| // Copyright 2017 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. |
| |
| #include "ui/accessibility/platform/ax_unique_id.h" |
| |
| #include <memory> |
| #include <unordered_set> |
| |
| #include "base/lazy_instance.h" |
| #include "base/stl_util.h" |
| |
| namespace ui { |
| |
| namespace { |
| |
| base::LazyInstance<std::unordered_set<int32_t>>::Leaky g_assigned_ids = |
| LAZY_INSTANCE_INITIALIZER; |
| |
| } // namespace |
| |
| AXUniqueId::AXUniqueId() : AXUniqueId(INT32_MAX) {} |
| |
| AXUniqueId::AXUniqueId(const int32_t max_id) : id_(GetNextAXUniqueId(max_id)) {} |
| |
| AXUniqueId::~AXUniqueId() { |
| g_assigned_ids.Get().erase(id_); |
| } |
| |
| bool AXUniqueId::operator==(const AXUniqueId& other) const { |
| return Get() == other.Get(); |
| } |
| |
| bool AXUniqueId::operator!=(const AXUniqueId& other) const { |
| return !(*this == other); |
| } |
| |
| bool AXUniqueId::IsAssigned(const int32_t id) const { |
| return base::Contains(g_assigned_ids.Get(), id); |
| } |
| |
| int32_t AXUniqueId::GetNextAXUniqueId(const int32_t max_id) { |
| static int32_t current_id = 0; |
| static bool has_wrapped = false; |
| |
| const int32_t prev_id = current_id; |
| do { |
| if (current_id == max_id) { |
| current_id = 1; |
| has_wrapped = true; |
| } else { |
| ++current_id; |
| } |
| if (current_id == prev_id) { |
| LOG(FATAL) << "There are over 2 billion available IDs, so the newly " |
| "created ID cannot be equal to the most recently created " |
| "ID."; |
| } |
| // If it |has_wrapped| then we need to continue until we find the first |
| // unassigned ID. |
| } while (has_wrapped && IsAssigned(current_id)); |
| |
| g_assigned_ids.Get().insert(current_id); |
| return current_id; |
| } |
| |
| } // namespace ui |