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- <h1><img src="../../../../boost.png" alt="boost.png (6897 bytes)" align=
- "middle" width="277" height="86">Boost.MultiIndex Tutorial</h1>
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- <h2>Contents</h2>
- <ul>
- <li><a href="#rationale">Rationale</a></li>
- <li><a href="#namespace">Namespace</a></li>
- <li><a href="basics.html">Basics</a></li>
- <li><a href="indices.html">Index types</a></li>
- <li><a href="key_extraction.html">Key extraction</a></li>
- <li><a href="creation.html">Container creation</a></li>
- <li><a href="debug.html">Debugging support</a></li>
- <li><a href="techniques.html">Techniques</a></li>
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- <h2><a name="rationale">Rationale</a></h2>
- <p>
- STL containers are designed around the concept that each container controls its
- own collection of elements, giving access to them in a manner specified by the
- container's type: so, an <code>std::set</code> maintains the elements ordered
- by a specified sorting criterion, <code>std::list</code> allows for free
- positioning of elements along a linear sequence, and so on.
- </p>
- <p>
- Sometimes, the necessity arises of having different access interfaces
- to the same underlying collection: for instance, some data might need to be
- sorted according to more than one comparison predicate, or a bidirectional list
- might benefit from a supplemental logarithmic lookup interface. In these
- situations, programmers typically resort to manual compositions of different
- containers, a solution that generally involves a fair amount of code
- devoted to preserve the synchronization of the different parts of
- the composition. Boost.MultiIndex allows for the specification of
- <code>multi_index_container</code>s comprised of one or more <i>indices</i> with
- different interfaces to the same collection of elements. The resulting constructs
- are conceptually cleaner than manual compositions, and often perform much better.
- An important design decision has been taken that the indices of a given
- <code>multi_index_container</code> instantiation be specified at compile time: this
- gives ample room for static type checking and code optimization.
- </p>
- <p>
- Boost.MultiIndex takes inspiration from basic concepts of indexing arising in the
- theory of relational databases, though it is not intended to provide a full-fledged
- relational database framework. <code>multi_index_container</code> integrates seamlessly
- into the STL container/algorithm design, and features some extra capabilities regarding
- lookup operations and element updating which are useful extensions even for
- single-indexed containers.
- </p>
- <p align="center">
- <img src="multi_index_cont_example.png"
- alt="diagram of a multi_index_container with three indices"
- width="600" height="304"><br>
- <b>Fig. 1: Diagram of a <code>multi_index_container</code> with three indices.</b>
- </p>
- <p>
- The figure above depicts a <code>multi_index_container</code> composed of three indices:
- the first two present a set-like interface to the elements sorted by
- shape and id, respectively, while the latter index provides the functionality
- of a bidirectional list in the spirit of <code>std::list</code>. These
- indices act as "views" to the internal collection of elements, but they do not only
- provide read access to the set: insertion/deletion methods are also implemented much
- as those of <code>std::set</code>s or <code>std::list</code>s. Insertion of an
- element through one given index will only succeed if the uniqueness constraints of all
- indices are met.
- </p>
- <h2>
- <a name="namespace">Namespace</a>
- </h2>
- <p>
- All the public types of Boost.MultiIndex reside in namespace <code>::boost::multi_index</code>.
- Additionaly, the main class template <code>multi_index_container</code> and global functions
- <code>get</code> and <code>project</code> are lifted to namespace <code>::boost</code>
- by means of <code>using</code> declarations. For brevity of exposition, the fragments
- of code in the documentation are written as if the following declarations were in effect:
- </p>
-
- <blockquote><pre>
- <span class=keyword>using</span> <span class=keyword>namespace</span> <span class=special>::</span><span class=identifier>boost</span><span class=special>;</span>
- <span class=keyword>using</span> <span class=keyword>namespace</span> <span class=special>::</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>multi_index</span><span class=special>;</span>
- </pre></blockquote>
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- <br>
- <p>Revised February 21st 2006</p>
- <p>© Copyright 2003-2006 Joaquín M López Muñoz.
- Distributed under the Boost Software
- License, Version 1.0. (See accompanying file <a href="../../../../LICENSE_1_0.txt">
- LICENSE_1_0.txt</a> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">
- http://www.boost.org/LICENSE_1_0.txt</a>)
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