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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.karma.reference.directive.maxwidth"></a><a class="link" href="maxwidth.html" title="Controlling the Maximum Field Width (maxwidth[])">Controlling |
| the Maximum Field Width (<code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">[]</span></code>)</a> |
| </h5></div></div></div> |
| <a name="spirit.karma.reference.directive.maxwidth.description"></a><h6> |
| <a name="id1047055"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.description">Description</a> |
| </h6> |
| <p> |
| The <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">[]</span></code> |
| directive allows to limit (truncate) the overall length of the output |
| generated by the embedded generator. |
| </p> |
| <a name="spirit.karma.reference.directive.maxwidth.header"></a><h6> |
| <a name="id1047082"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/directive/maxwidth.hpp> |
| </span><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_maxwidth</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="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">maxwidth</span> <span class="comment">// |
| alias: boost::spirit::karma::maxwidth</span></code> |
| </p> |
| </td></tr></tbody> |
| </table></div> |
| <a name="spirit.karma.reference.directive.maxwidth.model_of"></a><h6> |
| <a name="id1047223"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.model_of">Model |
| of</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a> |
| </p></blockquote></div> |
| <div class="variablelist"> |
| <p class="title"><b>Notation</b></p> |
| <dl> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt> |
| <dd><p> |
| A generator object |
| </p></dd> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">A</span></code></span></dt> |
| <dd><p> |
| Attribute type of the generator <code class="computeroutput"><span class="identifier">a</span></code> |
| </p></dd> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">num</span></code></span></dt> |
| <dd><p> |
| Numeric literal, any unsigned integer value, or a <a class="link" href="../karma_basics.html#spirit.karma.reference.karma_basics.lazy_argument">Lazy |
| Argument</a> that evaluates to an unsigned integer value |
| </p></dd> |
| </dl> |
| </div> |
| <a name="spirit.karma.reference.directive.maxwidth.expression_semantics"></a><h6> |
| <a name="id1047336"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <p> |
| Semantics of an expression is defined only where it differs from, or |
| is not defined in <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a>. |
| </p> |
| <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">maxwidth</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Limit the overall length of the emitted output of the embedded |
| generator (including characters generated by automatic delimiting) |
| to the number of characters as defined by the preprocessor |
| constant <code class="computeroutput"><span class="identifier">BOOST_KARMA_DEFAULT_FIELD_MAXWIDTH</span></code>. |
| Any additional output is truncated. The directive succeeds |
| as long as the embedded generator succeeded (unless the underlying |
| output stream reports an error). |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Limit the overall length of the emitted output of the embedded |
| generator (including characters generated by automatic delimiting) |
| to the number of characters as defined by <code class="computeroutput"><span class="identifier">num</span></code>. |
| Any additional output is truncated. The directive succeeds |
| as long as the embedded generator succeeded (unless the underlying |
| output stream reports an error). |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <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> |
| The <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">[]</span></code> |
| generator directive does not pad the generated output to fill the specified |
| column width. If the emitted output is shorter than the specified (or |
| implied) column width, the generated output will be more narrow than |
| the column width. |
| </p> |
| <p> |
| If the output needs to always be equal to a specified column width, |
| use one of the alignment directives <code class="computeroutput"><span class="identifier">left</span><span class="special">-</span><span class="identifier">align</span><span class="special">[]</span></code>, <code class="computeroutput"><span class="identifier">center</span><span class="special">[]</span></code>, or <code class="computeroutput"><span class="identifier">right_align</span><span class="special">[]</span></code>, for instance: |
| </p> |
| <pre class="programlisting"><span class="identifier">maxwidth</span><span class="special">(</span><span class="number">8</span><span class="special">)[</span><span class="identifier">left_align</span><span class="special">(</span><span class="number">8</span><span class="special">)[</span><span class="string">"1234"</span><span class="special">]]</span> |
| </pre> |
| <p> |
| which will output: <code class="computeroutput"><span class="string">"1234 "</span></code> |
| (without the quotes). |
| </p> |
| </td></tr> |
| </table></div> |
| <a name="spirit.karma.reference.directive.maxwidth.attributes"></a><h6> |
| <a name="id1047604"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.attributes">Attributes</a> |
| </h6> |
| <p> |
| See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.karma.quick_reference.compound_attribute_rules.notation">Compound |
| Attribute Notation</a>. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Expression |
| </p> |
| </th> |
| <th> |
| <p> |
| Attribute |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| |
| </p> |
| <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">maxwidth</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">maxwidth</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> |
| <p> |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| |
| </p> |
| <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--></span> <span class="identifier">maxwidth</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">A</span> |
| <span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--></span> <span class="identifier">maxwidth</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre> |
| <p> |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.karma.reference.directive.maxwidth.complexity"></a><h6> |
| <a name="id1047915"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.complexity">Complexity</a> |
| </h6> |
| <div class="blockquote"><blockquote class="blockquote"><p> |
| The overall complexity of the generator directive <code class="computeroutput"><span class="identifier">maxwidth</span><span class="special">[]</span></code> is defined by the complexity of its |
| embedded generator. The complexity of the directive itself is O(N), |
| where <code class="computeroutput"><span class="identifier">N</span></code> is the number |
| of characters generated by the maxwidth directive. |
| </p></blockquote></div> |
| <a name="spirit.karma.reference.directive.maxwidth.example"></a><h6> |
| <a name="id1049598"></a> |
| <a class="link" href="maxwidth.html#spirit.karma.reference.directive.maxwidth.example">Example</a> |
| </h6> |
| <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> |
| The test harness for the example(s) below is presented in the <a class="link" href="../karma_basics.html#spirit.karma.reference.karma_basics.examples">Basics Examples</a> |
| section. |
| </p></td></tr> |
| </table></div> |
| <p> |
| Some includes: |
| </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">string</span><span class="special">></span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Some using declarations: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">maxwidth</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">left_align</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">right_align</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| Basic usage of <code class="computeroutput"><span class="identifier">maxwidth</span></code> |
| generator directive: |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">test_generator</span><span class="special">(</span><span class="string">"01234"</span><span class="special">,</span> <span class="identifier">maxwidth</span><span class="special">(</span><span class="number">5</span><span class="special">)[</span><span class="string">"0123456789"</span><span class="special">]);</span> |
| <span class="identifier">test_generator</span><span class="special">(</span><span class="string">" 012"</span><span class="special">,</span> <span class="identifier">maxwidth</span><span class="special">(</span><span class="number">5</span><span class="special">)[</span><span class="identifier">right_align</span><span class="special">(</span><span class="number">12</span><span class="special">)[</span><span class="string">"0123456789"</span><span class="special">]]);</span> |
| <span class="identifier">test_generator</span><span class="special">(</span><span class="string">"0123 "</span><span class="special">,</span> <span class="identifier">maxwidth</span><span class="special">(</span><span class="number">8</span><span class="special">)[</span><span class="identifier">left_align</span><span class="special">(</span><span class="number">8</span><span class="special">)[</span><span class="string">"0123"</span><span class="special">]]);</span> |
| </pre> |
| <p> |
| </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> |
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