File: doc_quick_look.cpp

package info (click to toggle)
boost1.90 1.90.0-1
  • links: PTS, VCS
  • area: main
  • in suites:
  • size: 593,120 kB
  • sloc: cpp: 4,190,908; xml: 196,648; python: 34,618; ansic: 23,145; asm: 5,468; sh: 3,774; makefile: 1,161; perl: 1,020; sql: 728; ruby: 676; yacc: 478; java: 77; lisp: 24; csh: 6
file content (335 lines) | stat: -rw-r--r-- 9,212 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
//
// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/json
//

#include <boost/json.hpp>
#include <boost/container/pmr/vector.hpp>
#include <iostream>

#include "test_suite.hpp"

namespace boost {
namespace json {

static void set1() {

//----------------------------------------------------------
{
// tag::doc_quick_look_1[]
object obj;                                                     // construct an empty object
obj[ "pi" ] = 3.141;                                            // insert a double
obj[ "happy" ] = true;                                          // insert a bool
obj[ "name" ] = "Boost";                                        // insert a string
obj[ "nothing" ] = nullptr;                                     // insert a null
obj[ "answer" ].emplace_object()["everything"] = 42;            // insert an object with 1 element
obj[ "list" ] = { 1, 0, 2 };                                    // insert an array with 3 elements
obj[ "object" ] = { {"currency", "USD"}, {"value", 42.99} };    // insert an object with 2 elements
// end::doc_quick_look_1[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_2[]
value jv = {
    { "pi", 3.141 },
    { "happy", true },
    { "name", "Boost" },
    { "nothing", nullptr },
    { "answer", {
        { "everything", 42 } } },
    {"list", {1, 0, 2}},
    {"object", {
        { "currency", "USD" },
        { "value", 42.99 }
            } }
    };
// end::doc_quick_look_2[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_3[]
array arr;                                          // construct an empty array
arr = { 1, 2, 3 };                                  // replace the contents with 3 elements
value jv1( arr );                                   // this makes a copy of the array
value jv2( std::move(arr) );                        // this performs a move-construction

assert( arr.empty() );                              // moved-from arrays become empty
arr = { nullptr, true, "boost" };                   // fill in the array again
// end::doc_quick_look_3[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_4[]
{
    unsigned char buf[ 4096 ];                      // storage for our array
    static_resource mr( buf );                      // memory resource which uses buf
    array arr( &mr );                               // construct using the memory resource
    arr = { 1, 2, 3 };                              // all allocated memory comes from `buf`
}
// end::doc_quick_look_4[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_5[]
{
    monotonic_resource mr;                          // memory resource optimized for insertion
    array arr( &mr );                               // construct using the memory resource
    arr.resize( 1 );                                // make space for one element
    arr[ 0 ] = { 1, 2, 3 };                         // assign an array to element 0
    assert( *arr[0].storage() == *arr.storage() );  // same memory resource
}
// end::doc_quick_look_5[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_6[]
{
    monotonic_resource mr;
    boost::container::pmr::vector< value > vv( &mr );
    vv.resize( 3 );

    // The memory resource of the container is propagated to each element
    assert( *vv.get_allocator().resource() == *vv[0].storage() );
    assert( *vv.get_allocator().resource() == *vv[1].storage() );
    assert( *vv.get_allocator().resource() == *vv[2].storage() );
}
// end::doc_quick_look_6[]
}
//----------------------------------------------------------

} // set1()

//----------------------------------------------------------

// tag::doc_quick_look_7[]
value f()
{
    // create a reference-counted memory resource
    storage_ptr sp = make_shared_resource< monotonic_resource >();

    // construct with shared ownership of the resource
    value jv( sp );

    // assign an array with 3 elements, the monotonic resource will be used
    jv = { 1, 2, 3 };

    // The caller receives the value, which still owns the resource
    return jv;
}
// end::doc_quick_look_7[]
//----------------------------------------------------------

static void set2() {

//----------------------------------------------------------
{
// tag::doc_quick_look_8[]
value jv = parse( "[1, 2, 3]" );
// end::doc_quick_look_8[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_9[]
boost::system::error_code ec;
value jv = parse( R"( "Hello, world!" )", ec );
// end::doc_quick_look_9[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_10[]
unsigned char buf[ 4096 ];
static_resource mr( buf );
parse_options opt;
opt.allow_comments = true;
opt.allow_trailing_commas = true;
value jv = parse( "[1, 2, 3, ] // array ", &mr, opt );
// end::doc_quick_look_10[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_11[]
stream_parser p;
boost::system::error_code ec;
p.reset();
p.write( "[1, 2 ", ec );
if( ! ec )
    p.write( ", 3]", ec );
if( ! ec )
    p.finish( ec );
if( ec )
    return;
value jv = p.release();
// end::doc_quick_look_11[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_12[]
value jv = { 1, 2, 3 };
std::string s = serialize( jv );                // produces "[1,2,3]"
// end::doc_quick_look_12[]
}
//----------------------------------------------------------
{
value jv;
// tag::doc_quick_look_13[]
serializer sr;
sr.reset( &jv );                                // prepare to output `jv`
do
{
    char buf[ 16 ];
    std::cout << sr.read( buf );
}
while( ! sr.done() );
// end::doc_quick_look_13[]
}
//----------------------------------------------------------

} // set2()

//----------------------------------------------------------

// tag::doc_quick_look_14[]
namespace my_app {

struct customer
{
    int id;
    std::string name;
    bool current;
};

} // namespace my_app
// end::doc_quick_look_14[]

//----------------------------------------------------------

// tag::doc_quick_look_15[]
namespace my_app {

void tag_invoke( value_from_tag, value& jv, customer const& c )
{
    jv = {
        { "id" , c.id },
        { "name", c.name },
        { "current", c.current }
    };
}

} // namespace my_app
// end::doc_quick_look_15[]

static void set3() {

//----------------------------------------------------------
{
// tag::doc_quick_look_16[]
my_app::customer c{ 1001, "Boost", true };
std::cout << serialize( value_from( c ) );
// end::doc_quick_look_16[]
}
//----------------------------------------------------------
{
// tag::doc_quick_look_17[]
std::vector< my_app::customer > vc;
//...
value jv = value_from( vc );
// end::doc_quick_look_17[]
}
//----------------------------------------------------------

} // set3()

//----------------------------------------------------------

// tag::doc_quick_look_18[]
namespace my_app {

// This helper function deduces the type and assigns the value with the matching key
template<class T>
void extract( object const& obj, T& t, string_view key )
{
    t = value_to<T>( obj.at( key ) );
}

customer tag_invoke( value_to_tag< customer >, value const& jv )
{
    customer c;
    object const& obj = jv.as_object();
    extract( obj, c.id, "id" );
    extract( obj, c.name, "name" );
    extract( obj, c.current, "current" );
    return c;
}

} // namespace my_app
// end::doc_quick_look_18[]

//----------------------------------------------------------

namespace my_app_2 {
namespace my_app { using boost::json::my_app::customer; }
// tag::doc_quick_look_19[]
namespace my_app {

customer tag_invoke( value_to_tag< customer >, value const& jv )
{
    object const& obj = jv.as_object();
    return customer {
        value_to<int>( obj.at( "id" ) ),
        value_to<std::string>( obj.at( "name" ) ),
        value_to<bool>( obj.at( "current" ) )
    };
}

} // namespace my_app
// end::doc_quick_look_19[]
} // my_app_2

//----------------------------------------------------------

static void set4() {
using namespace my_app;

//----------------------------------------------------------
{
// tag::doc_quick_look_20[]
json::value jv;
//...
customer c( value_to<customer>(jv) );
// end::doc_quick_look_20[]
}
//----------------------------------------------------------
{
json::value jv;
// tag::doc_quick_look_21[]
std::vector< customer > vc = value_to< std::vector< customer > >( jv );
// end::doc_quick_look_21[]
}
//----------------------------------------------------------

//----------------------------------------------------------

} // set4

class doc_quick_look_test
{
public:
    void
    run()
    {
        (void)&set1;
        (void)&set2;
        (void)&set3;
        (void)&set4;
        BOOST_TEST_PASS();
    }
};

TEST_SUITE(doc_quick_look_test, "boost.json.doc_quick_look");

} // namespace json
} // namespace boost