<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Separate Output Into Columns (columns[])</title> <link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.0"> <link rel="home" href="../../../../index.html" title="Spirit 2.4"> <link rel="up" href="../directive.html" title="Directive"> <link rel="prev" href="duplicate.html" title="Duplicate Attribute (duplicate[])"> <link rel="next" href="../nonterminal.html" title="Nonterminal"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> <td align="center"><a href="../../../../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="duplicate.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../nonterminal.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h5 class="title"> <a name="spirit.karma.reference.directive.columns"></a><a class="link" href="columns.html" title="Separate Output Into Columns (columns[])"> Separate Output Into Columns (<code class="computeroutput"><span class="identifier">columns</span><span class="special">[]</span></code>)</a> </h5></div></div></div> <a name="spirit.karma.reference.directive.columns.description"></a><h6> <a name="id1098031"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.description">Description</a> </h6> <p> The <code class="computeroutput"><span class="identifier">columns</span><span class="special">[]</span></code> directive separates the output emitted by the embedded generator by inserting special column separators. </p> <a name="spirit.karma.reference.directive.columns.header"></a><h6> <a name="id1098059"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.header">Header</a> </h6> <pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/directive/columns.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_columns</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">columns</span> <span class="comment">// alias: boost::spirit::karma::columns</span></code> </p> </td></tr></tbody> </table></div> <a name="spirit.karma.reference.directive.columns.model_of"></a><h6> <a name="id1098199"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.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">g</span></code></span></dt> <dd><p> A generator object, or a <a class="link" href="../karma_basics.html#spirit.karma.reference.karma_basics.lazy_argument">Lazy Argument</a> that evaluates to a generator object, will be used to emit column separators </p></dd> <dt><span class="term"><code class="computeroutput"><span class="identifier">A</span></code></span></dt> <dd> <p> Attribute type of generator <code class="computeroutput"><span class="identifier">a</span></code> </p> <p> [<code class="computeroutput"><span class="identifier">num</span></code> </p> <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 defining the number of items to emit in between the column separators </p> </dd> </dl> </div> <a name="spirit.karma.reference.directive.columns.expression_semantics"></a><h6> <a name="id1098337"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.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">columns</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> </p> </td> <td> <p> The <code class="computeroutput"><span class="identifier">columns</span></code> directive invokes a generator after each N-th element of the embedded generator has been emitted. The number of columns is defined by the preprocessor constant <code class="computeroutput"><span class="identifier">BOOST_KARMA_DEFAULT_COLUMNS</span></code>. The column separator used will be <code class="computeroutput"><span class="identifier">karma</span><span class="special">::</span><span class="identifier">eol</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">columns</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> The <code class="computeroutput"><span class="identifier">columns</span></code> directive invokes a generator after each N-th element of the embedded generator has been emitted. The number of columns is defined by the argument to the directive <code class="computeroutput"><span class="identifier">num</span></code>. The column separator used will be <code class="computeroutput"><span class="identifier">karma</span><span class="special">::</span><span class="identifier">eol</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">columns</span><span class="special">(</span><span class="identifier">g</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> </p> </td> <td> <p> The <code class="computeroutput"><span class="identifier">columns</span></code> directive invokes a generator after each N-th element of the embedded generator has been emitted. The number of columns is defined by the preprocessor constant <code class="computeroutput"><span class="identifier">BOOST_KARMA_DEFAULT_COLUMNS</span></code>. The column separator used will be <code class="computeroutput"><span class="identifier">g</span></code>. </p> </td> </tr> <tr> <td> <p> <code class="computeroutput"><span class="identifier">columns</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">g</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code> </p> </td> <td> <p> The <code class="computeroutput"><span class="identifier">columns</span></code> directive invokes a generator after each N-th element of the embedded generator has been emitted. The number of columns is defined by the argument to the directive <code class="computeroutput"><span class="identifier">num</span></code>. The column separator used will be <code class="computeroutput"><span class="identifier">g</span></code>. </p> </td> </tr> </tbody> </table></div> <a name="spirit.karma.reference.directive.columns.attributes"></a><h6> <a name="id1098683"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.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">columns</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">columns</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">columns</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">columns</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">columns</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">columns</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> <tr> <td> <p> <code class="computeroutput"><span class="identifier">columns</span><span class="special">(</span><span class="identifier">g</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">columns</span><span class="special">(</span><span class="identifier">g</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">columns</span><span class="special">(</span><span class="identifier">g</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">columns</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">g</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">columns</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">g</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">columns</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">g</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.columns.complexity"></a><h6> <a name="id1099292"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.complexity">Complexity</a> </h6> <div class="blockquote"><blockquote class="blockquote"><p> The overall complexity of the <code class="computeroutput"><span class="identifier">columns</span></code> generator directive depends on the complexity of the embeddded generator. The complexitz of the <code class="computeroutput"><span class="identifier">columns</span></code> generator directive itself is O(N), where <code class="computeroutput"><span class="identifier">N</span></code> is the number of inserted column separators. </p></blockquote></div> <a name="spirit.karma.reference.directive.columns.example"></a><h6> <a name="id1099335"></a> <a class="link" href="columns.html#spirit.karma.reference.directive.columns.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">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">phoenix_core</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">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">phoenix_operator</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">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">std_pair</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">columns</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">space</span><span class="special">;</span> </pre> <p> </p> <p> Basic usage of the <code class="computeroutput"><span class="identifier">columns</span></code> generators: </p> <p> </p> <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">v</span><span class="special">;</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">1.0</span><span class="special">);</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">3.0</span><span class="special">);</span> <span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"1.0\n2.0\n3.0\n"</span><span class="special">,</span> <span class="identifier">columns</span><span class="special">(</span><span class="number">1</span><span class="special">)[*</span><span class="identifier">double_</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span> <span class="identifier">test_generator_attr_delim</span><span class="special">(</span><span class="string">"1.0 2.0 \n3.0 \n"</span><span class="special">,</span> <span class="identifier">columns</span><span class="special">(</span><span class="number">2</span><span class="special">)[*</span><span class="identifier">double_</span><span class="special">],</span> <span class="identifier">space</span><span class="special">,</span> <span class="identifier">v</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> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="duplicate.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../directive.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../nonterminal.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>