75 lines
4.6 KiB
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75 lines
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="property_tree.container"></a><a class="link" href="container.html" title="Property Tree as a Container">Property Tree as a Container</a>
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</h2></div></div></div>
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<p>
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Every property tree node models the ReversibleSequence concept, providing access
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to its immediate children. This means that iterating over a <code class="computeroutput"><a class="link" href="../boost/property_tree/ptree.html" title="Type definition ptree">ptree</a></code>
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(which is the same as its root node - every <code class="computeroutput"><a class="link" href="../boost/property_tree/ptree.html" title="Type definition ptree">ptree</a></code>
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node is also the subtree it starts) iterates only a single level of the hierarchy.
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There is no way to iterate over the entire tree.
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<p>
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It is very important to remember that the property sequence is <span class="bold"><strong>not</strong></span>
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ordered by the key. It preserves the order of insertion. It closely resembles
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a std::list. Fast access to children by name is provided via a separate lookup
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structure. Do not attempt to use algorithms that expect an ordered sequence
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(like binary_search) on a node's children.
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</p>
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<p>
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The property tree exposes a second container-like interface, called the associative
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view. Its iterator type is the nested type assoc_iterator (and its const counterpart
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const_assoc_iterator). You can get an ordered view of all children by using
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ordered_begin() and ordered_end().
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</p>
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<p>
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The associative view also provides find() and equal_range() members, which
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return assoc_iterators, but otherwise have the same semantics as the members
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of std::map of the same name.
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</p>
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<p>
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You can get a normal iterator from an assoc_iterator by using the to_iterator()
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member function. Converting the other way is not possible.
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<td align="right"><div class="copyright-footer">Copyright © 2008-2010 Marcin Kalicinski<br>Copyright © 2010-2013 Sebastian
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Redl<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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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