forked from boostorg/fusion
237 lines
14 KiB
HTML
237 lines
14 KiB
HTML
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
|
||
<title>cons</title>
|
||
<link rel="stylesheet" href="../../../boostbook.css" type="text/css">
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.66.1">
|
||
<link rel="start" href="../../../index.html" title="Chapter 1. Fusion 2.0">
|
||
<link rel="up" href="../containers.html" title="Containers">
|
||
<link rel="prev" href="vector.html" title="vector">
|
||
<link rel="next" href="list.html" title="list">
|
||
</head>
|
||
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
||
<table cellpadding="2" width="100%">
|
||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td>
|
||
<td align="center"><a href="../../../../../../../index.htm">Home</a></td>
|
||
<td align="center"><a href="../../../../../../libraries.htm">Libraries</a></td>
|
||
<td align="center"><a href="../../../../../../../people/people.htm">People</a></td>
|
||
<td align="center"><a href="../../../../../../../more/faq.htm">FAQ</a></td>
|
||
<td align="center"><a href="../../../../../../../more/index.htm">More</a></td>
|
||
</table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="vector.html"><img src="../../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../containers.html"><img src="../../../images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../images/home.png" alt="Home"></a><a accesskey="n" href="list.html"><img src="../../../images/next.png" alt="Next"></a>
|
||
</div>
|
||
<div class="section" lang="en">
|
||
<div class="titlepage"><div><div><h4 class="title">
|
||
<a name="fusion.sequences.containers.cons"></a><a href="cons.html" title="cons">cons</a></h4></div></div></div>
|
||
<a name="fusion.sequences.containers.cons.description"></a><h5>
|
||
<a name="id484257"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.description">Description</a>
|
||
</h5>
|
||
<p>
|
||
<tt class="computeroutput"><span class="identifier">cons</span></tt> is a simple <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward Sequence</a>.
|
||
It is a lisp style recursive list structure where <tt class="computeroutput"><span class="identifier">car</span></tt>
|
||
is the <span class="emphasis"><em>head</em></span> and <tt class="computeroutput"><span class="identifier">cdr</span></tt>
|
||
is the <span class="emphasis"><em>tail</em></span>: usually another cons structure or <tt class="computeroutput"><span class="identifier">nil</span></tt>: the empty list. Fusion's <a href="list.html" title="list"><tt class="computeroutput"><span class="identifier">list</span></tt></a> is built on top of this more
|
||
primitive data structure. It is more efficient than <a href="vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a> when the target sequence
|
||
is constructed piecemeal (a data at a time). The runtime cost of access
|
||
to each element is peculiarly constant (see <a href="../../notes.html#fusion.notes.recursive_inlined_functions">Recursive
|
||
Inlined Functions</a>).
|
||
</p>
|
||
<a name="fusion.sequences.containers.cons.header"></a><h5>
|
||
<a name="id484394"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.header">Header</a>
|
||
</h5>
|
||
<pre class="programlisting">
|
||
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">/</span><span class="identifier">container</span><span class="special">/</span><span class="identifier">list</span><span class="special">/</span><span class="identifier">cons</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
|
||
</pre>
|
||
<a name="fusion.sequences.containers.cons.synopsis"></a><h5>
|
||
<a name="id484508"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.synopsis">Synopsis</a>
|
||
</h5>
|
||
<pre class="programlisting">
|
||
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Car</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Cdr</span> <span class="special">=</span> <span class="identifier">nil</span><span class="special">></span>
|
||
<span class="keyword">struct</span> <span class="identifier">cons</span><span class="special">;</span>
|
||
</pre>
|
||
<a name="fusion.sequences.containers.cons.template_parameters"></a><h5>
|
||
<a name="id484616"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.template_parameters">Template
|
||
parameters</a>
|
||
</h5>
|
||
<div class="informaltable">
|
||
<h4>
|
||
<a name="id484638"></a>
|
||
</h4>
|
||
<table class="table">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th>Parameter</th>
|
||
<th>Description</th>
|
||
<th>Default</th>
|
||
</tr></thead>
|
||
<tbody>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">Car</span></tt></td>
|
||
<td>Head
|
||
type</td>
|
||
<td> </td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">Cdr</span></tt></td>
|
||
<td>Tail
|
||
type</td>
|
||
<td><tt class="computeroutput"><span class="identifier">nil</span></tt></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<a name="fusion.sequences.containers.cons.model_of"></a><h5>
|
||
<a name="id484727"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.model_of">Model of</a>
|
||
</h5>
|
||
<div class="itemizedlist"><ul type="disc"><li><a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward Sequence</a></li></ul></div>
|
||
<div class="variablelist">
|
||
<p class="title"><b>Notation</b></p>
|
||
<dl>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">nil</span></tt></span></dt>
|
||
<dd>
|
||
An empty <tt class="computeroutput"><span class="identifier">cons</span></tt>
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">C</span></tt></span></dt>
|
||
<dd>
|
||
A <tt class="computeroutput"><span class="identifier">cons</span></tt> type
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">l</span></tt>,
|
||
<tt class="computeroutput"><span class="identifier">l2</span></tt></span></dt>
|
||
<dd>
|
||
Instances of <tt class="computeroutput"><span class="identifier">cons</span></tt>
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">car</span></tt></span></dt>
|
||
<dd>
|
||
An arbitrary data
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">cdr</span></tt></span></dt>
|
||
<dd>
|
||
Another <tt class="computeroutput"><span class="identifier">cons</span></tt> list
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">s</span></tt></span></dt>
|
||
<dd>
|
||
A <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward
|
||
Sequence</a>
|
||
</dd>
|
||
<dt><span class="term"><tt class="computeroutput"><span class="identifier">N</span></tt></span></dt>
|
||
<dd>
|
||
An Integral Constant
|
||
</dd>
|
||
</dl>
|
||
</div>
|
||
<a name="fusion.sequences.containers.cons.expression_semantics"></a><h5>
|
||
<a name="id484959"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.expression_semantics">Expression
|
||
Semantics</a>
|
||
</h5>
|
||
<p>
|
||
Semantics of an expression is defined only where it differs from, or is
|
||
not defined in <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward
|
||
Sequence</a>.
|
||
</p>
|
||
<div class="informaltable">
|
||
<h4>
|
||
<a name="id484996"></a>
|
||
</h4>
|
||
<table class="table">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th>Expression</th>
|
||
<th>Semantics</th>
|
||
</tr></thead>
|
||
<tbody>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">nil</span><span class="special">()</span></tt></td>
|
||
<td>Creates
|
||
an empty list.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">C</span><span class="special">()</span></tt></td>
|
||
<td>Creates
|
||
a cons with default constructed elements.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">C</span><span class="special">(</span><span class="identifier">car</span><span class="special">)</span></tt></td>
|
||
<td>Creates
|
||
a cons with <tt class="computeroutput"><span class="identifier">car</span></tt> head
|
||
and default constructed tail.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">C</span><span class="special">(</span><span class="identifier">car</span><span class="special">,</span> <span class="identifier">cdr</span><span class="special">)</span></tt></td>
|
||
<td>Creates
|
||
a cons with <tt class="computeroutput"><span class="identifier">car</span></tt> head
|
||
and <tt class="computeroutput"><span class="identifier">cdr</span></tt> tail.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">C</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></tt></td>
|
||
<td>Copy
|
||
constructs a cons from a <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward
|
||
Sequence</a>, <tt class="computeroutput"><span class="identifier">s</span></tt>.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><span class="identifier">l</span> <span class="special">=</span> <span class="identifier">s</span></tt></td>
|
||
<td>Assigns to a cons,
|
||
<tt class="computeroutput"><span class="identifier">l</span></tt>, from a <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward
|
||
Sequence</a>, <tt class="computeroutput"><span class="identifier">s</span></tt>.</td>
|
||
</tr>
|
||
<tr>
|
||
<td><tt class="computeroutput"><a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">l</span><span class="special">)</span></tt></td>
|
||
<td>The
|
||
Nth element from the beginning of the sequence; see <a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a>.</td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<p class="blurb">
|
||
<span class="inlinemediaobject"><img src="../../../images/note.png" alt="note"></span> <tt class="computeroutput"><a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">l</span><span class="special">)</span></tt> is
|
||
provided for convenience and compatibility with the original <a href="http://www.boost.org/libs/tuple/doc/tuple_users_guide.html" target="_top">Boost.Tuple</a>
|
||
library, despite <tt class="computeroutput"><span class="identifier">cons</span></tt> being
|
||
a <a href="../concepts/forward_sequence.html" title="Forward
|
||
Sequence">Forward Sequence</a>
|
||
only (<tt class="computeroutput"><span class="identifier">at</span></tt> is supposed to
|
||
be a <a href="../concepts/random_access_sequence.html" title="Random
|
||
Access Sequence">Random
|
||
Access Sequence</a> requirement). The runtime complexity of <a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a> is constant (see <a href="../../notes.html#fusion.notes.recursive_inlined_functions">Recursive
|
||
Inlined Functions</a>).
|
||
</p>
|
||
<a name="fusion.sequences.containers.cons.example"></a><h5>
|
||
<a name="id485510"></a>
|
||
<a href="cons.html#fusion.sequences.containers.cons.example">Example</a>
|
||
</h5>
|
||
<pre class="programlisting">
|
||
<span class="identifier">cons</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">cons</span><span class="special"><</span><span class="keyword">float</span><span class="special">></span> <span class="special">></span> <span class="identifier">l</span><span class="special">(</span><span class="number">12</span><span class="special">,</span> <span class="identifier">cons</span><span class="special"><</span><span class="keyword">float</span><span class="special">>(</span><span class="number">5.5f</span><span class="special">));</span>
|
||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">l</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
|
||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <a href="../intrinsics/functions/at.html" title="at"><tt class="computeroutput"><span class="identifier">at</span></tt></a><span class="special"><</span><span class="number">1</span><span class="special">>(</span><span class="identifier">l</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
|
||
</pre>
|
||
</div>
|
||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||
<td align="left"></td>
|
||
<td align="right"><small>Copyright © 2001-2005 Joel de Guzman, Dan Marsden</small></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="vector.html"><img src="../../../images/prev.png" alt="Prev"></a><a accesskey="u" href="../containers.html"><img src="../../../images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../images/home.png" alt="Home"></a><a accesskey="n" href="list.html"><img src="../../../images/next.png" alt="Next"></a>
|
||
</div>
|
||
</body>
|
||
</html>
|