base/supports_user_data.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/supports_user_data.h"
   6
   7 namespace base {
   8
   9 std::unique_ptr<SupportsUserData::Data> SupportsUserData::Data::Clone() {
  10   return nullptr;
  11 }
  12
  13 SupportsUserData::SupportsUserData() {
  14   // Harmless to construct on a different execution sequence to subsequent
  15   // usage.
  16   sequence_checker_.DetachFromSequence();
  17 }
  18
  19 SupportsUserData::SupportsUserData(SupportsUserData&&) = default;
  20 SupportsUserData& SupportsUserData::operator=(SupportsUserData&&) = default;
  21
  22 SupportsUserData::Data* SupportsUserData::GetUserData(const void* key) const {
  23   DCHECK(sequence_checker_.CalledOnValidSequence());
  24   // Avoid null keys; they are too vulnerable to collision.
  25   DCHECK(key);
  26   auto found = user_data_.find(key);
  27   if (found != user_data_.end())
  28     return found->second.get();
  29   return nullptr;
  30 }
  31
  32 void SupportsUserData::SetUserData(const void* key,
  33                                    std::unique_ptr<Data> data) {
  34   DCHECK(sequence_checker_.CalledOnValidSequence());
  35   // Avoid null keys; they are too vulnerable to collision.
  36   DCHECK(key);
  37   if (data.get())
  38     user_data_[key] = std::move(data);
  39   else
  40     RemoveUserData(key);
  41 }
  42
  43 void SupportsUserData::RemoveUserData(const void* key) {
  44   DCHECK(sequence_checker_.CalledOnValidSequence());
  45   user_data_.erase(key);
  46 }
  47
  48 void SupportsUserData::DetachFromSequence() {
  49   sequence_checker_.DetachFromSequence();
  50 }
  51
  52 void SupportsUserData::CloneDataFrom(const SupportsUserData& other) {
  53   for (const auto& data_pair : other.user_data_) {
  54     auto cloned_data = data_pair.second->Clone();
  55     if (cloned_data)
  56       SetUserData(data_pair.first, std::move(cloned_data));
  57   }
  58 }
  59
  60 SupportsUserData::~SupportsUserData() {
  61   DCHECK(sequence_checker_.CalledOnValidSequence() || user_data_.empty());
  62   DataMap local_user_data;
  63   user_data_.swap(local_user_data);
  64   // Now this->user_data_ is empty, and any destructors called transitively from
  65   // the destruction of |local_user_data| will see it that way instead of
  66   // examining a being-destroyed object.
  67 }
  68
  69 void SupportsUserData::ClearAllUserData() {
  70   DCHECK(sequence_checker_.CalledOnValidSequence());
  71   user_data_.clear();
  72 }
  73
  74 }  // namespace base