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- <body>
- <div class="document" id="boost-pointer-container-library">
- <h1 class="title"><img alt="Boost" src="boost.png" /> Pointer Container Library</h1>
- <h2 class="subtitle" id="examples">Examples</h2>
- <p>Some examples are given here and in the accompanying test files:</p>
- <div class="contents local topic" id="contents">
- <ul class="simple">
- <li><a class="reference internal" href="#null-pointers-cannot-be-stored-in-the-containers" id="id2">1. Null pointers cannot be stored in the containers</a></li>
- <li><a class="reference internal" href="#iterators-and-other-operations-return-indirected-values" id="id3">2. Iterators and other operations return indirected values</a></li>
- <li><a class="reference internal" href="#copy-semantics-of-pointer-containers" id="id4">3. Copy-semantics of pointer containers</a></li>
- <li><a class="reference internal" href="#making-a-non-copyable-type-cloneable" id="id5">4. Making a non-copyable type Cloneable</a></li>
- <li><a class="reference internal" href="#objects-are-cloned-before-insertion-inserted-pointers-are-owned-by-the-container" id="id6">5. Objects are cloned before insertion, inserted pointers are owned by the container</a></li>
- <li><a class="reference internal" href="#transferring-ownership-of-a-single-element" id="id7">6. Transferring ownership of a single element</a></li>
- <li><a class="reference internal" href="#transferring-ownership-of-pointers-between-different-pointer-containers" id="id8">7. Transferring ownership of pointers between different pointer containers</a></li>
- <li><a class="reference internal" href="#selected-test-files" id="id9">8. Selected test files</a></li>
- <li><a class="reference internal" href="#a-large-example" id="id10">9. A large example</a></li>
- </ul>
- </div>
- <div class="section" id="null-pointers-cannot-be-stored-in-the-containers">
- <span id="example-1"></span><h1><a class="toc-backref" href="#id2">1. Null pointers cannot be stored in the containers</a></h1>
- <pre class="literal-block">
- my_container.push_back( 0 ); // throws bad_ptr
- my_container.replace( an_iterator, 0 ); // throws bad_ptr
- my_container.insert( an_iterator, 0 ); // throws bad_ptr
- std::auto_ptr<T> p( 0 );
- my_container.push_back( p ); // throws bad_ptr
- </pre>
- </div>
- <div class="section" id="iterators-and-other-operations-return-indirected-values">
- <span id="example-2"></span><h1><a class="toc-backref" href="#id3">2. Iterators and other operations return indirected values</a></h1>
- <pre class="literal-block">
- ptr_vector<X> pvec;
- std::vector<X*> vec;
- *vec.begin() = new X; // fine, memory leak
- *pvec.begin() = new X; // compile time error
- ( *vec.begin() )->foo(); // call X::foo(), a bit clumsy
- pvec.begin()->foo(); // no indirection needed
- *vec.front() = X(); // overwrite first element
- pvec.front() = X(); // no indirection needed
- </pre>
- </div>
- <div class="section" id="copy-semantics-of-pointer-containers">
- <span id="example-3"></span><h1><a class="toc-backref" href="#id4">3. Copy-semantics of pointer containers</a></h1>
- <pre class="literal-block">
- ptr_vector<T> vec1;
- ...
- ptr_vector<T> vec2( vec1.clone() ); // deep copy objects of 'vec1' and use them to construct 'vec2', could be very expensive
- vec2 = vec1.release(); // give up ownership of pointers in 'vec1' and pass the ownership to 'vec2', rather cheap
- vec2.release(); // give up ownership; the objects will be deallocated if not assigned to another container
- vec1 = vec2; // deep copy objects of 'vec2' and assign them to 'vec1', could be very expensive
- ptr_vector<T> vec3( vec1 ); // deep copy objects of 'vec1', could be very expensive
- </pre>
- </div>
- <div class="section" id="making-a-non-copyable-type-cloneable">
- <span id="example-4"></span><h1><a class="toc-backref" href="#id5">4. Making a non-copyable type Cloneable</a></h1>
- <pre class="literal-block">
- // a class that has no normal copy semantics
- class X : boost::noncopyable { public: X* clone() const; ... };
- // this will be found by the library by argument dependent lookup (ADL)
- X* new_clone( const X& x )
- { return x.clone(); }
- // we can now use the interface that requires cloneability
- ptr_vector<X> vec1, vec2;
- ...
- vec2 = vec1.clone(); // 'clone()' requires cloning <g>
- vec2.insert( vec2.end(), vec1.begin(), vec1.end() ); // inserting always means inserting clones
- </pre>
- </div>
- <div class="section" id="objects-are-cloned-before-insertion-inserted-pointers-are-owned-by-the-container">
- <span id="example-5"></span><h1><a class="toc-backref" href="#id6">5. Objects are cloned before insertion, inserted pointers are owned by the container</a></h1>
- <pre class="literal-block">
- class X { ... }; // assume 'X' is Cloneable
- X x; // and 'X' can be stack-allocated
- ptr_list<X> list;
- list.push_back( new_clone( x ) ); // insert a clone
- list.push_back( new X ); // always give the pointer directly to the container to avoid leaks
- list.push_back( &x ); // don't do this!!!
- std::auto_ptr<X> p( new X );
- list.push_back( p ); // give up ownership
- BOOST_ASSERT( p.get() == 0 );
- </pre>
- </div>
- <div class="section" id="transferring-ownership-of-a-single-element">
- <span id="example-6"></span><h1><a class="toc-backref" href="#id7">6. Transferring ownership of a single element</a></h1>
- <pre class="literal-block">
- ptr_deque<T> deq;
- typedef ptr_deque<T>::auto_type auto_type;
- // ... fill the container somehow
- auto_type ptr = deq.pop_back(); // remove back element from container and give up ownership
- auto_type ptr2 = deq.release( deq.begin() + 2 ); // use an iterator to determine the element to release
- ptr = deq.pop_front(); // supported for 'ptr_list' and 'ptr_deque'
- deq.push_back( ptr.release() ); // give ownership back to the container
- </pre>
- </div>
- <div class="section" id="transferring-ownership-of-pointers-between-different-pointer-containers">
- <span id="example-7"></span><h1><a class="toc-backref" href="#id8">7. Transferring ownership of pointers between different pointer containers</a></h1>
- <pre class="literal-block">
- ptr_list<X> list; ptr_vector<X> vec;
- ...
- //
- // note: no cloning happens in these examples
- //
- list.transfer( list.begin(), vec.begin(), vec ); // make the first element of 'vec' the first element of 'list'
- vec.transfer( vec.end(), list.begin(), list.end(), list ); // put all the lists element into the vector
- </pre>
- <p>We can also transfer objects from <tt class="docutils literal">ptr_container<Derived></tt> to <tt class="docutils literal">ptr_container<Base></tt> without any problems.</p>
- </div>
- <div class="section" id="selected-test-files">
- <span id="example-8"></span><h1><a class="toc-backref" href="#id9">8. Selected test files</a></h1>
- <table class="docutils field-list" frame="void" rules="none">
- <col class="field-name" />
- <col class="field-body" />
- <tbody valign="top">
- <tr class="field"><th class="field-name" colspan="2"><a class="reference external" href="../test/incomplete_type_test.cpp">incomplete_type_test.cpp</a>:</th></tr>
- <tr class="field"><td> </td><td class="field-body">Shows how to implement the Composite pattern.</td>
- </tr>
- <tr class="field"><th class="field-name" colspan="2"><a class="reference external" href="../test/simple_test.cpp">simple_test.cpp</a>:</th></tr>
- <tr class="field"><td> </td><td class="field-body">Shows how the usage of pointer container compares with a
- container of smart pointers</td>
- </tr>
- <tr class="field"><th class="field-name" colspan="2"><a class="reference external" href="../test/view_example.cpp">view_example.cpp</a>:</th></tr>
- <tr class="field"><td> </td><td class="field-body">Shows how to use a pointer container as a view into other container</td>
- </tr>
- <tr class="field"><th class="field-name"><a class="reference external" href="../test/tree_test.cpp">tree_test.cpp</a>:</th><td class="field-body">Shows how to make a tree-structure</td>
- </tr>
- <tr class="field"><th class="field-name"><a class="reference external" href="../test/ptr_array.cpp">array_test.cpp</a>:</th><td class="field-body">Shows how to make an n-ary tree</td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="section" id="a-large-example">
- <h1><a class="toc-backref" href="#id10">9. A large example</a></h1>
- <p>This example shows many of the most common
- features at work. The example provide lots of comments.
- The source code can also be found <a class="reference external" href="../test/tut1.cpp">here</a>.</p>
- <html>
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
- <title> </title>
- <link rel="stylesheet" href="default.css" type="text/css">
- </head>
- <body>
- <pre><span class=comment>//
- // Boost.Pointer Container
- //
- // Copyright Thorsten Ottosen 2003-2005. Use, modification and
- // distribution is subject to the Boost Software License, Version
- // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //
- // For more information, see http://www.boost.org/libs/ptr_container/
- //
- //
- // This example is intended to get you started.
- // Notice how the smart container
- //
- // 1. takes ownership of objects
- // 2. transfers ownership
- // 3. applies indirection to iterators
- // 4. clones objects from other smart containers
- //
- //
- // First we select which container to use.
- //</span>
- <span class=preprocessor>#include</span> <span class=special><</span><span class=identifier>boost</span><span class=special>/</span><span class=identifier>ptr_container</span><span class=special>/</span><span class=identifier>ptr_deque</span><span class=special>.</span><span class=identifier>hpp</span><span class=special>></span>
- <span class=comment>//
- // we need these later in the example
- //</span>
- <span class=preprocessor>#include</span> <span class=special><</span><span class=identifier>boost</span><span class=special>/</span><span class=identifier>assert</span><span class=special>.</span><span class=identifier>hpp</span><span class=special>></span>
- <span class=preprocessor>#include</span> <span class=special><</span><span class=identifier>string</span><span class=special>></span>
- <span class=preprocessor>#include</span> <span class=special><</span><span class=identifier>exception</span><span class=special>></span>
- <span class=comment>//
- // Then we define a small polymorphic class
- // hierarchy.
- //</span>
- <span class=keyword>class</span> <span class=identifier>animal</span> <span class=special>:</span> <span class=identifier>boost</span><span class=special>::</span><span class=identifier>noncopyable</span>
- <span class=special>{</span>
- <span class=keyword>virtual</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>do_speak</span><span class=special>()</span> <span class=keyword>const</span> <span class=special>=</span> <span class=number>0</span><span class=special>;</span>
- <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>name_</span><span class=special>;</span>
- <span class=keyword>protected</span><span class=special>:</span>
- <span class=comment>//
- // Animals cannot be copied...
- //</span>
- <span class=identifier>animal</span><span class=special>(</span> <span class=keyword>const</span> <span class=identifier>animal</span><span class=special>&</span> <span class=identifier>r</span> <span class=special>)</span> <span class=special>:</span> <span class=identifier>name_</span><span class=special>(</span> <span class=identifier>r</span><span class=special>.</span><span class=identifier>name_</span> <span class=special>)</span> <span class=special>{</span> <span class=special>}</span>
- <span class=keyword>void</span> <span class=keyword>operator</span><span class=special>=(</span> <span class=keyword>const</span> <span class=identifier>animal</span><span class=special>&</span> <span class=special>);</span>
- <span class=keyword>private</span><span class=special>:</span>
- <span class=comment>//
- // ...but due to advances in genetics, we can clone them!
- //</span>
- <span class=keyword>virtual</span> <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>do_clone</span><span class=special>()</span> <span class=keyword>const</span> <span class=special>=</span> <span class=number>0</span><span class=special>;</span>
-
- <span class=keyword>public</span><span class=special>:</span>
- <span class=identifier>animal</span><span class=special>(</span> <span class=keyword>const</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=identifier>name_</span><span class=special>(</span><span class=identifier>name</span><span class=special>)</span> <span class=special>{</span> <span class=special>}</span>
- <span class=keyword>virtual</span> <span class=special>~</span><span class=identifier>animal</span><span class=special>()</span> <span class=keyword>throw</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>string</span> <span class=identifier>speak</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>do_speak</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>name</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>name_</span><span class=special>;</span>
- <span class=special>}</span>
- <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>clone</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>do_clone</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=special>};</span>
- <span class=comment>//
- // An animal is still not Clonable. We need this last hook.
- //
- // Notice that we pass the animal by const reference
- // and return by pointer.
- //</span>
- <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>new_clone</span><span class=special>(</span> <span class=keyword>const</span> <span class=identifier>animal</span><span class=special>&</span> <span class=identifier>a</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>a</span><span class=special>.</span><span class=identifier>clone</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=comment>//
- // We do not need to define 'delete_clone()' since
- // since the default is to call the default 'operator delete()'.
- //</span>
- <span class=keyword>const</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>muuuh</span> <span class=special>=</span> <span class=string>"Muuuh!"</span><span class=special>;</span>
- <span class=keyword>const</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>oiink</span> <span class=special>=</span> <span class=string>"Oiiink"</span><span class=special>;</span>
- <span class=keyword>class</span> <span class=identifier>cow</span> <span class=special>:</span> <span class=keyword>public</span> <span class=identifier>animal</span>
- <span class=special>{</span>
- <span class=keyword>virtual</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>do_speak</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>muuuh</span><span class=special>;</span>
- <span class=special>}</span>
- <span class=keyword>virtual</span> <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>do_clone</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=keyword>new</span> <span class=identifier>cow</span><span class=special>(</span> <span class=special>*</span><span class=keyword>this</span> <span class=special>);</span>
- <span class=special>}</span>
- <span class=keyword>public</span><span class=special>:</span>
- <span class=identifier>cow</span><span class=special>(</span> <span class=keyword>const</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=identifier>animal</span><span class=special>(</span><span class=identifier>name</span><span class=special>)</span> <span class=special>{</span> <span class=special>}</span>
- <span class=special>};</span>
- <span class=keyword>class</span> <span class=identifier>pig</span> <span class=special>:</span> <span class=keyword>public</span> <span class=identifier>animal</span>
- <span class=special>{</span>
- <span class=keyword>virtual</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span> <span class=identifier>do_speak</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>oiink</span><span class=special>;</span>
- <span class=special>}</span>
- <span class=keyword>virtual</span> <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>do_clone</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=keyword>new</span> <span class=identifier>pig</span><span class=special>(</span> <span class=special>*</span><span class=keyword>this</span> <span class=special>);</span>
- <span class=special>}</span>
-
- <span class=keyword>public</span><span class=special>:</span>
- <span class=identifier>pig</span><span class=special>(</span> <span class=keyword>const</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=identifier>animal</span><span class=special>(</span><span class=identifier>name</span><span class=special>)</span> <span class=special>{</span> <span class=special>}</span>
- <span class=special>};</span>
- <span class=comment>//
- // Then we, of course, need a place to put all
- // those animals.
- //</span>
- <span class=keyword>class</span> <span class=identifier>farm</span>
- <span class=special>{</span>
- <span class=comment>//
- // This is where the smart containers are handy
- //</span>
- <span class=keyword>typedef</span> <span class=identifier>boost</span><span class=special>::</span><span class=identifier>ptr_deque</span><span class=special><</span><span class=identifier>animal</span><span class=special>></span> <span class=identifier>barn_type</span><span class=special>;</span>
- <span class=identifier>barn_type</span> <span class=identifier>barn</span><span class=special>;</span>
- <span class=comment>//
- // A convenience typedef for the compiler-appropriate
- // smart pointer used to manage barns
- //</span>
- <span class=keyword>typedef</span> <span class=identifier><a href="compatible_smart_ptr.html"><em>compatible-smart-ptr</em></a></span><span class=special><</span><span class=identifier>barn_type</span><span class=special>></span> <span class=identifier>raii_ptr</span><span class=special>;</span>
- <span class=comment>//
- // An error type
- //</span>
- <span class=keyword>struct</span> <span class=identifier>farm_trouble</span> <span class=special>:</span> <span class=keyword>public</span> <span class=identifier>std</span><span class=special>::</span><span class=identifier>exception</span> <span class=special>{</span> <span class=special>};</span>
- <span class=keyword>public</span><span class=special>:</span>
- <span class=comment>//
- // We would like to make it possible to
- // iterate over the animals in the farm
- //</span>
- <span class=keyword>typedef</span> <span class=identifier>barn_type</span><span class=special>::</span><span class=identifier>iterator</span> <span class=identifier>animal_iterator</span><span class=special>;</span>
- <span class=comment>//
- // We also need to count the farm's size...
- //</span>
- <span class=keyword>typedef</span> <span class=identifier>barn_type</span><span class=special>::</span><span class=identifier>size_type</span> <span class=identifier>size_type</span><span class=special>;</span>
-
- <span class=comment>//
- // And we also want to transfer an animal
- // safely around. The easiest way to think
- // about '::auto_type' is to imagine a simplified
- // 'std::auto_ptr<T>' ... this means you can expect
- //
- // T* operator->()
- // T* release()
- // deleting destructor
- //
- // but not more.
- //</span>
- <span class=keyword>typedef</span> <span class=identifier>barn_type</span><span class=special>::</span><span class=identifier>auto_type</span> <span class=identifier>animal_transport</span><span class=special>;</span>
- <span class=comment>//
- // Create an empty farm.
- //</span>
- <span class=identifier>farm</span><span class=special>()</span> <span class=special>{</span> <span class=special>}</span>
-
- <span class=comment>//
- // We need a constructor that can make a new
- // farm by cloning a range of animals.
- //</span>
- <span class=identifier>farm</span><span class=special>(</span> <span class=identifier>animal_iterator</span> <span class=identifier>begin</span><span class=special>,</span> <span class=identifier>animal_iterator</span> <span class=identifier>end</span> <span class=special>)</span>
- <span class=special>:</span>
- <span class=comment>//
- // Objects are always cloned before insertion
- // unless we explicitly add a pointer or
- // use 'release()'. Therefore we actually
- // clone all animals in the range
- //</span>
- <span class=identifier>barn</span><span class=special>(</span> <span class=identifier>begin</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>//
- // ... so we need some other function too
- //</span>
- <span class=identifier>animal_iterator</span> <span class=identifier>begin</span><span class=special>()</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>begin</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=identifier>animal_iterator</span> <span class=identifier>end</span><span class=special>()</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>end</span><span class=special>();</span>
- <span class=special>}</span>
-
- <span class=comment>//
- // Here it is quite ok to have an 'animal*' argument.
- // The smart container will handle all ownership
- // issues.
- //</span>
- <span class=keyword>void</span> <span class=identifier>buy_animal</span><span class=special>(</span> <span class=identifier>animal</span><span class=special>*</span> <span class=identifier>a</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=identifier>barn</span><span class=special>.</span><span class=identifier>push_back</span><span class=special>(</span> <span class=identifier>a</span> <span class=special>);</span>
- <span class=special>}</span>
- <span class=comment>//
- // The farm can also be in economical trouble and
- // therefore be in the need to sell animals.
- //</span>
- <span class=identifier>animal_transport</span> <span class=identifier>sell_animal</span><span class=special>(</span> <span class=identifier>animal_iterator</span> <span class=identifier>to_sell</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=keyword>if</span><span class=special>(</span> <span class=identifier>to_sell</span> <span class=special>==</span> <span class=identifier>end</span><span class=special>()</span> <span class=special>)</span>
- <span class=keyword>throw</span> <span class=identifier>farm_trouble</span><span class=special>();</span>
- <span class=comment>//
- // Here we remove the animal from the barn,
- // but the animal is not deleted yet...it's
- // up to the buyer to decide what
- // to do with it.
- //</span>
- <span class=keyword>return</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>release</span><span class=special>(</span> <span class=identifier>to_sell</span> <span class=special>);</span>
- <span class=special>}</span>
- <span class=comment>//
- // How big a farm do we have?
- //</span>
- <span class=identifier>size_type</span> <span class=identifier>size</span><span class=special>()</span> <span class=keyword>const</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>size</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=comment>//
- // If things are bad, we might choose to sell all animals :-(
- //</span>
- <span class=identifier>raii_ptr</span> <span class=identifier>sell_farm</span><span class=special>()</span>
- <span class=special>{</span>
- <span class=keyword>return</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>release</span><span class=special>();</span>
- <span class=special>}</span>
- <span class=comment>//
- // However, if things are good, we might buy somebody
- // else's farm :-)
- //</span>
- <span class=keyword>void</span> <span class=identifier>buy_farm</span><span class=special>(</span> <span class=identifier>raii_ptr</span> <span class=identifier>other</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=comment>//
- // This line inserts all the animals from 'other'
- // and is guaranteed either to succeed or to have no
- // effect
- //</span>
- <span class=identifier>barn</span><span class=special>.</span><span class=identifier>transfer</span><span class=special>(</span> <span class=identifier>barn</span><span class=special>.</span><span class=identifier>end</span><span class=special>(),</span> <span class=comment>// insert new animals at the end</span>
- <span class=special>*</span><span class=identifier>other</span> <span class=special>);</span> <span class=comment>// we want to transfer all animals,
- // so we use the whole container as argument
- //
- // You might think you would have to do
- //
- // other.release();
- //
- // but '*other' is empty and can go out of scope as it wants
- //</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>other</span><span class=special>-></span><span class=identifier>empty</span><span class=special>()</span> <span class=special>);</span>
- <span class=special>}</span>
-
- <span class=special>};</span> <span class=comment>// class 'farm'.</span>
- <span class=keyword>int</span> <span class=identifier>main</span><span class=special>()</span>
- <span class=special>{</span>
- <span class=comment>//
- // First we make a farm
- //</span>
- <span class=identifier>farm</span> <span class=identifier>animal_farm</span><span class=special>;</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>0u</span> <span class=special>);</span>
-
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>pig</span><span class=special>(</span><span class=string>"Betty"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>pig</span><span class=special>(</span><span class=string>"Benny"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>pig</span><span class=special>(</span><span class=string>"Jeltzin"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>cow</span><span class=special>(</span><span class=string>"Hanz"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>cow</span><span class=special>(</span><span class=string>"Mary"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=keyword>new</span> <span class=identifier>cow</span><span class=special>(</span><span class=string>"Frederik"</span><span class=special>)</span> <span class=special>);</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>6u</span> <span class=special>);</span>
- <span class=comment>//
- // Then we make another farm...it will actually contain
- // a clone of the other farm.
- //</span>
- <span class=identifier>farm</span> <span class=identifier>new_farm</span><span class=special>(</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>begin</span><span class=special>(),</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>end</span><span class=special>()</span> <span class=special>);</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>6u</span> <span class=special>);</span>
- <span class=comment>//
- // Is it really clones in the new farm?
- //</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>begin</span><span class=special>()-></span><span class=identifier>name</span><span class=special>()</span> <span class=special>==</span> <span class=string>"Betty"</span> <span class=special>);</span>
-
- <span class=comment>//
- // Then we search for an animal, Mary (the Crown Princess of Denmark),
- // because we would like to buy her ...
- //</span>
- <span class=keyword>typedef</span> <span class=identifier>farm</span><span class=special>::</span><span class=identifier>animal_iterator</span> <span class=identifier>iterator</span><span class=special>;</span>
- <span class=identifier>iterator</span> <span class=identifier>to_sell</span><span class=special>;</span>
- <span class=keyword>for</span><span class=special>(</span> <span class=identifier>iterator</span> <span class=identifier>i</span> <span class=special>=</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>begin</span><span class=special>(),</span>
- <span class=identifier>end</span> <span class=special>=</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>end</span><span class=special>();</span>
- <span class=identifier>i</span> <span class=special>!=</span> <span class=identifier>end</span><span class=special>;</span> <span class=special>++</span><span class=identifier>i</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=keyword>if</span><span class=special>(</span> <span class=identifier>i</span><span class=special>-></span><span class=identifier>name</span><span class=special>()</span> <span class=special>==</span> <span class=string>"Mary"</span> <span class=special>)</span>
- <span class=special>{</span>
- <span class=identifier>to_sell</span> <span class=special>=</span> <span class=identifier>i</span><span class=special>;</span>
- <span class=keyword>break</span><span class=special>;</span>
- <span class=special>}</span>
- <span class=special>}</span>
- <span class=identifier>farm</span><span class=special>::</span><span class=identifier>animal_transport</span> <span class=identifier>mary</span> <span class=special>=</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>sell_animal</span><span class=special>(</span> <span class=identifier>to_sell</span> <span class=special>);</span>
- <span class=keyword>if</span><span class=special>(</span> <span class=identifier>mary</span><span class=special>-></span><span class=identifier>speak</span><span class=special>()</span> <span class=special>==</span> <span class=identifier>muuuh</span> <span class=special>)</span>
- <span class=comment>//
- // Great, Mary is a cow, and she may live longer
- //</span>
- <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>buy_animal</span><span class=special>(</span> <span class=identifier>mary</span><span class=special>.</span><span class=identifier>release</span><span class=special>()</span> <span class=special>);</span>
- <span class=keyword>else</span>
- <span class=comment>//
- // Then the animal would be destroyed (!)
- // when we go out of scope.
- //</span>
- <span class=special>;</span>
- <span class=comment>//
- // Now we can observe some changes to the two farms...
- //</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>5u</span> <span class=special>);</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>7u</span> <span class=special>);</span>
- <span class=comment>//
- // The new farm has however underestimated how much
- // it cost to feed Mary and its owner is forced to sell the farm...
- //</span>
- <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>buy_farm</span><span class=special>(</span> <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>sell_farm</span><span class=special>()</span> <span class=special>);</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>new_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>0u</span> <span class=special>);</span>
- <span class=identifier>BOOST_ASSERT</span><span class=special>(</span> <span class=identifier>animal_farm</span><span class=special>.</span><span class=identifier>size</span><span class=special>()</span> <span class=special>==</span> <span class=number>12u</span> <span class=special>);</span>
- <span class=special>}</span>
- </pre>
- </body>
- </html>
- <!-- 10. Changing the Clone Allocator
- ++++++++++++++++++++++++++++++++
- This example shows how we can change
- the Clone Allocator to use the pointer containers
- as view into other containers:
- .. raw:: html
- :file: tut2.html -->
- <hr><p><strong>Navigate:</strong></p>
- <ul class="simple">
- <li><a class="reference external" href="ptr_container.html">home</a></li>
- <li><a class="reference external" href="reference.html">reference</a></li>
- </ul>
- <hr><table class="docutils field-list" frame="void" rules="none">
- <col class="field-name" />
- <col class="field-body" />
- <tbody valign="top">
- <tr class="field"><th class="field-name">Copyright:</th><td class="field-body">Thorsten Ottosen 2004-2006. Use, modification and distribution is subject to the Boost Software License, Version 1.0 (see <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt">LICENSE_1_0.txt</a>).</td>
- </tr>
- </tbody>
- </table>
- </div>
- </div>
- </body>
- </html>
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