1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4 <TITLE>Class Template basic_regex_filter</TITLE> 5 <LINK REL="stylesheet" HREF="../../../../boost.css"> 6 <LINK REL="stylesheet" HREF="../theme/iostreams.css"> 7</HEAD> 8<BODY> 9 10<!-- Begin Banner --> 11 12 <H1 CLASS="title">Class Template <CODE>basic_regex_filter</CODE></H1> 13 <HR CLASS="banner"> 14 15<!-- End Banner --> 16 17<DL class="page-index"> 18 <DT><A href="#description">Description</A></DT> 19 <DT><A href="#headers">Headers</A></DT> 20 <DT><A href="#installation">Installation</A></DT> 21 <DT><A href="#reference">Reference</A></DT> 22</DL> 23 24<HR> 25 26<A NAME="description"></A> 27<H2>Description</H2> 28 29<P> 30 The class template <CODE>basic_regex_filter</CODE> performs text substitutions using 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>). 31</P> 32<P> 33 Each <CODE>basic_regex_filter</CODE> stores a regular expression and a formatting function. As unfiltered data is scanned for matches, portions of data which fall between regular expression matches are forwarded unchanged. Each time a match is found, the corresponding <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/match_results.html" TARGET="_top"><CODE>match_results</CODE></A> object is passed to the formatting function and the return value is forwarded in place of the matched text. 34</P> 35<P> 36 Users may construct instances of <CODE>basic_regex_filter</CODE> either from <A HREF="#formatter">formatting functions</A> or from <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/format.html" TARGET="_top">format strings</A>. 37</P> 38<P> 39 Since a regular expression may need to look arbitrarily far ahead in a character sequence, <CODE>basic_regex_filter</CODE> derives from <A HREF="aggregate.html"><CODE>aggregate_filter</CODE></A> and processes an entire sequence of data at once. 40</P> 41 42<A NAME="headers"></A> 43<H2>Headers</H2> 44 45<DL class="page-index"> 46 <DT><A CLASS="header" HREF="../../../../boost/iostreams/filter/regex.hpp"><CODE><boost/iostreams/filter/regex.hpp></CODE></A></DT> 47</DL> 48 49<A NAME="installation"></A> 50<H2>Installation</H2> 51 52<P> 53 The template <CODE>basic_regex_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. 54</P> 55 56<A NAME="reference"></A> 57<H2>Reference</H2> 58 59<H4>Synopsis</H4> 60 61<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 62 63<SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/function.hpp" TARGET="_top"><SPAN CLASS="literal"><boost/function.hpp></SPAN></A> 64<SPAN CLASS="preprocessor">#include</SPAN> <A CLASS="header" HREF="../../../../boost/regex.hpp" TARGET="_top"><SPAN CLASS="literal"><boost/regex.hpp></SPAN></A> 65 66<SPAN CLASS="keyword">template</SPAN>< <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Ch</A>, 67 <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Tr</A> = regex_traits<Ch>, 68 <SPAN CLASS="keyword">typename</SPAN> <A HREF="#template_params" CLASS="documented">Alloc</A> = std::allocator<Ch> > 69<SPAN CLASS="keyword">class</SPAN> <A HREF="#template_params" CLASS="documented">basic_regex_filter</A> 70 : <SPAN CLASS="keyword">public</SPAN> <A CLASS="documented" HREF="aggregate.html">aggregate_filter</A><Ch, std::char_traits<Ch>, Alloc> // Exposition only 71{ 72<SPAN CLASS="keyword">public:</SPAN> 73 <SPAN CLASS="keyword">typedef</SPAN> <A CLASS="documented" HREF="../../../../doc/html/function.html" TARGET="_top">boost::function1<</A> 74 std::basic_string<Ch>, 75 <SPAN CLASS="keyword">const</SPAN> match_results<const Ch*>& 76 > 77 <A CLASS="documented" HREF="#formatter">formatter</A>; 78 <A CLASS="documented" HREF="#first_constructor">basic_regex_filter</A>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 79 <SPAN CLASS="keyword">const</SPAN> formatter& replace, 80 regex_constants::match_flag_type flags = 81 regex_constants::match_default ); 82 <A CLASS="documented" HREF="#second_constructor">basic_regex_filter</A>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 83 <SPAN CLASS="keyword">const</SPAN> std::basic_string<Ch>& fmt, 84 regex_constants::match_flag_type flags = 85 regex_constants::match_default, 86 regex_constants::match_flag_type fmt_flags = 87 regex_constants::format_default ); 88 <A CLASS="documented" HREF="#third_constructor">basic_regex_filter</A>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 89 <SPAN CLASS="keyword">const</SPAN> Ch* fmt, 90 regex_constants::match_flag_type flags = 91 regex_constants::match_default, 92 regex_constants::match_flag_type fmt_flags = 93 regex_constants::format_default ); 94}; 95 96<SPAN CLASS="keyword">typedef</SPAN> basic_regex_filter<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">regex_filter</SPAN>; 97<SPAN CLASS="keyword">typedef</SPAN> basic_regex_filter<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wregex_filter</SPAN>; 98 99} } // End namespace boost::io</PRE> 100 101<A NAME="template_params"></A> 102<H4>Template parameters</H4> 103 104<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 105<TR> 106 <TR> 107 <TD VALIGN="top"><I>Ch</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 108 <TD>The character type</TD> 109 </TR> 110 <TR> 111 <TD VALIGN="top"><I>Tr</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 112 <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> 113 </TR> 114 <TR> 115 <TD VALIGN="top"><I>Alloc</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 116 <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> 117 </TR> 118</TABLE> 119 120<A NAME="formatter"></A> 121<H4><CODE>basic_regex_filter::formatter</CODE></H4> 122 123<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">typedef</SPAN> boost::function1< 124 std::basic_string<Ch>, 125 <SPAN CLASS="keyword">const</SPAN> match_results<const Ch*>& 126 > 127 <B>formatter</B>;</PRE> 128 129<P> 130 The type of object which a <CODE>basic_regex_filter</CODE> uses to determine the replacement text for a given regular expression match. Each time a match is found, a corresponding <CODE>match_results</CODE> object is passed to a <CODE>formatter</CODE>, which returns the appropriate replacement text. Since <A HREF="http://www.boost.org/libs/function" TARGET="_top">Boost.Function</A> objects are implictly constructible from function objects with the correct signature, users of regular expression Filters may define their own function objects with the correct signature and pass them to the <CODE>basic_regex_filter</CODE> constructor which takes a <CODE>formatter</CODE>. E.g., 131<PRE CLASS="broken_ie"> struct my_formatter { 132 std::string operator()(const match_results<const char*>& match) 133 { 134 <SPAN CLASS="comment">// Examine match and return the appropriate replacement text</SPAN> 135 } 136 }; 137 int main() 138 { 139 regex pattern( <SPAN CLASS="omitted">...</SPAN> ); 140 regex_filter filter(pattern, my_formatter()); 141 <SPAN CLASS="omitted">...</SPAN> 142 }</PRE> 143</P> 144 145<H4><CODE>basic_regex_filter::basic_regex_filter</CODE></H4> 146 147<A NAME="first_constructor"></A> 148<PRE CLASS="broken_ie"> <B>basic_regex_filter</B>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 149 <SPAN CLASS="keyword">const</SPAN> formatter& replace, 150 regex_constants::match_flag_type flags = 151 regex_constants::match_default );</PRE> 152 153<P>Constructs a <CODE>basic_regex_filter</CODE> from the given regular expression, formatting function and match flags. The parameters have the following interpretations:</P> 154 155<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 156<TR> 157 <TR> 158 <TD VALIGN="top"><I>pattern</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 159 <TD>The regular expression to be matched against the stream of unfiltered data</TD> 160 </TR> 161 <TR> 162 <TD VALIGN="top"><I>replace</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 163 <TD>A function which will be passed each <CODE>match_results</CODE> object in succession and whose return values will be be used as replacement text</TD> 164 </TR> 165 <TR> 166 <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 167 <TD>Used to construct a <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_iterator.html" TARGET="_top">regex_iterator</A></TD> 168 </TR> 169</TABLE> 170 171</P> 172 173<A NAME="second_constructor"></A> 174 175<PRE CLASS="broken_ie"> <B>basic_regex_filter</B>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 176 <SPAN CLASS="keyword">const</SPAN> std::basic_string<Ch>& fmt, 177 regex_constants::match_flag_type flags = 178 regex_constants::match_default, 179 regex_constants::match_flag_type fmt_flags = 180 regex_constants::format_default );</PRE> 181 182<P>Constructs a <CODE>basic_regex_filter</CODE> from the given regular expression, format string and pair of match flags. The parameters have the following interpretations:</P> 183 184<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 185<TR> 186 <TR> 187 <TD VALIGN="top"><I>pattern</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 188 <TD>The regular expression to be matched against the stream of unfiltered data</TD> 189 </TR> 190 <TR> 191 <TD VALIGN="top"><I>fmt</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 192 <TD>A <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/format.html" TARGET="_top">format string</A> which specifies the replacement text for each regular expression match, using <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/match_results.html#boost_regex.match_results.format2" TARGET="_top">match_results::format</A></TD> 193 </TR> 194 <TR> 195 <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 196 <TD>Used to construct a <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_iterator.html" TARGET="_top">regex_iterator</A></TD> 197 </TR> 198 <TR> 199 <TD VALIGN="top"><I>fmt_flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 200 <TD>The flags argument to <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/match_results.html#boost_regex.match_results.format2" TARGET="_top">match_results::format</A></TD> 201 </TR> 202</TABLE> 203 204<A NAME="third_constructor"></A> 205 206<PRE CLASS="broken_ie"> <B>basic_regex_filter</B>( <SPAN CLASS="keyword">const</SPAN> basic_regex<Ch, Tr, Alloc>& pattern, 207 <SPAN CLASS="keyword">const</SPAN> Ch* fmt, 208 regex_constants::match_flag_type flags = 209 regex_constants::match_default, 210 regex_constants::match_flag_type fmt_flags = 211 regex_constants::format_default );</PRE> 212 213<P>Constructs a <CODE>basic_regex_filter</CODE> from the given regular expression, format string and pair of match flags. The parameters have the following interpretations:</P> 214 215<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 216<TR> 217 <TR> 218 <TD VALIGN="top"><I>pattern</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 219 <TD>The regular expression to be matched against the stream of unfiltered data</TD> 220 </TR> 221 <TR> 222 <TD VALIGN="top"><I>fmt</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 223 <TD>A <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/format.html" TARGET="_top">format string</A> which specifies the replacement text for each regular expression match, using <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/match_results.html#boost_regex.match_results.format2" TARGET="_top">match_results::format</A></TD> 224 </TR> 225 <TR> 226 <TD VALIGN="top"><I>flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 227 <TD>Used to construct a <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/regex_iterator.html" TARGET="_top">regex_iterator</A></TD> 228 </TR> 229 <TR> 230 <TD VALIGN="top"><I>fmt_flags</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 231 <TD>The flags argument to <A HREF="http://www.boost.org/libs/regex/doc/html/boost_regex/ref/match_results.html#boost_regex.match_results.format2" TARGET="_top">match_results::format</A></TD> 232 </TR> 233</TABLE> 234 235<!-- Begin Footer --> 236 237<HR> 238 239<P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>© Copyright 2004-2007 <a href="https://www.boost.org/users/people/jonathan_turkanis.html" target="_top">Jonathan Turkanis</a></P> 240<P CLASS="copyright"> 241 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>) 242</P> 243 244<!-- End Footer --> 245 246</BODY> 247