The Tor Browser: ipc/chromium/src/base/id

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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.

     5 #ifndef BASE_ID_MAP_H__

     6 #define BASE_ID_MAP_H__

     8 #include "base/basictypes.h"

     9 #include "base/hash_tables.h"

    10 #include "base/logging.h"

    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;

    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;

    31   IDMap() : next_id_(1) {

    32   }

    33   IDMap(const IDMap& other) : next_id_(other.next_id_),

    34                                         data_(other.data_) {

    35   }

    37   const_iterator begin() const {

    38     return data_.begin();

    39   }

    40   const_iterator end() const {

    41     return data_.end();

    42   }

    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   }

    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   }

    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   }

    71   bool IsEmpty() const {

    72     return data_.empty();

    73   }

    75   void Clear() {

    76     data_.clear();

    77   }

    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   }

    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   }

    94   size_t size() const {

    95     return data_.size();

    96   }

    98  protected:

    99   // The next ID that we will return from Add()

   100   int32_t next_id_;

   102   HashTable data_;

   103 };

   105 #endif  // BASE_ID_MAP_H__

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