248 lines
11 KiB
HTML
248 lines
11 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
||
<title>Concepts</title>
|
||
<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css">
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
|
||
<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
|
||
<link rel="up" href="../string_algo.html" title="Chapter 2. Boost String Algorithms Library">
|
||
<link rel="prev" href="design.html" title="Design Topics">
|
||
<link rel="next" href="reference.html" title="Reference">
|
||
</head>
|
||
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
||
<table cellpadding="2" width="100%"><tr>
|
||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td>
|
||
<td align="center"><a href="../../../index.html">Home</a></td>
|
||
<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td>
|
||
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
|
||
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
||
<td align="center"><a href="../../../more/index.htm">More</a></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="design.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../string_algo.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="reference.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
|
||
<a name="string_algo.concept"></a>Concepts</h2></div></div></div>
|
||
<div class="toc"><dl class="toc">
|
||
<dt><span class="section"><a href="concept.html#id-1.3.3.8.2">Definitions</a></span></dt>
|
||
<dt><span class="section"><a href="concept.html#string_algo.finder_concept">Finder Concept</a></span></dt>
|
||
<dt><span class="section"><a href="concept.html#string_algo.formatter_concept">Formatter concept</a></span></dt>
|
||
</dl></div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="id-1.3.3.8.2"></a>Definitions</h3></div></div></div>
|
||
<div class="table">
|
||
<a name="id-1.3.3.8.2.2"></a><p class="title"><b>Table 2.13. Notation</b></p>
|
||
<div class="table-contents"><table class="table" summary="Notation">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<tbody>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">F</code></td>
|
||
<td align="left">A type that is a model of Finder</td>
|
||
</tr>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">Fmt</code></td>
|
||
<td align="left">A type that is a model of Formatter</td>
|
||
</tr>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">Iter</code></td>
|
||
<td align="left">
|
||
Iterator Type
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">f</code></td>
|
||
<td align="left">Object of type <code class="computeroutput">F</code>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">fmt</code></td>
|
||
<td align="left">Object of type <code class="computeroutput">Fmt</code>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td align="left"><code class="computeroutput">i,j</code></td>
|
||
<td align="left">Objects of type <code class="computeroutput">Iter</code>
|
||
</td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
</div>
|
||
<br class="table-break">
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="string_algo.finder_concept"></a>Finder Concept</h3></div></div></div>
|
||
<p>
|
||
Finder is a functor which searches for an arbitrary part of a container.
|
||
The result of the search is given as an <code class="computeroutput">iterator_range</code>
|
||
delimiting the selected part.
|
||
</p>
|
||
<div class="table">
|
||
<a name="id-1.3.3.8.3.3"></a><p class="title"><b>Table 2.14. Valid Expressions</b></p>
|
||
<div class="table-contents"><table class="table" summary="Valid Expressions">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th align="left">Expression</th>
|
||
<th align="left">Return Type</th>
|
||
<th align="left">Effects</th>
|
||
</tr></thead>
|
||
<tbody><tr>
|
||
<td align="left"><code class="computeroutput">f(i,j)</code></td>
|
||
<td align="left">Convertible to <code class="computeroutput">iterator_range<Iter></code>
|
||
</td>
|
||
<td align="left">Perform the search on the interval [i,j) and returns the result of the search</td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
</div>
|
||
<br class="table-break"><p>
|
||
Various algorithms need to perform a search in a container and a Finder is a generalization of such
|
||
search operations that allows algorithms to abstract from searching. For instance, generic replace
|
||
algorithms can replace any part of the input, and the Finder is used to select the desired one.
|
||
</p>
|
||
<p>
|
||
Note, that it is only required that the finder works with a particular iterator type. However,
|
||
a Finder operation can be defined as a template, allowing the Finder to work with any iterator.
|
||
</p>
|
||
<p>
|
||
<span class="bold"><strong>Examples</strong></span>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||
<li class="listitem">
|
||
Finder implemented as a class. This Finder always returns the whole input as a match. <code class="computeroutput">operator()</code>
|
||
is templated, so that the finder can be used on any iterator type.
|
||
|
||
<pre class="programlisting">
|
||
struct simple_finder
|
||
{
|
||
template<typename ForwardIteratorT>
|
||
boost::iterator_range<ForwardIteratorT> operator()(
|
||
ForwardIteratorT Begin,
|
||
ForwardIteratorT End )
|
||
{
|
||
return boost::make_range( Begin, End );
|
||
}
|
||
};
|
||
</pre>
|
||
</li>
|
||
<li class="listitem">
|
||
Function Finder. Finder can be any function object. That is, any ordinary function with the
|
||
required signature can be used as well. However, such a function can be used only for
|
||
a specific iterator type.
|
||
|
||
<pre class="programlisting">
|
||
boost::iterator_range<std::string> simple_finder(
|
||
std::string::const_iterator Begin,
|
||
std::string::const_iterator End )
|
||
{
|
||
return boost::make_range( Begin, End );
|
||
}
|
||
</pre>
|
||
</li>
|
||
</ul></div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
<div class="section">
|
||
<div class="titlepage"><div><div><h3 class="title">
|
||
<a name="string_algo.formatter_concept"></a>Formatter concept</h3></div></div></div>
|
||
<p>
|
||
Formatters are used by <a class="link" href="design.html#string_algo.replace" title="Replace Algorithms">replace algorithms</a>.
|
||
They are used in close combination with finders.
|
||
A formatter is a functor, which takes a result from a Finder operation and transforms it in a specific way.
|
||
The operation of the formatter can use additional information provided by a specific finder,
|
||
for example <code class="computeroutput"><a class="link" href="../boost/algorithm/regex_formatter.html" title="Function template regex_formatter">regex_formatter()</a></code> uses the match information from
|
||
<code class="computeroutput"><a class="link" href="../boost/algorithm/regex_finder.html" title="Function template regex_finder">regex_finder()</a></code> to format the result of formatter operation.
|
||
</p>
|
||
<div class="table">
|
||
<a name="id-1.3.3.8.4.3"></a><p class="title"><b>Table 2.15. Valid Expressions</b></p>
|
||
<div class="table-contents"><table class="table" summary="Valid Expressions">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th align="left">Expression</th>
|
||
<th align="left">Return Type</th>
|
||
<th align="left">Effects</th>
|
||
</tr></thead>
|
||
<tbody><tr>
|
||
<td align="left"><code class="computeroutput">fmt(f(i,j))</code></td>
|
||
<td align="left">A container type, accessible using container traits</td>
|
||
<td align="left">Formats the result of the finder operation</td>
|
||
</tr></tbody>
|
||
</table></div>
|
||
</div>
|
||
<br class="table-break"><p>
|
||
Similarly to finders, formatters generalize format operations. When a finder is used to
|
||
select a part of the input, formatter takes this selection and performs some formatting
|
||
on it. Algorithms can abstract from formatting using a formatter.
|
||
</p>
|
||
<p>
|
||
<span class="bold"><strong>Examples</strong></span>
|
||
</p>
|
||
<p>
|
||
</p>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||
<li class="listitem">
|
||
Formatter implemented as a class. This Formatter does not perform any formatting and
|
||
returns the match, repackaged. <code class="computeroutput">operator()</code>
|
||
is templated, so that the Formatter can be used on any Finder type.
|
||
|
||
<pre class="programlisting">
|
||
struct simple_formatter
|
||
{
|
||
template<typename FindResultT>
|
||
std::string operator()( const FindResultT& Match )
|
||
{
|
||
std::string Temp( Match.begin(), Match.end() );
|
||
return Temp;
|
||
}
|
||
};
|
||
</pre>
|
||
</li>
|
||
<li class="listitem">
|
||
Function Formatter. Similarly to Finder, Formatter can be any function object.
|
||
However, as a function, it can be used only with a specific Finder type.
|
||
|
||
<pre class="programlisting">
|
||
std::string simple_formatter( boost::iterator_range<std::string::const_iterator>& Match )
|
||
{
|
||
std::string Temp( Match.begin(), Match.end() );
|
||
return Temp;
|
||
}
|
||
</pre>
|
||
</li>
|
||
</ul></div>
|
||
<p>
|
||
</p>
|
||
</div>
|
||
</div>
|
||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||
<td align="left"></td>
|
||
<td align="right"><div class="copyright-footer">Copyright © 2002-2004 Pavol Droba<p>Use, modification and distribution is subject to the Boost
|
||
Software License, Version 1.0. (See accompanying file
|
||
<code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||
</p>
|
||
</div></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="design.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../string_algo.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="reference.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
</body>
|
||
</html>
|