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| <div class="section"> |
| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.advanced.customize.iterate.container_iterator"></a><a class="link" href="container_iterator.html" title="Determine the Type of the Iterator of a Container (Karma)">Determine |
| the Type of the Iterator of a Container (Karma)</a> |
| </h5></div></div></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.container_iterator"></a><h6> |
| <a name="id1178443"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.container_iterator">container_iterator</a> |
| </h6> |
| <p> |
| The template <code class="computeroutput"><span class="identifier">container_iterator</span></code> |
| is a template meta-function used as an attribute customization point. |
| It is invoked by the <span class="emphasis"><em>Karma</em></span> repetitive generators |
| (such as <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene |
| (unary <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary <code class="computeroutput"><span class="special">+</span></code>)</a>, and <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>) |
| in order to determine the type of the iterator to use to iterate over |
| the items to be exposed as the elements of a container. |
| </p> |
| <a name="spirit.advanced.customize.iterate.container_iterator.module_headers"></a><h6> |
| <a name="id1178511"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.module_headers">Module |
| Headers</a> |
| </h6> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">home</span><span class="special">/</span><span class="identifier">support</span><span class="special">/</span><span class="identifier">container</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>. |
| </p> |
| <div class="note"><table border="0" summary="Note"> |
| <tr> |
| <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td> |
| <th align="left">Note</th> |
| </tr> |
| <tr><td align="left" valign="top"><p> |
| This header file does not need to be included directly by any user |
| program as it is normally included by other Spirit header files relying |
| on its content. |
| </p></td></tr> |
| </table></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.namespace"></a><h6> |
| <a name="id1178599"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.namespace">Namespace</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup><col></colgroup> |
| <thead><tr><th> |
| <p> |
| Name |
| </p> |
| </th></tr></thead> |
| <tbody><tr><td> |
| <p> |
| <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">traits</span></code> |
| </p> |
| </td></tr></tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.synopsis"></a><h6> |
| <a name="id1178677"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Container</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Enable</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">container_iterator</span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="special"><</span><span class="identifier">unspecified</span><span class="special">></span> <span class="identifier">type</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <a name="spirit.advanced.customize.iterate.container_iterator.template_parameters"></a><h6> |
| <a name="id1178775"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.template_parameters">Template |
| parameters</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| <th> |
| <p> |
| Default |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">Container</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| The type, <code class="computeroutput"><span class="identifier">Container</span></code> |
| for which the iterator type has to be returned |
| </p> |
| </td> |
| <td> |
| <p> |
| none |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">Enable</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Helper template parameter usable to selectively enable or disable |
| certain specializations of <code class="computeroutput"><span class="identifier">container_iterator</span></code> |
| utilizing SFINAE (i.e. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">enable_if</span></code> |
| or <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">disable_if</span></code>). |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="keyword">void</span></code> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.notation"></a><h6> |
| <a name="id1178948"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.notation">Notation</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">C</span></code></span></dt> |
| <dd><p> |
| A container type the iterator type needs to be evaluated for. |
| </p></dd> |
| </dl> |
| </div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.expression_semantics"></a><h6> |
| <a name="id1178989"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Semantics |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">container_iterator</span><span class="special"><</span><span class="identifier">C</span><span class="special">>::</span><span class="identifier">type</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Result of the metafunction that evaluates the type to be used |
| as the iterator for accessing all elements of a container, |
| <code class="computeroutput"><span class="identifier">C</span></code>. |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <p> |
| The returned type conceptually needs to be equivalent to a standard forward |
| iterator. But it does not have to expose the standardized interface. |
| If this customization point is implemented for a certain container type, |
| all related customization points need to be implemented as well (see |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.related_attribute_customization_points">Related |
| Attribute Customization Points</a> below). This encapsulates the specific |
| iterator interface required for a given type. The minimal requirements |
| for a type to be exposed as an iterator in this context are: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| it needs to be comparable for equality (see <a class="link" href="compare_iterators.html" title="Compare two Iterator pointing into a Container Attribute for Equality"><code class="computeroutput"><span class="identifier">compare_iterators</span></code></a>), |
| </li> |
| <li class="listitem"> |
| it needs to be incrementable (see <a class="link" href="next_iterator.html" title="Increment the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">next_iterator</span></code></a>), |
| </li> |
| <li class="listitem"> |
| it needs to be dereferencible (see <a class="link" href="deref_iterator.html" title="Dereference the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">deref_iterator</span></code></a>). |
| </li> |
| </ul></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.predefined_specializations"></a><h6> |
| <a name="id1179147"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.predefined_specializations">Predefined |
| Specializations</a> |
| </h6> |
| <p> |
| <a href="http://boost-spirit.com" target="_top">Spirit</a> predefines specializations |
| of this customization point for several types. The following table lists |
| those types together with the types returned by the embedded typedef |
| <code class="computeroutput"><span class="identifier">type</span></code>: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Template Parameters |
| </p> |
| </th> |
| <th> |
| <p> |
| Value |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">C</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Returns <code class="computeroutput"><span class="identifier">C</span><span class="special">::</span><span class="identifier">iterator</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">C</span> <span class="keyword">const</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Returns <code class="computeroutput"><span class="identifier">C</span><span class="special">::</span><span class="identifier">const_iterator</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">unused_type</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Returns <code class="computeroutput"><span class="identifier">unused_type</span></code><code class="computeroutput"> |
| <span class="keyword">const</span><span class="special">*</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.when_to_implement"></a><h6> |
| <a name="id1179339"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.when_to_implement">When |
| to implement</a> |
| </h6> |
| <p> |
| The customization point <code class="computeroutput"><span class="identifier">container_iterator</span></code> |
| needs to be implemented for a specific type whenever this type is to |
| be used as an attribute in place of a STL container. It is applicable |
| for generators (<span class="emphasis"><em>Spirit.Karma</em></span>) only. As a rule of |
| thumb: it has to be implemented whenever a certain type is to be passed |
| as an attribute to a generator normally exposing a STL container, <code class="computeroutput"><span class="identifier">C</span></code> and if the type does not expose the |
| interface of a STL container (i.e. <code class="computeroutput"><span class="identifier">is_container</span><span class="special"><</span><span class="identifier">C</span><span class="special">>::</span><span class="identifier">type</span></code> |
| would normally return <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code>). |
| </p> |
| <a name="spirit.advanced.customize.iterate.container_iterator.related_attribute_customization_points"></a><h6> |
| <a name="id1179410"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.related_attribute_customization_points">Related |
| Attribute Customization Points</a> |
| </h6> |
| <p> |
| If this customization point is implemented, the following other customization |
| points might need to be implemented as well. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Name |
| </p> |
| </th> |
| <th> |
| <p> |
| When to implement |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="../is_container.html" title="Determine if a Type Should be Treated as a Container (Qi and Karma)"><code class="computeroutput"><span class="identifier">is_container</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Needs to be implemented whenever a type is to be used as a |
| container attribute in <span class="emphasis"><em>Karma</em></span>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="container_iterator.html" title="Determine the Type of the Iterator of a Container (Karma)"><code class="computeroutput"><span class="identifier">container_iterator</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="begin_container.html" title="Get the Iterator pointing to the Begin of a Container Attribute"><code class="computeroutput"><span class="identifier">begin_container</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="end_container.html" title="Get the Iterator pointing to the End of a Container Attribute"><code class="computeroutput"><span class="identifier">end_container</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="deref_iterator.html" title="Dereference the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">deref_iterator</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="next_iterator.html" title="Increment the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">next_iterator</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="compare_iterators.html" title="Compare two Iterator pointing into a Container Attribute for Equality"><code class="computeroutput"><span class="identifier">compare_iterators</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Karma: <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/kleene.html" title="Kleene Star (*a)">Kleene (unary |
| <code class="computeroutput"><span class="special">*</span></code>)</a>, <a class="link" href="../../../karma/reference/operator/plus.html" title="Plus (+a)">Plus (unary |
| <code class="computeroutput"><span class="special">+</span></code>)</a>, <a class="link" href="../../../karma/reference/directive/repeat.html" title="Repetition Directive (repeat[])">Repeat</a>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.iterate.container_iterator.example"></a><h6> |
| <a name="id1180522"></a> |
| <a class="link" href="container_iterator.html#spirit.advanced.customize.iterate.container_iterator.example">Example</a> |
| </h6> |
| <p> |
| Here are the header files needed to make the example code below compile: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma</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">iostream</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The example (for the full source code please see here: <a href="../../../../../../example/karma/customize_embedded_container.cpp" target="_top">customize_embedded_container.cpp</a>) |
| uses the data structure |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">client</span> |
| <span class="special">{</span> |
| <span class="keyword">struct</span> <span class="identifier">embedded_container</span> |
| <span class="special">{</span> |
| <span class="comment">// expose the iterator of the embedded vector as our iterator |
| </span> <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">const_iterator</span> <span class="identifier">iterator</span><span class="special">;</span> |
| |
| <span class="comment">// expose the type of the held data elements as our type |
| </span> <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">>::</span><span class="identifier">value_type</span> <span class="identifier">type</span><span class="special">;</span> |
| |
| <span class="comment">// this is the vector holding the actual elements we need to generate |
| </span> <span class="comment">// output from |
| </span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="identifier">data</span><span class="special">;</span> |
| <span class="special">};</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| as a direct container attribute to the <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List |
| (<code class="computeroutput"><span class="special">%</span></code>)</a> generator. In |
| order to make this data structure compatible we need to specialize a |
| couple of attribute customization points: <a class="link" href="../is_container.html" title="Determine if a Type Should be Treated as a Container (Qi and Karma)"><code class="computeroutput"><span class="identifier">is_container</span></code></a>, <a class="link" href="container_iterator.html" title="Determine the Type of the Iterator of a Container (Karma)"><code class="computeroutput"><span class="identifier">container_iterator</span></code></a>, <a class="link" href="begin_container.html" title="Get the Iterator pointing to the Begin of a Container Attribute"><code class="computeroutput"><span class="identifier">begin_container</span></code></a>, and <a class="link" href="end_container.html" title="Get the Iterator pointing to the End of a Container Attribute"><code class="computeroutput"><span class="identifier">end_container</span></code></a>. As you can see |
| the specializations simply expose the embedded <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span></code> as the container to use. We don't |
| need to specialize the customization points related to iterators (<a class="link" href="deref_iterator.html" title="Dereference the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">deref_iterator</span></code></a>, <a class="link" href="next_iterator.html" title="Increment the Iterator pointing into a Container Attribute"><code class="computeroutput"><span class="identifier">next_iterator</span></code></a>, and <a class="link" href="compare_iterators.html" title="Compare two Iterator pointing into a Container Attribute for Equality"><code class="computeroutput"><span class="identifier">compare_iterators</span></code></a>) as we expose |
| a standard iterator and the default implementation of these customizations |
| handles standard iterators out of the box. |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="comment">// All specializations of attribute customization points have to be placed into |
| </span><span class="comment">// the namespace boost::spirit::traits. |
| </span><span class="comment">// |
| </span><span class="comment">// Note that all templates below are specialized using the 'const' type. |
| </span><span class="comment">// This is necessary as all attributes in Karma are 'const'. |
| </span><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">spirit</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">traits</span> |
| <span class="special">{</span> |
| <span class="comment">// The specialization of the template 'is_container<>' will tell the |
| </span> <span class="comment">// library to treat the type 'client::embedded_container' as a |
| </span> <span class="comment">// container holding the items to generate output from. |
| </span> <span class="keyword">template</span> <span class="special"><></span> |
| <span class="keyword">struct</span> <span class="identifier">is_container</span><span class="special"><</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">></span> |
| <span class="special">:</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span> |
| <span class="special">{};</span> |
| |
| <span class="comment">// The specialization of the template 'container_iterator<>' will be |
| </span> <span class="comment">// invoked by the library to evaluate the iterator type to be used |
| </span> <span class="comment">// for iterating the data elements in the container. We simply return |
| </span> <span class="comment">// the type of the iterator exposed by the embedded 'std::vector<int>'. |
| </span> <span class="keyword">template</span> <span class="special"><></span> |
| <span class="keyword">struct</span> <span class="identifier">container_iterator</span><span class="special"><</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">></span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">type</span><span class="special">;</span> |
| <span class="special">};</span> |
| |
| <span class="comment">// The specialization of the templates 'begin_container<>' and |
| </span> <span class="comment">// 'end_container<>' below will be used by the library to get the iterators |
| </span> <span class="comment">// pointing to the begin and the end of the data to generate output from. |
| </span> <span class="comment">// These specializations simply return the 'begin' and 'end' iterators as |
| </span> <span class="comment">// exposed by the embedded 'std::vector<int>'. |
| </span> <span class="comment">// |
| </span> <span class="comment">// The passed argument refers to the attribute instance passed to the list |
| </span> <span class="comment">// generator. |
| </span> <span class="keyword">template</span> <span class="special"><></span> |
| <span class="keyword">struct</span> <span class="identifier">begin_container</span><span class="special"><</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">></span> |
| <span class="special">{</span> |
| <span class="keyword">static</span> <span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span><span class="special">::</span><span class="identifier">iterator</span> |
| <span class="identifier">call</span><span class="special">(</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">d</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="keyword">return</span> <span class="identifier">d</span><span class="special">.</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span> |
| <span class="special">}</span> |
| <span class="special">};</span> |
| |
| <span class="keyword">template</span> <span class="special"><></span> |
| <span class="keyword">struct</span> <span class="identifier">end_container</span><span class="special"><</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">></span> |
| <span class="special">{</span> |
| <span class="keyword">static</span> <span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span><span class="special">::</span><span class="identifier">iterator</span> |
| <span class="identifier">call</span><span class="special">(</span><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">d</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="keyword">return</span> <span class="identifier">d</span><span class="special">.</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">end</span><span class="special">();</span> |
| <span class="special">}</span> |
| <span class="special">};</span> |
| <span class="special">}}}</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The last code snippet shows an example using an instance of the data |
| structure <code class="computeroutput"><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span></code> to generate output |
| from a <a class="link" href="../../../karma/reference/operator/list.html" title="Lists (a % b)">List (<code class="computeroutput"><span class="special">%</span></code>)</a> generator: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">client</span><span class="special">::</span><span class="identifier">embedded_container</span> <span class="identifier">d1</span><span class="special">;</span> <span class="comment">// create some test data |
| </span><span class="identifier">d1</span><span class="special">.</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">1</span><span class="special">);</span> |
| <span class="identifier">d1</span><span class="special">.</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">2</span><span class="special">);</span> |
| <span class="identifier">d1</span><span class="special">.</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">3</span><span class="special">);</span> |
| |
| <span class="comment">// use the instance of an 'client::embedded_container' instead of a |
| </span><span class="comment">// STL vector |
| </span><span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">karma</span><span class="special">::</span><span class="identifier">format</span><span class="special">(</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">int_</span> <span class="special">%</span> <span class="string">", "</span><span class="special">,</span> <span class="identifier">d1</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints: '1, 2, 3' |
| </span></pre> |
| <p> |
| </p> |
| <p> |
| As you can see, the specializations for the customization points as defined |
| above enable the seamless integration of the custom data structure without |
| having to modify the output format or the generator itself. |
| </p> |
| <p> |
| For other examples of how to use the customization point <code class="computeroutput"><span class="identifier">container_iterator</span></code> please see here: |
| <a class="link" href="next_iterator.html#spirit.advanced.customize.iterate.next_iterator.example">use_as_container</a> |
| and <a class="link" href="deref_iterator.html#spirit.advanced.customize.iterate.deref_iterator.example">counter_example</a>. |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2010 Joel de Guzman, Hartmut Kaiser<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
| </div></td> |
| </tr></table> |
| <hr> |
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