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| author | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-07-20 20:00:05 +0100 |
|---|---|---|
| committer | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-07-20 20:00:05 +0100 |
| commit | 3ef782d3745ea8f25a3151561a3cfb882190210e (patch) | |
| tree | 86b9c2f5fde051dd0bced99b3fc9f5a3ba08db69 /docs/programmer_reference/stl_container_specific.html | |
| download | berkeleydb-3ef782d3745ea8f25a3151561a3cfb882190210e.tar.gz | |
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| -rw-r--r-- | docs/programmer_reference/stl_container_specific.html | 168 |
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diff --git a/docs/programmer_reference/stl_container_specific.html b/docs/programmer_reference/stl_container_specific.html new file mode 100644 index 00000000..bfe4907e --- /dev/null +++ b/docs/programmer_reference/stl_container_specific.html @@ -0,0 +1,168 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!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"> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <title>Dbstl container specific notes</title> + <link rel="stylesheet" href="gettingStarted.css" type="text/css" /> + <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> + <link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" /> + <link rel="up" href="stl.html" title="Chapter 7. Standard Template Library API" /> + <link rel="prev" href="stl_persistence.html" title="Dbstl persistence" /> + <link rel="next" href="stl_efficienct_use.html" title="Using dbstl efficiently" /> + </head> + <body> + <div xmlns="" class="navheader"> + <div class="libver"> + <p>Library Version 11.2.5.3</p> + </div> + <table width="100%" summary="Navigation header"> + <tr> + <th colspan="3" align="center">Dbstl container specific notes</th> + </tr> + <tr> + <td width="20%" align="left"><a accesskey="p" href="stl_persistence.html">Prev</a> </td> + <th width="60%" align="center">Chapter 7. Standard Template Library API</th> + <td width="20%" align="right"> <a accesskey="n" href="stl_efficienct_use.html">Next</a></td> + </tr> + </table> + <hr /> + </div> + <div class="sect1" lang="en" xml:lang="en"> + <div class="titlepage"> + <div> + <div> + <h2 class="title" style="clear: both"><a id="stl_container_specific"></a>Dbstl container specific notes</h2> + </div> + </div> + </div> + <div class="toc"> + <dl> + <dt> + <span class="sect2"> + <a href="stl_container_specific.html#idp1313840">db_vector specific notes</a> + </span> + </dt> + <dt> + <span class="sect2"> + <a href="stl_container_specific.html#idp1381768">Associative container specific notes</a> + </span> + </dt> + </dl> + </div> + <div class="sect2" lang="en" xml:lang="en"> + <div class="titlepage"> + <div> + <div> + <h3 class="title"><a id="idp1313840"></a>db_vector specific notes</h3> + </div> + </div> + </div> + <div class="itemizedlist"> + <ul type="disc"> + <li> + <p> + Set the <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> flag in the database handle if you want + <code class="classname">db_vector<></code> to work like + <code class="classname">std::vector</code> or <code class="classname">std::deque</code>. Do not set + <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> if you want <code class="classname">db_vector<></code> to work like + <code class="classname">std::list</code>. Note that without <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> set, + <code class="classname">db_vector<></code> can work faster. + </p> + <p> + For example, to construct a fast std::queue/std::stack object, you only need a + <code class="classname">db_vector<></code> object whose database handle does not have + <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> set. Of course, if the database handle has <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> set, it + still works for this kind of scenario, just not as fast. + </p> + <p> + <code class="classname">db_vector</code> does not check whether <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> is set. If + you do not set it, <code class="classname">db_vector<></code> will not work like + std::vector<>/std::deque<> with regard to operator[], because the + indices are not maintained in that case. + </p> + <p> + You can find example code showing how to use this feature in the + <code class="methodname">StlAdvancedFeaturesExample::queue_stack()</code> method. + </p> + </li> + <li> + <p> + Just as is the case with <code class="classname">std::vector</code>, inserting/deleting in + the middle of a <code class="classname">db_vector</code> is slower than doing the same + action at the end of the sequence. This is because the underlying DB_RECNO DB (with + the <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> flag set) is relatively slow when inserting/deleting in the middle + or the head — it has to update the index numbers of all the records following + the one that was inserted/deleted. If you do not need to keep the index ordered on + insert/delete, you can use <code class="classname">db_map</code> instead. + </p> + <p> + <code class="classname">db_vector</code> also contains methods inherited from + <code class="classname">std::list</code> and <code class="classname">std::deque</code>, + including <code class="classname">std::list<>'s</code> unique methods + <code class="methodname">remove()</code>, <code class="methodname">remove_if()</code>, + <code class="methodname">unique()</code>, <code class="methodname">merge()</code>, + <code class="methodname">sort()</code>, <code class="methodname">reverse()</code>, and + <code class="methodname">splice()</code>. These use the identical semantics/behaviors + of the <code class="classname">std::list<></code> methods, although + pushing/deleting at the head is slower than the + <code class="methodname">std::deque</code> and <code class="methodname">std::list</code> + equivalent when there are quite a lot of elements in the database. + </p> + </li> + <li> + <p> + You can use <code class="classname">std::queue</code>, + <code class="classname">std::priority_queue</code> and <code class="classname">std::stack</code> + container adapters with <code class="classname">db_vector</code>; they work with db_vector + even without <a href="../api_reference/C/dbset_flags.html#dbset_flags_DB_RENUMBER" class="olink">DB_RENUMBER</a> set. + </p> + </li> + </ul> + </div> + </div> + <div class="sect2" lang="en" xml:lang="en"> + <div class="titlepage"> + <div> + <div> + <h3 class="title"><a id="idp1381768"></a>Associative container specific notes</h3> + </div> + </div> + </div> + <p> + <code class="classname">db_map</code> contains the union of method set from + <code class="classname">std::map</code> and <code class="classname">hash_map</code>, but there are some + methods that can only be called on containers backed by <code class="literal">DB_BTREE</code> or + <code class="literal">DB_HASH</code> databases. You can call + <code class="function">db_map<>::is_hash()</code> to figure out the type of the backing + database. If you call unsupported methods then an InvalidFunctionCall exception is thrown. + </p> + <p> + These are the <code class="literal">DB_BTREE</code> specific methods: <code class="methodname">upper_bound()</code>, + <code class="methodname">lower_bound()</code>, <code class="methodname">key_comp()</code>, + and <code class="methodname">value_comp()</code>. The <code class="literal">DB_HASH</code> specific methods are + <code class="methodname">key_eq()</code>, <code class="methodname">hash_funct()</code>. + </p> + </div> + </div> + <div class="navfooter"> + <hr /> + <table width="100%" summary="Navigation footer"> + <tr> + <td width="40%" align="left"><a accesskey="p" href="stl_persistence.html">Prev</a> </td> + <td width="20%" align="center"> + <a accesskey="u" href="stl.html">Up</a> + </td> + <td width="40%" align="right"> <a accesskey="n" href="stl_efficienct_use.html">Next</a></td> + </tr> + <tr> + <td width="40%" align="left" valign="top">Dbstl persistence </td> + <td width="20%" align="center"> + <a accesskey="h" href="index.html">Home</a> + </td> + <td width="40%" align="right" valign="top"> Using dbstl efficiently</td> + </tr> + </table> + </div> + </body> +</html> |