| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
| <HTML> |
| <HEAD> |
| <TITLE>Class Template basic_grep_filter</TITLE> |
| <LINK REL="stylesheet" HREF="../../../../boost.css"> |
| <LINK REL="stylesheet" HREF="../theme/iostreams.css"> |
| </HEAD> |
| <BODY> |
| |
| <!-- Begin Banner --> |
| |
| <H1 CLASS="title">Class Template <CODE>basic_grep_filter</CODE></H1> |
| <HR CLASS="banner"> |
| |
| <!-- End Banner --> |
| |
| <DL class="page-index"> |
| <DT><A href="#description">Description</A></DT> |
| <DT><A href="#headers">Headers</A></DT> |
| <DT><A href="#installation">Installation</A></DT> |
| <DT><A href="#reference">Reference</A></DT> |
| </DL> |
| |
| <HR> |
| |
| <A NAME="description"></A> |
| <H2>Description</H2> |
| |
| <P> |
| The class template <CODE>basic_grep_filter</CODE> filters a character sequence line by line using a regular expression provided at construction, in a manner similar to the command-line utility <i>grep</i> (<A CLASS="bib_ref" HREF="../bibliography.html#grep">[IEEE]</A>). The filter uses regular expressions from the <A HREF="http://www.boost.org/libs/regex" TARGET="_top">Boost Regular Expression Library</A> (<A CLASS="bib_ref" HREF="../bibliography.html#maddock">[Maddock]</A>). |
| </P> |
| <P> |
| By default, the filtered character sequence consists of those lines of the unfilitered sequence that contain a subsequence matching the regular expression. By specifying appropriate options at construction, <CODE>basic_grep_filter</CODE> can be made to pass through only those lines which exactly match the regular expression (as if the option <i>-x</i> had been passed to the command-line utility) or only those lines that <i>do not</i> contain a match (as if the option <i>-v</i> had been passed to the command-line utility). |
| </P> |
| <P> |
| A running count of the lines in the filtered character sequence is available via the member function <code><a href="#count">count</a></code>. |
| </P> |
| |
| <A NAME="headers"></A> |
| <H2>Headers</H2> |
| |
| <DL class="page-index"> |
| <DT><A CLASS="header" HREF="../../../../boost/iostreams/filter/grep.hpp"><CODE><boost/iostreams/filter/grep.hpp></CODE></A></DT> |
| </DL> |
| |
| <A NAME="installation"></A> |
| <H2>Installation</H2> |
| |
| <P> |
| The template <CODE>basic_grep_filter</CODE> uses the <A HREF="http://www.boost.org/libs/regex" TARGET="_top">Boost Regular Expression Library</A>, which must be built separately. See <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/install.html" TARGET="_top">here</A> for details. |
| </P> |
| |
| <A NAME="reference"></A> |
| <H2>Reference</H2> |
| |
| <H4>Synopsis</H4> |
| |
| <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { |
| |
| <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/function.hpp" TARGET="_top"><SPAN CLASS="literal"><boost/function.hpp></SPAN></A> |
| <SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/regex.hpp" TARGET="_top"><SPAN CLASS="literal"><boost/regex.hpp></SPAN></A> |
| |
| <SPAN CLASS="keyword">namespace</SPAN> grep { |
| |
| <SPAN CLASS="keyword">const</SPAN> <SPAN CLASS="keyword">int</SPAN> invert; |
| <SPAN CLASS="keyword">const</SPAN> <SPAN CLASS="keyword">int</SPAN> whole_line; |
| |
| } |
| |
| <SPAN CLASS="keyword">template</SPAN>< <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Ch</A>, |
| <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Tr</A> = regex_traits<Ch>, |
| <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Alloc</A> = std::allocator<Ch> > |
| <SPAN CLASS="keyword">class</SPAN> <A HREF="#template_params" CLASS="documented">basic_grep_filter</A> { |
| <SPAN CLASS="keyword">public:</SPAN> |
| <A CLASS="documented" HREF="#constructor">basic_grep_filter</A>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, |
| regex_constants::match_flag_type flags = |
| regex_constants::match_default, |
| <SPAN CLASS="keyword">int</SPAN> options = <SPAN CLASS="numeric_literal">0</SPAN> ); |
| <SPAN CLASS="keyword">int</SPAN> <A CLASS="documented" HREF="#count">count</A>() <SPAN CLASS="keyword">const</SPAN>; |
| }; |
| |
| <SPAN CLASS="keyword">typedef</SPAN> basic_grep_filter<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">grep_filter</SPAN>; |
| <SPAN CLASS="keyword">typedef</SPAN> basic_grep_filter<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wgrep_filter</SPAN>; |
| |
| } } // End namespace boost::io</PRE> |
| |
| <A NAME="template_params"></A> |
| <H4>Template parameters</H4> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>Ch</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The character type</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>Tr</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_traits.html" TARGET="_top">regular expression traits</A> type</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>Alloc</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>A standard library allocator type (<A CLASS="bib_ref" HREF="../bibliography.html#iso">[ISO]</A>, 20.1.5), used to allocate character buffers</TD> |
| </TR> |
| </TABLE> |
| |
| <A NAME="constructor"></A> |
| <H4><CODE>basic_grep_filter::basic_grep_filter</CODE></H4> |
| |
| <PRE CLASS="broken_ie"> <B>basic_grep_filter</B>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, |
| regex_constants::match_flag_type flags = |
| regex_constants::match_default, |
| <SPAN CLASS="keyword">int</SPAN> options = <SPAN CLASS="numeric_literal">0</SPAN> );</PRE> |
| |
| <P>Constructs a <CODE>basic_grep_filter</CODE> from the given regular expression, match flags, and grep options. The parameters have the following interpretations:</P> |
| |
| <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> |
| <TR> |
| <TR> |
| <TD VALIGN="top"><I>pattern</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The regular expression to be matched against the stream of unfiltered data</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>The flags passed to <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_search.html" TARGET="_top">regex_search</A> or <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_match.html" TARGET="_top">regex_match</A> to specify regular expression matching behavior</TD> |
| </TR> |
| <TR> |
| <TD VALIGN="top"><I>options</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> |
| <TD>A bitwise OR of zero or more constants from the namespace <CODE>boost::iostreams::grep</CODE>. Currently two constants are recongnized: <CODE>grep::whole_line</CODE> causes the filter to pass through only those lines which exactly match the regular expression, and <CODE>grep::invert</CODE> causes the filter to pass through only those lines that <i>do not</i> contain a match.</TD> |
| </TR> |
| </TABLE> |
| |
| </P> |
| |
| <A NAME="count"></A> |
| <H4><CODE>basic_grep_filter::count</CODE></H4> |
| |
| <A NAME="second_constructor"></A> |
| |
| <PRE CLASS="broken_ie"> <SPAN CLASS="keyword">int</SPAN> count() <SPAN CLASS="keyword">const</SPAN>;</PRE> |
| |
| <P>Returns a running count of the lines passed through from the unfiltered character sequence to the filtered character sequence. The count is reset to zero automatically when the filter begins processing a new character sequence.</P> |
| |
| <!-- Begin Footer --> |
| |
| <HR> |
| <P CLASS="copyright">Revised 28 May 2008</P> |
| |
| <P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a></P> |
| <P CLASS="copyright"> |
| 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">http://www.boost.org/LICENSE_1_0.txt</A>) |
| </P> |
| |
| <!-- End Footer --> |
| |
| </BODY> |