forked from boostorg/range
133 lines
4.9 KiB
HTML
133 lines
4.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Boost.Range Terminology and Style Guidelines </title>
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<link rel="stylesheet" href="style.css" type="text/css">
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</head>
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<body>
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<table border="0" >
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<tr>
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<td ><img src="../../../boost.png" border="0" ></td>
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<td ><h1 align="center">Boost.Range </h1></td>
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</tr>
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</table>
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<h2>Terminology and style guidelines </h2>
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<p>
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The use of a consistent terminology is as important for <a href="range.html">Range</a>s
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and range-based algorithms as it is for iterators and iterator-based algorithms.
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If a conventional set of names are adopted, we can avoid misunderstandings and
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write generic function prototypes that are <i>self-documenting</i>.
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</p>
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<p>
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Since ranges are characterized by a specific underlying iterator type, we get a
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type of range for each type of iterator. Hence we can speak of the following
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types of ranges:
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<ul>
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<li>
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<i>Value access</i> category:
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<ul>
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<li>
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Readable Range
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<li>
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Writeable Range
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<li>
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Swappable Range
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<li>
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Lvalue Range
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</ul>
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<li>
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<i>Traversal</i> category:
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<ul>
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<li>
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<a href="range.html#single_pass_range">Single Pass Range</a>
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<li>
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<a href="range.html#forward_range">Forward Range</a>
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<li>
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<a href="range.html#bidirectional_range">Bidirectional Range</a> <li>
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<a href="range.html#random_access_range">Random Access Range</a> </ul>
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</ul>
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Notice how we have used the categories from the <a href="../../iterator/doc/new-iter-concepts.html">new
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style iterators</a>.
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<p>
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Notice that an iterator (and therefore an range) has one <i>traversal</i>
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property and one or more properties from the <i>value access</i> category. So in
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reality we will mostly talk about mixtures such as
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<ul>
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<li>
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Random Access Readable Writeable Range
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<li>
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Forward Lvalue Range
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</ul>
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By convention, we should always specify the <i>traversal</i> property first as
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done above. This seems reasonable since there will only be one <i>traversal</i>
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property, but perhaps many <i>value access</i> properties.
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</p>
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<p>
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It might, however, be reasonable to specify only one category if the other
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category does not matter. For example, the <a
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href="utility_class.html#iter_range">iterator_range</a> can be constructed from
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a Forward Range. This means that we do not care about what <i>value access</i>
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properties the Range has. Similarly, a Readable Range will be one that has the
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lowest possible <i>traversal</i> property (Single Pass).
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</p>
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<p>
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As another example, consider how we specify the interface of <code>std::sort()</code>.
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Algorithms are usually more cumbersome to specify the interface of since both <i>traversal</i>
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and <i>value access</i> properties must be exactly defined. The iterator-based
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version looks like this:
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<pre>
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<span class=keyword>template</span><span class=special>< </span><span class=keyword>class </span><span class=identifier>RandomAccessTraversalReadableWritableIterator </span><span class=special>>
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</span><span class=keyword>void </span><span class=identifier>sort</span><span class=special>( </span><span class=identifier>RandomAccessTraversalReadableWritableIterator </span><span class=identifier>first</span><span class=special>,
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</span><span class=identifier>RandomAccessTraversalReadableWritableIterator </span><span class=identifier>last </span><span class=special>);</span>
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</pre>
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For ranges the interface becomes
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<pre>
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<span class=keyword>template</span><span class=special>< </span><span class=keyword>class </span><span class=identifier>RandomAccessReadableWritableRange </span><span class=special>>
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</span><span class=keyword>void </span><span class=identifier>sort</span><span class=special>( </span><span class=identifier>RandomAccessReadableWritableRange</span><span class=special>& </span><span class=identifier>r </span><span class=special>);</span>
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</pre>
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</p>
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<p>
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</p>
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<hr>
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<p>
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© <a name="Copyright" id="Copyright">Copyright</a> Thorsten Ottosen 2008.
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</p>
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<p>
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Distributed under the Boost Software License, Version 1.0. (See
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accompanying file LICENSE_1_0.txt or copy
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at <a href=
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"http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)
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</p>
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<br>
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</body>
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