252 lines
		
	
	
		
			9.5 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			252 lines
		
	
	
		
			9.5 KiB
		
	
	
	
		
			C++
		
	
	
	
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef COMPONENTS_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_
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#define COMPONENTS_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_
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#include <map>
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#include <memory>
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#include <string>
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#include <vector>
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#include "base/macros.h"
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namespace base {
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class DictionaryValue;
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class ListValue;
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class Value;
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}
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//==============================================================================
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// This class implements a subset of JSON Schema.
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// See: http://www.json.com/json-schema-proposal/ for more details.
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//
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// There is also an older JavaScript implementation of the same functionality in
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// chrome/renderer/resources/json_schema.js.
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//
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// The following features of JSON Schema are not implemented:
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// - requires
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// - unique
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// - disallow
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// - union types (but replaced with 'choices')
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// - number.maxDecimal
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//
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// The following properties are not applicable to the interface exposed by
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// this class:
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// - options
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// - readonly
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// - title
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// - description
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// - format
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// - default
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// - transient
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// - hidden
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//
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// There are also these departures from the JSON Schema proposal:
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// - null counts as 'unspecified' for optional values
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// - added the 'choices' property, to allow specifying a list of possible types
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//   for a value
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// - by default an "object" typed schema does not allow additional properties.
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//   if present, "additionalProperties" is to be a schema against which all
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//   additional properties will be validated.
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// - regular expression supports all syntaxes that re2 accepts.
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//   See https://github.com/google/re2/blob/master/doc/syntax.txt for details.
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//==============================================================================
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class JSONSchemaValidator {
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 public:
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  // Details about a validation error.
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  struct Error {
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    Error();
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    explicit Error(const std::string& message);
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    Error(const std::string& path, const std::string& message);
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    // The path to the location of the error in the JSON structure.
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    std::string path;
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    // An english message describing the error.
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    std::string message;
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  };
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  enum Options {
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    // Ignore unknown attributes. If this option is not set then unknown
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    // attributes will make the schema validation fail.
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    OPTIONS_IGNORE_UNKNOWN_ATTRIBUTES = 1 << 0,
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  };
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  // Error messages.
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  static const char kUnknownTypeReference[];
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  static const char kInvalidChoice[];
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  static const char kInvalidEnum[];
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  static const char kObjectPropertyIsRequired[];
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  static const char kUnexpectedProperty[];
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  static const char kArrayMinItems[];
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  static const char kArrayMaxItems[];
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  static const char kArrayItemRequired[];
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  static const char kStringMinLength[];
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  static const char kStringMaxLength[];
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  static const char kStringPattern[];
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  static const char kNumberMinimum[];
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  static const char kNumberMaximum[];
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  static const char kInvalidType[];
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  static const char kInvalidTypeIntegerNumber[];
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  static const char kInvalidRegex[];
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  // Classifies a Value as one of the JSON schema primitive types.
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  static std::string GetJSONSchemaType(const base::Value* value);
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  // Utility methods to format error messages. The first method can have one
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  // wildcard represented by '*', which is replaced with s1. The second method
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  // can have two, which are replaced by s1 and s2.
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  static std::string FormatErrorMessage(const std::string& format,
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                                        const std::string& s1);
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  static std::string FormatErrorMessage(const std::string& format,
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                                        const std::string& s1,
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                                        const std::string& s2);
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  // Verifies if |schema| is a valid JSON v3 schema. When this validation passes
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  // then |schema| is valid JSON that can be parsed into a DictionaryValue,
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  // and that DictionaryValue can be used to build a JSONSchemaValidator.
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  // Returns the parsed DictionaryValue when |schema| validated, otherwise
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  // returns NULL. In that case, |error| contains an error description.
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  // For performance reasons, currently IsValidSchema() won't check the
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  // correctness of regular expressions used in "pattern" and
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  // "patternProperties" and in Validate() invalid regular expression don't
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  // accept any strings.
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  static std::unique_ptr<base::DictionaryValue> IsValidSchema(
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      const std::string& schema,
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      std::string* error);
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  // Same as above but with |options|, which is a bitwise-OR combination of the
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  // Options above.
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  static std::unique_ptr<base::DictionaryValue>
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  IsValidSchema(const std::string& schema, int options, std::string* error);
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  // Creates a validator for the specified schema.
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  //
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  // NOTE: This constructor assumes that |schema| is well formed and valid.
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  // Errors will result in CHECK at runtime; this constructor should not be used
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  // with untrusted schemas.
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  explicit JSONSchemaValidator(base::DictionaryValue* schema);
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  // Creates a validator for the specified schema and user-defined types. Each
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  // type must be a valid JSONSchema type description with an additional "id"
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  // field. Schema objects in |schema| can refer to these types with the "$ref"
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  // property.
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  //
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  // NOTE: This constructor assumes that |schema| and |types| are well-formed
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  // and valid. Errors will result in CHECK at runtime; this constructor should
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  // not be used with untrusted schemas.
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  JSONSchemaValidator(base::DictionaryValue* schema, base::ListValue* types);
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  ~JSONSchemaValidator();
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  // Whether the validator allows additional items for objects and lists, beyond
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  // those defined by their schema, by default.
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  //
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  // This setting defaults to false: all items in an instance list or object
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  // must be defined by the corresponding schema.
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  //
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  // This setting can be overridden on individual object and list schemas by
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  // setting the "additionalProperties" field.
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  bool default_allow_additional_properties() const {
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    return default_allow_additional_properties_;
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  }
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  void set_default_allow_additional_properties(bool val) {
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    default_allow_additional_properties_ = val;
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  }
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  // Returns any errors from the last call to to Validate().
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  const std::vector<Error>& errors() const {
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    return errors_;
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  }
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  // Validates a JSON value. Returns true if the instance is valid, false
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  // otherwise. If false is returned any errors are available from the errors()
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  // getter.
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  bool Validate(const base::Value* instance);
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 private:
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  typedef std::map<std::string, const base::DictionaryValue*> TypeMap;
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  // Each of the below methods handle a subset of the validation process. The
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  // path paramater is the path to |instance| from the root of the instance tree
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  // and is used in error messages.
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  // Validates any instance node against any schema node. This is called for
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  // every node in the instance tree, and it just decides which of the more
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  // detailed methods to call.
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  void Validate(const base::Value* instance,
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                const base::DictionaryValue* schema,
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                const std::string& path);
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  // Validates a node against a list of possible schemas. If any one of the
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  // schemas match, the node is valid.
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  void ValidateChoices(const base::Value* instance,
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                       const base::ListValue* choices,
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                       const std::string& path);
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  // Validates a node against a list of exact primitive values, eg 42, "foobar".
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  void ValidateEnum(const base::Value* instance,
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                    const base::ListValue* choices,
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                    const std::string& path);
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  // Validates a JSON object against an object schema node.
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  void ValidateObject(const base::DictionaryValue* instance,
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                      const base::DictionaryValue* schema,
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                      const std::string& path);
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  // Validates a JSON array against an array schema node.
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  void ValidateArray(const base::ListValue* instance,
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                     const base::DictionaryValue* schema,
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                     const std::string& path);
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  // Validates a JSON array against an array schema node configured to be a
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  // tuple. In a tuple, there is one schema node for each item expected in the
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  // array.
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  void ValidateTuple(const base::ListValue* instance,
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                     const base::DictionaryValue* schema,
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                     const std::string& path);
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  // Validate a JSON string against a string schema node.
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  void ValidateString(const base::Value* instance,
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                      const base::DictionaryValue* schema,
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                      const std::string& path);
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  // Validate a JSON number against a number schema node.
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  void ValidateNumber(const base::Value* instance,
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                      const base::DictionaryValue* schema,
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                      const std::string& path);
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  // Validates that the JSON node |instance| has |expected_type|.
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  bool ValidateType(const base::Value* instance,
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                    const std::string& expected_type,
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                    const std::string& path);
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  // Returns true if |schema| will allow additional items of any type.
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  bool SchemaAllowsAnyAdditionalItems(
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      const base::DictionaryValue* schema,
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      const base::DictionaryValue** addition_items_schema);
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  // The root schema node.
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  base::DictionaryValue* schema_root_;
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  // Map of user-defined name to type.
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  TypeMap types_;
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  // Whether we allow additional properties on objects by default. This can be
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  // overridden by the allow_additional_properties flag on an Object schema.
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  bool default_allow_additional_properties_;
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  // Errors accumulated since the last call to Validate().
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  std::vector<Error> errors_;
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  DISALLOW_COPY_AND_ASSIGN(JSONSchemaValidator);
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};
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#endif  // COMPONENTS_JSON_SCHEMA_JSON_SCHEMA_VALIDATOR_H_
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