blob: bdd17effd4bcba691e29f4dbd6aed05fb636cc49 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2006-2008 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.
#ifndef BASE_ID_MAP_H__
#define BASE_ID_MAP_H__
#include "base/basictypes.h"
#include "base/hash_tables.h"
#include "base/logging.h"
// This object maintains a list of IDs that can be quickly converted to
// pointers to objects. It is implemented as a hash table, optimized for
// relatively small data sets (in the common case, there will be exactly one
// item in the list).
//
// Items can be inserted into the container with arbitrary ID, but the caller
// must ensure they are unique. Inserting IDs and relying on automatically
// generated ones is not allowed because they can collide.
template<class T>
class IDMap {
private:
typedef base::hash_map<int32_t, T*> HashTable;
typedef typename HashTable::iterator iterator;
public:
// support const iterators over the items
// Note, use iterator->first to get the ID, iterator->second to get the T*
typedef typename HashTable::const_iterator const_iterator;
IDMap() : next_id_(1) {
}
IDMap(const IDMap& other) : next_id_(other.next_id_),
data_(other.data_) {
}
const_iterator begin() const {
return data_.begin();
}
const_iterator end() const {
return data_.end();
}
// Adds a view with an automatically generated unique ID. See AddWithID.
int32_t Add(T* data) {
int32_t this_id = next_id_;
DCHECK(data_.find(this_id) == data_.end()) << "Inserting duplicate item";
data_[this_id] = data;
next_id_++;
return this_id;
}
// Adds a new data member with the specified ID. The ID must not be in
// the list. The caller either must generate all unique IDs itself and use
// this function, or allow this object to generate IDs and call Add. These
// two methods may not be mixed, or duplicate IDs may be generated
void AddWithID(T* data, int32_t id) {
DCHECK(data_.find(id) == data_.end()) << "Inserting duplicate item";
data_[id] = data;
}
void Remove(int32_t id) {
iterator i = data_.find(id);
if (i == data_.end()) {
NOTREACHED() << "Attempting to remove an item not in the list";
return;
}
data_.erase(i);
}
bool IsEmpty() const {
return data_.empty();
}
void Clear() {
data_.clear();
}
bool HasData(const T* data) const {
// XXX would like to use <algorithm> here ...
for (const_iterator it = begin(); it != end(); ++it)
if (data == it->second)
return true;
return false;
}
T* Lookup(int32_t id) const {
const_iterator i = data_.find(id);
if (i == data_.end())
return NULL;
return i->second;
}
size_t size() const {
return data_.size();
}
protected:
// The next ID that we will return from Add()
int32_t next_id_;
HashTable data_;
};
#endif // BASE_ID_MAP_H__
|
