1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>any_range</title> 5<link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../index.html" title="Chapter 1. Range 2.0"> 8<link rel="up" href="../ranges.html" title="Provided Ranges"> 9<link rel="prev" href="../ranges.html" title="Provided Ranges"> 10<link rel="next" href="counting_range.html" title="counting_range"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../ranges.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ranges.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="counting_range.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="range.reference.ranges.any_range"></a><a class="link" href="any_range.html" title="any_range">any_range</a> 28</h4></div></div></div> 29<h6> 30<a name="range.reference.ranges.any_range.h0"></a> 31 <span class="phrase"><a name="range.reference.ranges.any_range.description"></a></span><a class="link" href="any_range.html#range.reference.ranges.any_range.description">Description</a> 32 </h6> 33<p> 34 <code class="computeroutput"><span class="identifier">any_range</span></code> is a range that 35 has the type information erased hence a <code class="computeroutput"><span class="identifier">any_range</span><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward_traversal_tag</span><span class="special">,</span> <span class="keyword">int</span><span class="special">,</span> 36 <span class="identifier">std</span><span class="special">::</span><span class="identifier">ptrdiff_t</span><span class="special">></span></code> 37 can be used to represent a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span></code>, a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span></code> or many other types. 38 </p> 39<p> 40 The <a href="http://www.artima.com/cppsource/type_erasure.html" target="_top">type 41 erasure article</a> covers the motivation and goals of type erasure 42 in this context. Clearly my implementation is building upon a lot of prior 43 art created by others. Thomas Becker's <code class="computeroutput"><span class="identifier">any_iterator</span></code> 44 was a strong influence. Adobe also have an <code class="computeroutput"><span class="identifier">any_iterator</span></code> 45 implementation, but this has very tight coupling to other parts of the 46 library that precluded it from use in Boost.Range. Early development versions 47 of this Range Adaptor directly used Thomas Becker's any_iterator implementation. 48 Subsequently I discovered that the heap allocations of this and many other 49 implementations cause poor speed performance particularly at the tails 50 of the distribution. To solve this required a new design that incorporated 51 the embedded buffer optimization. 52 </p> 53<p> 54 Despite the underlying <code class="computeroutput"><span class="identifier">any_iterator</span></code> 55 being the fastest available implementation, the performance overhead of 56 <code class="computeroutput"><span class="identifier">any_range</span></code> is still appreciable 57 due to the cost of virtual function calls required to implement <code class="computeroutput"><span class="identifier">increment</span></code>, <code class="computeroutput"><span class="identifier">decrement</span></code>, 58 <code class="computeroutput"><span class="identifier">advance</span></code>, <code class="computeroutput"><span class="identifier">equal</span></code> etc. Frequently a better design 59 choice is to convert to a canonical form. 60 </p> 61<p> 62 Please see the <a class="link" href="../adaptors/reference/type_erased.html" title="type_erased">type_erased</a> 63 for a Range Adaptor that returns <code class="computeroutput"><span class="identifier">any_range</span></code> 64 instances. 65 </p> 66<h6> 67<a name="range.reference.ranges.any_range.h1"></a> 68 <span class="phrase"><a name="range.reference.ranges.any_range.synopsis"></a></span><a class="link" href="any_range.html#range.reference.ranges.any_range.synopsis">Synopsis</a> 69 </h6> 70<p> 71</p> 72<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 73 <span class="keyword">class</span> <span class="identifier">Value</span> 74 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traversal</span> 75 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Reference</span> 76 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Difference</span> 77 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Buffer</span> <span class="special">=</span> <span class="identifier">any_iterator_default_buffer</span> 78<span class="special">></span> 79<span class="keyword">class</span> <span class="identifier">any_range</span> 80 <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">iterator_range</span><span class="special"><</span> 81 <span class="identifier">range_detail</span><span class="special">::</span><span class="identifier">any_iterator</span><span class="special"><</span> 82 <span class="identifier">Value</span> 83 <span class="special">,</span> <span class="identifier">Traversal</span> 84 <span class="special">,</span> <span class="identifier">Reference</span> 85 <span class="special">,</span> <span class="identifier">Difference</span> 86 <span class="special">,</span> <span class="identifier">Buffer</span> 87 <span class="special">></span> 88 <span class="special">></span> 89<span class="special">{</span> 90 <span class="keyword">typedef</span> <span class="identifier">range_detail</span><span class="special">::</span><span class="identifier">any_iterator</span><span class="special"><</span> 91 <span class="identifier">Value</span> 92 <span class="special">,</span> <span class="identifier">Traversal</span> 93 <span class="special">,</span> <span class="identifier">Reference</span> 94 <span class="special">,</span> <span class="identifier">Difference</span> 95 <span class="special">,</span> <span class="identifier">Buffer</span> 96 <span class="special">></span> <span class="identifier">any_iterator_type</span><span class="special">;</span> 97 98 <span class="keyword">typedef</span> <span class="identifier">iterator_range</span><span class="special"><</span><span class="identifier">any_iterator_type</span><span class="special">></span> <span class="identifier">base_type</span><span class="special">;</span> 99 100 <span class="keyword">struct</span> <span class="identifier">enabler</span> <span class="special">{};</span> 101 <span class="keyword">struct</span> <span class="identifier">disabler</span> <span class="special">{};</span> 102<span class="keyword">public</span><span class="special">:</span> 103 <span class="keyword">typedef</span> <span class="identifier">any_iterator_type</span> <span class="identifier">iterator</span><span class="special">;</span> 104 <span class="keyword">typedef</span> <span class="identifier">any_iterator_type</span> <span class="identifier">const_iterator</span><span class="special">;</span> 105 106 <span class="identifier">any_range</span><span class="special">()</span> 107 <span class="special">{</span> 108 <span class="special">}</span> 109 110 <span class="identifier">any_range</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">any_range</span><span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> 111 <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">other</span><span class="special">)</span> 112 <span class="special">{</span> 113 <span class="special">}</span> 114 115 <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">WrappedRange</span><span class="special">></span> 116 <span class="identifier">any_range</span><span class="special">(</span><span class="identifier">WrappedRange</span><span class="special">&</span> <span class="identifier">wrapped_range</span><span class="special">)</span> 117 <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">wrapped_range</span><span class="special">),</span> 118 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">wrapped_range</span><span class="special">))</span> 119 <span class="special">{</span> 120 <span class="special">}</span> 121 122 <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">WrappedRange</span><span class="special">></span> 123 <span class="identifier">any_range</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">WrappedRange</span><span class="special">&</span> <span class="identifier">wrapped_range</span><span class="special">)</span> 124 <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">wrapped_range</span><span class="special">),</span> 125 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">wrapped_range</span><span class="special">))</span> 126 <span class="special">{</span> 127 <span class="special">}</span> 128 129 <span class="keyword">template</span><span class="special"><</span> 130 <span class="keyword">class</span> <span class="identifier">OtherValue</span> 131 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">OtherTraversal</span> 132 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">OtherReference</span> 133 <span class="special">,</span> <span class="keyword">class</span> <span class="identifier">OtherDifference</span> 134 <span class="special">></span> 135 <span class="identifier">any_range</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">any_range</span><span class="special"><</span> 136 <span class="identifier">OtherValue</span> 137 <span class="special">,</span> <span class="identifier">OtherTraversal</span> 138 <span class="special">,</span> <span class="identifier">OtherReference</span> 139 <span class="special">,</span> <span class="identifier">OtherDifference</span> 140 <span class="special">,</span> <span class="identifier">Buffer</span> 141 <span class="special">>&</span> <span class="identifier">other</span><span class="special">)</span> 142 <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">other</span><span class="special">),</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">other</span><span class="special">))</span> 143 <span class="special">{</span> 144 <span class="special">}</span> 145 146 <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">Iterator</span><span class="special">></span> 147 <span class="identifier">any_range</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">Iterator</span> <span class="identifier">last</span><span class="special">)</span> 148 <span class="special">:</span> <span class="identifier">base_type</span><span class="special">(</span><span class="identifier">first</span><span class="special">,</span> <span class="identifier">last</span><span class="special">)</span> 149 <span class="special">{</span> 150 <span class="special">}</span> 151<span class="special">};</span> 152</pre> 153<p> 154 </p> 155<h6> 156<a name="range.reference.ranges.any_range.h2"></a> 157 <span class="phrase"><a name="range.reference.ranges.any_range.definition"></a></span><a class="link" href="any_range.html#range.reference.ranges.any_range.definition">Definition</a> 158 </h6> 159<p> 160 Defined in header file <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">range</span><span class="special">/</span><span class="identifier">any_range</span><span class="special">.</span><span class="identifier">hpp</span></code> 161 </p> 162</div> 163<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 164<td align="left"></td> 165<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 166 Neil Groves<p> 167 Distributed under the Boost Software License, Version 1.0. (See accompanying 168 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 169 </p> 170</div></td> 171</tr></table> 172<hr> 173<div class="spirit-nav"> 174<a accesskey="p" href="../ranges.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ranges.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="counting_range.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 175</div> 176</body> 177</html> 178
