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- <div class="document" id="iterator-traits">
- <h1 class="title">Iterator Traits</h1>
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- <tr><th class="docinfo-name">Author:</th>
- <td>David Abrahams</td></tr>
- <tr><th class="docinfo-name">Contact:</th>
- <td><a class="first last reference external" href="mailto:dave@boost-consulting.com">dave@boost-consulting.com</a></td></tr>
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- <td><a class="first last reference external" href="http://www.boost-consulting.com">Boost Consulting</a></td></tr>
- <tr><th class="docinfo-name">Date:</th>
- <td>$Date$</td></tr>
- <tr><th class="docinfo-name">Copyright:</th>
- <td>Copyright David Abrahams 2004.</td></tr>
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- <tr class="field"><th class="field-name">abstract:</th><td class="field-body">Header <tt class="docutils literal"><boost/iterator/iterator_traits.hpp></tt> provides
- the ability to access an iterator's associated types using
- MPL-compatible <a class="reference external" href="../../mpl/doc/index.html#metafunctions">metafunctions</a>.</td>
- </tr>
- </tbody>
- </table>
- <div class="section" id="overview">
- <h1>Overview</h1>
- <p><tt class="docutils literal"><span class="pre">std::iterator_traits</span></tt> provides access to five associated types
- of any iterator: its <tt class="docutils literal">value_type</tt>, <tt class="docutils literal">reference</tt>, <tt class="docutils literal">pointer</tt>,
- <tt class="docutils literal">iterator_category</tt>, and <tt class="docutils literal">difference_type</tt>. Unfortunately,
- such a "multi-valued" traits template can be difficult to use in a
- metaprogramming context. <tt class="docutils literal"><boost/iterator/iterator_traits.hpp></tt>
- provides access to these types using a standard <a class="reference external" href="../../mpl/doc/index.html#metafunctions">metafunctions</a>.</p>
- </div>
- <div class="section" id="summary">
- <h1>Summary</h1>
- <p>Header <tt class="docutils literal"><boost/iterator/iterator_traits.hpp></tt>:</p>
- <pre class="literal-block">
- template <class Iterator>
- struct iterator_value
- {
- typedef typename
- std::iterator_traits<Iterator>::value_type
- type;
- };
- template <class Iterator>
- struct iterator_reference
- {
- typedef typename
- std::iterator_traits<Iterator>::reference
- type;
- };
- template <class Iterator>
- struct iterator_pointer
- {
- typedef typename
- std::iterator_traits<Iterator>::pointer
- type;
- };
- template <class Iterator>
- struct iterator_difference
- {
- typedef typename
- detail::iterator_traits<Iterator>::difference_type
- type;
- };
- template <class Iterator>
- struct iterator_category
- {
- typedef typename
- detail::iterator_traits<Iterator>::iterator_category
- type;
- };
- </pre>
- </div>
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