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开源软件名称:danielaparker/jsoncons开源软件地址:https://github.com/danielaparker/jsoncons开源编程语言:C++ 99.6%开源软件介绍:JSONCONSjsoncons is a C++, header-only library for constructing JSON and JSON-like data formats such as CBOR. For each supported data format, it enables you to work with the data in a number of ways:
Compared to other JSON libraries, jsoncons has been designed to handle very large JSON texts. At its heart are SAX-style parsers and serializers. It supports reading an entire JSON text in memory in a variant-like structure. But it also supports efficient access to the underlying data using StAX-style pull parsing and push serializing. And it supports incremental parsing into a user's preferred form, using information about user types provided by specializations of json_type_traits. The jsoncons data model supports the familiar JSON types - nulls, booleans, numbers, strings, arrays, objects - plus byte strings. In addition, jsoncons supports semantic tagging of datetimes, epoch times, big integers, big decimals, big floats and binary encodings. This allows it to preserve these type semantics when parsing JSON-like data formats such as CBOR that have them. jsoncons is distributed under the Boost Software License. jsoncons is free but welcomes support to sustain its development. If you find this library helpful, please consider making a one time donation
or becoming a As the Extensions
What users say"I am so happy I have come across your json c++ library!" "I finally decided on jsoncons after evaluating quite a few json libraries out there." "I’m using your library for an external interface to pass data, as well as using the conversions from csv to json, which are really helpful for converting data for use in javascript" "Verified that, for my needs in JSON and CBOR, it is working perfectly" "the JSONPath feature of this library, it's great" "We use JMESPath implementation quite extensively" "the serialization lib of choice with its beautiful mappings and ease of use" "really good" "awesome project" "very solid and very dependable" "my team loves it" "Your repo rocks!!!!!" Get jsonconsYou can use the vcpkg platform library manager to install the jsoncons package. Or, download the latest release and unpack the zip file. Copy the directory Or, download the latest code on master. How to use itThe library requires a C++ Compiler with C++11 support. In addition the library defines The library uses exceptions and in some cases std::error_code's to report errors. Apart from Benchmarksjson_benchmarks provides some measurements about how JSONPath Comparison shows how jsoncons JsonPath compares with other implementations ExamplesWorking with JSON dataFor the examples below you need to include some header files and initialize a string of JSON data: #include <jsoncons/json.hpp>
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
#include <iostream>
using namespace jsoncons; // for convenience
std::string data = R"(
{
"application": "hiking",
"reputons": [
{
"rater": "HikingAsylum",
"assertion": "advanced",
"rated": "Marilyn C",
"rating": 0.90,
"generated": 1514862245
}
]
}
)"; jsoncons allows you to work with the data in a number of ways:
As a variant-like data structureint main()
{
// Parse the string of data into a json value
json j = json::parse(data);
// Does object member reputons exist?
std::cout << "(1) " << std::boolalpha << j.contains("reputons") << "\n\n";
// Get a reference to reputons array
const json& v = j["reputons"];
// Iterate over reputons array
std::cout << "(2)\n";
for (const auto& item : v.array_range())
{
// Access rated as string and rating as double
std::cout << item["rated"].as<std::string>() << ", " << item["rating"].as<double>() << "\n";
}
std::cout << "\n";
// Select all "rated" with JSONPath
std::cout << "(3)\n";
json result = jsonpath::json_query(j,"$..rated");
std::cout << pretty_print(result) << "\n\n";
// Serialize back to JSON
std::cout << "(4)\n" << pretty_print(j) << "\n\n";
} Output:
As a strongly typed C++ data structurejsoncons supports transforming JSON texts into C++ data structures.
The functions decode_json and encode_json
convert strings or streams of JSON data to C++ data structures and back.
Decode and encode work for all C++ classes that have
json_type_traits
defined. jsoncons already supports many types in the standard library,
and your own types will be supported too if you specialize namespace ns {
enum class hiking_experience {beginner,intermediate,advanced};
class hiking_reputon
{
std::string rater_;
hiking_experience assertion_;
std::string rated_;
double rating_;
std::optional<std::chrono::seconds> generated_; // assumes C++17, if not use jsoncons::optional
std::optional<std::chrono::seconds> expires_;
public:
hiking_reputon(const std::string& rater,
hiking_experience assertion,
const std::string& rated,
double rating,
const std::optional<std::chrono::seconds>& generated =
std::optional<std::chrono::seconds>(),
const std::optional<std::chrono::seconds>& expires =
std::optional<std::chrono::seconds>())
: rater_(rater), assertion_(assertion), rated_(rated), rating_(rating),
generated_(generated), expires_(expires)
{
}
const std::string& rater() const {return rater_;}
hiking_experience assertion() const {return assertion_;}
const std::string& rated() const {return rated_;}
double rating() const {return rating_;}
std::optional<std::chrono::seconds> generated() const {return generated_;}
std::optional<std::chrono::seconds> expires() const {return expires_;}
friend bool operator==(const hiking_reputon& lhs, const hiking_reputon& rhs)
{
return lhs.rater_ == rhs.rater_ && lhs.assertion_ == rhs.assertion_ &&
lhs.rated_ == rhs.rated_ && lhs.rating_ == rhs.rating_ &&
lhs.confidence_ == rhs.confidence_ && lhs.expires_ == rhs.expires_;
}
friend bool operator!=(const hiking_reputon& lhs, const hiking_reputon& rhs)
{
return !(lhs == rhs);
};
};
class hiking_reputation
{
std::string application_;
std::vector<hiking_reputon> reputons_;
public:
hiking_reputation(const std::string& application,
const std::vector<hiking_reputon>& reputons)
: application_(application),
reputons_(reputons)
{}
const std::string& application() const { return application_;}
const std::vector<hiking_reputon>& reputons() const { return reputons_;}
};
} // namespace ns
// Declare the traits. Specify which data members need to be serialized.
JSONCONS_ENUM_TRAITS(ns::hiking_experience, beginner, intermediate, advanced)
// First four members listed are mandatory, generated and expires are optional
JSONCONS_N_CTOR_GETTER_TRAITS(ns::hiking_reputon, 4, rater, assertion, rated, rating,
generated, expires)
// All members are mandatory
JSONCONS_ALL_CTOR_GETTER_TRAITS(ns::hiking_reputation, application, reputons)
int main()
{
// Decode the string of data into a c++ structure
ns::hiking_reputation v = decode_json<ns::hiking_reputation>(data);
// Iterate over reputons array value
std::cout << "(1)\n";
for (const auto& item : v.reputons())
{
std::cout << item.rated() << ", " << item.rating();
if (item.generated())
{
std::cout << ", " << (*item.generated()).count();
}
std::cout << "\n";
}
// Encode the c++ structure into a string
std::string s;
encode_json_pretty(v, s);
std::cout << "(2)\n";
std::cout << s << "\n";
} Output:
This example makes use of the convenience macros See examples for other ways of specializing With cursor-level accessA typical pull parsing application will repeatedly process the int main()
{
json_string_cursor cursor(data);
for (; !cursor.done(); cursor.next())
{
const auto& event = cursor.current();
switch (event.event_type())
{
case staj_event_type::begin_array:
std::cout << event.event_type() << " " << "\n";
break;
case staj_event_type::end_array:
std::cout << event.event_type() << " " << "\n";
break;
case staj_event_type::begin_object:
std::cout << event.event_type() << " " << "\n";
break;
case staj_event_type::end_object:
std::cout << event.event_type() << " " << "\n";
break;
case staj_event_type::key:
// Or std::string_view, if supported
std::cout << event.event_type() << ": " << event.get<jsoncons::string_view>() << "\n";
break;
case staj_event_type::string_value:
// Or std::string_view, if supported
std::cout << event.event_type() << ": " << event.get<jsoncons::string_view>() << "\n";
break;
case staj_event_type::null_value:
std::cout << event.event_type() << "\n";
break;
case staj_event_type::bool_value:
std::cout << event.event_type() << ": " << std::boolalpha << event.get<bool>() << "\n";
break;
case staj_event_type::int64_value:
std::cout << event.event_type() << ": " << event.get<int64_t>() << "\n";
break;
case staj_event_type::uint64_value:
std::cout << event.event_type() << ": " << event.get<uint64_t>() << "\n";
break;
case staj_event_type::double_value:
std::cout << event.event_type() << ": " << event.get<double>() << "\n";
break;
default:
std::cout << "Unhandled event type: " << event.event_type() << " " << "\n";
break;
}
}
} Output:
You can apply a filter to a cursor using the pipe syntax (e.g., int main()
{
std::string name;
auto filter = [&](const staj_event& ev, const ser_context&) -> bool
{
if (ev.event_type() == staj_event_type::key)
{
name = ev.get<std::string>();
return false;
}
if (name == "rated")
{
name.clear();
return true;
}
return false;
};
json_string_cursor cursor(data);
auto filtered_c = cursor | filter;
for (; !filtered_c.done(); filtered_c.next())
{
const auto& event = filtered_c.current();
switch (event.event_type())
{
case staj_event_type::string_value:
// Or std::string_view, if C++17
std::cout << event.event_type() << ": " << event.get<jsoncons::string_view>() << "\n";
break;
default:
std::cout << "Unhandled event type\n";
break;
}
}
} Output:
Working with CBOR dataFor the examples below you need to include some header files and initialize a buffer of CBOR data: #include <iomanip>
#include <iostream>
#include <jsoncons/json.hpp>
#include <jsoncons_ext/cbor/cbor.hpp>
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
using namespace jsoncons; // for convenience
const std::vector<uint8_t> data = {
0x9f, // Start indefinte length array
0x83, // Array of length 3
0x63, // String value of length 3
0x66,0x6f,0x6f, // "foo"
0x44, // Byte string value of length 4
0x50,0x75,0x73,0x73, // 'P''u''s''s'
0xc5, // Tag 5 (bigfloat)
0x82, // Array of length 2
0x20, // -1
0x03, // 3
0x83, // Another array of length 3
0x63, // String value of length 3
0x62,0x61,0x72, // "bar"
0xd6, // Expected conversion to base64
0x44, // Byte string value of length 4
0x50,0x75,0x73,0x73, // 'P''u''s''s'
0xc4, // Tag 4 (decimal fraction)
0x82, // Array of length 2
0x38, // Negative integer of length 1
0x1c, // -29
0xc2, // Tag 2 (positive bignum)
0x4d, // Byte string value of length 13
0x01,0x8e,0xe9,0x0f,0xf6,0xc3,0x73,0xe0,0xee,0x4e,0x3f,0x0a,0xd2,
0xff // "break"
}; jsoncons allows you to work with the CBOR data similarly to JSON data:
As a variant-like data structureint main()
{
// Parse the CBOR data into a json value
json j = cbor::decode_cbor<json>(data);
// Pretty print
std::cout << "(1)\n" << pretty_print(j) << "\n\n";
// Iterate over rows
std::cout << "(2)\n";
for (const auto& row : j.array_range())
{
std::cout << row[1].as<jsoncons::byte_string>() << " (" << row[1].tag() << ")\n";
}
std::cout << "\n";
// Select the third column with JSONPath
std::cout << "(3)\n";
json result = jsonpath::json_query(j,"$[*][2]");
std::cout << pretty_print(result) << "\n\n";
// Serialize back to CBOR
std::vector<uint8_t> buffer;
cbor::encode_cbor(j, buffer);
std::cout << "(4)\n" << byte_string_view(buffer) << "\n\n";
} Output: 全部评论
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