base/supports_user_data.cc

   1 // Copyright 2012 The Chromium Authors
   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 #include "base/sequence_checker.h"
   8
   9 namespace base {
  10
  11 std::unique_ptr<SupportsUserData::Data> SupportsUserData::Data::Clone() {
  12   return nullptr;
  13 }
  14
  15 SupportsUserData::SupportsUserData() {
  16   // Harmless to construct on a different execution sequence to subsequent
  17   // usage.
  18   DETACH_FROM_SEQUENCE(sequence_checker_);
  19 }
  20
  21 SupportsUserData::SupportsUserData(SupportsUserData&&) = default;
  22 SupportsUserData& SupportsUserData::operator=(SupportsUserData&&) = default;
  23
  24 SupportsUserData::Data* SupportsUserData::GetUserData(const void* key) const {
  25   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  26   // Avoid null keys; they are too vulnerable to collision.
  27   DCHECK(key);
  28   auto found = user_data_.find(key);
  29   if (found != user_data_.end())
  30     return found->second.get();
  31   return nullptr;
  32 }
  33
  34 void SupportsUserData::SetUserData(const void* key,
  35                                    std::unique_ptr<Data> data) {
  36   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  37   // Avoid null keys; they are too vulnerable to collision.
  38   DCHECK(key);
  39   if (data.get())
  40     user_data_[key] = std::move(data);
  41   else
  42     RemoveUserData(key);
  43 }
  44
  45 void SupportsUserData::RemoveUserData(const void* key) {
  46   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  47   user_data_.erase(key);
  48 }
  49
  50 void SupportsUserData::DetachFromSequence() {
  51   DETACH_FROM_SEQUENCE(sequence_checker_);
  52 }
  53
  54 void SupportsUserData::CloneDataFrom(const SupportsUserData& other) {
  55   for (const auto& data_pair : other.user_data_) {
  56     auto cloned_data = data_pair.second->Clone();
  57     if (cloned_data)
  58       SetUserData(data_pair.first, std::move(cloned_data));
  59   }
  60 }
  61
  62 SupportsUserData::~SupportsUserData() {
  63   if (!user_data_.empty()) {
  64     DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  65   }
  66   DataMap local_user_data;
  67   user_data_.swap(local_user_data);
  68   // Now this->user_data_ is empty, and any destructors called transitively from
  69   // the destruction of |local_user_data| will see it that way instead of
  70   // examining a being-destroyed object.
  71 }
  72
  73 void SupportsUserData::ClearAllUserData() {
  74   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  75   user_data_.clear();
  76 }
  77
  78 }  // namespace base