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Thorsten Jørgen Ottosen 5eaf3a0e88 *** empty log message *** 
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<span class=comment>//
// This example is intended to show you how to
// use the 'view_clone_manager'. The idea
// is that we have a container of non-polymorphic
// objects and want to keep then sorted by different
// criteria at the same time.
//
//
// We'll go for 'ptr_vector' here. Using a node-based
// container would be a waste of space here.
// All container headers will also include
// the Clone Managers.
// </span>
<span class=preprocessor>#include </span><span class=special>&lt;</span><span class=identifier>boost</span><span class=special>/</span><span class=identifier>smart_container</span><span class=special>/</span><span class=identifier>ptr_vector</span><span class=special>.</span><span class=identifier>hpp</span><span class=special>&gt;</span>
<span class=preprocessor>#include </span><span class=special>&lt;</span><span class=identifier>boost</span><span class=special>/</span><span class=identifier>smart_container</span><span class=special>/</span><span class=identifier>ptr_predicate</span><span class=special>.</span><span class=identifier>hpp</span><span class=special>&gt;
</span>
<span class=preprocessor>#include </span><span class=special>&lt;</span><span class=identifier>cstdlib</span><span class=special>&gt; </span><span class=comment>// For 'rand()'</span>
<span class=preprocessor>#include </span><span class=special>&lt;</span><span class=identifier>algorithm</span><span class=special>&gt; </span><span class=comment>// For 'std::sort()'</span>
<span class=preprocessor>#include </span><span class=special>&lt;</span><span class=identifier>iostream</span><span class=special>&gt; </span><span class=comment>// For 'std::cout'
//
// This is our simple example data-structure. It can
// be ordered in three ways.
//</span>
<span class=keyword>struct </span><span class=identifier>photon</span>
<span class=special>{
</span><span class=identifier>photon</span><span class=special>() </span><span class=special>: </span><span class=identifier>color</span><span class=special>( </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>rand</span><span class=special>() </span><span class=special>),
</span><span class=identifier>direction</span><span class=special>( </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>rand</span><span class=special>() </span><span class=special>),
</span><span class=identifier>power</span><span class=special>( </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>rand</span><span class=special>() </span><span class=special>)
</span><span class=special>{ </span><span class=special>}
</span><span class=keyword>int </span><span class=identifier>color</span><span class=special>;
</span><span class=keyword>int </span><span class=identifier>direction</span><span class=special>;
</span><span class=keyword>int </span><span class=identifier>power</span><span class=special>;</span>
<span class=special>};
</span>
<span class=comment>//
// Our big container is a standard vector
//</span>
<span class=keyword>typedef </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>vector</span><span class=special>&lt;</span><span class=identifier>photon</span><span class=special>&gt; </span><span class=identifier>vector_type</span><span class=special>;
</span>
<span class=comment>//
// Now we define our view type by adding a second template argument.
// The 'view_clone_manager' will implements Cloning by taking address
// of objects.
//
// Notice the first template argument is 'photon' and not
// 'const photon' to allow the view container write access.
//</span>
<span class=keyword>typedef </span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>ptr_vector</span><span class=special>&lt;</span><span class=identifier>photon</span><span class=special>,</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>view_clone_manager</span><span class=special>&gt; </span><span class=identifier>view_type</span><span class=special>;
</span>
<span class=comment>//
// Our first sort criterium
//</span>
<span class=keyword>struct </span><span class=identifier>sort_by_color</span>
<span class=special>{
</span><span class=keyword>bool </span><span class=keyword>operator</span><span class=special>()( </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>l</span><span class=special>, </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>r </span><span class=special>) </span><span class=keyword>const
</span><span class=special>{
</span><span class=keyword>return </span><span class=identifier>l</span><span class=special>.</span><span class=identifier>color </span><span class=special>&lt; </span><span class=identifier>r</span><span class=special>.</span><span class=identifier>color</span><span class=special>;
</span><span class=special>}</span>
<span class=special>};
</span>
<span class=comment>//
// Our second sort criterium
//</span>
<span class=keyword>struct </span><span class=identifier>sort_by_direction</span>
<span class=special>{
</span><span class=keyword>bool </span><span class=keyword>operator</span><span class=special>()( </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>l</span><span class=special>, </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>r </span><span class=special>) </span><span class=keyword>const
</span><span class=special>{
</span><span class=keyword>return </span><span class=identifier>l</span><span class=special>.</span><span class=identifier>direction </span><span class=special>&lt; </span><span class=identifier>r</span><span class=special>.</span><span class=identifier>direction</span><span class=special>;
</span><span class=special>}</span>
<span class=special>};
</span>
<span class=comment>//
// Our third sort criterium
//</span>
<span class=keyword>struct </span><span class=identifier>sort_by_power</span>
<span class=special>{
</span><span class=keyword>bool </span><span class=keyword>operator</span><span class=special>()( </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>l</span><span class=special>, </span><span class=keyword>const </span><span class=identifier>photon</span><span class=special>&amp; </span><span class=identifier>r </span><span class=special>) </span><span class=keyword>const
</span><span class=special>{
</span><span class=keyword>return </span><span class=identifier>l</span><span class=special>.</span><span class=identifier>power </span><span class=special>&lt; </span><span class=identifier>r</span><span class=special>.</span><span class=identifier>power</span><span class=special>;
</span><span class=special>}</span>
<span class=special>};
</span>
<span class=comment>//
// This function inserts &quot;Clones&quot; into the
// the view.
//
// We need to pass the first argument
// as a non-const reference to be able to store
// 'T*' instead of 'const T*' objects. Alternatively,
// we might change the declaration of the 'view_type'
// to
// typedef boost::ptr_vector&lt;const photon,boost::view_clone_manager&gt;
// view_type; ^^^^^^
//</span>
<span class=keyword>void </span><span class=identifier>insert</span><span class=special>( </span><span class=identifier>vector_type</span><span class=special>&amp; </span><span class=identifier>from</span><span class=special>, </span><span class=identifier>view_type</span><span class=special>&amp; </span><span class=identifier>to </span><span class=special>)</span>
<span class=special>{
</span><span class=identifier>to</span><span class=special>.</span><span class=identifier>insert</span><span class=special>( </span><span class=identifier>to</span><span class=special>.</span><span class=identifier>end</span><span class=special>(),
</span><span class=identifier>from</span><span class=special>.</span><span class=identifier>begin</span><span class=special>(),
</span><span class=identifier>from</span><span class=special>.</span><span class=identifier>end</span><span class=special>() </span><span class=special>);</span>
<span class=special>}
</span>
<span class=keyword>int </span><span class=identifier>main</span><span class=special>()</span>
<span class=special>{
</span><span class=keyword>enum </span><span class=special>{ </span><span class=identifier>sz </span><span class=special>= </span><span class=number>10</span><span class=special>, </span><span class=identifier>count </span><span class=special>= </span><span class=number>500 </span><span class=special>};
</span><span class=comment>//
// First we create the main container and two views
//
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>vector</span><span class=special>&lt;</span><span class=identifier>vector_type</span><span class=special>&gt; </span><span class=identifier>photons</span><span class=special>;
</span><span class=identifier>view_type </span><span class=identifier>color_view</span><span class=special>;
</span><span class=identifier>view_type </span><span class=identifier>direction_view</span><span class=special>;
</span><span class=comment>//
// Then we fill the main container with some random data
//
</span><span class=keyword>for</span><span class=special>( </span><span class=keyword>int </span><span class=identifier>i </span><span class=special>= </span><span class=number>0</span><span class=special>; </span><span class=identifier>i </span><span class=special>!= </span><span class=identifier>sz</span><span class=special>; </span><span class=special>++</span><span class=identifier>i </span><span class=special>)
</span><span class=special>{
</span><span class=identifier>photons</span><span class=special>.</span><span class=identifier>push_back</span><span class=special>( </span><span class=identifier>vector_type</span><span class=special>() </span><span class=special>);
</span><span class=keyword>for</span><span class=special>( </span><span class=keyword>int </span><span class=identifier>j </span><span class=special>= </span><span class=number>0</span><span class=special>; </span><span class=identifier>j </span><span class=special>!= </span><span class=identifier>count</span><span class=special>; </span><span class=special>++</span><span class=identifier>j </span><span class=special>)
</span><span class=identifier>photons</span><span class=special>[</span><span class=identifier>i</span><span class=special>].</span><span class=identifier>push_back</span><span class=special>( </span><span class=identifier>photon</span><span class=special>() </span><span class=special>);
</span><span class=special>}
</span><span class=comment>//
// Then we create the two views.
//
</span><span class=keyword>for</span><span class=special>( </span><span class=keyword>int </span><span class=identifier>i </span><span class=special>= </span><span class=number>0</span><span class=special>; </span><span class=identifier>i </span><span class=special>!= </span><span class=identifier>sz</span><span class=special>; </span><span class=special>++</span><span class=identifier>i </span><span class=special>)
</span><span class=special>{
</span><span class=identifier>insert</span><span class=special>( </span><span class=identifier>photons</span><span class=special>[</span><span class=identifier>i</span><span class=special>], </span><span class=identifier>color_view </span><span class=special>);
</span><span class=identifier>insert</span><span class=special>( </span><span class=identifier>photons</span><span class=special>[</span><span class=identifier>i</span><span class=special>], </span><span class=identifier>direction_view </span><span class=special>);
</span><span class=special>}
</span><span class=comment>//
// First we sort the original photons, using one of
// the view classes. This may sound trivial, but consider that
// the objects are scatered all around 'sz' different vectors;
// the view makes them act as one big vector.
//
// Notice how we simple use
// '.begin()/end()' instead of '.ptr_begin()/ptr_end()':
//
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>sort</span><span class=special>( </span><span class=identifier>color_view</span><span class=special>.</span><span class=identifier>begin</span><span class=special>(), </span><span class=identifier>color_view</span><span class=special>.</span><span class=identifier>end</span><span class=special>(), </span><span class=identifier>sort_by_power</span><span class=special>() </span><span class=special>);
</span><span class=comment>//
// And now we can sort the views themselves. Notice how
// we switch to different iterators and different predicates:
//
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>sort</span><span class=special>( </span><span class=identifier>color_view</span><span class=special>.</span><span class=identifier>ptr_begin</span><span class=special>(), </span><span class=identifier>color_view</span><span class=special>.</span><span class=identifier>ptr_end</span><span class=special>(),
</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>indirected2</span><span class=special>&lt;</span><span class=identifier>sort_by_color</span><span class=special>&gt;() </span><span class=special>);
</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>sort</span><span class=special>( </span><span class=identifier>direction_view</span><span class=special>.</span><span class=identifier>ptr_begin</span><span class=special>(), </span><span class=identifier>direction_view</span><span class=special>.</span><span class=identifier>ptr_end</span><span class=special>(),
</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>indirected2</span><span class=special>&lt;</span><span class=identifier>sort_by_direction</span><span class=special>&gt;() </span><span class=special>);
</span><span class=keyword>return </span><span class=number>0</span><span class=special>;</span>
<span class=special>}</span>
</pre>
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