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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 "base/containers/hash_tables.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "components/prefs/base_prefs_export.h"
#include "components/prefs/pref_value_map.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.
enum PrefRegistrationFlags : uint32_t {
// No flags are specified.
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.
LOSSY_PREF = 1 << 8,
};
typedef PrefValueMap::const_iterator const_iterator;
typedef base::hash_map<std::string, uint32_t> PrefRegistrationFlagsMap;
PrefRegistry();
// 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. Takes ownership of |value|.
//
// |pref_name| must be a previously registered preference.
void SetDefaultPrefValue(const std::string& pref_name, base::Value* value);
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);
scoped_refptr<DefaultPrefStore> defaults_;
// A map of pref name to a bitmask of PrefRegistrationFlags.
PrefRegistrationFlagsMap registration_flags_;
private:
DISALLOW_COPY_AND_ASSIGN(PrefRegistry);
};
#endif // COMPONENTS_PREFS_PREF_REGISTRY_H_
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