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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_ | |
6 #define CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_ | |
7 | |
8 #include <map> | |
9 #include <string> | |
10 #include <vector> | |
11 | |
12 #include "base/basictypes.h" | |
13 #include "base/memory/scoped_ptr.h" | |
14 | |
15 namespace base { | |
16 class DictionaryValue; | |
17 class ListValue; | |
18 class StringValue; | |
19 class Value; | |
20 } | |
21 | |
22 //============================================================================== | |
23 // This class implements a subset of JSON Schema. | |
24 // See: http://www.json.com/json-schema-proposal/ for more details. | |
25 // | |
26 // There is also an older JavaScript implementation of the same functionality in | |
27 // chrome/renderer/resources/json_schema.js. | |
28 // | |
29 // The following features of JSON Schema are not implemented: | |
30 // - requires | |
31 // - unique | |
32 // - disallow | |
33 // - union types (but replaced with 'choices') | |
34 // - number.maxDecimal | |
35 // - string.pattern | |
36 // | |
37 // The following properties are not applicable to the interface exposed by | |
38 // this class: | |
39 // - options | |
40 // - readonly | |
41 // - title | |
42 // - description | |
43 // - format | |
44 // - default | |
45 // - transient | |
46 // - hidden | |
47 // | |
48 // There are also these departures from the JSON Schema proposal: | |
49 // - null counts as 'unspecified' for optional values | |
50 // - added the 'choices' property, to allow specifying a list of possible types | |
51 // for a value | |
52 // - by default an "object" typed schema does not allow additional properties. | |
53 // if present, "additionalProperties" is to be a schema against which all | |
54 // additional properties will be validated. | |
55 //============================================================================== | |
56 class JSONSchemaValidator { | |
57 public: | |
58 // Details about a validation error. | |
59 struct Error { | |
60 Error(); | |
61 | |
62 explicit Error(const std::string& message); | |
63 | |
64 Error(const std::string& path, const std::string& message); | |
65 | |
66 // The path to the location of the error in the JSON structure. | |
67 std::string path; | |
68 | |
69 // An english message describing the error. | |
70 std::string message; | |
71 }; | |
72 | |
73 // Error messages. | |
74 static const char kUnknownTypeReference[]; | |
75 static const char kInvalidChoice[]; | |
76 static const char kInvalidEnum[]; | |
77 static const char kObjectPropertyIsRequired[]; | |
78 static const char kUnexpectedProperty[]; | |
79 static const char kArrayMinItems[]; | |
80 static const char kArrayMaxItems[]; | |
81 static const char kArrayItemRequired[]; | |
82 static const char kStringMinLength[]; | |
83 static const char kStringMaxLength[]; | |
84 static const char kStringPattern[]; | |
85 static const char kNumberMinimum[]; | |
86 static const char kNumberMaximum[]; | |
87 static const char kInvalidType[]; | |
88 static const char kInvalidTypeIntegerNumber[]; | |
89 | |
90 // Classifies a Value as one of the JSON schema primitive types. | |
91 static std::string GetJSONSchemaType(const base::Value* value); | |
92 | |
93 // Utility methods to format error messages. The first method can have one | |
94 // wildcard represented by '*', which is replaced with s1. The second method | |
95 // can have two, which are replaced by s1 and s2. | |
96 static std::string FormatErrorMessage(const std::string& format, | |
97 const std::string& s1); | |
98 static std::string FormatErrorMessage(const std::string& format, | |
99 const std::string& s1, | |
100 const std::string& s2); | |
101 | |
102 // Verifies if |schema| is a valid JSON v3 schema. When this validation passes | |
103 // then |schema| is valid JSON that can be parsed into a DictionaryValue, | |
104 // and that DictionaryValue can be used to build a JSONSchemaValidator. | |
105 // Returns the parsed DictionaryValue when |schema| validated, otherwise | |
106 // returns NULL. In that case, |error| contains an error description. | |
107 static scoped_ptr<base::DictionaryValue> IsValidSchema( | |
108 const std::string& schema, | |
109 std::string* error); | |
110 | |
111 // Creates a validator for the specified schema. | |
112 // | |
113 // NOTE: This constructor assumes that |schema| is well formed and valid. | |
114 // Errors will result in CHECK at runtime; this constructor should not be used | |
115 // with untrusted schemas. | |
116 explicit JSONSchemaValidator(base::DictionaryValue* schema); | |
117 | |
118 // Creates a validator for the specified schema and user-defined types. Each | |
119 // type must be a valid JSONSchema type description with an additional "id" | |
120 // field. Schema objects in |schema| can refer to these types with the "$ref" | |
121 // property. | |
122 // | |
123 // NOTE: This constructor assumes that |schema| and |types| are well-formed | |
124 // and valid. Errors will result in CHECK at runtime; this constructor should | |
125 // not be used with untrusted schemas. | |
126 JSONSchemaValidator(base::DictionaryValue* schema, base::ListValue* types); | |
127 | |
128 ~JSONSchemaValidator(); | |
129 | |
130 // Whether the validator allows additional items for objects and lists, beyond | |
131 // those defined by their schema, by default. | |
132 // | |
133 // This setting defaults to false: all items in an instance list or object | |
134 // must be defined by the corresponding schema. | |
135 // | |
136 // This setting can be overridden on individual object and list schemas by | |
137 // setting the "additionalProperties" field. | |
138 bool default_allow_additional_properties() const { | |
139 return default_allow_additional_properties_; | |
140 } | |
141 | |
142 void set_default_allow_additional_properties(bool val) { | |
143 default_allow_additional_properties_ = val; | |
144 } | |
145 | |
146 // Returns any errors from the last call to to Validate(). | |
147 const std::vector<Error>& errors() const { | |
148 return errors_; | |
149 } | |
150 | |
151 // Validates a JSON value. Returns true if the instance is valid, false | |
152 // otherwise. If false is returned any errors are available from the errors() | |
153 // getter. | |
154 bool Validate(const base::Value* instance); | |
155 | |
156 private: | |
157 typedef std::map<std::string, const base::DictionaryValue*> TypeMap; | |
158 | |
159 // Each of the below methods handle a subset of the validation process. The | |
160 // path paramater is the path to |instance| from the root of the instance tree | |
161 // and is used in error messages. | |
162 | |
163 // Validates any instance node against any schema node. This is called for | |
164 // every node in the instance tree, and it just decides which of the more | |
165 // detailed methods to call. | |
166 void Validate(const base::Value* instance, | |
167 const base::DictionaryValue* schema, | |
168 const std::string& path); | |
169 | |
170 // Validates a node against a list of possible schemas. If any one of the | |
171 // schemas match, the node is valid. | |
172 void ValidateChoices(const base::Value* instance, | |
173 const base::ListValue* choices, | |
174 const std::string& path); | |
175 | |
176 // Validates a node against a list of exact primitive values, eg 42, "foobar". | |
177 void ValidateEnum(const base::Value* instance, | |
178 const base::ListValue* choices, | |
179 const std::string& path); | |
180 | |
181 // Validates a JSON object against an object schema node. | |
182 void ValidateObject(const base::DictionaryValue* instance, | |
183 const base::DictionaryValue* schema, | |
184 const std::string& path); | |
185 | |
186 // Validates a JSON array against an array schema node. | |
187 void ValidateArray(const base::ListValue* instance, | |
188 const base::DictionaryValue* schema, | |
189 const std::string& path); | |
190 | |
191 // Validates a JSON array against an array schema node configured to be a | |
192 // tuple. In a tuple, there is one schema node for each item expected in the | |
193 // array. | |
194 void ValidateTuple(const base::ListValue* instance, | |
195 const base::DictionaryValue* schema, | |
196 const std::string& path); | |
197 | |
198 // Validate a JSON string against a string schema node. | |
199 void ValidateString(const base::Value* instance, | |
200 const base::DictionaryValue* schema, | |
201 const std::string& path); | |
202 | |
203 // Validate a JSON number against a number schema node. | |
204 void ValidateNumber(const base::Value* instance, | |
205 const base::DictionaryValue* schema, | |
206 const std::string& path); | |
207 | |
208 // Validates that the JSON node |instance| has |expected_type|. | |
209 bool ValidateType(const base::Value* instance, | |
210 const std::string& expected_type, | |
211 const std::string& path); | |
212 | |
213 // Returns true if |schema| will allow additional items of any type. | |
214 bool SchemaAllowsAnyAdditionalItems( | |
215 const base::DictionaryValue* schema, | |
216 const base::DictionaryValue** addition_items_schema); | |
217 | |
218 // The root schema node. | |
219 base::DictionaryValue* schema_root_; | |
220 | |
221 // Map of user-defined name to type. | |
222 TypeMap types_; | |
223 | |
224 // Whether we allow additional properties on objects by default. This can be | |
225 // overridden by the allow_additional_properties flag on an Object schema. | |
226 bool default_allow_additional_properties_; | |
227 | |
228 // Errors accumulated since the last call to Validate(). | |
229 std::vector<Error> errors_; | |
230 | |
231 | |
232 DISALLOW_COPY_AND_ASSIGN(JSONSchemaValidator); | |
233 }; | |
234 | |
235 #endif // CHROME_COMMON_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_ | |
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