1 // __ _____ _____ _____
2 // __| | __| | | | JSON for Modern C++ (supporting code)
3 // | | |__ | | | | | | version 3.11.2
4 // |_____|_____|_____|_|___| https://github.com/nlohmann/json
5 //
6 // SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me>
7 // SPDX-License-Identifier: MIT
8
9 #include "doctest_compatibility.h"
10
11 #include <nlohmann/json.hpp>
12 using nlohmann::json;
13 #ifdef JSON_TEST_NO_GLOBAL_UDLS
14 using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
15 #endif
16
17 #include <deque>
18 #include <forward_list>
19 #include <list>
20 #include <set>
21 #include <unordered_map>
22 #include <unordered_set>
23 #include <iostream>
24 #include <sstream>
25 #include <iomanip>
26
27 // local variable is initialized but not referenced
28 DOCTEST_MSVC_SUPPRESS_WARNING_PUSH
29 DOCTEST_MSVC_SUPPRESS_WARNING(4189)
30
skip()31 TEST_CASE("README" * doctest::skip())
32 {
33 {
34 // redirect std::cout for the README file
35 auto* old_cout_buffer = std::cout.rdbuf();
36 std::ostringstream new_stream;
37 std::cout.rdbuf(new_stream.rdbuf());
38 {
39 // create an empty structure (null)
40 json j;
41
42 // add a number that is stored as double (note the implicit conversion of j to an object)
43 j["pi"] = 3.141;
44
45 // add a Boolean that is stored as bool
46 j["happy"] = true;
47
48 // add a string that is stored as std::string
49 j["name"] = "Niels";
50
51 // add another null object by passing nullptr
52 j["nothing"] = nullptr;
53
54 // add an object inside the object
55 j["answer"]["everything"] = 42;
56
57 // add an array that is stored as std::vector (using an initializer list)
58 j["list"] = { 1, 0, 2 };
59
60 // add another object (using an initializer list of pairs)
61 j["object"] = { {"currency", "USD"}, {"value", 42.99} };
62
63 // instead, you could also write (which looks very similar to the JSON above)
64 json j2 =
65 {
66 {"pi", 3.141},
67 {"happy", true},
68 {"name", "Niels"},
69 {"nothing", nullptr},
70 {
71 "answer", {
72 {"everything", 42}
73 }
74 },
75 {"list", {1, 0, 2}},
76 {
77 "object", {
78 {"currency", "USD"},
79 {"value", 42.99}
80 }
81 }
82 };
83 }
84
85 {
86 // ways to express the empty array []
87 json empty_array_implicit = {{}};
88 CHECK(empty_array_implicit.is_array());
89 json empty_array_explicit = json::array();
90 CHECK(empty_array_explicit.is_array());
91
92 // a way to express the empty object {}
93 json empty_object_explicit = json::object();
94 CHECK(empty_object_explicit.is_object());
95
96 // a way to express an _array_ of key/value pairs [["currency", "USD"], ["value", 42.99]]
97 json array_not_object = json::array({ {"currency", "USD"}, {"value", 42.99} });
98 CHECK(array_not_object.is_array());
99 CHECK(array_not_object.size() == 2);
100 CHECK(array_not_object[0].is_array());
101 CHECK(array_not_object[1].is_array());
102 }
103
104 {
105 // create object from string literal
106 json j = "{ \"happy\": true, \"pi\": 3.141 }"_json; // NOLINT(modernize-raw-string-literal)
107
108 // or even nicer with a raw string literal
109 auto j2 = R"({
110 "happy": true,
111 "pi": 3.141
112 })"_json;
113
114 // or explicitly
115 auto j3 = json::parse(R"({"happy": true, "pi": 3.141})");
116
117 // explicit conversion to string
118 std::string s = j.dump(); // {\"happy\":true,\"pi\":3.141}
119
120 // serialization with pretty printing
121 // pass in the amount of spaces to indent
122 std::cout << j.dump(4) << std::endl;
123 // {
124 // "happy": true,
125 // "pi": 3.141
126 // }
127
128 std::cout << std::setw(2) << j << std::endl;
129 }
130
131 {
132 // create an array using push_back
133 json j;
134 j.push_back("foo");
135 j.push_back(1);
136 j.push_back(true);
137
138 // comparison
139 bool x = (j == R"(["foo", 1, true])"_json); // true
140 CHECK(x == true);
141
142 // iterate the array
143 for (json::iterator it = j.begin(); it != j.end(); ++it) // NOLINT(modernize-loop-convert)
144 {
145 std::cout << *it << '\n';
146 }
147
148 // range-based for
149 for (auto& element : j)
150 {
151 std::cout << element << '\n';
152 }
153
154 // getter/setter
155 const auto tmp = j[0].get<std::string>();
156 j[1] = 42;
157 bool foo{j.at(2)};
158 CHECK(foo == true);
159
160 // other stuff
161 CHECK(j.size() == 3); // 3 entries
162 CHECK_FALSE(j.empty()); // false
163 CHECK(j.type() == json::value_t::array); // json::value_t::array
164 j.clear(); // the array is empty again
165
166 // create an object
167 json o;
168 o["foo"] = 23;
169 o["bar"] = false;
170 o["baz"] = 3.141;
171
172 // find an entry
173 CHECK(o.find("foo") != o.end());
174 if (o.find("foo") != o.end())
175 {
176 // there is an entry with key "foo"
177 }
178 }
179
180 {
181 std::vector<int> c_vector {1, 2, 3, 4};
182 json j_vec(c_vector);
183 // [1, 2, 3, 4]
184
185 std::deque<float> c_deque {1.2f, 2.3f, 3.4f, 5.6f};
186 json j_deque(c_deque);
187 // [1.2, 2.3, 3.4, 5.6]
188
189 std::list<bool> c_list {true, true, false, true};
190 json j_list(c_list);
191 // [true, true, false, true]
192
193 std::forward_list<int64_t> c_flist {12345678909876, 23456789098765, 34567890987654, 45678909876543};
194 json j_flist(c_flist);
195 // [12345678909876, 23456789098765, 34567890987654, 45678909876543]
196
197 std::array<unsigned long, 4> c_array {{1, 2, 3, 4}};
198 json j_array(c_array);
199 // [1, 2, 3, 4]
200
201 std::set<std::string> c_set {"one", "two", "three", "four", "one"};
202 json j_set(c_set); // only one entry for "one" is used
203 // ["four", "one", "three", "two"]
204
205 std::unordered_set<std::string> c_uset {"one", "two", "three", "four", "one"};
206 json j_uset(c_uset); // only one entry for "one" is used
207 // maybe ["two", "three", "four", "one"]
208
209 std::multiset<std::string> c_mset {"one", "two", "one", "four"};
210 json j_mset(c_mset); // both entries for "one" are used
211 // maybe ["one", "two", "one", "four"]
212
213 std::unordered_multiset<std::string> c_umset {"one", "two", "one", "four"};
214 json j_umset(c_umset); // both entries for "one" are used
215 // maybe ["one", "two", "one", "four"]
216 }
217
218 {
219 std::map<std::string, int> c_map { {"one", 1}, {"two", 2}, {"three", 3} };
220 json j_map(c_map);
221 // {"one": 1, "two": 2, "three": 3}
222
223 std::unordered_map<const char*, float> c_umap { {"one", 1.2f}, {"two", 2.3f}, {"three", 3.4f} };
224 json j_umap(c_umap);
225 // {"one": 1.2, "two": 2.3, "three": 3.4}
226
227 std::multimap<std::string, bool> c_mmap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
228 json j_mmap(c_mmap); // only one entry for key "three" is used
229 // maybe {"one": true, "two": true, "three": true}
230
231 std::unordered_multimap<std::string, bool> c_ummap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
232 json j_ummap(c_ummap); // only one entry for key "three" is used
233 // maybe {"one": true, "two": true, "three": true}
234 }
235
236 {
237 // strings
238 std::string s1 = "Hello, world!";
239 json js = s1;
240 auto s2 = js.get<std::string>();
241
242 // Booleans
243 bool b1 = true;
244 json jb = b1;
245 bool b2{jb};
246 CHECK(b2 == true);
247
248 // numbers
249 int i = 42;
250 json jn = i;
251 double f{jn};
252 CHECK(f == 42);
253
254 // etc.
255
256 std::string vs = js.get<std::string>();
257 bool vb = jb.get<bool>();
258 CHECK(vb == true);
259 int vi = jn.get<int>();
260 CHECK(vi == 42);
261
262 // etc.
263 }
264
265 {
266 // a JSON value
267 json j_original = R"({
268 "baz": ["one", "two", "three"],
269 "foo": "bar"
270 })"_json;
271
272 // access members with a JSON pointer (RFC 6901)
273 j_original["/baz/1"_json_pointer];
274 // "two"
275
276 // a JSON patch (RFC 6902)
277 json j_patch = R"([
278 { "op": "replace", "path": "/baz", "value": "boo" },
279 { "op": "add", "path": "/hello", "value": ["world"] },
280 { "op": "remove", "path": "/foo"}
281 ])"_json;
282
283 // apply the patch
284 json j_result = j_original.patch(j_patch);
285 // {
286 // "baz": "boo",
287 // "hello": ["world"]
288 // }
289
290 // calculate a JSON patch from two JSON values
291 auto res = json::diff(j_result, j_original);
292 // [
293 // { "op":" replace", "path": "/baz", "value": ["one", "two", "three"] },
294 // { "op":"remove","path":"/hello" },
295 // { "op":"add","path":"/foo","value":"bar" }
296 // ]
297 }
298
299 // restore old std::cout
300 std::cout.rdbuf(old_cout_buffer);
301 }
302 }
303
304 DOCTEST_MSVC_SUPPRESS_WARNING_POP
305