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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="range.reference.adaptors.general_requirements"></a><a class="link" href="general_requirements.html" title="General Requirements"> General |
| Requirements</a> |
| </h4></div></div></div> |
| <p> |
| In the 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>) |
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