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diff --git a/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/trie_based_containers.html b/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/trie_based_containers.html deleted file mode 100644 index 72bdd0697..000000000 --- a/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/trie_based_containers.html +++ /dev/null @@ -1,241 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> - -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> -<head> - <meta name="generator" content= - "HTML Tidy for Linux/x86 (vers 12 April 2005), see www.w3.org" /> - - <title>Trie-Based Containers</title> - <meta http-equiv="Content-Type" content= - "text/html; charset=us-ascii" /> - </head> - -<body> - <div id="page"> - <h1>Trie Design</h1> - - <h2><a name="overview" id="overview">Overview</a></h2> - - <p>The trie-based container has the following declaration:</p> - <pre> -<b>template</b>< - <b>typename</b> Key, - <b>typename</b> Mapped, - <b>typename</b> Cmp_Fn = std::less<Key>, - <b>typename</b> Tag = <a href="pat_trie_tag.html">pat_trie_tag</a>, - <b>template</b>< - <b>typename</b> Const_Node_Iterator, - <b>typename</b> Node_Iterator, - <b>typename</b> E_Access_Traits_, - <b>typename</b> Allocator_> - <b>class</b> Node_Update = <a href= -"null_trie_node_update.html">null_trie_node_update</a>, - <b>typename</b> Allocator = std::allocator<<b>char</b>> > -<b>class</b> <a href= -"trie.html">trie</a>; -</pre> - - <p>The parameters have the following meaning:</p> - - <ol> - <li><tt>Key</tt> is the key type.</li> - - <li><tt>Mapped</tt> is the mapped-policy, and is explained in - <a href="tutorial.html#assoc_ms">Tutorial::Associative - Containers::Associative Containers Others than Maps</a>.</li> - - <li><tt>E_Access_Traits</tt> is described in <a href= - "#e_access_traits">Element-Access Traits</a>.</li> - - <li><tt>Tag</tt> specifies which underlying data structure - to use, and is described shortly.</li> - - <li><tt>Node_Update</tt> is a policy for updating node - invariants. This is described in <a href="#invariants">Node - Invariants</a>.</li> - - <li><tt>Allocator</tt> is an allocator - type.</li> - </ol> - - <p>The <tt>Tag</tt> parameter specifies which underlying - data structure to use. Instantiating it by <a href= - "pat_trie_tag.html">pat_trie_tag</a>, specifies an - underlying PATRICIA trie (explained shortly); any other tag is - currently illegal.</p> - <hr /> - - <p>Following is a description of a (PATRICIA) trie - (<tt>pb_ds</tt> follows specifically [<a href= - "references.html#okasaki98mereable">okasaki98mereable</a>] and - [<a href= - "references.html#filliatre2000ptset">filliatre2000ptset</a>]).</p> - - <p>A (PATRICIA) trie is similar to a tree, but with the - following differences:</p> - - <ol> - <li>It explicitly views keys as a sequence of elements. - <i>E.g.</i>, a trie can view a string as a sequence of - characters; a trie can view a number as a sequence of - bits.</li> - - <li>It is not (necessarily) binary. Each node has fan-out <i>n - + 1</i>, where <i>n</i> is the number of distinct - elements.</li> - - <li>It stores values only at leaf nodes.</li> - - <li>Internal nodes have the properties that A) each has at - least two children, and B) each shares the same prefix with - any of its descendant.</li> - </ol> - - <p><a href="#e_access_traits">Element-Access Traits</a> shows - an example of such a trie.</p> - - <p>A (PATRICIA) trie has some useful properties:</p> - - <ol> - <li>It can be configured to use large node fan-out, giving it - very efficient find performance (albeit at insertion - complexity and size).</li> - - <li>It works well for common-prefix keys.</li> - - <li>It can support efficiently queries such as which keys - match a certain prefix. This is sometimes useful in - file systems and routers.</li> - </ol> - - <p>(We would like to thank Matt Austern for the suggestion to - include tries.)</p> - - <h2><a name="e_access_traits" id= - "e_access_traits">Element-Access Traits</a></h2> - - <p>A trie inherently views its keys as sequences of elements. - For example, a trie can view a string as a sequence of - characters. A trie needs to map each of <i>n</i> elements to a - number in <i>{0, n - 1}</i>. For example, a trie can map a - character <tt>c</tt> to - <tt>static_cast<size_t>(c)</tt>.</p> - - <p>Seemingly, then, a trie can assume that its keys support - (const) iterators, and that the <tt>value_type</tt> of this - iterator can be cast to a <tt>size_t</tt>. There are several - reasons, though, to decouple the mechanism by which the trie - accesses its keys' elements from the trie:</p> - - <ol> - <li>In some cases, the numerical value of an element is - inappropriate. Consider a trie storing DNA strings. It is - logical to use a trie with a fan-out of <i>5 = 1 + |{'A', 'C', - 'G', 'T'}|</i>. This requires mapping 'T' to 3, though.</li> - - <li>In some cases the keys' iterators are different than what - is needed. For example, a trie can be used to search for - common <u>suffixes</u>, by using strings' - <tt>reverse_iterator</tt>. As another example, a trie mapping - UNICODE strings would have a huge fan-out if each node would - branch on a UNICODE character; instead, one can define an - iterator iterating over 8-bit (or less) groups.</li> - </ol> - - <p><a href= - "trie.html">trie</a> is, - consequently, parametrized by <tt>E_Access_Traits</tt> - - traits which instruct how to access sequences' elements. - <a href= - "string_trie_e_access_traits.html"><tt>string_trie_e_access_traits</tt></a> - is a traits class for strings. Each such traits define some - types, <i>e.g.</i>,</p> - <pre> -<b>typename</b> E_Access_Traits::const_iterator -</pre> - - <p>is a const iterator iterating over a key's elements. The - traits class must also define methods for obtaining an iterator - to the first and last element of a key.</p> - - <p>Figure <a href="#pat_trie">A PATRICIA trie</a> shows a - (PATRICIA) trie resulting from inserting the words: "I wish - that I could ever see a poem lovely as a trie" (which, - unfortunately, does not rhyme).</p> - - <p>The leaf nodes contain values; each internal node contains - two <tt><b>typename</b> E_Access_Traits::const_iterator</tt> - objects, indicating the maximal common prefix of all keys in - the sub-tree. For example, the shaded internal node roots a - sub-tree with leafs "a" and "as". The maximal common prefix is - "a". The internal node contains, consequently, to const - iterators, one pointing to <tt>'a'</tt>, and the other to - <tt>'s'</tt>.</p> - - <h6 class="c1"><a name="pat_trie" id="pat_trie"><img src= - "pat_trie.png" alt="no image" /></a></h6> - - <h6 class="c1">A PATRICIA trie.</h6> - - <h2><a name="invariants" id="invariants">Node - Invariants</a></h2> - - <p>Trie-based containers support node invariants, as do - tree-based containers (see <a href= - "tree_based_containers.html#invariants">Tree-Based - Containers::Node Invariants</a>). There are two minor - differences, though, which, unfortunately, thwart sharing them - sharing the same node-updating policies:</p> - - <ol> - <li>A trie's <tt>Node_Update</tt> template-template - parameter is parametrized by <tt>E_Access_Traits</tt>, while - a tree's <tt>Node_Update</tt> template-template parameter is - parametrized by <tt>Cmp_Fn</tt>.</li> - - <li>Tree-based containers store values in all nodes, while - trie-based containers (at least in this implementation) store - values in leafs.</li> - </ol> - - <p>Figure <a href="#trie_node_update_cd">A trie and its update - policy</a> shows the scheme, as well as some predefined - policies (which are explained below).</p> - - <h6 class="c1"><a name="trie_node_update_cd" id= - "trie_node_update_cd"><img src= - "trie_node_update_policy_cd.png" alt="no image" /></a></h6> - - <h6 class="c1">A trie and its update policy.</h6> - - <p><tt>pb_ds</tt> offers the following pre-defined trie node - updating policies:</p> - - <ol> - <li><a href= - "trie_order_statistics_node_update.html"><tt>trie_order_statistics_node_update</tt></a> - supports order statistics.</li> - - <li><a href= - "trie_prefix_search_node_update.html"><tt>trie_prefix_search_node_update</tt></a> - supports searching for ranges that match a given prefix. See - <a href= - "http://gcc.gnu.org/viewcvs/*checkout*/trunk/libstdc%2B%2B-v3/testsuite/ext/pb_ds/example/trie_prefix_search.cc"><tt>trie_prefix_search.cc</tt></a>.</li> - - <li><a href= - "null_trie_node_update.html"><tt>null_trie_node_update</tt></a> - is the null node updater.</li> - </ol> - - <h2><a name="add_methods" id="add_methods">Additional - Methods</a></h2> - - <p>Trie-based containers support split and join methods; the - rationale is equal to that of tree-based containers supporting - these methods (see <a href= - "tree_based_containers.html#add_methods">Tree-Based - Containers::Additional Methods</a>).</p> - </div> -</body> -</html> |