ui/gfx/sequential_id_generator.cc

   1 // Copyright (c) 2013 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 "ui/gfx/sequential_id_generator.h"
   6
   7 #include "base/logging.h"
   8
   9 namespace {
  10
  11 // Removes |key| from |first|, and |first[key]| from |second|.
  12 template<typename T>
  13 void Remove(uint32 key, T* first, T* second) {
  14   typename T::iterator iter = first->find(key);
  15   if (iter == first->end())
  16     return;
  17
  18   uint32 second_key = iter->second;
  19   first->erase(iter);
  20
  21   iter = second->find(second_key);
  22   DCHECK(iter != second->end());
  23   second->erase(iter);
  24 }
  25
  26 }  // namespace
  27
  28 namespace ui {
  29
  30 SequentialIDGenerator::SequentialIDGenerator(uint32 min_id)
  31     : min_id_(min_id),
  32       min_available_id_(min_id) {
  33 }
  34
  35 SequentialIDGenerator::~SequentialIDGenerator() {
  36 }
  37
  38 uint32 SequentialIDGenerator::GetGeneratedID(uint32 number) {
  39   IDMap::iterator find = number_to_id_.find(number);
  40   if (find != number_to_id_.end())
  41     return find->second;
  42
  43   int id = GetNextAvailableID();
  44   number_to_id_.insert(std::make_pair(number, id));
  45   id_to_number_.insert(std::make_pair(id, number));
  46   return id;
  47 }
  48
  49 bool SequentialIDGenerator::HasGeneratedIDFor(uint32 number) const {
  50   return number_to_id_.find(number) != number_to_id_.end();
  51 }
  52
  53 void SequentialIDGenerator::ReleaseGeneratedID(uint32 id) {
  54   UpdateNextAvailableIDAfterRelease(id);
  55   Remove(id, &id_to_number_, &number_to_id_);
  56 }
  57
  58 void SequentialIDGenerator::ReleaseNumber(uint32 number) {
  59   DCHECK_GT(number_to_id_.count(number), 0U);
  60   UpdateNextAvailableIDAfterRelease(number_to_id_[number]);
  61   Remove(number, &number_to_id_, &id_to_number_);
  62 }
  63
  64 uint32 SequentialIDGenerator::GetNextAvailableID() {
  65   const uint32 kMaxID = 128;
  66   while (id_to_number_.count(min_available_id_) > 0 &&
  67          min_available_id_ < kMaxID) {
  68     ++min_available_id_;
  69   }
  70   if (min_available_id_ >= kMaxID)
  71     min_available_id_ = min_id_;
  72   return min_available_id_;
  73 }
  74
  75 void SequentialIDGenerator::UpdateNextAvailableIDAfterRelease(uint32 id) {
  76   if (id < min_available_id_) {
  77     min_available_id_ = id;
  78     DCHECK_GE(min_available_id_, min_id_);
  79   }
  80 }
  81
  82 }  // namespace ui