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- // Copyright (c) 2012 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_PREFS_PREF_REGISTRY_H_
- #define COMPONENTS_PREFS_PREF_REGISTRY_H_
- #include <stdint.h>
- #include <set>
- #include <unordered_map>
- #include "base/memory/ref_counted.h"
- #include "components/prefs/pref_value_map.h"
- #include "components/prefs/prefs_export.h"
- namespace base {
- class Value;
- }
- class DefaultPrefStore;
- class PrefStore;
- // Preferences need to be registered with a type and default value
- // before they are used.
- //
- // The way you use a PrefRegistry is that you register all required
- // preferences on it (via one of its subclasses), then pass it as a
- // construction parameter to PrefService.
- //
- // Currently, registrations after constructing the PrefService will
- // also work, but this is being deprecated.
- class COMPONENTS_PREFS_EXPORT PrefRegistry
- : public base::RefCounted<PrefRegistry> {
- public:
- // Registration flags that can be specified which impact how the pref will
- // behave or be stored. This will be passed in a bitmask when the pref is
- // registered. Subclasses of PrefRegistry can specify their own flags. Care
- // must be taken to ensure none of these overlap with the flags below.
- using PrefRegistrationFlags = uint32_t;
- // No flags are specified.
- static constexpr PrefRegistrationFlags NO_REGISTRATION_FLAGS = 0;
- // The first 8 bits are reserved for subclasses of PrefRegistry to use.
- // This marks the pref as "lossy". There is no strict time guarantee on when
- // a lossy pref will be persisted to permanent storage when it is modified.
- static constexpr PrefRegistrationFlags LOSSY_PREF = 1 << 8;
- // Registering a pref as public allows other services to access it.
- static constexpr PrefRegistrationFlags PUBLIC = 1 << 9;
- typedef PrefValueMap::const_iterator const_iterator;
- typedef std::unordered_map<std::string, uint32_t> PrefRegistrationFlagsMap;
- PrefRegistry();
- PrefRegistry(const PrefRegistry&) = delete;
- PrefRegistry& operator=(const PrefRegistry&) = delete;
- // Retrieve the set of registration flags for the given preference. The return
- // value is a bitmask of PrefRegistrationFlags.
- uint32_t GetRegistrationFlags(const std::string& pref_name) const;
- // Gets the registered defaults.
- scoped_refptr<PrefStore> defaults();
- // Allows iteration over defaults.
- const_iterator begin() const;
- const_iterator end() const;
- // Changes the default value for a preference.
- //
- // |pref_name| must be a previously registered preference.
- void SetDefaultPrefValue(const std::string& pref_name, base::Value value);
- // Registers a pref owned by another service for use with the current service.
- // The owning service must register that pref with the |PUBLIC| flag.
- void RegisterForeignPref(const std::string& path);
- // Sets the default value and flags of a previously-registered foreign pref
- // value.
- void SetDefaultForeignPrefValue(const std::string& path,
- base::Value default_value,
- uint32_t flags);
- const std::set<std::string>& foreign_pref_keys() const {
- return foreign_pref_keys_;
- }
- protected:
- friend class base::RefCounted<PrefRegistry>;
- virtual ~PrefRegistry();
- // Used by subclasses to register a default value and registration flags for
- // a preference. |flags| is a bitmask of |PrefRegistrationFlags|.
- void RegisterPreference(const std::string& path,
- base::Value default_value,
- uint32_t flags);
- // Allows subclasses to hook into pref registration.
- virtual void OnPrefRegistered(const std::string& path,
- uint32_t flags);
- scoped_refptr<DefaultPrefStore> defaults_;
- // A map of pref name to a bitmask of PrefRegistrationFlags.
- PrefRegistrationFlagsMap registration_flags_;
- std::set<std::string> foreign_pref_keys_;
- };
- #endif // COMPONENTS_PREFS_PREF_REGISTRY_H_
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