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The QPtrDict class is a template class that provides a dictionary based on void* keys. More...
#include <qptrdict.h>
Inherits QPtrCollection.
QPtrDict is implemented as a template class. Define a template instance QPtrDict<X> to create a dictionary that operates on pointers to X (X*).
A dictionary is a collection of key-value pairs. The key is a void* used for insertion, removal and lookup. The value is a pointer. Dictionaries provide very fast insertion and lookup.
Example:
QPtrDict<char> extra;
QLineEdit *le1 = new QLineEdit( this );
le1->setText( "Simpson" );
QLineEdit *le2 = new QLineEdit( this );
le2->setText( "Homer" );
QLineEdit *le3 = new QLineEdit( this );
le3->setText( "45" );
extra.insert( le1, "Surname" );
extra.insert( le2, "Forename" );
extra.insert( le3, "Age" );
QPtrDictIterator<char> it( extra ); // See QPtrDictIterator
for( ; it.current(); ++it )
cout << it.current() << endl;
cout << endl;
if ( extra[le1] ) // Prints "Surname: Simpson"
cout << extra[le1] << ": " << le1->text() << endl;
if ( extra[le2] ) // Prints "Forename: Homer"
cout << extra[le2] << ": " << le2->text() << endl;
extra.remove( le1 ); // Removes le1 from the dictionary
cout << le1->text() << endl; // Prints "Simpson"
In this example we use a dictionary to add an extra property (a
char*) to the line edits we're using.
See QDict for full details, including the choice of dictionary size, and how deletions are handled.
See also QPtrDictIterator, QDict, QAsciiDict, QIntDict, Collection Classes, Collection Classes and Non-GUI Classes.
Setting size to a suitably large prime number (equal to or greater than the expected number of entries) makes the hash distribution better and hence the lookup faster.
Each item in dict is inserted into this dictionary. Only the pointers are copied (shallow copy).
All iterators that access this dictionary will be reset.
See also setAutoDelete().
Returns the setting of the auto-delete option. The default is FALSE.
See also setAutoDelete().
The removed items are deleted if auto-deletion is enabled.
All dictionary iterators that access this dictionary will be reset.
See also remove(), take() and setAutoDelete().
Reimplemented from QPtrCollection.
See also isEmpty().
Reimplemented from QPtrCollection.
This function uses an internal hashing algorithm to optimize lookup.
If there are two or more items with equal keys, then the last item that was inserted will be found.
Equivalent to the [] operator.
Warning: Your application will crash if you call find() on an empty dictionary; you can check with isEmpty() or count(). We don't perform this check for efficiency reasons.
See also operator[]().
The key does not have to be a unique dictionary key. If multiple items are inserted with the same key, only the last item will be visible.
Null items are not allowed.
See also replace().
See also count().
This dictionary is first cleared and then each item in dict is inserted into the dictionary. Only the pointers are copied (shallow copy), unless newItem() has been reimplemented.
This function uses an internal hashing algorithm to optimize lookup.
If there are two or more items with equal keys, then the last item that was inserted will be found.
Equivalent to the find() function.
Warning: Your application will crash if you call find() on an empty dictionary; you can check with isEmpty() or count(). We don't perform this check for efficiency reasons.
See also find().
The default implementation sets item to 0.
See also write().
Removes the item associated with key from the dictionary. Returns TRUE if successful, or FALSE if the key does not exist in the dictionary.
If there are two or more items with equal keys, then the last item that was inserted of will be removed.
The removed item is deleted if auto-deletion is enabled.
All dictionary iterators that refer to the removed item will be set to point to the next item in the dictionary traversal order.
See also take(), clear() and setAutoDelete().
If the dictionary has key key, this key's item is replaced with item. If the dictionary doesn't contain key key, item is inserted into the dictionary using key key.
Null items are not allowed.
Equivalent to
QPtrDict<char> dict;
...
if ( dict.find( key ) )
dict.remove( key );
dict.insert( key, item );
If there are two or more items with equal keys, then the last inserted of these will be replaced.
See also insert().
Sets the collection to auto-delete its contents if enable is TRUE and to never delete them if enable is FALSE.
If auto-deleting is turned on, all the items in a collection are deleted when the collection itself is deleted. This is convenient if the collection has the only pointer to the items.
The default setting is FALSE, for safety. If you turn it on, be careful about copying the collection - you might find yourself with two collections deleting the same items.
Note that the auto-delete setting may also affect other functions in subclasses. For example, a subclass that has a remove() function will remove the item from its data structure, and if auto-delete is enabled, will also delete the item.
See also autoDelete().
Examples: grapher/grapher.cpp, scribble/scribble.cpp and table/bigtable/main.cpp.
See also count().
If there are two or more items with equal keys, then the last item that was inserted of will be removed.
Returns a pointer to the item taken out, or null if the key does not exist in the dictionary.
All dictionary iterators that refer to the taken item will be set to point to the next item in the dictionary traversal order.
See also remove(), clear() and setAutoDelete().
See also read().
This file is part of the Qt toolkit. Copyright © 1995-2002 Trolltech. All Rights Reserved.
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