1 /*
2  * Copyright (c) Facebook, Inc. and its affiliates.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 #include <folly/ExceptionWrapper.h>
20 #include <folly/Range.h>
21 #include <folly/dynamic.h>
22 
23 /**
24  * Validation according to the draft v4 standard: http://json-schema.org/
25  *
26  * If your schema is invalid, then it won't validate anything. For example, if
27  * you set "type": "invalid_type" in your schema, then it won't check for any
28  * type, as if you had left that property out. If you want to make sure your
29  * schema is valid, you can optionally validate it first according to the
30  * metaschema.
31  *
32  * Limitations:
33  * - We don't support fetching schemas via HTTP.
34  * - We don't support remote $refs.
35  * - We don't support $ref via id (only by path).
36  * - We don't support UTF-8 for string lengths, i.e. we will count bytes for
37  *   schemas that use minLength/maxLength.
38  */
39 
40 namespace folly {
41 namespace jsonschema {
42 
43 /**
44  * Interface for a schema validator.
45  */
46 struct Validator {
47   virtual ~Validator() = 0;
48 
49   /**
50    * Check whether the given value passes the schema. Throws if it fails.
51    */
52   virtual void validate(const dynamic& value) const = 0;
53 
54   /**
55    * Check whether the given value passes the schema. Returns an
56    * exception_wrapper indicating success or what the failure was.
57    */
58   virtual exception_wrapper try_validate(
59       const dynamic& value) const noexcept = 0;
60 };
61 
62 /**
63  * Make a validator that can be used to check various json. Thread-safe.
64  */
65 std::unique_ptr<Validator> makeValidator(const dynamic& schema);
66 
67 /**
68  * Makes a validator for schemas. You should probably check your schema with
69  * this before you use makeValidator().
70  */
71 std::shared_ptr<Validator> makeSchemaValidator();
72 } // namespace jsonschema
73 } // namespace folly
74