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
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
/*!
JSON Schema types.
*/

#[cfg(feature = "impl_json_schema")]
use crate as schemars;
#[cfg(feature = "impl_json_schema")]
use crate::JsonSchema;
use crate::{Map, Set};
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::ops::Deref;

/// A JSON Schema.
#[allow(clippy::large_enum_variant)]
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(untagged)]
pub enum Schema {
    /// A trivial boolean JSON Schema.
    ///
    /// The schema `true` matches everything (always passes validation), whereas the schema `false`
    /// matches nothing (always fails validation).
    Bool(bool),
    /// A JSON Schema object.
    Object(SchemaObject),
}

impl Schema {
    /// Creates a new `$ref` schema.
    ///
    /// The given reference string should be a URI reference. This will usually be a JSON Pointer
    /// in [URI Fragment representation](https://tools.ietf.org/html/rfc6901#section-6).
    pub fn new_ref(reference: String) -> Self {
        SchemaObject::new_ref(reference).into()
    }

    /// Returns `true` if `self` is a `$ref` schema.
    ///
    /// If `self` is a [`SchemaObject`] with `Some` [`reference`](struct.SchemaObject.html#structfield.reference) set, this returns `true`.
    /// Otherwise, returns `false`.
    pub fn is_ref(&self) -> bool {
        match self {
            Schema::Object(o) => o.is_ref(),
            _ => false,
        }
    }

    /// Converts the given schema (if it is a boolean schema) into an equivalent schema object.
    ///
    /// If the given schema is already a schema object, this has no effect.
    ///
    /// # Example
    /// ```
    /// use schemars::schema::{Schema, SchemaObject};
    ///
    /// let bool_schema = Schema::Bool(true);
    ///
    /// assert_eq!(bool_schema.into_object(), SchemaObject::default());
    /// ```
    pub fn into_object(self) -> SchemaObject {
        match self {
            Schema::Object(o) => o,
            Schema::Bool(true) => SchemaObject::default(),
            Schema::Bool(false) => SchemaObject {
                subschemas: Some(Box::new(SubschemaValidation {
                    not: Some(Schema::Object(Default::default()).into()),
                    ..Default::default()
                })),
                ..Default::default()
            },
        }
    }
}

impl From<SchemaObject> for Schema {
    fn from(o: SchemaObject) -> Self {
        Schema::Object(o)
    }
}

impl From<bool> for Schema {
    fn from(b: bool) -> Self {
        Schema::Bool(b)
    }
}

/// The root object of a JSON Schema document.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct RootSchema {
    /// The `$schema` keyword.
    ///
    /// See [JSON Schema 8.1.1. The "$schema" Keyword](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.1.1).
    #[serde(rename = "$schema", skip_serializing_if = "Option::is_none")]
    pub meta_schema: Option<String>,
    /// The root schema itself.
    #[serde(flatten)]
    pub schema: SchemaObject,
    /// The `definitions` keyword.
    ///
    /// In JSON Schema draft 2019-09 this was replaced by $defs, but in Schemars this is still
    /// serialized as `definitions` for backward-compatibility.
    ///
    /// See [JSON Schema 8.2.5. Schema Re-Use With "$defs"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.2.5),
    /// and [JSON Schema (draft 07) 9. Schema Re-Use With "definitions"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-01#section-9).
    #[serde(alias = "$defs", skip_serializing_if = "Map::is_empty")]
    pub definitions: Map<String, Schema>,
}

/// A JSON Schema object.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct SchemaObject {
    /// Properties which annotate the [`SchemaObject`] which typically have no effect when an object is being validated against the schema.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub metadata: Option<Box<Metadata>>,
    /// The `type` keyword.
    ///
    /// See [JSON Schema Validation 6.1.1. "type"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.1.1)
    /// and [JSON Schema 4.2.1. Instance Data Model](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-4.2.1).
    #[serde(rename = "type", skip_serializing_if = "Option::is_none")]
    pub instance_type: Option<SingleOrVec<InstanceType>>,
    /// The `format` keyword.
    ///
    /// See [JSON Schema Validation 7. A Vocabulary for Semantic Content With "format"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-7).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub format: Option<String>,
    /// The `enum` keyword.
    ///
    /// See [JSON Schema Validation 6.1.2. "enum"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.1.2)
    #[serde(rename = "enum", skip_serializing_if = "Option::is_none")]
    pub enum_values: Option<Vec<Value>>,
    /// The `const` keyword.
    ///
    /// See [JSON Schema Validation 6.1.3. "const"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.1.3)
    #[serde(
        rename = "const",
        skip_serializing_if = "Option::is_none",
        deserialize_with = "allow_null"
    )]
    pub const_value: Option<Value>,
    /// Properties of the [`SchemaObject`] which define validation assertions in terms of other schemas.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub subschemas: Option<Box<SubschemaValidation>>,
    /// Properties of the [`SchemaObject`] which define validation assertions for numbers.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub number: Option<Box<NumberValidation>>,
    /// Properties of the [`SchemaObject`] which define validation assertions for strings.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub string: Option<Box<StringValidation>>,
    /// Properties of the [`SchemaObject`] which define validation assertions for arrays.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub array: Option<Box<ArrayValidation>>,
    /// Properties of the [`SchemaObject`] which define validation assertions for objects.
    #[serde(flatten, deserialize_with = "skip_if_default")]
    pub object: Option<Box<ObjectValidation>>,
    /// The `$ref` keyword.
    ///
    /// See [JSON Schema 8.2.4.1. Direct References with "$ref"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.2.4.1).
    #[serde(rename = "$ref", skip_serializing_if = "Option::is_none")]
    pub reference: Option<String>,
    /// Arbitrary extra properties which are not part of the JSON Schema specification, or which `schemars` does not support.
    #[serde(flatten)]
    pub extensions: Map<String, Value>,
}

// Deserializing "null" to `Option<Value>` directly results in `None`,
// this function instead makes it deserialize to `Some(Value::Null)`.
fn allow_null<'de, D>(de: D) -> Result<Option<Value>, D::Error>
where
    D: serde::Deserializer<'de>,
{
    Value::deserialize(de).map(Option::Some)
}

fn skip_if_default<'de, D, T>(deserializer: D) -> Result<Option<Box<T>>, D::Error>
where
    D: serde::Deserializer<'de>,
    T: Deserialize<'de> + Default + PartialEq,
{
    let value = T::deserialize(deserializer)?;
    if value == T::default() {
        Ok(None)
    } else {
        Ok(Some(Box::new(value)))
    }
}

macro_rules! get_or_insert_default_fn {
    ($name:ident, $ret:ty) => {
        get_or_insert_default_fn!(
            concat!(
                "Returns a mutable reference to this schema's [`",
                stringify!($ret),
                "`](#structfield.",
                stringify!($name),
                "), creating it if it was `None`."
            ),
            $name,
            $ret
        );
    };
    ($doc:expr, $name:ident, $ret:ty) => {
        #[doc = $doc]
        pub fn $name(&mut self) -> &mut $ret {
            self.$name.get_or_insert_with(Default::default)
        }
    };
}

impl SchemaObject {
    /// Creates a new `$ref` schema.
    ///
    /// The given reference string should be a URI reference. This will usually be a JSON Pointer
    /// in [URI Fragment representation](https://tools.ietf.org/html/rfc6901#section-6).
    pub fn new_ref(reference: String) -> Self {
        SchemaObject {
            reference: Some(reference),
            ..Default::default()
        }
    }

    /// Returns `true` if `self` is a `$ref` schema.
    ///
    /// If `self` has `Some` [`reference`](struct.SchemaObject.html#structfield.reference) set, this returns `true`.
    /// Otherwise, returns `false`.
    pub fn is_ref(&self) -> bool {
        self.reference.is_some()
    }

    /// Returns `true` if `self` accepts values of the given type, according to the [`instance_type`](struct.SchemaObject.html#structfield.instance_type) field.
    ///
    /// This is a basic check that always returns `true` if no `instance_type` is specified on the schema,
    /// and does not check any subschemas. Because of this, both `{}` and  `{"not": {}}` accept any type according
    /// to this method.
    pub fn has_type(&self, ty: InstanceType) -> bool {
        self.instance_type
            .as_ref()
            .map_or(true, |x| x.contains(&ty))
    }

    get_or_insert_default_fn!(metadata, Metadata);
    get_or_insert_default_fn!(subschemas, SubschemaValidation);
    get_or_insert_default_fn!(number, NumberValidation);
    get_or_insert_default_fn!(string, StringValidation);
    get_or_insert_default_fn!(array, ArrayValidation);
    get_or_insert_default_fn!(object, ObjectValidation);
}

impl From<Schema> for SchemaObject {
    fn from(schema: Schema) -> Self {
        schema.into_object()
    }
}

/// Properties which annotate a [`SchemaObject`] which typically have no effect when an object is being validated against the schema.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct Metadata {
    /// The `$id` keyword.
    ///
    /// See [JSON Schema 8.2.2. The "$id" Keyword](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-8.2.2).
    #[serde(rename = "$id", skip_serializing_if = "Option::is_none")]
    pub id: Option<String>,
    /// The `title` keyword.
    ///
    /// See [JSON Schema Validation 9.1. "title" and "description"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub title: Option<String>,
    /// The `description` keyword.
    ///
    /// See [JSON Schema Validation 9.1. "title" and "description"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub description: Option<String>,
    /// The `default` keyword.
    ///
    /// See [JSON Schema Validation 9.2. "default"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.2).
    #[serde(
        skip_serializing_if = "Option::is_none",
        deserialize_with = "allow_null"
    )]
    pub default: Option<Value>,
    /// The `deprecated` keyword.
    ///
    /// See [JSON Schema Validation 9.3. "deprecated"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.3).
    #[serde(skip_serializing_if = "is_false")]
    pub deprecated: bool,
    /// The `readOnly` keyword.
    ///
    /// See [JSON Schema Validation 9.4. "readOnly" and "writeOnly"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).
    #[serde(skip_serializing_if = "is_false")]
    pub read_only: bool,
    /// The `writeOnly` keyword.
    ///
    /// See [JSON Schema Validation 9.4. "readOnly" and "writeOnly"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.4).
    #[serde(skip_serializing_if = "is_false")]
    pub write_only: bool,
    /// The `examples` keyword.
    ///
    /// See [JSON Schema Validation 9.5. "examples"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-9.5).
    #[serde(skip_serializing_if = "Vec::is_empty")]
    pub examples: Vec<Value>,
}

#[allow(clippy::trivially_copy_pass_by_ref)]
fn is_false(b: &bool) -> bool {
    !b
}

/// Properties of a [`SchemaObject`] which define validation assertions in terms of other schemas.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct SubschemaValidation {
    /// The `allOf` keyword.
    ///
    /// See [JSON Schema 9.2.1.1. "allOf"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.1.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub all_of: Option<Vec<Schema>>,
    /// The `anyOf` keyword.
    ///
    /// See [JSON Schema 9.2.1.2. "anyOf"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.1.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub any_of: Option<Vec<Schema>>,
    /// The `oneOf` keyword.
    ///
    /// See [JSON Schema 9.2.1.3. "oneOf"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.1.3).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub one_of: Option<Vec<Schema>>,
    /// The `not` keyword.
    ///
    /// See [JSON Schema 9.2.1.4. "not"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.1.4).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub not: Option<Box<Schema>>,
    /// The `if` keyword.
    ///
    /// See [JSON Schema 9.2.2.1. "if"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.2.1).
    #[serde(rename = "if", skip_serializing_if = "Option::is_none")]
    pub if_schema: Option<Box<Schema>>,
    /// The `then` keyword.
    ///
    /// See [JSON Schema 9.2.2.2. "then"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.2.2).
    #[serde(rename = "then", skip_serializing_if = "Option::is_none")]
    pub then_schema: Option<Box<Schema>>,
    /// The `else` keyword.
    ///
    /// See [JSON Schema 9.2.2.3. "else"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.2.2.3).
    #[serde(rename = "else", skip_serializing_if = "Option::is_none")]
    pub else_schema: Option<Box<Schema>>,
}

/// Properties of a [`SchemaObject`] which define validation assertions for numbers.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct NumberValidation {
    /// The `multipleOf` keyword.
    ///
    /// See [JSON Schema Validation 6.2.1. "multipleOf"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.2.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub multiple_of: Option<f64>,
    /// The `maximum` keyword.
    ///
    /// See [JSON Schema Validation 6.2.2. "maximum"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.2.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub maximum: Option<f64>,
    /// The `exclusiveMaximum` keyword.
    ///
    /// See [JSON Schema Validation 6.2.3. "exclusiveMaximum"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.2.3).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub exclusive_maximum: Option<f64>,
    /// The `minimum` keyword.
    ///
    /// See [JSON Schema Validation 6.2.4. "minimum"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.2.4).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub minimum: Option<f64>,
    /// The `exclusiveMinimum` keyword.
    ///
    /// See [JSON Schema Validation 6.2.5. "exclusiveMinimum"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.2.5).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub exclusive_minimum: Option<f64>,
}

/// Properties of a [`SchemaObject`] which define validation assertions for strings.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct StringValidation {
    /// The `maxLength` keyword.
    ///
    /// See [JSON Schema Validation 6.3.1. "maxLength"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.3.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_length: Option<u32>,
    /// The `minLength` keyword.
    ///
    /// See [JSON Schema Validation 6.3.2. "minLength"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.3.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub min_length: Option<u32>,
    /// The `pattern` keyword.
    ///
    /// See [JSON Schema Validation 6.3.3. "pattern"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.3.3).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub pattern: Option<String>,
}

/// Properties of a [`SchemaObject`] which define validation assertions for arrays.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct ArrayValidation {
    /// The `items` keyword.
    ///
    /// See [JSON Schema 9.3.1.1. "items"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.1.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub items: Option<SingleOrVec<Schema>>,
    /// The `additionalItems` keyword.
    ///
    /// See [JSON Schema 9.3.1.2. "additionalItems"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.1.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub additional_items: Option<Box<Schema>>,
    /// The `maxItems` keyword.
    ///
    /// See [JSON Schema Validation 6.4.1. "maxItems"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.4.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_items: Option<u32>,
    /// The `minItems` keyword.
    ///
    /// See [JSON Schema Validation 6.4.2. "minItems"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.4.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub min_items: Option<u32>,
    /// The `uniqueItems` keyword.
    ///
    /// See [JSON Schema Validation 6.4.3. "uniqueItems"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.4.3).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub unique_items: Option<bool>,
    /// The `contains` keyword.
    ///
    /// See [JSON Schema 9.3.1.4. "contains"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.1.4).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub contains: Option<Box<Schema>>,
}

/// Properties of a [`SchemaObject`] which define validation assertions for objects.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase", default)]
pub struct ObjectValidation {
    /// The `maxProperties` keyword.
    ///
    /// See [JSON Schema Validation 6.5.1. "maxProperties"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.1).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_properties: Option<u32>,
    /// The `minProperties` keyword.
    ///
    /// See [JSON Schema Validation 6.5.2. "minProperties"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.2).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub min_properties: Option<u32>,
    /// The `required` keyword.
    ///
    /// See [JSON Schema Validation 6.5.3. "required"](https://tools.ietf.org/html/draft-handrews-json-schema-validation-02#section-6.5.3).
    #[serde(skip_serializing_if = "Set::is_empty")]
    pub required: Set<String>,
    /// The `properties` keyword.
    ///
    /// See [JSON Schema 9.3.2.1. "properties"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.1).
    #[serde(skip_serializing_if = "Map::is_empty")]
    pub properties: Map<String, Schema>,
    /// The `patternProperties` keyword.
    ///
    /// See [JSON Schema 9.3.2.2. "patternProperties"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.2).
    #[serde(skip_serializing_if = "Map::is_empty")]
    pub pattern_properties: Map<String, Schema>,
    /// The `additionalProperties` keyword.
    ///
    /// See [JSON Schema 9.3.2.3. "additionalProperties"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.3).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub additional_properties: Option<Box<Schema>>,
    /// The `propertyNames` keyword.
    ///
    /// See [JSON Schema 9.3.2.5. "propertyNames"](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-9.3.2.5).
    #[serde(skip_serializing_if = "Option::is_none")]
    pub property_names: Option<Box<Schema>>,
}

/// The possible types of values in JSON Schema documents.
///
/// See [JSON Schema 4.2.1. Instance Data Model](https://tools.ietf.org/html/draft-handrews-json-schema-02#section-4.2.1).
#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(rename_all = "camelCase")]
pub enum InstanceType {
    Null,
    Boolean,
    Object,
    Array,
    Number,
    String,
    Integer,
}

/// A type which can be serialized as a single item, or multiple items.
///
/// In some contexts, a `Single` may be semantically distinct from a `Vec` containing only item.
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
#[cfg_attr(feature = "impl_json_schema", derive(JsonSchema))]
#[serde(untagged)]
pub enum SingleOrVec<T> {
    Single(Box<T>),
    Vec(Vec<T>),
}

impl<T> From<T> for SingleOrVec<T> {
    fn from(single: T) -> Self {
        SingleOrVec::Single(Box::new(single))
    }
}

impl<T> From<Vec<T>> for SingleOrVec<T> {
    fn from(vec: Vec<T>) -> Self {
        SingleOrVec::Vec(vec)
    }
}

impl<T: PartialEq> SingleOrVec<T> {
    /// Returns `true` if `self` is either a `Single` equal to `x`, or a `Vec` containing `x`.
    ///
    /// # Examples
    ///
    /// ```
    /// use schemars::schema::SingleOrVec;
    ///
    /// let s = SingleOrVec::from(10);
    /// assert!(s.contains(&10));
    /// assert!(!s.contains(&20));
    ///
    /// let v = SingleOrVec::from(vec![10, 20]);
    /// assert!(v.contains(&10));
    /// assert!(v.contains(&20));
    /// assert!(!v.contains(&30));
    /// ```
    pub fn contains(&self, x: &T) -> bool {
        match self {
            SingleOrVec::Single(s) => s.deref() == x,
            SingleOrVec::Vec(v) => v.contains(x),
        }
    }
}