<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>General Requirements</title> <link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../../../index.html" title="Chapter 1. Range 2.0"> <link rel="up" href="../adaptors.html" title="Range Adaptors"> <link rel="prev" href="introduction.html" title="Introduction and motivation"> <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 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description of generator expressions, the following notation is used: </p> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"> <code class="computeroutput"><span class="identifier">fwdRng</span></code> is an expression of a type <code class="computeroutput"><span class="identifier">R</span></code> that models <code class="computeroutput"><span class="identifier">ForwardRange</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">biRng</span></code> is an expression of a type <code class="computeroutput"><span class="identifier">R</span></code> that models <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">rndRng</span></code> is an expression of a type <code class="computeroutput"><span class="identifier">R</span></code> that models <code class="computeroutput"><span class="identifier">RandomAccessRange</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">pred</span></code> is an expression of a type that models <code class="computeroutput"><span class="identifier">UnaryPredicate</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">bi_pred</span></code> is an expression of a type that models <code class="computeroutput"><span class="identifier">BinaryPredicate</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">fun</span></code> is an expression of a type that models <code class="computeroutput"><span class="identifier">UnaryFunction</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">value</span></code>, <code class="computeroutput"><span class="identifier">new_value</span></code> and <code class="computeroutput"><span class="identifier">old_value</span></code> are objects convertible to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_value</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span></code> </li> <li class="listitem"> <code class="computeroutput"><span class="identifier">n</span><span class="special">,</span><span class="identifier">m</span></code> are integer expressions convertible to <code class="computeroutput"><span class="identifier">range_difference</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span></code> </li> </ul></div> <p> Also note that <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_value</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span></code> must be implicitly convertible to the type arguments to <code class="computeroutput"><span class="identifier">pred</span></code>, <code class="computeroutput"><span class="identifier">bi_pred</span></code> and <code class="computeroutput"><span class="identifier">fun</span></code>. </p> <p> Range Category in the following adaptor descriptions refers to the minimum range concept required by the range passed to the adaptor. The resultant range is a model of the same range concept as the input range unless specified otherwise. </p> <p> Returned Range Category is the concept of the returned range. In some cases the returned range is of a lesser category than the range passed to the adaptor. For example, the <code class="computeroutput"><span class="identifier">filtered</span></code> adaptor returns only a <code class="computeroutput"><span class="identifier">ForwardRange</span></code> regardless of the input. </p> <p> Furthermore, the following rules apply to any expression of the form </p> <pre class="programlisting"><span class="identifier">rng</span> <span class="special">|</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">adaptor_generator</span> </pre> <p> </p> <p> 1. Applying <code class="computeroutput"><span class="keyword">operator</span><span class="special">|()</span></code> to a range <code class="computeroutput"><span class="identifier">R</span></code> (always left argument) and a range adapter <code class="computeroutput"><span class="identifier">RA</span></code> (always right argument) yields a new range type which may not conform to the same range concept as <code class="computeroutput"><span class="identifier">R</span></code>. </p> <p> 2. The return-type of <code class="computeroutput"><span class="keyword">operator</span><span class="special">|()</span></code> is otherwise unspecified. </p> <p> 3. <code class="computeroutput"><span class="keyword">operator</span><span class="special">|()</span></code> is found by Argument Dependent Lookup (ADL) because a range adaptor is implemented in namespace <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span></code>. </p> <p> 4. <code class="computeroutput"><span class="keyword">operator</span><span class="special">|()</span></code> is used to add new behaviour <span class="emphasis"><em><span class="bold"><strong>lazily</strong></span></em></span> and never modifies its left argument. </p> <p> 5. All iterators extracted from the left argument are extracted using qualified calls to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">()</span></code>. </p> <p> 6. In addition to the <code class="computeroutput"><span class="keyword">throw</span></code>-clauses below, <code class="computeroutput"><span class="keyword">operator</span><span class="special">|()</span></code> may throw exceptions as a result of copying iterators. If such copying cannot throw an exception, then neither can the whole expression. </p> </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 © 2003 -2010 Thorsten Ottosen, Neil Groves<p> Distributed under the Boost Software License, Version 1.0. (See accompanying 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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="introduction.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../adaptors.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>