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diff --git a/doc/html/qcache.html b/doc/html/qcache.html new file mode 100644 index 0000000..577b996 --- /dev/null +++ b/doc/html/qcache.html @@ -0,0 +1,279 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/doc/qcache.doc:41 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>QCache Class</title> +<style type="text/css"><!-- +fn { margin-left: 1cm; text-indent: -1cm; } +a:link { color: #004faf; text-decoration: none } +a:visited { color: #672967; text-decoration: none } +body { background: #ffffff; color: black; } +--></style> +</head> +<body> + +<table border="0" cellpadding="0" cellspacing="0" width="100%"> +<tr bgcolor="#E5E5E5"> +<td valign=center> + <a href="index.html"> +<font color="#004faf">Home</font></a> + | <a href="classes.html"> +<font color="#004faf">All Classes</font></a> + | <a href="mainclasses.html"> +<font color="#004faf">Main Classes</font></a> + | <a href="annotated.html"> +<font color="#004faf">Annotated</font></a> + | <a href="groups.html"> +<font color="#004faf">Grouped Classes</font></a> + | <a href="functions.html"> +<font color="#004faf">Functions</font></a> +</td> +<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QCache Class Reference</h1> + +<p>The QCache class is a template class that provides a cache based on QString keys. +<a href="#details">More...</a> +<p><tt>#include <<a href="qcache-h.html">qcache.h</a>></tt> +<p>Inherits <a href="qptrcollection.html">QPtrCollection</a>. +<p><a href="qcache-members.html">List of all member functions.</a> +<h2>Public Members</h2> +<ul> +<li class=fn><a href="#QCache-2"><b>QCache</b></a> ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE )</li> +<li class=fn><a href="#~QCache"><b>~QCache</b></a> ()</li> +<li class=fn>int <a href="#maxCost"><b>maxCost</b></a> () const</li> +<li class=fn>int <a href="#totalCost"><b>totalCost</b></a> () const</li> +<li class=fn>void <a href="#setMaxCost"><b>setMaxCost</b></a> ( int m )</li> +<li class=fn>virtual uint <a href="#count"><b>count</b></a> () const</li> +<li class=fn>uint <a href="#size"><b>size</b></a> () const</li> +<li class=fn>bool <a href="#isEmpty"><b>isEmpty</b></a> () const</li> +<li class=fn>virtual void <a href="#clear"><b>clear</b></a> ()</li> +<li class=fn>bool <a href="#insert"><b>insert</b></a> ( const QString & k, const type * d, int c = 1, int p = 0 )</li> +<li class=fn>bool <a href="#remove"><b>remove</b></a> ( const QString & k )</li> +<li class=fn>type * <a href="#take"><b>take</b></a> ( const QString & k )</li> +<li class=fn>type * <a href="#find"><b>find</b></a> ( const QString & k, bool ref = TRUE ) const</li> +<li class=fn>type * <a href="#operator[]"><b>operator[]</b></a> ( const QString & k ) const</li> +<li class=fn>void <a href="#statistics"><b>statistics</b></a> () const</li> +</ul> +<h2>Important Inherited Members</h2> +<ul> +<li class=fn>bool <a href="#autoDelete"><b>autoDelete</b></a> () const</li> +<li class=fn>void <a href="#setAutoDelete"><b>setAutoDelete</b></a> ( bool enable )</li> +</ul> +<hr><a name="details"></a><h2>Detailed Description</h2> + + +The QCache class is a template class that provides a cache based on <a href="qstring.html">QString</a> keys. +<p> + +<p> +<p> A cache is a least recently used (LRU) list of cache items. Each +cache item has a key and a certain cost. The sum of item costs, +<a href="#totalCost">totalCost</a>(), never exceeds the maximum cache cost, <a href="#maxCost">maxCost</a>(). 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. +<p> QCache is a template class. QCache<X> defines a cache that +operates on pointers to X, or X*. +<p> Apart from <a href="#insert">insert</a>(), by far the most important function is <a href="#find">find</a>() +(which also exists as <a href="#operator[]">operator[]</a>()). This function looks up an +item, returns it, and by default marks it as being the most +recently used item. +<p> There are also methods to <a href="#remove">remove</a>() or <a href="#take">take</a>() an object from the +cache. Calling <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE) for a cache tells it to delete +items that are removed. The default is to not delete items when +they are removed (i.e., remove() and take() are equivalent). +<p> When inserting an item into the cache, only the pointer is copied, +not the item itself. This is called a <a href="shclass.html#shallow-copy">shallow copy</a>. It is possible +to make the cache copy all of the item's data (known as a <a href="shclass.html#deep-copy">deep copy</a>) when an item is inserted. insert() calls the virtual +function <a href="qptrcollection.html#newItem">QPtrCollection::newItem</a>() for the item to be inserted. +Inherit a cache and reimplement <a href="qptrcollection.html#newItem">newItem</a>() if you want deep copies. +<p> When removing a cache item, the virtual function +<a href="qptrcollection.html#deleteItem">QPtrCollection::deleteItem</a>() is called. The default +implementation deletes the item if auto-deletion is enabled, and +does nothing otherwise. +<p> There is a <a href="qcacheiterator.html">QCacheIterator</a> that can be used to traverse the items +in the cache in arbitrary order. +<p> In QCache, the cache items are accessed via <a href="qstring.html">QString</a> keys, which +are Unicode strings. If you want to use non-Unicode, plain 8-bit +<tt>char*</tt> keys, use the <a href="qasciicache.html">QAsciiCache</a> template. A QCache has the +same performance as a QAsciiCache. +<p> <p>See also <a href="qcacheiterator.html">QCacheIterator</a>, <a href="qasciicache.html">QAsciiCache</a>, <a href="qintcache.html">QIntCache</a>, <a href="collection.html">Collection Classes</a>, and <a href="tools.html">Non-GUI Classes</a>. + +<hr><h2>Member Function Documentation</h2> +<h3 class=fn><a name="QCache-2"></a>QCache::QCache ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE ) +</h3> + +<p> Constructs a cache whose contents will never have a total cost +greater than <em>maxCost</em> and which is expected to contain less than +<em>size</em> items. +<p> <em>size</em> is actually the size of an internal hash array; it's +usually best to make it a <a href="primes.html#prime">prime</a> number and at least 50% bigger +than the largest expected number of items in the cache. +<p> Each inserted item has an associated cost. When inserting a new +item, if the total cost of all items in the cache will exceed <em>maxCost</em>, the cache will start throwing out the older (least +recently used) items until there is enough room for the new item +to be inserted. +<p> If <em>caseSensitive</em> is TRUE (the default), the cache keys are case +sensitive; if it is FALSE, they are case-insensitive. +Case-insensitive comparison considers all Unicode letters. + +<h3 class=fn><a name="~QCache"></a>QCache::~QCache () +</h3> + +<p> Removes all items from the cache and destroys it. All iterators +that access this cache will be reset. + +<h3 class=fn>bool <a name="autoDelete"></a>QPtrCollection::autoDelete () const +</h3> + +<p> Returns the setting of the auto-delete option. The default is FALSE. +<p> <p>See also <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>(). + +<h3 class=fn>void <a name="clear"></a>QCache::clear ()<tt> [virtual]</tt> +</h3> + +<p> Removes all items from the cache and deletes them if auto-deletion +has been enabled. +<p> All cache iterators that operate this on cache are reset. +<p> <p>See also <a href="#remove">remove</a>() and <a href="#take">take</a>(). + +<p>Reimplemented from <a href="qptrcollection.html#clear">QPtrCollection</a>. +<h3 class=fn>uint <a name="count"></a>QCache::count () const<tt> [virtual]</tt> +</h3> + +<p> Returns the number of items in the cache. +<p> <p>See also <a href="#totalCost">totalCost</a>(). + +<p>Reimplemented from <a href="qptrcollection.html#count">QPtrCollection</a>. +<h3 class=fn>type * <a name="find"></a>QCache::find ( const <a href="qstring.html">QString</a> & k, bool ref = TRUE ) const +</h3> + +<p> Returns the item associated with key <em>k</em>, or 0 if the key does +not exist in the cache. If <em>ref</em> is TRUE (the default), the item +is moved to the front of the least recently used list. +<p> If there are two or more items with equal keys, the one that was +inserted last is returned. + +<h3 class=fn>bool <a name="insert"></a>QCache::insert ( const <a href="qstring.html">QString</a> & k, const type * d, int c = 1, int p = 0 ) +</h3> + +<p> Inserts the item <em>d</em> into the cache with key <em>k</em> and associated +cost, <em>c</em>. Returns TRUE if it is successfully inserted; otherwise +returns FALSE. +<p> The cache's size is limited, and if the total cost is too high, +QCache will remove old, least recently used items until there is +room for this new item. +<p> The parameter <em>p</em> is internal and should be left at the default +value (0). +<p> <b>Warning:</b> If this function returns FALSE (which could happen, e.g. +if the cost of this item alone exceeds <a href="#maxCost">maxCost</a>()) you must delete +<em>d</em> yourself. Additionally, be very careful about using <em>d</em> +after calling this function because any other insertions into the +cache, from anywhere in the application or within Qt itself, could +cause the object to be discarded from the cache and the pointer to +become invalid. + +<h3 class=fn>bool <a name="isEmpty"></a>QCache::isEmpty () const +</h3> + +<p> Returns TRUE if the cache is empty; otherwise returns FALSE. + +<h3 class=fn>int <a name="maxCost"></a>QCache::maxCost () const +</h3> + +<p> Returns the maximum allowed total cost of the cache. +<p> <p>See also <a href="#setMaxCost">setMaxCost</a>() and <a href="#totalCost">totalCost</a>(). + +<h3 class=fn>type * <a name="operator[]"></a>QCache::operator[] ( const <a href="qstring.html">QString</a> & k ) const +</h3> + +<p> Returns the item associated with key <em>k</em>, or 0 if <em>k</em> does not +exist in the cache, and moves the item to the front of the least +recently used list. +<p> If there are two or more items with equal keys, the one that was +inserted last is returned. +<p> This is the same as <a href="#find">find</a>( k, TRUE ). +<p> <p>See also <a href="#find">find</a>(). + +<h3 class=fn>bool <a name="remove"></a>QCache::remove ( const <a href="qstring.html">QString</a> & k ) +</h3> + +<p> Removes the item associated with <em>k</em>, and returns TRUE if the +item was present in the cache; otherwise returns FALSE. +<p> The item is deleted if auto-deletion has been enabled, i.e., if +you have called <a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>(TRUE). +<p> If there are two or more items with equal keys, the one that was +inserted last is removed. +<p> All iterators that refer to the removed item are set to point to +the next item in the cache's traversal order. +<p> <p>See also <a href="#take">take</a>() and <a href="#clear">clear</a>(). + +<h3 class=fn>void <a name="setAutoDelete"></a>QPtrCollection::setAutoDelete ( bool enable ) +</h3> + +<p> Sets the collection to auto-delete its contents if <em>enable</em> is +TRUE and to never delete them if <em>enable</em> is FALSE. +<p> 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. +<p> 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. +<p> Note that the auto-delete setting may also affect other functions +in subclasses. For example, a subclass that has a <a href="#remove">remove</a>() +function will remove the item from its data structure, and if +auto-delete is enabled, will also delete the item. +<p> <p>See also <a href="qptrcollection.html#autoDelete">autoDelete</a>(). + +<p>Examples: <a href="grapher-nsplugin-example.html#x2769">grapher/grapher.cpp</a>, <a href="scribble-example.html#x924">scribble/scribble.cpp</a>, and <a href="bigtable-example.html#x1291">table/bigtable/main.cpp</a>. +<h3 class=fn>void <a name="setMaxCost"></a>QCache::setMaxCost ( int m ) +</h3> + +<p> Sets the maximum allowed total cost of the cache to <em>m</em>. If the +current total cost is greater than <em>m</em>, some items are deleted +immediately. +<p> <p>See also <a href="#maxCost">maxCost</a>() and <a href="#totalCost">totalCost</a>(). + +<h3 class=fn>uint <a name="size"></a>QCache::size () const +</h3> + +<p> Returns the size of the hash array used to implement the cache. +This should be a bit bigger than <a href="#count">count</a>() is likely to be. + +<h3 class=fn>void <a name="statistics"></a>QCache::statistics () const +</h3> + +<p> A debug-only utility function. Prints out cache usage, hit/miss, +and distribution information using <a href="qapplication.html#qDebug">qDebug</a>(). This function does +nothing in the release library. + +<h3 class=fn>type * <a name="take"></a>QCache::take ( const <a href="qstring.html">QString</a> & k ) +</h3> + +<p> Takes the item associated with <em>k</em> 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. +<p> If there are two or more items with equal keys, the one that was +inserted last is taken. +<p> All iterators that refer to the taken item are set to point to the +next item in the cache's traversal order. +<p> <p>See also <a href="#remove">remove</a>() and <a href="#clear">clear</a>(). + +<h3 class=fn>int <a name="totalCost"></a>QCache::totalCost () const +</h3> + +<p> Returns the total cost of the items in the cache. This is an +integer in the range 0 to <a href="#maxCost">maxCost</a>(). +<p> <p>See also <a href="#setMaxCost">setMaxCost</a>(). + +<!-- eof --> +<hr><p> +This file is part of the <a href="index.html">Qt toolkit</a>. +Copyright © 1995-2007 +<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center> +<table width=100% cellspacing=0 border=0><tr> +<td>Copyright © 2007 +<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a> +<td align=right><div align=right>Qt 3.3.8</div> +</table></div></address></body> +</html> |