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