json/test/src/unit-readme.cpp
2018-08-18 18:46:15 +02:00

323 lines
10 KiB
C++

/*
__ _____ _____ _____
__| | __| | | | JSON for Modern C++ (test suite)
| | |__ | | | | | | version 3.2.0
|_____|_____|_____|_|___| https://github.com/nlohmann/json
Licensed under the MIT License <http://opensource.org/licenses/MIT>.
SPDX-License-Identifier: MIT
Copyright (c) 2013-2018 Niels Lohmann <http://nlohmann.me>.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "catch.hpp"
#include <nlohmann/json.hpp>
using nlohmann::json;
#include <deque>
#include <forward_list>
#include <list>
#include <unordered_map>
#include <unordered_set>
#include <iostream>
#if defined(_MSC_VER)
#pragma warning (push)
#pragma warning (disable : 4189) // local variable is initialized but not referenced
#endif
TEST_CASE("README", "[hide]")
{
{
// redirect std::cout for the README file
auto old_cout_buffer = std::cout.rdbuf();
std::ostringstream new_stream;
std::cout.rdbuf(new_stream.rdbuf());
{
// create an empty structure (null)
json j;
// add a number that is stored as double (note the implicit conversion of j to an object)
j["pi"] = 3.141;
// add a Boolean that is stored as bool
j["happy"] = true;
// add a string that is stored as std::string
j["name"] = "Niels";
// add another null object by passing nullptr
j["nothing"] = nullptr;
// add an object inside the object
j["answer"]["everything"] = 42;
// add an array that is stored as std::vector (using an initializer list)
j["list"] = { 1, 0, 2 };
// add another object (using an initializer list of pairs)
j["object"] = { {"currency", "USD"}, {"value", 42.99} };
// instead, you could also write (which looks very similar to the JSON above)
json j2 =
{
{"pi", 3.141},
{"happy", true},
{"name", "Niels"},
{"nothing", nullptr},
{
"answer", {
{"everything", 42}
}
},
{"list", {1, 0, 2}},
{
"object", {
{"currency", "USD"},
{"value", 42.99}
}
}
};
}
{
// ways to express the empty array []
json empty_array_implicit = {{}};
CHECK(empty_array_implicit.is_array());
json empty_array_explicit = json::array();
CHECK(empty_array_explicit.is_array());
// a way to express the empty object {}
json empty_object_explicit = json::object();
CHECK(empty_object_explicit.is_object());
// a way to express an _array_ of key/value pairs [["currency", "USD"], ["value", 42.99]]
json array_not_object = json::array({ {"currency", "USD"}, {"value", 42.99} });
CHECK(array_not_object.is_array());
CHECK(array_not_object.size() == 2);
CHECK(array_not_object[0].is_array());
CHECK(array_not_object[1].is_array());
}
{
// create object from string literal
json j = "{ \"happy\": true, \"pi\": 3.141 }"_json;
// or even nicer with a raw string literal
auto j2 = R"(
{
"happy": true,
"pi": 3.141
}
)"_json;
// or explicitly
auto j3 = json::parse("{ \"happy\": true, \"pi\": 3.141 }");
// explicit conversion to string
std::string s = j.dump(); // {\"happy\":true,\"pi\":3.141}
// serialization with pretty printing
// pass in the amount of spaces to indent
std::cout << j.dump(4) << std::endl;
// {
// "happy": true,
// "pi": 3.141
// }
std::cout << std::setw(2) << j << std::endl;
}
{
// create an array using push_back
json j;
j.push_back("foo");
j.push_back(1);
j.push_back(true);
// comparison
bool x = (j == "[\"foo\", 1, true]"_json); // true
CHECK(x == true);
// iterate the array
for (json::iterator it = j.begin(); it != j.end(); ++it)
{
std::cout << *it << '\n';
}
// range-based for
for (auto element : j)
{
std::cout << element << '\n';
}
// getter/setter
const std::string tmp = j[0];
j[1] = 42;
bool foo = j.at(2);
CHECK(foo == true);
// other stuff
j.size(); // 3 entries
j.empty(); // false
j.type(); // json::value_t::array
j.clear(); // the array is empty again
// create an object
json o;
o["foo"] = 23;
o["bar"] = false;
o["baz"] = 3.141;
// find an entry
if (o.find("foo") != o.end())
{
// there is an entry with key "foo"
}
}
{
std::vector<int> c_vector {1, 2, 3, 4};
json j_vec(c_vector);
// [1, 2, 3, 4]
std::deque<float> c_deque {1.2f, 2.3f, 3.4f, 5.6f};
json j_deque(c_deque);
// [1.2, 2.3, 3.4, 5.6]
std::list<bool> c_list {true, true, false, true};
json j_list(c_list);
// [true, true, false, true]
std::forward_list<int64_t> c_flist {12345678909876, 23456789098765, 34567890987654, 45678909876543};
json j_flist(c_flist);
// [12345678909876, 23456789098765, 34567890987654, 45678909876543]
std::array<unsigned long, 4> c_array {{1, 2, 3, 4}};
json j_array(c_array);
// [1, 2, 3, 4]
std::set<std::string> c_set {"one", "two", "three", "four", "one"};
json j_set(c_set); // only one entry for "one" is used
// ["four", "one", "three", "two"]
std::unordered_set<std::string> c_uset {"one", "two", "three", "four", "one"};
json j_uset(c_uset); // only one entry for "one" is used
// maybe ["two", "three", "four", "one"]
std::multiset<std::string> c_mset {"one", "two", "one", "four"};
json j_mset(c_mset); // both entries for "one" are used
// maybe ["one", "two", "one", "four"]
std::unordered_multiset<std::string> c_umset {"one", "two", "one", "four"};
json j_umset(c_umset); // both entries for "one" are used
// maybe ["one", "two", "one", "four"]
}
{
std::map<std::string, int> c_map { {"one", 1}, {"two", 2}, {"three", 3} };
json j_map(c_map);
// {"one": 1, "two": 2, "three": 3}
std::unordered_map<const char*, float> c_umap { {"one", 1.2f}, {"two", 2.3f}, {"three", 3.4f} };
json j_umap(c_umap);
// {"one": 1.2, "two": 2.3, "three": 3.4}
std::multimap<std::string, bool> c_mmap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
json j_mmap(c_mmap); // only one entry for key "three" is used
// maybe {"one": true, "two": true, "three": true}
std::unordered_multimap<std::string, bool> c_ummap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
json j_ummap(c_ummap); // only one entry for key "three" is used
// maybe {"one": true, "two": true, "three": true}
}
{
// strings
std::string s1 = "Hello, world!";
json js = s1;
std::string s2 = js;
// Booleans
bool b1 = true;
json jb = b1;
bool b2 = jb;
CHECK(b2 == true);
// numbers
int i = 42;
json jn = i;
double f = jn;
CHECK(f == 42);
// etc.
std::string vs = js.get<std::string>();
bool vb = jb.get<bool>();
CHECK(vb == true);
int vi = jn.get<int>();
CHECK(vi == 42);
// etc.
}
{
// a JSON value
json j_original = R"({
"baz": ["one", "two", "three"],
"foo": "bar"
})"_json;
// access members with a JSON pointer (RFC 6901)
j_original["/baz/1"_json_pointer];
// "two"
// a JSON patch (RFC 6902)
json j_patch = R"([
{ "op": "replace", "path": "/baz", "value": "boo" },
{ "op": "add", "path": "/hello", "value": ["world"] },
{ "op": "remove", "path": "/foo"}
])"_json;
// apply the patch
json j_result = j_original.patch(j_patch);
// {
// "baz": "boo",
// "hello": ["world"]
// }
// calculate a JSON patch from two JSON values
json::diff(j_result, j_original);
// [
// { "op":" replace", "path": "/baz", "value": ["one", "two", "three"] },
// { "op":"remove","path":"/hello" },
// { "op":"add","path":"/foo","value":"bar" }
// ]
}
// restore old std::cout
std::cout.rdbuf(old_cout_buffer);
}
}
#if defined(_MSC_VER)
#pragma warning (pop)
#endif