forked from boostorg/fusion
Sync from trunk (except adapt class)
[SVN r56714]
This commit is contained in:
Joel de Guzman
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<title>Quick Start</title>
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<div class="spirit-nav">
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<a accesskey="p" href="introduction.html"><img src="../../../../../doc/html/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/html/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/html/images/home.png" alt="Home"></a><a accesskey="n" href="organization.html"><img src="../../../../../doc/html/images/next.png" alt="Next"></a>
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<div class="section" title="Quick Start">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="fusion.quick_start"></a><a class="link" href="quick_start.html" title="Quick Start">Quick Start</a>
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</h2></div></div></div>
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<div class="section" lang="en">
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<div class="titlepage">
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<div><div><h2 class="title" style="clear: both">
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<a name="fusion.quick_start"></a><a href="quick_start.html" title="Quick Start">Quick Start</a>
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</h2></div></div>
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<div></div>
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</div>
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<p>
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I assume the reader is already familiar with tuples (<a href="http://www.boost.org/libs/tuple/doc/tuple_users_guide.html" target="_top">Boost.Tuple</a>)
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and its ancestor <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>. The tuple is a generalization of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>
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and its ancestor <tt class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></tt>. The tuple is a generalization of <tt class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></tt>
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for multiple heterogeneous elements (triples, quadruples, etc.). The tuple
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is more or less a synonym for fusion's <code class="computeroutput"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a></code>.
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is more or less a synonym for fusion's <tt class="computeroutput"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a></tt>.
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</p>
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<p>
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For starters, we shall include all of Fusion's <a class="link" href="sequence.html" title="Sequence">Sequence</a>(s)
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<sup>[<a name="id543668" href="#ftn.id543668" class="footnote">2</a>]</sup>
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For starters, we shall include all of Fusion's <a href="sequence.html" title="Sequence">Sequence</a>(s)
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<sup>[<a name="id409214" href="#ftn.id409214">2</a>]</sup>
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:
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</p>
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<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
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<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
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</pre>
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<p>
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Let's begin with a <code class="computeroutput"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a></code>
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<sup>[<a name="id543783" href="#ftn.id543783" class="footnote">3</a>]</sup>
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Let's begin with a <tt class="computeroutput"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a></tt>
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<sup>[<a name="id409361" href="#ftn.id409361">3</a>]</sup>
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:
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</p>
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<pre class="programlisting"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">char</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">stuff</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="char">'x'</span><span class="special">,</span> <span class="string">"howdy"</span><span class="special">);</span>
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<span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <a class="link" href="sequence/intrinsic/functions/at_c.html" title="at_c"><code class="computeroutput"><span class="identifier">at_c</span></code></a><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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<span class="keyword">char</span> <span class="identifier">ch</span> <span class="special">=</span> <a class="link" href="sequence/intrinsic/functions/at_c.html" title="at_c"><code class="computeroutput"><span class="identifier">at_c</span></code></a><span class="special"><</span><span class="number">1</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s</span> <span class="special">=</span> <a class="link" href="sequence/intrinsic/functions/at_c.html" title="at_c"><code class="computeroutput"><span class="identifier">at_c</span></code></a><span class="special"><</span><span class="number">2</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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<pre class="programlisting"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">char</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">stuff</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="char">'x'</span><span class="special">,</span> <span class="string">"howdy"</span><span class="special">);</span>
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<span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <a href="sequence/intrinsic/functions/at_c.html" title="at_c"><tt class="computeroutput"><span class="identifier">at_c</span></tt></a><span class="special"><</span><span class="number">0</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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<span class="keyword">char</span> <span class="identifier">ch</span> <span class="special">=</span> <a href="sequence/intrinsic/functions/at_c.html" title="at_c"><tt class="computeroutput"><span class="identifier">at_c</span></tt></a><span class="special"><</span><span class="number">1</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s</span> <span class="special">=</span> <a href="sequence/intrinsic/functions/at_c.html" title="at_c"><tt class="computeroutput"><span class="identifier">at_c</span></tt></a><span class="special"><</span><span class="number">2</span><span class="special">>(</span><span class="identifier">stuff</span><span class="special">);</span>
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</pre>
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<p>
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Just replace <code class="computeroutput"><span class="identifier">tuple</span></code> for <code class="computeroutput"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a></code>
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and <code class="computeroutput"><span class="identifier">get</span></code> for <code class="computeroutput"><a class="link" href="sequence/intrinsic/functions/at_c.html" title="at_c"><code class="computeroutput"><span class="identifier">at_c</span></code></a></code> and this is exactly like
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Just replace <tt class="computeroutput"><span class="identifier">tuple</span></tt> for <tt class="computeroutput"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a></tt>
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and <tt class="computeroutput"><span class="identifier">get</span></tt> for <tt class="computeroutput"><a href="sequence/intrinsic/functions/at_c.html" title="at_c"><tt class="computeroutput"><span class="identifier">at_c</span></tt></a></tt> and this is exactly like
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<a href="http://www.boost.org/libs/tuple/doc/tuple_users_guide.html" target="_top">Boost.Tuple</a>.
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Actually, either names can be used interchangeably. Yet, the similarity ends
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there. You can do a lot more with Fusion <code class="computeroutput"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a></code> or <code class="computeroutput"><span class="identifier">tuple</span></code>.
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there. You can do a lot more with Fusion <tt class="computeroutput"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a></tt> or <tt class="computeroutput"><span class="identifier">tuple</span></tt>.
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Let's see some examples.
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</p>
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<a name="fusion.quick_start.print_the_vector_as_xml"></a><h4>
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<a name="id544099"></a>
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<a class="link" href="quick_start.html#fusion.quick_start.print_the_vector_as_xml">Print the vector
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<a name="fusion.quick_start.print_the_vector_as_xml"></a><h3>
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<a name="id409777"></a>
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<a href="quick_start.html#fusion.quick_start.print_the_vector_as_xml">Print the vector
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as XML</a>
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</h4>
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</h3>
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<p>
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First, let's include the algorithms:
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</p>
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@ -89,38 +92,38 @@
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<p>
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Now, finally:
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</p>
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<pre class="programlisting"><a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a><span class="special">(</span><span class="identifier">stuff</span><span class="special">,</span> <span class="identifier">print_xml</span><span class="special">());</span>
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<pre class="programlisting"><a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a><span class="special">(</span><span class="identifier">stuff</span><span class="special">,</span> <span class="identifier">print_xml</span><span class="special">());</span>
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</pre>
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<p>
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That's it! <code class="computeroutput"><a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a></code> is a fusion algorithm.
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That's it! <tt class="computeroutput"><a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a></tt> is a fusion algorithm.
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It is a generic algorithm similar to <a href="http://en.wikipedia.org/wiki/Standard_Template_Library" target="_top">STL</a>'s.
|
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It iterates over the sequence and calls a user supplied function. In our case,
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||||
it calls <code class="computeroutput"><span class="identifier">print_xml</span></code>'s <code class="computeroutput"><span class="keyword">operator</span><span class="special">()</span></code> for
|
||||
each element in <code class="computeroutput"><span class="identifier">stuff</span></code>.
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it calls <tt class="computeroutput"><span class="identifier">print_xml</span></tt>'s <tt class="computeroutput"><span class="keyword">operator</span><span class="special">()</span></tt> for
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each element in <tt class="computeroutput"><span class="identifier">stuff</span></tt>.
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||||
</p>
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<div class="caution" title="Caution"><table border="0" summary="Caution">
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<div class="caution"><table border="0" summary="Caution">
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<tr>
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<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="../../../../../doc/html/images/caution.png"></td>
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<th align="left">Caution</th>
|
||||
</tr>
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<tr><td align="left" valign="top"><p>
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||||
The result of <code class="computeroutput"><span class="keyword">typeid</span><span class="special">(</span><span class="identifier">x</span><span class="special">).</span><span class="identifier">name</span><span class="special">()</span></code> is platform specific. The code here is
|
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<tr><td colspan="2" align="left" valign="top"><p>
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The result of <tt class="computeroutput"><span class="keyword">typeid</span><span class="special">(</span><span class="identifier">x</span><span class="special">).</span><span class="identifier">name</span><span class="special">()</span></tt> is platform specific. The code here is
|
||||
just for exposition. Of course you already know that :-)
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</p></td></tr>
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</table></div>
|
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<p>
|
||||
<code class="computeroutput"><a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a></code> is generic. With
|
||||
<code class="computeroutput"><span class="identifier">print_xml</span></code>, you can use it to
|
||||
print just about any Fusion <a class="link" href="sequence.html" title="Sequence">Sequence</a>.
|
||||
<tt class="computeroutput"><a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a></tt> is generic. With
|
||||
<tt class="computeroutput"><span class="identifier">print_xml</span></tt>, you can use it to
|
||||
print just about any Fusion <a href="sequence.html" title="Sequence">Sequence</a>.
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</p>
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<a name="fusion.quick_start.print_only_pointers"></a><h4>
|
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<a name="id548148"></a>
|
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<a class="link" href="quick_start.html#fusion.quick_start.print_only_pointers">Print only pointers</a>
|
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</h4>
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<a name="fusion.quick_start.print_only_pointers"></a><h3>
|
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<a name="id410372"></a>
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<a href="quick_start.html#fusion.quick_start.print_only_pointers">Print only pointers</a>
|
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</h3>
|
||||
<p>
|
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Let's get a little cleverer. Say we wish to write a <span class="emphasis"><em>generic</em></span>
|
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function that takes in an arbitrary sequence and XML prints only those elements
|
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which are pointers. Ah, easy. First, let's include the <code class="computeroutput"><span class="identifier">is_pointer</span></code>
|
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which are pointers. Ah, easy. First, let's include the <tt class="computeroutput"><span class="identifier">is_pointer</span></tt>
|
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boost type trait:
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</p>
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<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">is_pointer</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
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@ -131,37 +134,37 @@
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<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Sequence</span><span class="special">></span>
|
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<span class="keyword">void</span> <span class="identifier">xml_print_pointers</span><span class="special">(</span><span class="identifier">Sequence</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">seq</span><span class="special">)</span>
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<span class="special">{</span>
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<a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a><span class="special">(</span><a class="link" href="algorithm/transformation/functions/filter_if.html" title="filter_if"><code class="computeroutput"><span class="identifier">filter_if</span></code></a><span class="special"><</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_pointer</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span> <span class="special">>(</span><span class="identifier">seq</span><span class="special">),</span> <span class="identifier">print_xml</span><span class="special">());</span>
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<a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a><span class="special">(</span><a href="algorithm/transformation/functions/filter_if.html" title="filter_if"><tt class="computeroutput"><span class="identifier">filter_if</span></tt></a><span class="special"><</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_pointer</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span> <span class="special">>(</span><span class="identifier">seq</span><span class="special">),</span> <span class="identifier">print_xml</span><span class="special">());</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
<code class="computeroutput"><a class="link" href="algorithm/transformation/functions/filter_if.html" title="filter_if"><code class="computeroutput"><span class="identifier">filter_if</span></code></a></code> is another Fusion
|
||||
algorithm. It returns a <a class="link" href="view/filter_view.html" title="filter_view"><code class="computeroutput"><span class="identifier">filter_view</span></code></a>, a conforming Fusion sequence.
|
||||
<tt class="computeroutput"><a href="algorithm/transformation/functions/filter_if.html" title="filter_if"><tt class="computeroutput"><span class="identifier">filter_if</span></tt></a></tt> is another Fusion
|
||||
algorithm. It returns a <a href="view/filter_view.html" title="filter_view"><tt class="computeroutput"><span class="identifier">filter_view</span></tt></a>, a conforming Fusion sequence.
|
||||
This view reflects only those elements that pass the given predicate. In this
|
||||
case, the predicate is <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_pointer</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span></code>.
|
||||
This "filtered view" is then passed to the <a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a> algorithm, which then prints
|
||||
case, the predicate is <tt class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_pointer</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span></tt>.
|
||||
This "filtered view" is then passed to the <a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a> algorithm, which then prints
|
||||
the "filtered view" as XML.
|
||||
</p>
|
||||
<p>
|
||||
Easy, right?
|
||||
</p>
|
||||
<a name="fusion.quick_start.associative_tuples"></a><h4>
|
||||
<a name="id548421"></a>
|
||||
<a class="link" href="quick_start.html#fusion.quick_start.associative_tuples">Associative tuples</a>
|
||||
</h4>
|
||||
<a name="fusion.quick_start.associative_tuples"></a><h3>
|
||||
<a name="id410736"></a>
|
||||
<a href="quick_start.html#fusion.quick_start.associative_tuples">Associative tuples</a>
|
||||
</h3>
|
||||
<p>
|
||||
Ok, moving on...
|
||||
</p>
|
||||
<p>
|
||||
Apart from <code class="computeroutput"><a class="link" href="container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a></code>,
|
||||
Apart from <tt class="computeroutput"><a href="container/vector.html" title="vector"><tt class="computeroutput"><span class="identifier">vector</span></tt></a></tt>,
|
||||
fusion has a couple of other sequence types to choose from. Each sequence has
|
||||
its own characteristics. We have <code class="computeroutput"><a class="link" href="container/list.html" title="list"><code class="computeroutput"><span class="identifier">list</span></code></a></code>, <code class="computeroutput"><a class="link" href="container/set.html" title="set"><code class="computeroutput"><span class="identifier">set</span></code></a></code>, <code class="computeroutput"><a class="link" href="container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a></code>, plus a multitude of <code class="computeroutput"><span class="identifier">views</span></code> that provide various ways to present
|
||||
its own characteristics. We have <tt class="computeroutput"><a href="container/list.html" title="list"><tt class="computeroutput"><span class="identifier">list</span></tt></a></tt>, <tt class="computeroutput"><a href="container/set.html" title="set"><tt class="computeroutput"><span class="identifier">set</span></tt></a></tt>, <tt class="computeroutput"><a href="container/map.html" title="map"><tt class="computeroutput"><span class="identifier">map</span></tt></a></tt>, plus a multitude of <tt class="computeroutput"><span class="identifier">views</span></tt> that provide various ways to present
|
||||
the sequences.
|
||||
</p>
|
||||
<p>
|
||||
Fusion's <code class="computeroutput"><a class="link" href="container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a></code>
|
||||
Fusion's <tt class="computeroutput"><a href="container/map.html" title="map"><tt class="computeroutput"><span class="identifier">map</span></tt></a></tt>
|
||||
associate types with elements. It can be used as a cleverer replacement of
|
||||
the <code class="computeroutput"><span class="keyword">struct</span></code>. Example:
|
||||
the <tt class="computeroutput"><span class="keyword">struct</span></tt>. Example:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">fields</span>
|
||||
<span class="special">{</span>
|
||||
@ -169,31 +172,31 @@
|
||||
<span class="keyword">struct</span> <span class="identifier">age</span><span class="special">;</span>
|
||||
<span class="special">}</span>
|
||||
|
||||
<span class="keyword">typedef</span> <a class="link" href="container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a><span class="special"><</span>
|
||||
<a class="link" href="support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">fusion</span><span class="special">::</span><span class="identifier">pair</span></code></a><span class="special"><</span><span class="identifier">fields</span><span class="special">::</span><span class="identifier">name</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="special">,</span> <a class="link" href="support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">fusion</span><span class="special">::</span><span class="identifier">pair</span></code></a><span class="special"><</span><span class="identifier">fields</span><span class="special">::</span><span class="identifier">age</span><span class="special">,</span> <span class="keyword">int</span><span class="special">></span> <span class="special">></span>
|
||||
<span class="keyword">typedef</span> <a href="container/map.html" title="map"><tt class="computeroutput"><span class="identifier">map</span></tt></a><span class="special"><</span>
|
||||
<a href="support/pair.html" title="pair"><tt class="computeroutput"><span class="identifier">fusion</span><span class="special">::</span><span class="identifier">pair</span></tt></a><span class="special"><</span><span class="identifier">fields</span><span class="special">::</span><span class="identifier">name</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="special">,</span> <a href="support/pair.html" title="pair"><tt class="computeroutput"><span class="identifier">fusion</span><span class="special">::</span><span class="identifier">pair</span></tt></a><span class="special"><</span><span class="identifier">fields</span><span class="special">::</span><span class="identifier">age</span><span class="special">,</span> <span class="keyword">int</span><span class="special">></span> <span class="special">></span>
|
||||
<span class="identifier">person</span><span class="special">;</span>
|
||||
</pre>
|
||||
<p>
|
||||
<code class="computeroutput"><a class="link" href="container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a></code>
|
||||
<tt class="computeroutput"><a href="container/map.html" title="map"><tt class="computeroutput"><span class="identifier">map</span></tt></a></tt>
|
||||
is an associative sequence. Its elements are Fusion pairs which differ somewhat
|
||||
from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>. Fusion pairs only contain one member,
|
||||
from <tt class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></tt>. Fusion pairs only contain one member,
|
||||
with the type of their second template parameter. The first type parameter
|
||||
of the pair is used as an index to the associated element in the sequence.
|
||||
For example, given a <code class="computeroutput"><span class="identifier">a_person</span></code>
|
||||
of type, <code class="computeroutput"><span class="identifier">person</span></code>, you can do:
|
||||
For example, given a <tt class="computeroutput"><span class="identifier">a_person</span></tt>
|
||||
of type, <tt class="computeroutput"><span class="identifier">person</span></tt>, you can do:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">fields</span><span class="special">;</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">person_name</span> <span class="special">=</span> <a class="link" href="sequence/intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">name</span><span class="special">>(</span><span class="identifier">a_person</span><span class="special">);</span>
|
||||
<span class="keyword">int</span> <span class="identifier">person_age</span> <span class="special">=</span> <a class="link" href="sequence/intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">age</span><span class="special">>(</span><span class="identifier">a_person</span><span class="special">);</span>
|
||||
<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">person_name</span> <span class="special">=</span> <a href="sequence/intrinsic/functions/at_key.html" title="at_key"><tt class="computeroutput"><span class="identifier">at_key</span></tt></a><span class="special"><</span><span class="identifier">name</span><span class="special">>(</span><span class="identifier">a_person</span><span class="special">);</span>
|
||||
<span class="keyword">int</span> <span class="identifier">person_age</span> <span class="special">=</span> <a href="sequence/intrinsic/functions/at_key.html" title="at_key"><tt class="computeroutput"><span class="identifier">at_key</span></tt></a><span class="special"><</span><span class="identifier">age</span><span class="special">>(</span><span class="identifier">a_person</span><span class="special">);</span>
|
||||
</pre>
|
||||
<p>
|
||||
Why go through all this trouble, you say? Well, for one, unlike the <code class="computeroutput"><span class="keyword">struct</span></code>, we are dealing with a generic data structure.
|
||||
Why go through all this trouble, you say? Well, for one, unlike the <tt class="computeroutput"><span class="keyword">struct</span></tt>, we are dealing with a generic data structure.
|
||||
There are a multitude of facilities available at your disposal provided out
|
||||
of the box with fusion or written by others. With these facilities, introspection
|
||||
comes for free, for example. We can write one serialization function (well,
|
||||
two, if you consider loading and saving) that will work for all your fusion
|
||||
<code class="computeroutput"><a class="link" href="container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a></code>s.
|
||||
<tt class="computeroutput"><a href="container/map.html" title="map"><tt class="computeroutput"><span class="identifier">map</span></tt></a></tt>s.
|
||||
Example:
|
||||
</p>
|
||||
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">saver</span>
|
||||
@ -208,19 +211,19 @@
|
||||
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Stuff</span><span class="special">></span>
|
||||
<span class="keyword">void</span> <span class="identifier">save</span><span class="special">(</span><span class="identifier">Stuff</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">stuff</span><span class="special">)</span>
|
||||
<span class="special">{</span>
|
||||
<a class="link" href="algorithm/iteration/functions/for_each.html" title="for_each"><code class="computeroutput"><span class="identifier">for_each</span></code></a><span class="special">(</span><span class="identifier">stuff</span><span class="special">,</span> <span class="identifier">saver</span><span class="special">());</span>
|
||||
<a href="algorithm/iteration/functions/for_each.html" title="for_each"><tt class="computeroutput"><span class="identifier">for_each</span></tt></a><span class="special">(</span><span class="identifier">stuff</span><span class="special">,</span> <span class="identifier">saver</span><span class="special">());</span>
|
||||
<span class="special">}</span>
|
||||
</pre>
|
||||
<p>
|
||||
The <code class="computeroutput"><span class="identifier">save</span></code> function is generic
|
||||
and will work for all types of <code class="computeroutput"><span class="identifier">stuff</span></code>
|
||||
regardless if it is a <code class="computeroutput"><span class="identifier">person</span></code>,
|
||||
a <code class="computeroutput"><span class="identifier">dog</span></code> or a whole <code class="computeroutput"><span class="identifier">alternate_universe</span></code>.
|
||||
The <tt class="computeroutput"><span class="identifier">save</span></tt> function is generic
|
||||
and will work for all types of <tt class="computeroutput"><span class="identifier">stuff</span></tt>
|
||||
regardless if it is a <tt class="computeroutput"><span class="identifier">person</span></tt>,
|
||||
a <tt class="computeroutput"><span class="identifier">dog</span></tt> or a whole <tt class="computeroutput"><span class="identifier">alternate_universe</span></tt>.
|
||||
</p>
|
||||
<a name="fusion.quick_start.tip_of_the_iceberg"></a><h4>
|
||||
<a name="id549132"></a>
|
||||
<a class="link" href="quick_start.html#fusion.quick_start.tip_of_the_iceberg">Tip of the Iceberg</a>
|
||||
</h4>
|
||||
<a name="fusion.quick_start.tip_of_the_iceberg"></a><h3>
|
||||
<a name="id411650"></a>
|
||||
<a href="quick_start.html#fusion.quick_start.tip_of_the_iceberg">Tip of the Iceberg</a>
|
||||
</h3>
|
||||
<p>
|
||||
And... we've barely scratched the surface! You can compose and expand the data
|
||||
structures, remove elements from the structures, find specific data types,
|
||||
@ -229,14 +232,14 @@
|
||||
</p>
|
||||
<div class="footnotes">
|
||||
<br><hr width="100" align="left">
|
||||
<div class="footnote"><p><sup>[<a name="ftn.id543668" href="#id543668" class="para">2</a>] </sup>
|
||||
<div class="footnote"><p><sup>[<a name="ftn.id409214" href="#id409214">2</a>] </sup>
|
||||
There are finer grained header files available if you wish to have more
|
||||
control over which components to include (see section <a class="link" href="organization.html" title="Organization">Orgainization</a>
|
||||
control over which components to include (see section <a href="organization.html" title="Organization">Orgainization</a>
|
||||
for details).
|
||||
</p></div>
|
||||
<div class="footnote"><p><sup>[<a name="ftn.id543783" href="#id543783" class="para">3</a>] </sup>
|
||||
Unless otherwise noted, components are in namespace <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">fusion</span></code>.
|
||||
For the sake of simplicity, code in this quick start implies <code class="computeroutput"><span class="keyword">using</span></code> directives for the fusion components
|
||||
<div class="footnote"><p><sup>[<a name="ftn.id409361" href="#id409361">3</a>] </sup>
|
||||
Unless otherwise noted, components are in namespace <tt class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">fusion</span></tt>.
|
||||
For the sake of simplicity, code in this quick start implies <tt class="computeroutput"><span class="keyword">using</span></tt> directives for the fusion components
|
||||
we will be using.
|
||||
</p></div>
|
||||
</div>
|
||||
|
||||
Reference in New Issue
Block a user