From d796c9dd933ab96ec83b9a634feedd5d32e1ba3f Mon Sep 17 00:00:00 2001 From: Timothy Pearson Date: Tue, 8 Nov 2011 12:31:36 -0600 Subject: Test conversion to TQt3 from Qt3 8c6fc1f8e35fd264dd01c582ca5e7549b32ab731 --- doc/html/qasciicache.html | 252 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 252 insertions(+) create mode 100644 doc/html/qasciicache.html (limited to 'doc/html/qasciicache.html') diff --git a/doc/html/qasciicache.html b/doc/html/qasciicache.html new file mode 100644 index 000000000..5b0b79931 --- /dev/null +++ b/doc/html/qasciicache.html @@ -0,0 +1,252 @@ + + + + + +TQAsciiCache Class + + + + + + + +

TQAsciiCache Class Reference

+ +

The TQAsciiCache class is a template class that provides a cache based on char* keys. +More... +

#include <qasciicache.h> +

Inherits TQPtrCollection. +

List of all member functions. +

Public Members

TQAsciiCache ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE, bool copyKeys = TRUE )
~TQAsciiCache ()
int maxCost () const
int totalCost () const
void setMaxCost ( int m )
virtual uint count () const
uint size () const
bool isEmpty () const
virtual void clear ()
bool insert ( const char * k, const type * d, int c = 1, int p = 0 )
bool remove ( const char * k )
type * take ( const char * k )
type * find ( const char * k, bool ref = TRUE ) const
type * operator[] ( const char * k ) const
void statistics () const

Detailed Description

+ + +

The TQAsciiCache class is a template class that provides a cache based on char* keys. +

+ +

TQAsciiCache is implemented as a template class. Define a template +instance TQAsciiCache<X> to create a cache that operates on +pointers to X (X*). +

A cache is a least recently used (LRU) list of cache items. The +cache items are accessed via char* keys. For Unicode keys use +the TQCache template instead, which uses TQString keys. A TQCache +has the same performace as a TQAsciiCache. +

Each cache item has a cost. The sum of item costs, totalCost(), +will not exceed the maximum cache cost, maxCost(). If inserting a +new item would cause the total cost to exceed the maximum cost, +the least recently used items in the cache are removed. +

Apart from insert(), by far the most important function is find() +(which also exists as operator[]()). This function looks up an +item, returns it, and by default marks it as being the most +recently used item. +

There are also methods to remove() or take() an object from the +cache. Calling setAutoDelete(TRUE) tells the cache to delete items that +are removed. The default is to not delete items when then are +removed (i.e., remove() and take() are equivalent). +

When inserting an item into the cache, only the pointer is copied, +not the item itself. This is called a shallow copy. It is possible +to make the cache copy all of the item's data (known as a deep copy) when an item is inserted. insert() calls the virtual +function TQPtrCollection::newItem() for the item to be inserted. +Inherit a cache and reimplement newItem() if you want deep copies. +

When removing a cache item the virtual function +TQPtrCollection::deleteItem() is called. Its default implementation +in TQAsciiCache is to delete the item if auto-deletion is enabled. +

There is a TQAsciiCacheIterator which may be used to traverse the +items in the cache in arbitrary order. +

Member Function Documentation

TQAsciiCache::TQAsciiCache ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE, bool copyKeys = TRUE ) +

+ +

Constructs a cache whose contents will never have a total cost +greater than maxCost and which is expected to contain less than +size items. +

size is actually the size of an internal hash array; it's +usually best to make it prime and at least 50% bigger than the +largest expected number of items in the cache. +

Each inserted item has an associated cost. When inserting a new +item, if the total cost of all items in the cache will exceed maxCost, the cache will start throwing out the older (least +recently used) items until there is enough room for the new item +to be inserted. +

If caseSensitive is TRUE (the default), the cache keys are case +sensitive; if it is FALSE, they are case-insensitive. +Case-insensitive comparison only affects the 26 letters in +US-ASCII. If copyKeys is TRUE (the default), TQAsciiCache makes +a copy of the cache keys, otherwise it copies just the const char +* pointer - slightly faster if you can guarantee that the keys +will never change, but very risky. + +

TQAsciiCache::~TQAsciiCache () +

+ +

Removes all items from the cache and destroys it. +All iterators that access this cache will be reset. + +

void TQAsciiCache::clear () `[virtual]` +

+ +

Removes all items from the cache, and deletes them if auto-deletion has been +enabled. +

All cache iterators that operate on this cache are reset. +

uint TQAsciiCache::count () const `[virtual]` +

+ +

Returns the number of items in the cache. +

type * TQAsciiCache::find ( const char * k, bool ref = TRUE ) const +

+ +

Returns the item with key k, or 0 if the key does not exist +in the cache. If ref is TRUE (the default), the item is moved +to the front of the least recently used list. +

If there are two or more items with equal keys, the one that was +inserted last is returned. + +

bool TQAsciiCache::insert ( const char * k, const type * d, int c = 1, int p = 0 ) +

+ +

Inserts the item d into the cache using key k, and with an +associated cost of c. Returns TRUE if the item is successfully +inserted. Returns FALSE if the item is not inserted, for example, +if the cost of the item exceeds maxCost(). +

The cache's size is limited, and if the total cost is too high, +TQAsciiCache will remove old, least recently used items until there +is room for this new item. +

Items with duplicate keys can be inserted. +

The parameter p is internal and should be left at the default +value (0). +

Warning: If this function returns FALSE, you must delete d +yourself. Additionally, be very careful about using d after +calling this function, because any other insertions into the +cache, from anywhere in the application or within TQt itself, could +cause the object to be discarded from the cache and the pointer to +become invalid. + +

bool TQAsciiCache::isEmpty () const +

+ +

Returns TRUE if the cache is empty; otherwise returns FALSE. + +

int TQAsciiCache::maxCost () const +

+ +

Returns the maximum allowed total cost of the cache. +

See also setMaxCost() and totalCost(). + +

type * TQAsciiCache::operator[] ( const char * k ) const +

+ +

Returns the item with key k, or 0 if k does not exist in +the cache, and moves the item to the front of the least recently +used list. +

If there are two or more items with equal keys, the one that was +inserted last is returned. +

This is the same as find( k, TRUE ). +

bool TQAsciiCache::remove ( const char * k ) +

+ +

Removes the item with key k and returns TRUE if the item was +present in the cache; otherwise returns FALSE. +

The item is deleted if auto-deletion has been enabled, i.e., if +you have called setAutoDelete(TRUE). +

If there are two or more items with equal keys, the one that was +inserted last is removed. +

All iterators that refer to the removed item are set to point to +the next item in the cache's traversal order. +

void TQAsciiCache::setMaxCost ( int m ) +

+ +

Sets the maximum allowed total cost of the cache to m. If the +current total cost is greater than m, some items are removed +immediately. +

uint TQAsciiCache::size () const +

+ +

Returns the size of the hash array used to implement the cache. +This should be a bit bigger than count() is likely to be. + +

void TQAsciiCache::statistics () const +

+ +

A debug-only utility function. Prints out cache usage, hit/miss, +and distribution information using qDebug(). This function does +nothing in the release library. + +

type * TQAsciiCache::take ( const char * k ) +

+ +

Takes the item associated with k out of the cache without +deleting it and returns a pointer to the item taken out, or 0 +if the key does not exist in the cache. +

If there are two or more items with equal keys, the one that was +inserted last is taken. +

All iterators that refer to the taken item are set to point to the +next item in the cache's traversal order. +

int TQAsciiCache::totalCost () const +

+ +

Returns the total cost of the items in the cache. This is an +integer in the range 0 to maxCost(). +