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| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_bimap.the_tutorial.bimaps_with_user_defined_names"></a><a class="link" href="bimaps_with_user_defined_names.html" title="Bimaps with user defined names">Bimaps |
| with user defined names</a> |
| </h3></div></div></div> |
| <p> |
| In the following example, the library user inserted comments to guide future |
| programmers: |
| </p> |
| <p> |
| <a href="../../../../example/user_defined_names.cpp" target="_top">Go to source code</a> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">bimap</span> |
| <span class="special"><</span> |
| <span class="identifier">multiset_of</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">>,</span> |
| <span class="keyword">int</span> |
| |
| <span class="special">></span> <span class="identifier">People</span><span class="special">;</span> |
| |
| <span class="identifier">People</span> <span class="identifier">people</span><span class="special">;</span> |
| |
| <span class="comment">// ... |
| </span> |
| <span class="keyword">int</span> <span class="identifier">user_id</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cin</span> <span class="special">>></span> <span class="identifier">user_id</span><span class="special">;</span> |
| |
| <span class="comment">// people.right : map<id,name> |
| </span> |
| <span class="identifier">People</span><span class="special">::</span><span class="identifier">right_const_iterator</span> <span class="identifier">id_iter</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">right</span><span class="special">.</span><span class="identifier">find</span><span class="special">(</span><span class="identifier">user_id</span><span class="special">);</span> |
| <span class="keyword">if</span><span class="special">(</span> <span class="identifier">id_iter</span> <span class="special">!=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">right</span><span class="special">.</span><span class="identifier">end</span><span class="special">()</span> <span class="special">)</span> |
| <span class="special">{</span> |
| <span class="comment">// first : id |
| </span> <span class="comment">// second : name |
| </span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"name: "</span> <span class="special"><<</span> <span class="identifier">id_iter</span><span class="special">-></span><span class="identifier">second</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span> |
| <span class="special"><<</span> <span class="string">"id: "</span> <span class="special"><<</span> <span class="identifier">id_iter</span><span class="special">-></span><span class="identifier">first</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="special">}</span> |
| <span class="keyword">else</span> |
| <span class="special">{</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Unknown id, users are:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="comment">// people.left : map<name,id> |
| </span> |
| <span class="keyword">for</span><span class="special">(</span> <span class="identifier">People</span><span class="special">::</span><span class="identifier">left_const_iterator</span> |
| <span class="identifier">name_iter</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">left</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> |
| <span class="identifier">iend</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">left</span><span class="special">.</span><span class="identifier">end</span><span class="special">();</span> |
| |
| <span class="identifier">name_iter</span> <span class="special">!=</span> <span class="identifier">iend</span><span class="special">;</span> <span class="special">++</span><span class="identifier">name_iter</span> <span class="special">)</span> |
| <span class="special">{</span> |
| <span class="comment">// first : name |
| </span> <span class="comment">// second : id |
| </span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"name: "</span> <span class="special"><<</span> <span class="identifier">name_iter</span><span class="special">-></span><span class="identifier">first</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span> |
| <span class="special"><<</span> <span class="string">"id: "</span> <span class="special"><<</span> <span class="identifier">name_iter</span><span class="special">-></span><span class="identifier">second</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="special">}</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| In Boost.Bimap there is a better way to document the code and in the meantime |
| helping you to write more mantainable and readable code. You can tag the |
| two collections of the bimap so they can be accessed by more descriptive |
| names. |
| </p> |
| <p> |
| <span class="inlinemediaobject"><img src="../../images/bimap/tagged.png" alt="tagged"></span> |
| </p> |
| <p> |
| A tagged type is a type that has been labelled using a tag. A tag is any |
| valid C++ type. In a bimap, the types are always tagged. If you do not specify |
| your own tag, the container uses <code class="computeroutput"><span class="identifier">member_at</span><span class="special">::</span><span class="identifier">left</span></code> |
| and <code class="computeroutput"><span class="identifier">member_at</span><span class="special">::</span><span class="identifier">right</span></code> to tag the left and right sides respectively. |
| In order to specify a custom tag, the type of each side has to be tagged. |
| Tagging a type is very simple: |
| </p> |
| <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">tagged</span><span class="special"><</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">a_tag</span> <span class="special">></span> <span class="identifier">tagged_int</span><span class="special">;</span> |
| </pre> |
| <p> |
| Now we can rewrite the example: |
| </p> |
| <p> |
| <a href="../../../../example/user_defined_names.cpp" target="_top">Go to source code</a> |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">id</span> <span class="special">{};</span> <span class="comment">// Tag for the identification number |
| </span><span class="keyword">struct</span> <span class="identifier">name</span> <span class="special">{};</span> <span class="comment">// Tag for the name of the person |
| </span> |
| <span class="keyword">typedef</span> <span class="identifier">bimap</span> |
| <span class="special"><</span> |
| <span class="identifier">tagged</span><span class="special"><</span> <span class="keyword">int</span> <span class="special">,</span> <span class="identifier">id</span> <span class="special">></span> <span class="special">,</span> |
| <span class="identifier">multiset_of</span><span class="special"><</span> <span class="identifier">tagged</span><span class="special"><</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">,</span> <span class="identifier">name</span> <span class="special">></span> <span class="special">></span> |
| |
| <span class="special">></span> <span class="identifier">People</span><span class="special">;</span> |
| |
| <span class="identifier">People</span> <span class="identifier">people</span><span class="special">;</span> |
| |
| <span class="comment">// ... |
| </span> |
| <span class="keyword">int</span> <span class="identifier">user_id</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cin</span> <span class="special">>></span> <span class="identifier">user_id</span><span class="special">;</span> |
| |
| <span class="identifier">People</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">id</span><span class="special">>::</span><span class="identifier">const_iterator</span> <span class="identifier">id_iter</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">id</span><span class="special">>().</span><span class="identifier">find</span><span class="special">(</span><span class="identifier">user_id</span><span class="special">);</span> |
| <span class="keyword">if</span><span class="special">(</span> <span class="identifier">id_iter</span> <span class="special">!=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">id</span><span class="special">>().</span><span class="identifier">end</span><span class="special">()</span> <span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"name: "</span> <span class="special"><<</span> <span class="identifier">id_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">name</span><span class="special">>()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span> |
| <span class="special"><<</span> <span class="string">"id: "</span> <span class="special"><<</span> <span class="identifier">id_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">id</span><span class="special">>()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="special">}</span> |
| <span class="keyword">else</span> |
| <span class="special">{</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Unknown id, users are:"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="keyword">for</span><span class="special">(</span> <span class="identifier">People</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">name</span><span class="special">>::</span><span class="identifier">const_iterator</span> |
| <span class="identifier">name_iter</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">name</span><span class="special">>().</span><span class="identifier">begin</span><span class="special">(),</span> |
| <span class="identifier">iend</span> <span class="special">=</span> <span class="identifier">people</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">name</span><span class="special">>().</span><span class="identifier">end</span><span class="special">();</span> |
| |
| <span class="identifier">name_iter</span> <span class="special">!=</span> <span class="identifier">iend</span><span class="special">;</span> <span class="special">++</span><span class="identifier">name_iter</span> <span class="special">)</span> |
| <span class="special">{</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"name: "</span> <span class="special"><<</span> <span class="identifier">name_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">name</span><span class="special">>()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span> |
| <span class="special"><<</span> <span class="string">"id: "</span> <span class="special"><<</span> <span class="identifier">name_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">id</span><span class="special">>()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="special">}</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Here is a list of common structures in both tagged and untagged versions. |
| Remember that when the bimap has user defined tags you can still use the |
| untagged version structures. |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">Left</span> <span class="special">{};</span> |
| <span class="keyword">struct</span> <span class="identifier">Right</span> <span class="special">{};</span> |
| <span class="keyword">typedef</span> <span class="identifier">bimap</span><span class="special"><</span> |
| <span class="identifier">multiset_of</span><span class="special"><</span> <span class="identifier">tagged</span><span class="special"><</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">Left</span> <span class="special">></span> <span class="special">>,</span> |
| <span class="identifier">unordered_set_of</span><span class="special"><</span> <span class="identifier">tagged</span><span class="special"><</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">Right</span> <span class="special">></span> <span class="special">></span> |
| <span class="special">></span> <span class="identifier">bm_type</span><span class="special">;</span> |
| |
| <span class="identifier">bm_type</span> <span class="identifier">bm</span><span class="special">;</span> |
| |
| <span class="comment">//... |
| </span> |
| <span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iter</span> <span class="special">=</span> <span class="identifier">bm</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">left_iterator</span> <span class="identifier">left_iter</span> <span class="special">=</span> <span class="identifier">bm</span><span class="special">.</span><span class="identifier">left</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">right_iterator</span> <span class="identifier">right_iter</span> <span class="special">=</span> <span class="identifier">bm</span><span class="special">.</span><span class="identifier">right</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| </pre> |
| <div class="table"> |
| <a name="id782992"></a><p class="title"><b>Table 1.3. Equivalence of expresions using user defined names</b></p> |
| <div class="table-contents"><table class="table" summary="Equivalence of expresions using user defined names"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Untagged version |
| </p> |
| </th> |
| <th> |
| <p> |
| Tagged version |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">left</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">right</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">by</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">left_map</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>::</span><span class="identifier">type</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">right_value_type</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>::</span><span class="identifier">value_type</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">left_iterator</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>::</span><span class="identifier">iterator</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm_type</span><span class="special">::</span><span class="identifier">right_const_iterator</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">::</span><span class="identifier">map_by</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>::</span><span class="identifier">const_iterator</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">iter</span><span class="special">-></span><span class="identifier">left</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">iter</span><span class="special">-></span><span class="identifier">right</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">left_iter</span><span class="special">-></span><span class="identifier">first</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">left_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">left_iter</span><span class="special">-></span><span class="identifier">second</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">left_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">right_iter</span><span class="special">-></span><span class="identifier">first</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">right_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">right_iter</span><span class="special">-></span><span class="identifier">second</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">right_iter</span><span class="special">-></span><span class="identifier">get</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>()</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">project_left</span><span class="special">(</span><span class="identifier">iter</span><span class="special">)</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">project</span><span class="special"><</span><span class="identifier">Left</span><span class="special">>(</span><span class="identifier">iter</span><span class="special">)</span></code> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">project_right</span><span class="special">(</span><span class="identifier">iter</span><span class="special">)</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">bm</span><span class="special">.</span><span class="identifier">project</span><span class="special"><</span><span class="identifier">Right</span><span class="special">>(</span><span class="identifier">iter</span><span class="special">)</span></code> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"> |
| </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 © 2006 -2007 Matias Capeletto<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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| </div></td> |
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