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