内容

• 公共函数
• 重实现公共函数
• 保护函数
• 详细描述

Q3AsciiDict Class

The Q3AsciiDict class is a template class that provides a dictionary based on char* keys. 更多...

头：	#include <Q3AsciiDict>
继承：	Q3PtrCollection

• 所有成员列表，包括继承成员

公共函数

	Q3AsciiDict (int size = 17, bool caseSensitive = true, bool copyKeys = true)
	Q3AsciiDict (const Q3AsciiDict<type> & dict )
	~Q3AsciiDict ()
type *	find (const char * key ) const
void	insert (const char * key , const type * item )
bool	isEmpty () const
bool	remove (const char * key )
void	replace (const char * key , const type * item )
void	resize (uint newsize )
uint	size () const
void	statistics () const
type *	take (const char * key )
Q3AsciiDict<type> &	operator= (const Q3AsciiDict<type> & dict )
type *	operator[] (const char * key ) const

重实现公共函数

virtual void	clear ()
virtual uint	count () const

• 4 公共函数继承自 Q3PtrCollection

保护函数

virtual QDataStream &	read (QDataStream & s , Q3PtrCollection::Item & item )
virtual QDataStream &	write (QDataStream & s , Q3PtrCollection::Item item ) const

• 2 保护函数继承自 Q3PtrCollection

详细描述

The Q3AsciiDict class is a template class that provides a dictionary based on char* keys.

Q3AsciiDict is implemented as a template class. Define a template instance Q3AsciiDict <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 char* used for insertion, removal and lookup. The value is a pointer. Dictionaries provide very fast insertion and lookup.

Q3AsciiDict cannot handle Unicode keys; use the Q3Dict template instead, which uses QString keys. A Q3Dict has the same performace as a Q3AsciiDict .

范例：

Q3AsciiDict<QLineEdit> fields; // char* keys, QLineEdit* values
fields.insert( "forename", new QLineEdit( this ) );
fields.insert( "surname", new QLineEdit( this ) );
fields["forename"]->setText( "Homer" );
fields["surname"]->setText( "Simpson" );
Q3AsciiDictIterator<QLineEdit> it( fields ); // See Q3AsciiDictIterator
for( ; it.current(); ++it )
    cout << it.currentKey() << ": " << it.current()->text() << endl;
cout << endl;
if ( fields["forename"] && fields["surname"] )
    cout << fields["forename"]->text() << " "
        << fields["surname"]->text() << endl;  // Prints "Homer Simpson"
fields.remove( "forename" ); // Does not delete the line edit
if ( ! fields["forename"] )
    cout << "forename is not in the dictionary" << endl;
					

In this example we use a dictionary to keep track of the line edits we're using. We insert each line edit into the dictionary with a unique name and then access the line edits via the dictionary. See Q3PtrDict , Q3IntDict and Q3Dict .

见 Q3Dict for full details, including the choice of dictionary size, and how deletions are handled.

另请参阅 Q3AsciiDictIterator , Q3Dict , Q3IntDict ，和 Q3PtrDict .

成员函数文档编制

Q3AsciiDict:: Q3AsciiDict ( int size = 17, bool caseSensitive = true, bool copyKeys = true)

Constructs a dictionary optimized for less than size 条目。

We recommend setting size to a suitably large prime number (a bit larger than the expected number of entries). This makes the hash distribution better and will improve lookup performance.

当 caseSensitive is TRUE (the default) Q3AsciiDict treats "abc" and "Abc" as different keys; when it is FALSE "abc" and "Abc" are the same. Case-insensitive comparison only considers the 26 letters in US-ASCII.

若 copyKeys is TRUE (the default), the dictionary copies keys using strcpy(); if it is FALSE, the dictionary just copies the pointers.

Q3AsciiDict:: Q3AsciiDict (const Q3AsciiDict < type > & dict )

构造副本为 dict .

Each item in dict is inserted into this dictionary. Only the pointers are copied (shallow copy).

Q3AsciiDict:: ~Q3AsciiDict ()

Removes all items from the dictionary and destroys it.

The items are deleted if auto-delete is enabled.

All iterators that access this dictionary will be reset.

另请参阅 setAutoDelete ().

[虚拟] void Q3AsciiDict:: clear ()

重实现自 Q3PtrCollection::clear ().

Removes all items from the dictionary.

The removed items are deleted if auto-deletion is enabled.

All dictionary iterators that operate on dictionary are reset.

另请参阅 remove (), take ()，和 setAutoDelete ().

[虚拟] uint Q3AsciiDict:: count () const

重实现自 Q3PtrCollection::count ().

Returns the number of items in the dictionary.

另请参阅 isEmpty ().

type * Q3AsciiDict:: find (const char * key ) const

Returns the item associated with key , or 0 if the key does not exist in the dictionary.

This function uses an internal hashing algorithm to optimize lookup.

If there are two or more items with equal keys, then the item that was most recently inserted will be found.

Equivalent to the [] operator.

另请参阅 operator[] ().

void Q3AsciiDict:: insert (const char * key , const type * item )

插入 key 采用 item into the dictionary.

Multiple items can have the same key, in which case only the last item will be accessible using operator[] ().

item 不可以为 0。

另请参阅 replace ().

bool Q3AsciiDict:: isEmpty () const

Returns TRUE if the dictionary is empty, i.e. count () == 0; otherwise it returns FALSE.

另请参阅 count ().

[virtual protected] QDataStream & Q3AsciiDict:: read ( QDataStream & s , Q3PtrCollection::Item & item )

Reads a dictionary item from the stream s 并返回流引用。

The default implementation sets item 为 0。

另请参阅 write ().

bool Q3AsciiDict:: remove (const char * key )

Removes the item associated with key from the dictionary. Returns TRUE if successful, i.e. if the key existed in the dictionary; otherwise returns FALSE.

If there are two or more items with equal keys, then the most recently inserted item 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.

另请参阅 take (), clear ()，和 setAutoDelete ().

void Q3AsciiDict:: replace (const char * key , const type * item )

Replaces an item that has a key equal to key with item .

If the item does not already exist, it will be inserted.

item 不可以为 0。

Equivalent to:

Q3AsciiDict<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 most recently inserted item will be replaced.

另请参阅 insert ().

void Q3AsciiDict:: resize ( uint newsize )

Changes the size of the hashtable to newsize . The contents of the dictionary are preserved but all iterators on the dictionary become invalid.

uint Q3AsciiDict:: size () const

Returns the size of the internal hash array (as specified in the constructor).

另请参阅 count ().

void Q3AsciiDict:: statistics () const

Debugging-only function that prints out the dictionary distribution using qDebug ().

type * Q3AsciiDict:: take (const char * key )

Takes the item associated with key out of the dictionary without deleting it (even if auto-deletion is enabled).

If there are two or more items with equal keys, then the most recently inserted item will be taken.

Returns a pointer to the item taken out, or 0 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.

另请参阅 remove (), clear ()，和 setAutoDelete ().

[virtual protected] QDataStream & Q3AsciiDict:: write ( QDataStream & s , Q3PtrCollection::Item item ) const

Writes a dictionary item 到流 s 并返回流引用。

另请参阅 read ().

Q3AsciiDict < type > & Q3AsciiDict:: operator= (const Q3AsciiDict < type > & dict )

赋值 dict to this dictionary and returns a reference to this dictionary.

This dictionary is first cleared and then each item in dict is inserted into this dictionary. Only the pointers are copied (shallow copy) unless newItem () has been reimplemented().

type * Q3AsciiDict:: operator[] (const char * key ) const

Returns the item associated with key , or 0 if the key does not exist in the dictionary.

This function uses an internal hashing algorithm to optimize lookup.

If there are two or more items with equal keys, then the item that was most recently inserted will be found.

Equivalent to the find () 函数。

另请参阅 find ().