diff options
Diffstat (limited to 'doc/html/qasciicache.html')
| -rw-r--r-- | doc/html/qasciicache.html | 252 |
1 files changed, 252 insertions, 0 deletions
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 @@ +<!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/qasciicache.doc:41 --> +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> +<title>TQAsciiCache 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>TQAsciiCache Class Reference</h1> + +<p>The TQAsciiCache class is a template class that provides a cache based on char* keys. +<a href="#details">More...</a> +<p><tt>#include <<a href="qasciicache-h.html">qasciicache.h</a>></tt> +<p>Inherits <a href="qptrcollection.html">TQPtrCollection</a>. +<p><a href="qasciicache-members.html">List of all member functions.</a> +<h2>Public Members</h2> +<ul> +<li class=fn><a href="#TQAsciiCache-2"><b>TQAsciiCache</b></a> ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE, bool copyKeys = TRUE )</li> +<li class=fn><a href="#~TQAsciiCache"><b>~TQAsciiCache</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 char * k, const type * d, int c = 1, int p = 0 )</li> +<li class=fn>bool <a href="#remove"><b>remove</b></a> ( const char * k )</li> +<li class=fn>type * <a href="#take"><b>take</b></a> ( const char * k )</li> +<li class=fn>type * <a href="#find"><b>find</b></a> ( const char * k, bool ref = TRUE ) const</li> +<li class=fn>type * <a href="#operator[]"><b>operator[]</b></a> ( const char * k ) const</li> +<li class=fn>void <a href="#statistics"><b>statistics</b></a> () const</li> +</ul> +<hr><a name="details"></a><h2>Detailed Description</h2> + + +<p> The TQAsciiCache class is a template class that provides a cache based on char* keys. +<p> + +<p> TQAsciiCache is implemented as a template class. Define a template +instance TQAsciiCache<X> to create a cache that operates on +pointers to X (X*). +<p> A cache is a least recently used (LRU) list of cache items. The +cache items are accessed via <tt>char*</tt> keys. For Unicode keys use +the <a href="qcache.html">TQCache</a> template instead, which uses <a href="qstring.html">TQString</a> keys. A TQCache +has the same performace as a TQAsciiCache. +<p> Each cache item has a cost. The sum of item costs, <a href="#totalCost">totalCost</a>(), +will not exceed 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> 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(TRUE)</a> 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). +<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">TQPtrCollection::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">TQPtrCollection::deleteItem</a>() is called. Its default implementation +in TQAsciiCache is to delete the item if <a href="qptrcollection.html#setAutoDelete">auto-deletion</a> is enabled. +<p> There is a <a href="qasciicacheiterator.html">TQAsciiCacheIterator</a> which may be used to traverse the +items in the cache in arbitrary order. +<p> <p>See also <a href="qasciicacheiterator.html">TQAsciiCacheIterator</a>, <a href="qcache.html">TQCache</a>, <a href="qintcache.html">TQIntCache</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="TQAsciiCache-2"></a>TQAsciiCache::TQAsciiCache ( int maxCost = 100, int size = 17, bool caseSensitive = TRUE, bool copyKeys = 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 href="primes.html#prime">prime</a> 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 only affects the 26 letters in +US-ASCII. If <em>copyKeys</em> 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. + +<h3 class=fn><a name="~TQAsciiCache"></a>TQAsciiCache::~TQAsciiCache () +</h3> + +<p> Removes all items from the cache and destroys it. +All iterators that access this cache will be reset. + +<h3 class=fn>void <a name="clear"></a>TQAsciiCache::clear ()<tt> [virtual]</tt> +</h3> + +<p> Removes all items from the cache, and deletes them if <a href="qptrcollection.html#setAutoDelete">auto-deletion</a> has been +enabled. +<p> All cache iterators that operate on this 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">TQPtrCollection</a>. +<h3 class=fn>uint <a name="count"></a>TQAsciiCache::count () const<tt> [virtual]</tt> +</h3> + +<p> Returns the number of items in the cache. +<p> <p>See also <a href="#totalCost">totalCost</a>() and <a href="#size">size</a>(). + +<p>Reimplemented from <a href="qptrcollection.html#count">TQPtrCollection</a>. +<h3 class=fn>type * <a name="find"></a>TQAsciiCache::find ( const char * k, bool ref = TRUE ) const +</h3> + +<p> Returns the item 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>TQAsciiCache::insert ( const char * k, const type * d, int c = 1, int p = 0 ) +</h3> + +<p> Inserts the item <em>d</em> into the cache using key <em>k</em>, and with an +associated cost of <em>c</em>. 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 <a href="#maxCost">maxCost</a>(). +<p> 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. +<p> Items with duplicate keys can be inserted. +<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, 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 TQt 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>TQAsciiCache::isEmpty () const +</h3> + +<p> Returns TRUE if the cache is empty; otherwise returns FALSE. + +<h3 class=fn>int <a name="maxCost"></a>TQAsciiCache::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>TQAsciiCache::operator[] ( const char * k ) const +</h3> + +<p> Returns the item 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>TQAsciiCache::remove ( const char * k ) +</h3> + +<p> Removes the item with key <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(TRUE)</a>. +<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="setMaxCost"></a>TQAsciiCache::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 removed +immediately. +<p> <p>See also <a href="#maxCost">maxCost</a>() and <a href="#totalCost">totalCost</a>(). + +<h3 class=fn>uint <a name="size"></a>TQAsciiCache::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>TQAsciiCache::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>TQAsciiCache::take ( const char * 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>TQAsciiCache::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">TQt 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>TQt 3.3.8</div> +</table></div></address></body> +</html> |