback_t.cpp -o parse__string__parser_callback_t .
- See also
- parse(std::istream&, parser_callback_t) for a version that reads from an input stream
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