1QPtrDict(3qt) QPtrDict(3qt)
2
6 QPtrDict - Template class that provides a dictionary based on void*
7 keys
8
10 #include <qptrdict.h>
11 Inherits QPtrCollection.
13 Public Members
15 QPtrDict ( int size = 17 )
16 QPtrDict ( const QPtrDict<type> & dict )
17 ~QPtrDict ()
18 QPtrDict<type> & operator= ( const QPtrDict<type> & dict )
19 virtual uint count () const
20 uint size () const
21 bool isEmpty () const
22 void insert ( void * key, const type * item )
23 void replace ( void * key, const type * item )
24 bool remove ( void * key )
25 type * take ( void * key )
26 type * find ( void * key ) const
27 type * operator[] ( void * key ) const
28 virtual void clear ()
29 void resize ( uint newsize )
30 void statistics () const
31 Important Inherited Members
33 bool autoDelete () const
34 void setAutoDelete ( bool enable )
35 Protected Members
37 virtual QDataStream & read ( QDataStream & s, QPtrCollection::Item &
38 item )
39 virtual QDataStream & write ( QDataStream & s, QPtrCollection::Item )
40 const
41
43 The QPtrDict class is a template class that provides a dictionary based
44 on void* keys.
45 QPtrDict is implemented as a template class. Define a template instance
47 QPtrDict<X> to create a dictionary that operates on pointers to X (X*).
48 A dictionary is a collection of key-value pairs. The key is a void*
50 used for insertion, removal and lookup. The value is a pointer.
51 Dictionaries provide very fast insertion and lookup.
52 Example:
54 QPtrDict<char> fields; // void* keys, char* values
56 QLineEdit *le1 = new QLineEdit( this );
57 le1->setText( "Simpson" );
58 QLineEdit *le2 = new QLineEdit( this );
59 le2->setText( "Homer" );
60 QLineEdit *le3 = new QLineEdit( this );
61 le3->setText( "45" );
62 fields.insert( le1, "Surname" );
63 fields.insert( le2, "Forename" );
64 fields.insert( le3, "Age" );
65 QPtrDictIterator<char> it( fields );
66 for( ; it.current(); ++it )
67 cout << it.current() << endl;
68 cout << endl;
69 if ( fields[le1] ) // Prints "Surname: Simpson"
70 cout << fields[le1] << ": " << le1->text() << endl;
71 if ( fields[le2] ) // Prints "Forename: Homer"
72 cout << fields[le2] << ": " << le2->text() << endl;
73 fields.remove( le1 ); // Removes le1 from the dictionary
74 cout << le1->text() << endl; // Prints "Simpson"
75 In this example we use a dictionary to add an extra property (a char*)
76 to the line edits we're using.
77 See QDict for full details, including the choice of dictionary size,
79 and how deletions are handled.
80 See also QPtrDictIterator, QDict, QAsciiDict, QIntDict, Collection
82 Classes, Collection Classes, and Non-GUI Classes.
83
86 Constructs a dictionary using an internal hash array with the size
87 size.
88 Setting size to a suitably large prime number (equal to or greater than
90 the expected number of entries) makes the hash distribution better and
91 improves lookup performance.
92
94 Constructs a copy of dict.
95 Each item in dict is inserted into this dictionary. Only the pointers
97 are copied (shallow copy).
98
100 Removes all items from the dictionary and destroys it.
101 All iterators that access this dictionary will be reset.
103 See also setAutoDelete().
105
107 Returns the setting of the auto-delete option. The default is FALSE.
108 See also setAutoDelete().
110
112 Removes all items from the dictionary.
113 The removed items are deleted if auto-deletion is enabled.
115 All dictionary iterators that access this dictionary will be reset.
117 See also remove(), take(), and setAutoDelete().
119 Reimplemented from QPtrCollection.
121
123 Returns the number of items in the dictionary.
124 See also isEmpty().
126 Reimplemented from QPtrCollection.
128
130 Returns the item associated with key, or 0 if the key does not exist in
131 the dictionary.
132 If there are two or more items with equal keys, then the most recently
134 inserted item will be found.
135 Equivalent to operator[].
137 See also operator[]().
139
141 Inserts the key with the item into the dictionary.
142 Multiple items can have the same key, in which case only the last item
144 will be accessible using operator[]().
145 item may not be 0.
147 See also replace().
149
151 Returns TRUE if the dictionary is empty; otherwise returns FALSE.
152 See also count().
154
156 Assigns dict to this dictionary and returns a reference to this
157 dictionary.
158 This dictionary is first cleared and then each item in dict is inserted
160 into the dictionary. Only the pointers are copied (shallow copy),
161 unless newItem() has been reimplemented.
162
164 Returns the item associated with key, or 0 if the key does not exist in
165 the dictionary.
166 If there are two or more items with equal keys, then the most recently
168 inserted item will be found.
169 Equivalent to the find() function.
171 See also find().
173
175 [virtual protected]
176 Reads a dictionary item from the stream s and returns a reference to
177 the stream.
178 The default implementation sets item to 0.
180 See also write().
182
184 Removes the item associated with key from the dictionary. Returns TRUE
185 if successful, i.e. if key is in the dictionary; otherwise returns
186 FALSE.
187 If there are two or more items with equal keys, then the most recently
189 inserted item will be removed.
190 The removed item is deleted if auto-deletion is enabled.
192 All dictionary iterators that refer to the removed item will be set to
194 point to the next item in the dictionary traversal order.
195 See also take(), clear(), and setAutoDelete().
197
199 If the dictionary has key key, this key's item is replaced with item.
200 If the dictionary doesn't contain key key, item is inserted into the
201 dictionary using key key.
202 item may not be 0.
204 Equivalent to
206 QPtrDict<ItemType> dict;
208 ...
209 if ( dict.find( key ) )
210 dict.remove( key );
211 dict.insert( key, item );
212 If there are two or more items with equal keys, then the most recently
214 inserted item will be replaced.
215 See also insert().
217
219 Changes the size of the hash table to newsize. The contents of the
220 dictionary are preserved, but all iterators on the dictionary become
221 invalid.
222
224 Sets the collection to auto-delete its contents if enable is TRUE and
225 to never delete them if enable is FALSE.
226 If auto-deleting is turned on, all the items in a collection are
228 deleted when the collection itself is deleted. This is convenient if
229 the collection has the only pointer to the items.
230 The default setting is FALSE, for safety. If you turn it on, be careful
232 about copying the collection - you might find yourself with two
233 collections deleting the same items.
234 Note that the auto-delete setting may also affect other functions in
236 subclasses. For example, a subclass that has a remove() function will
237 remove the item from its data structure, and if auto-delete is enabled,
238 will also delete the item.
239 See also autoDelete().
241 Examples:
243
245 Returns the size of the internal hash table (as specified in the
246 constructor).
247 See also count().
249
251 Debugging-only function that prints out the dictionary distribution
252 using qDebug().
253
255 Takes the item associated with key out of the dictionary without
256 deleting it (even if auto-deletion is enabled).
257 If there are two or more items with equal keys, then the most recently
259 inserted item will be removed.
260 Returns a pointer to the item taken out, or 0 if the key does not exist
262 in the dictionary.
263 All dictionary iterators that refer to the taken item will be set to
265 point to the next item in the dictionary traversal order.
266 See also remove(), clear(), and setAutoDelete().
268
270 [virtual protected]
271 Writes a dictionary item to the stream s and returns a reference to the
272 stream.
273 See also read().
275
278 http://doc.trolltech.com/qptrdict.html
279 http://www.trolltech.com/faq/tech.html
280
282 Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the
283 license file included in the distribution for a complete license
284 statement.
285
287 Generated automatically from the source code.
288
290 If you find a bug in Qt, please report it as described in
291 http://doc.trolltech.com/bughowto.html. Good bug reports help us to
292 help you. Thank you.
293 The definitive Qt documentation is provided in HTML format; it is
295 located at $QTDIR/doc/html and can be read using Qt Assistant or with a
296 web browser. This man page is provided as a convenience for those users
297 who prefer man pages, although this format is not officially supported
298 by Trolltech.
299 If you find errors in this manual page, please report them to qt-
301 bugs@trolltech.com. Please include the name of the manual page
302 (qptrdict.3qt) and the Qt version (3.3.8).
303Trolltech AS 2 February 2007 QPtrDict(3qt)