base/prefs/overlay_user_pref_store.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/prefs/overlay_user_pref_store.h"
   6
   7 #include "base/memory/scoped_ptr.h"
   8 #include "base/values.h"
   9
  10 OverlayUserPrefStore::OverlayUserPrefStore(
  11     PersistentPrefStore* underlay)
  12     : underlay_(underlay) {
  13   underlay_->AddObserver(this);
  14 }
  15
  16 bool OverlayUserPrefStore::IsSetInOverlay(const std::string& key) const {
  17   return overlay_.GetValue(key, NULL);
  18 }
  19
  20 void OverlayUserPrefStore::AddObserver(PrefStore::Observer* observer) {
  21   observers_.AddObserver(observer);
  22 }
  23
  24 void OverlayUserPrefStore::RemoveObserver(PrefStore::Observer* observer) {
  25   observers_.RemoveObserver(observer);
  26 }
  27
  28 size_t OverlayUserPrefStore::NumberOfObservers() const {
  29   return observers_.size();
  30 }
  31
  32 bool OverlayUserPrefStore::IsInitializationComplete() const {
  33   return underlay_->IsInitializationComplete();
  34 }
  35
  36 bool OverlayUserPrefStore::GetValue(const std::string& key,
  37                                     const Value** result) const {
  38   // If the |key| shall NOT be stored in the overlay store, there must not
  39   // be an entry.
  40   DCHECK(ShallBeStoredInOverlay(key) || !overlay_.GetValue(key, NULL));
  41
  42   if (overlay_.GetValue(key, result))
  43     return true;
  44   return underlay_->GetValue(GetUnderlayKey(key), result);
  45 }
  46
  47 bool OverlayUserPrefStore::GetMutableValue(const std::string& key,
  48                                            Value** result) {
  49   if (!ShallBeStoredInOverlay(key))
  50     return underlay_->GetMutableValue(GetUnderlayKey(key), result);
  51
  52   if (overlay_.GetValue(key, result))
  53     return true;
  54
  55   // Try to create copy of underlay if the overlay does not contain a value.
  56   Value* underlay_value = NULL;
  57   if (!underlay_->GetMutableValue(GetUnderlayKey(key), &underlay_value))
  58     return false;
  59
  60   *result = underlay_value->DeepCopy();
  61   overlay_.SetValue(key, *result);
  62   return true;
  63 }
  64
  65 void OverlayUserPrefStore::SetValue(const std::string& key,
  66                                     Value* value) {
  67   if (!ShallBeStoredInOverlay(key)) {
  68     underlay_->SetValue(GetUnderlayKey(key), value);
  69     return;
  70   }
  71
  72   if (overlay_.SetValue(key, value))
  73     ReportValueChanged(key);
  74 }
  75
  76 void OverlayUserPrefStore::SetValueSilently(const std::string& key,
  77                                             Value* value) {
  78   if (!ShallBeStoredInOverlay(key)) {
  79     underlay_->SetValueSilently(GetUnderlayKey(key), value);
  80     return;
  81   }
  82
  83   overlay_.SetValue(key, value);
  84 }
  85
  86 void OverlayUserPrefStore::RemoveValue(const std::string& key) {
  87   if (!ShallBeStoredInOverlay(key)) {
  88     underlay_->RemoveValue(GetUnderlayKey(key));
  89     return;
  90   }
  91
  92   if (overlay_.RemoveValue(key))
  93     ReportValueChanged(key);
  94 }
  95
  96 void OverlayUserPrefStore::MarkNeedsEmptyValue(const std::string& key) {
  97   if (!ShallBeStoredInOverlay(key))
  98     underlay_->MarkNeedsEmptyValue(key);
  99 }
 100
 101 bool OverlayUserPrefStore::ReadOnly() const {
 102   return false;
 103 }
 104
 105 PersistentPrefStore::PrefReadError OverlayUserPrefStore::GetReadError() const {
 106   return PersistentPrefStore::PREF_READ_ERROR_NONE;
 107 }
 108
 109 PersistentPrefStore::PrefReadError OverlayUserPrefStore::ReadPrefs() {
 110   // We do not read intentionally.
 111   OnInitializationCompleted(true);
 112   return PersistentPrefStore::PREF_READ_ERROR_NONE;
 113 }
 114
 115 void OverlayUserPrefStore::ReadPrefsAsync(
 116     ReadErrorDelegate* error_delegate_raw) {
 117   scoped_ptr<ReadErrorDelegate> error_delegate(error_delegate_raw);
 118   // We do not read intentionally.
 119   OnInitializationCompleted(true);
 120 }
 121
 122 void OverlayUserPrefStore::CommitPendingWrite() {
 123   underlay_->CommitPendingWrite();
 124   // We do not write our content intentionally.
 125 }
 126
 127 void OverlayUserPrefStore::ReportValueChanged(const std::string& key) {
 128   FOR_EACH_OBSERVER(PrefStore::Observer, observers_, OnPrefValueChanged(key));
 129 }
 130
 131 void OverlayUserPrefStore::OnPrefValueChanged(const std::string& key) {
 132   if (!overlay_.GetValue(GetOverlayKey(key), NULL))
 133     ReportValueChanged(GetOverlayKey(key));
 134 }
 135
 136 void OverlayUserPrefStore::OnInitializationCompleted(bool succeeded) {
 137   FOR_EACH_OBSERVER(PrefStore::Observer, observers_,
 138                     OnInitializationCompleted(succeeded));
 139 }
 140
 141 void OverlayUserPrefStore::RegisterOverlayPref(const std::string& key) {
 142   RegisterOverlayPref(key, key);
 143 }
 144
 145 void OverlayUserPrefStore::RegisterOverlayPref(
 146     const std::string& overlay_key,
 147     const std::string& underlay_key) {
 148   DCHECK(!overlay_key.empty()) << "Overlay key is empty";
 149   DCHECK(overlay_to_underlay_names_map_.find(overlay_key) ==
 150          overlay_to_underlay_names_map_.end()) <<
 151       "Overlay key already registered";
 152   DCHECK(!underlay_key.empty()) << "Underlay key is empty";
 153   DCHECK(underlay_to_overlay_names_map_.find(underlay_key) ==
 154          underlay_to_overlay_names_map_.end()) <<
 155       "Underlay key already registered";
 156   overlay_to_underlay_names_map_[overlay_key] = underlay_key;
 157   underlay_to_overlay_names_map_[underlay_key] = overlay_key;
 158 }
 159
 160 OverlayUserPrefStore::~OverlayUserPrefStore() {
 161   underlay_->RemoveObserver(this);
 162 }
 163
 164 const std::string& OverlayUserPrefStore::GetOverlayKey(
 165     const std::string& underlay_key) const {
 166   NamesMap::const_iterator i =
 167       underlay_to_overlay_names_map_.find(underlay_key);
 168   return i != underlay_to_overlay_names_map_.end() ? i->second : underlay_key;
 169 }
 170
 171 const std::string& OverlayUserPrefStore::GetUnderlayKey(
 172     const std::string& overlay_key) const {
 173   NamesMap::const_iterator i =
 174       overlay_to_underlay_names_map_.find(overlay_key);
 175   return i != overlay_to_underlay_names_map_.end() ? i->second : overlay_key;
 176 }
 177
 178 bool OverlayUserPrefStore::ShallBeStoredInOverlay(
 179     const std::string& key) const {
 180   return overlay_to_underlay_names_map_.find(key) !=
 181       overlay_to_underlay_names_map_.end();
 182 }