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comparison: ipc/chromium/src/base/id_map.h
ipc/chromium/src/base/id_map.h
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| 1 // Copyright (c) 2006-2008 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 #ifndef BASE_ID_MAP_H__ | |
| 6 #define BASE_ID_MAP_H__ | |
| 7 | |
| 8 #include "base/basictypes.h" | |
| 9 #include "base/hash_tables.h" | |
| 10 #include "base/logging.h" | |
| 11 | |
| 12 // This object maintains a list of IDs that can be quickly converted to | |
| 13 // pointers to objects. It is implemented as a hash table, optimized for | |
| 14 // relatively small data sets (in the common case, there will be exactly one | |
| 15 // item in the list). | |
| 16 // | |
| 17 // Items can be inserted into the container with arbitrary ID, but the caller | |
| 18 // must ensure they are unique. Inserting IDs and relying on automatically | |
| 19 // generated ones is not allowed because they can collide. | |
| 20 template<class T> | |
| 21 class IDMap { | |
| 22 private: | |
| 23 typedef base::hash_map<int32_t, T*> HashTable; | |
| 24 typedef typename HashTable::iterator iterator; | |
| 25 | |
| 26 public: | |
| 27 // support const iterators over the items | |
| 28 // Note, use iterator->first to get the ID, iterator->second to get the T* | |
| 29 typedef typename HashTable::const_iterator const_iterator; | |
| 30 | |
| 31 IDMap() : next_id_(1) { | |
| 32 } | |
| 33 IDMap(const IDMap& other) : next_id_(other.next_id_), | |
| 34 data_(other.data_) { | |
| 35 } | |
| 36 | |
| 37 const_iterator begin() const { | |
| 38 return data_.begin(); | |
| 39 } | |
| 40 const_iterator end() const { | |
| 41 return data_.end(); | |
| 42 } | |
| 43 | |
| 44 // Adds a view with an automatically generated unique ID. See AddWithID. | |
| 45 int32_t Add(T* data) { | |
| 46 int32_t this_id = next_id_; | |
| 47 DCHECK(data_.find(this_id) == data_.end()) << "Inserting duplicate item"; | |
| 48 data_[this_id] = data; | |
| 49 next_id_++; | |
| 50 return this_id; | |
| 51 } | |
| 52 | |
| 53 // Adds a new data member with the specified ID. The ID must not be in | |
| 54 // the list. The caller either must generate all unique IDs itself and use | |
| 55 // this function, or allow this object to generate IDs and call Add. These | |
| 56 // two methods may not be mixed, or duplicate IDs may be generated | |
| 57 void AddWithID(T* data, int32_t id) { | |
| 58 DCHECK(data_.find(id) == data_.end()) << "Inserting duplicate item"; | |
| 59 data_[id] = data; | |
| 60 } | |
| 61 | |
| 62 void Remove(int32_t id) { | |
| 63 iterator i = data_.find(id); | |
| 64 if (i == data_.end()) { | |
| 65 NOTREACHED() << "Attempting to remove an item not in the list"; | |
| 66 return; | |
| 67 } | |
| 68 data_.erase(i); | |
| 69 } | |
| 70 | |
| 71 bool IsEmpty() const { | |
| 72 return data_.empty(); | |
| 73 } | |
| 74 | |
| 75 void Clear() { | |
| 76 data_.clear(); | |
| 77 } | |
| 78 | |
| 79 bool HasData(const T* data) const { | |
| 80 // XXX would like to use <algorithm> here ... | |
| 81 for (const_iterator it = begin(); it != end(); ++it) | |
| 82 if (data == it->second) | |
| 83 return true; | |
| 84 return false; | |
| 85 } | |
| 86 | |
| 87 T* Lookup(int32_t id) const { | |
| 88 const_iterator i = data_.find(id); | |
| 89 if (i == data_.end()) | |
| 90 return NULL; | |
| 91 return i->second; | |
| 92 } | |
| 93 | |
| 94 size_t size() const { | |
| 95 return data_.size(); | |
| 96 } | |
| 97 | |
| 98 protected: | |
| 99 // The next ID that we will return from Add() | |
| 100 int32_t next_id_; | |
| 101 | |
| 102 HashTable data_; | |
| 103 }; | |
| 104 | |
| 105 #endif // BASE_ID_MAP_H__ |
