diff options
Diffstat (limited to 'gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/ds_gen.html')
| -rw-r--r-- | gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/ds_gen.html | 344 |
1 files changed, 0 insertions, 344 deletions
diff --git a/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/ds_gen.html b/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/ds_gen.html deleted file mode 100644 index ec99c4d5f..000000000 --- a/gcc-4.4.3/libstdc++-v3/doc/html/ext/pb_ds/ds_gen.html +++ /dev/null @@ -1,344 +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>Data-Structure Genericity</title> - <meta http-equiv="Content-Type" content= - "text/html; charset=us-ascii" /> - </head> - -<body> - <div id="page"> - <h1>Data-Structure Genericity</h1> - - <h2><a name="problem" id="problem">The Basic Problem</a></h2> - - <p>The design attempts to address the following problem. When - writing a function manipulating a generic container object, - what is the behavior of the object? <i>E.g.</i>, suppose one - writes</p> - <pre> -<b>template</b><<b>typename</b> Cntnr> -<b>void</b> -some_op_sequence(Cntnr &r_container) -{ - ... -} -</pre>then one needs to address the following questions in the body -of <tt>some_op_sequence</tt>: - - <ol> - <li>Which types and methods does <tt>Cntnr</tt> support? - Containers based on hash tables can be queries for the - hash-functor type and object; this is meaningless for - tree-based containers. Containers based on trees can be - split, joined, or can erase iterators and return the - following iterator; this cannot be done by hash-based - containers.</li> - - <li>What are the guarantees of <tt>Cntnr</tt>? A container - based on a probing hash-table invalidates all iterators when - it is modified; this is not the case for containers based on - node-based trees. Containers based on a node-based tree can - be split or joined without exceptions; this is not the case - for containers based on vector-based trees.</li> - - <li>How does the container maintain its elements? Tree-based - and Trie-based containers store elements by key order; - others, typically, do not. A container based on a splay trees - or lists with update policies "cache" "frequently accessed" - elements; containers based on most other underlying - data structures do not.</li> - </ol> - - <p>The remainder of this section deals with these issues.</p> - - <h2><a name="ds_hierarchy" id="ds_hierarchy">Container - Hierarchy</a></h2> - - <p>Figure <a href="#cd">Container class hierarchy</a> shows the - container hierarchy.</p> - - <h6 class="c1"><a name="cd" id="cd"><img src="container_cd.png" alt= - "no image" /></a></h6> - - <h6 class="c1">Container class hierarchy.</h6> - - <ol> - <li><a href= - "container_base.html"><tt>container_base</tt></a> is an - abstract base class for associative containers.</li> - - <li>Tree-Like-Based Associative-Containers: - - <ol> - <li><a href= - "basic_tree.html"><tt>basic_tree</tt></a> - is an abstract base class for tree-like-based - associative-containers</li> - - <li><a href= - "tree.html"><tt>tree</tt></a> - is a concrete base class for tree-based - associative-containers</li> - - <li><a href= - "trie.html"><tt>trie</tt></a> - is a concrete base class trie-based - associative-containers</li> - </ol> - </li> - - <li>Hash-Based Associative-Containers: - - <ol> - <li><a href= - "basic_hash_table.html"><tt>basic_hash_table</tt></a> - is an abstract base class for hash-based - associative-containers</li> - - <li><a href= - "cc_hash_table.html"><tt>cc_hash_table</tt></a> - is a concrete collision-chaining hash-based - associative-containers</li> - - <li><a href= - "gp_hash_table.html"><tt>gp_hash_table</tt></a> - is a concrete (general) probing hash-based - associative-containers</li> - </ol> - </li> - - <li>List-Based Associative-Containers: - - <ol> - <li><a href= - "list_update.html"><tt>list_update</tt></a> - - list-based update-policy associative container</li> - </ol> - </li> - </ol> - - <p>The hierarchy is composed naturally so that commonality is - captured by base classes. Thus <tt><b>operator[]</b></tt> is - defined <a href= - "container_base.html"><tt>container_base</tt></a>, since - all containers support it. Conversely <tt>split</tt> is defined - in <a href= - "basic_tree.html"><tt>basic_tree</tt></a>, - since only tree-like containers support it. <a href= - "#container_traits">Data-Structure Tags and Traits</a> discusses how - to query which types and methods each container supports.</p> - - <h2><a name="container_traits" id="container_traits">Data-Structure Tags and - Traits</a></h2> - - <p>Tags and traits are very useful for manipulating generic - types. For example, if <tt>It</tt> is an iterator class, then - <tt><b>typename</b> It::iterator_category</tt> or - <tt><b>typename</b> - std::iterator_traits<It>::iterator_category</tt> will - yield its category, and <tt><b>typename</b> - std::iterator_traits<It>::value_type</tt> will yield its - value type.</p> - - <p><tt>pb_ds</tt> contains a tag hierarchy corresponding to the - hierarchy in Figure <a href="#cd">Class hierarchy</a>. The tag - hierarchy is shown in Figure <a href= - "#tag_cd">Data-structure tag class hierarchy</a>.</p> - - <h6 class="c1"><a name="tag_cd" id="tag_cd"><img src= - "assoc_container_tag_cd.png" alt="no image" /></a></h6> - - <h6 class="c1">Data-structure tag class hierarchy.</h6> - - <p><a href= - "container_base.html"><tt>container_base</tt></a> - publicly defines <tt>container_category</tt> as one of the classes in - Figure <a href="#tag_cd">Data-structure tag class - hierarchy</a>. Given any container <tt>Cntnr</tt>, the tag of - the underlying data structure can be found via - <tt><b>typename</b> Cntnr::container_category</tt>.</p> - - <p>Additionally, a traits mechanism can be used to query a - container type for its attributes. Given any container - <tt>Cntnr</tt>, then <tt><a href= - "assoc_container_traits.html">__gnu_pbds::container_traits</a><Cntnr></tt> - is a traits class identifying the properties of the - container.</p> - - <p>To find if a container can throw when a key is erased (which - is true for vector-based trees, for example), one can - use</p><a href= - "assoc_container_traits.html"><tt>container_traits</tt></a><tt><Cntnr>::erase_can_throw</tt>, - for example. - - <p>Some of the definitions in <a href= - "assoc_container_traits.html"><tt>container_traits</tt></a> are - dependent on other definitions. <i>E.g.</i>, if <a href= - "assoc_container_traits.html"><tt>container_traits</tt></a><tt><Cntnr>::order_preserving</tt> - is <tt><b>true</b></tt> (which is the case for containers based - on trees and tries), then the container can be split or joined; - in this case, <a href= - "assoc_container_traits.html"><tt>container_traits</tt></a><tt><Cntnr>::split_join_can_throw</tt> - indicates whether splits or joins can throw exceptions (which - is true for vector-based trees); otherwise <a href= - "assoc_container_traits.html"><tt>container_traits</tt></a><tt><Cntnr>::split_join_can_throw</tt> - will yield a compilation error. (This is somewhat similar to a - compile-time version of the COM model [<a href= - "references.html#mscom">mscom</a>]).</p> - - <h2><a name="find_range" id="find_range">Point-Type and - Range-Type Methods and Iterators</a></h2> - - <h3><a name="it_unordered" id="it_unordered">Iterators in - Unordered Container Types</a></h3> - - <p><tt>pb_ds</tt> differentiates between two types of methods - and iterators: point-type methods and iterators, and range-type - methods and iterators (see <a href= - "motivation.html#assoc_diff_it">Motivation::Associative - Containers::Differentiating between Iterator Types</a> and - <a href="tutorial.html#assoc_find_range">Tutorial::Associative - Containers::Point-Type and Range-Type Methods and - Iterators</a>). Each associative container's interface includes - the methods:</p> - <pre> -const_point_iterator -find(const_key_reference r_key) const; - -point_iterator -find(const_key_reference r_key); - -std::pair<point_iterator,<b>bool</b>> -insert(const_reference r_val); -</pre> - - <p>The relationship between these iterator types varies between - container types. Figure <a href= - "#point_iterators_cd">Point-type and range-type iterators</a>-A - shows the most general invariant between point-type and - range-type iterators: <tt>iterator</tt>, <i>e.g.</i>, can - always be converted to <tt>point_iterator</tt>. Figure <a href= - "#point_iterators_cd">Point-type and range-type iterators</a>-B - shows invariants for order-preserving containers: point-type - iterators are synonymous with range-type iterators. - Orthogonally, Figure <a href="#point_iterators_cd">Point-type - and range-type iterators</a>-C shows invariants for "set" - containers: iterators are synonymous with const iterators.</p> - - <h6 class="c1"><a name="point_iterators_cd" id= - "point_iterators_cd"><img src="point_iterators_cd.png" alt= - "no image" /></a></h6> - - <h6 class="c1">Point-type and range-type iterators.</h6> - - <p>Note that point-type iterators in self-organizing containers - (<i>e.g.</i>, hash-based associative containers) lack movement - operators, such as <tt><b>operator++</b></tt> - in fact, this - is the reason why <tt>pb_ds</tt> differentiates from the STL's - design on this point.</p> - - <p>Typically, one can determine an iterator's movement - capabilities in the STL using - <tt>std::iterator_traits<It>iterator_category</tt>, which - is a <tt><b>struct</b></tt> indicating the iterator's movement - capabilities. Unfortunately, none of the STL's predefined - categories reflect a pointer's <u>not</u> having any movement - capabilities whatsoever. Consequently, <tt>pb_ds</tt> adds a - type <a href= - "trivial_iterator_tag.html"><tt>trivial_iterator_tag</tt></a> - (whose name is taken from a concept in [<a href= - "references.html#sgi_stl">sgi_stl</a>]), which is the category - of iterators with no movement capabilities. All other STL tags, - such as <tt>forward_iterator_tag</tt> retain their common - use.</p> - - <h3><a name="inv_guar" id="inv_guar">Invalidation - Guarantees</a></h3> - - <p><a href= - "motivation.html#assoc_inv_guar">Motivation::Associative - Containers::Differentiating between Iterator - Types::Invalidation Guarantees</a> posed a problem. Given three - different types of associative containers, a modifying - operation (in that example, <tt>erase</tt>) invalidated - iterators in three different ways: the iterator of one - container remained completely valid - it could be de-referenced - and incremented; the iterator of a different container could - not even be de-referenced; the iterator of the third container - could be de-referenced, but its "next" iterator changed - unpredictably.</p> - - <p>Distinguishing between find and range types allows - fine-grained invalidation guarantees, because these questions - correspond exactly to the question of whether point-type - iterators and range-type iterators are valid. <a href= - "#invalidation_guarantee_cd">Invalidation guarantees class - hierarchy</a> shows tags corresponding to different types of - invalidation guarantees.</p> - - <h6 class="c1"><a name="invalidation_guarantee_cd" id= - "invalidation_guarantee_cd"><img src= - "invalidation_guarantee_cd.png" alt="no image" /></a></h6> - - <h6 class="c1">Invalidation guarantees class hierarchy.</h6> - - <ol> - <li><a href= - "basic_invalidation_guarantee.html"><tt>basic_invalidation_guarantee</tt></a> - corresponds to a basic guarantee that a point-type iterator, - a found pointer, or a found reference, remains valid as long - as the container object is not modified.</li> - - <li><a href= - "point_invalidation_guarantee.html"><tt>point_invalidation_guarantee</tt></a> - corresponds to a guarantee that a point-type iterator, a - found pointer, or a found reference, remains valid even if - the container object is modified.</li> - - <li><a href= - "range_invalidation_guarantee.html"><tt>range_invalidation_guarantee</tt></a> - corresponds to a guarantee that a range-type iterator remains - valid even if the container object is modified.</li> - </ol> - - <p>As shown in <a href= - "tutorial.html#assoc_find_range">Tutorial::Associative - Containers::Point-Type and Range-Type Methods and - Iterators</a>, to find the invalidation guarantee of a - container, one can use</p> - <pre> -<b>typename</b> <a href= -"assoc_container_traits.html">container_traits</a><Cntnr>::invalidation_guarantee -</pre> - - <p>which is one of the classes in Figure <a href= - "#invalidation_guarantee_cd">Invalidation guarantees class - hierarchy</a>.</p> - - <p>Note that this hierarchy corresponds to the logic it - represents: if a container has range-invalidation guarantees, - then it must also have find invalidation guarantees; - correspondingly, its invalidation guarantee (in this case - <a href= - "range_invalidation_guarantee.html"><tt>range_invalidation_guarantee</tt></a>) - can be cast to its base class (in this case <a href= - "point_invalidation_guarantee.html"><tt>point_invalidation_guarantee</tt></a>). - This means that this this hierarchy can be used easily using - standard metaprogramming techniques, by specializing on the - type of <tt>invalidation_guarantee</tt>.</p> - - <p>(These types of problems were addressed, in a more general - setting, in [<a href= - "references.html#meyers96more">meyers96more</a>] - Item 2. In - our opinion, an invalidation-guarantee hierarchy would solve - these problems in all container types - not just associative - containers.)</p> - </div> -</body> -</html> |