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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
2<html>
3   <head>
4      <title>Boost.Regex: Algorithm regex_replace</title>
5      <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
6      <LINK href="../../../boost.css" type="text/css" rel="stylesheet"></head>
7   <body>
8      <P>
9         <TABLE id="Table1" cellSpacing="1" cellPadding="1" width="100%" border="0">
10            <TR>
11               <td vAlign="top" width="300">
12                  <h3><A href="../../../index.htm"><IMG height="86" alt="C++ Boost" src="../../../boost.png" width="277" border="0"></A></h3>
13               </td>
14               <TD width="353">
15                  <H1 align="center">Boost.Regex</H1>
16                  <H2 align="center">Algorithm regex_replace</H2>
17               </TD>
18               <td width="50">
19                  <h3><A href="index.html"><IMG height="45" alt="Boost.Regex Index" src="uarrow.gif" width="43" border="0"></A></h3>
20               </td>
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22         </TABLE>
23      </P>
24      <HR>
25      <H3>Contents</H3>
26      <dl class="index">
27         <dt><A href="#synopsis">Synopsis</A> <dt><a href="#description">Description</a> <dt><A href="#examples">
28                     Examples</A></dt></dl>
29      <H3><A name="synopsis"></A>Synopsis</H3>
30      <PRE>#include &lt;<A href="../../../boost/regex.hpp">boost/regex.hpp</A>&gt; </PRE>
31      <P>The algorithm regex_replace&nbsp;searches&nbsp;through&nbsp;a string finding
32         all the matches to the regular expression: for each match it then calls <A href="match_results.html#format">
33            match_results::format</A> to format the string and sends the result to the
34         output iterator. Sections of text that do not match are copied to the output
35         unchanged only if the <EM>flags</EM> parameter does not have the flag <A href="match_flag_type.html">
36            format_no_copy</A> set. If the flag <A href="match_flag_type.html">format_first_only</A>
37         is set then only the first occurrence is replaced rather than all
38         occurrences.&nbsp;<PRE>template &lt;class OutputIterator, class BidirectionalIterator, class traits, class charT&gt;
39OutputIterator <A href="#f1">regex_replace</A>(OutputIterator out,
40                           BidirectionalIterator first,
41                           BidirectionalIterator last,
42                           const <A href="basic_regex.html">basic_regex</A>&lt;charT, traits&gt;&amp; e,
43                           const basic_string&lt;charT&gt;&amp; fmt,
44                           <A href="match_flag_type.html">match_flag_type flags = match_default</A>);
45
46template &lt;class traits, class charT&gt;
47basic_string&lt;charT&gt; <A href="#f2">regex_replace</A>(const basic_string&lt;charT&gt;&amp; s,
48                            const <A href="basic_regex.html">basic_regex</A>&lt;charT, traits&gt;&amp; e,
49                            const basic_string&lt;charT&gt;&amp; fmt,
50                            <A href="match_flag_type.html">match_flag_type flags = match_default</A>);
51
52</PRE>
53         <H3><A name="description"></A>Description</H3>
54         <PRE><A name=f1></A>template &lt;class OutputIterator, class BidirectionalIterator, class traits, class charT&gt;
55OutputIterator regex_replace(OutputIterator out,
56                           BidirectionalIterator first,
57                           BidirectionalIterator last,
58                           const <A href="basic_regex.html">basic_regex</A>&lt;charT, traits&gt;&amp; e,
59                           const basic_string&lt;charT&gt;&amp; fmt,
60                           <A href="match_flag_type.html">match_flag_type flags = match_default</A>);</PRE>
61      <P>Enumerates all the occurences of expression <EM>e</EM> in the sequence [first,
62         last), replacing each occurence with the string that results by merging the
63         match found with the format string <EM>fmt</EM>, and copies the resulting
64         string to <EM>out</EM>.&nbsp;</P>
65      <P>If the flag format_no_copy is set in <EM>flags</EM> then unmatched sections of
66         text are not copied to output.&nbsp;
67      </P>
68      <P>If the flag format_first_only is set in <EM>flags</EM> then only the first
69         occurence of <EM>e</EM> is replaced.&nbsp;
70      </P>
71      <P>The manner in which the format string <EM>fmt</EM> is interpretted, along with
72         the rules used&nbsp;for finding matches,&nbsp;are determined by the <A href="match_flag_type.html">
73            flags</A> set in <EM>flags</EM></P>
74      <P><B>Effects:</B> Constructs an
75         <SPAN class="spelle">regex_iterator</SPAN>
76         object:
77      </P>
78      <PRE><SPAN style="FONT-SIZE: 10pt">regex_iterator&lt;</SPAN><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">BidirectionalIterator</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt">, </SPAN><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">charT</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt">, traits, Allocator&gt; <BR>                                            </SPAN><SPAN class=grame><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">i(</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt">first, last, e, flags)</SPAN>, </PRE>
79      <P>and uses
80         <SPAN class="spelle">
81            <I>i</I></SPAN>
82         to enumerate through all of the matches <I>m</I> of type
83         <SPAN class="spelle">
84            <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">match_results</SPAN>
85         </SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">&lt;<SPAN class="spelle">BidirectionalIterator</SPAN>&gt; </SPAN>that
86         occur within the sequence [first, last).
87      </P>
88      <P>If no such matches are found
89         <SPAN class="grame">and </SPAN></P>
90      <PRE><SPAN class=grame></SPAN><SPAN class=grame><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">!</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(flags &amp; <SPAN class=spelle>format_no_copy</SPAN>)</SPAN> </PRE>
91      <P>then calls
92      </P>
93      <PRE><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">std::copy</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(first, last, out)</SPAN>. </PRE>
94      <P>Otherwise, for each match found,
95         <SPAN class="grame">if </SPAN></P>
96      <PRE><SPAN class=grame></SPAN><SPAN class=grame><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">!</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(flags &amp; <SPAN class=spelle>format_no_copy</SPAN>)</SPAN> </PRE>
97      <P>calls
98      </P>
99      <PRE><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">std::copy</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(<SPAN class=spelle>m.prefix</SPAN>().first, <SPAN class=spelle>m.prefix</SPAN>().last, out)</SPAN>, </PRE>
100      <P>and then calls
101      </P>
102      <PRE><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">m.format</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(out, <SPAN class=spelle>fmt</SPAN>, flags)</SPAN>. </PRE>
103      <P>Finally
104         <SPAN class="grame">if </SPAN></P>
105      <PRE><SPAN class=grame></SPAN><SPAN class=grame><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">!</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(flags &amp; <SPAN class=spelle>format_no_copy</SPAN>)</SPAN> </PRE>
106      <P>calls
107      </P>
108      <PRE><SPAN class=spelle><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">std::copy</SPAN></SPAN><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">(<SPAN class=spelle>last_m.suffix</SPAN>().first, <SPAN class=spelle>last_m,suffix</SPAN>().last, out) </SPAN></PRE>
109      <P><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'"></SPAN>where
110         <SPAN class="spelle">
111            <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">last_m</SPAN>
112         </SPAN>
113         is a copy of the last match found.
114      </P>
115      <P>If
116         <SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'">flags &amp; 
117<SPAN class="spelle">format_first_only</SPAN></SPAN>
118         is non-zero then only the first match found is replaced.</P>
119      <P><STRONG>Throws:</STRONG> <CODE>std::runtime_error</CODE> if the complexity of
120         matching the expression against an N character string begins to exceed O(N<SUP>2</SUP>),
121         or if the program runs out of stack space while matching the expression (if
122         Boost.regex is <A href="configuration.html">configured</A> in recursive mode),
123         or if the matcher exhausts it's permitted memory allocation (if Boost.regex is <A href="configuration.html">
124            configured</A> in non-recursive mode).</P>
125      <P><B> Returns:</B> <CODE>out</CODE>.
126      </P>
127      <PRE><A name=f2></A>template &lt;class traits, class charT&gt;
128basic_string&lt;charT&gt; regex_replace(const basic_string&lt;charT&gt;&amp; s,
129                            const <A href="basic_regex.html">basic_regex</A>&lt;charT, traits&gt;&amp; e,
130                            const basic_string&lt;charT&gt;&amp; fmt,
131                            <A href="match_flag_type.html">match_flag_type flags = match_default</A>);</PRE>
132      <P><B> Effects:</B> Constructs an object <CODE>basic_string&lt;charT&gt; result</CODE>,
133         calls <CODE>regex_replace(back_inserter(result), s.begin(), s.end(), e, fmt,
134            flags)</CODE>, and then returns <CODE>result</CODE>.
135         <H3><A name="examples"></A>Examples</H3>
136      <P>The following <A href="../example/snippets/regex_replace_example.cpp">example</A>
137         takes C/C++ source code as input, and outputs syntax highlighted HTML code.</P>
138      <P></P>
139      <PRE><FONT color=#008080>#include &lt;fstream&gt;
140#include &lt;sstream&gt;
141#include &lt;string&gt;
142#include &lt;iterator&gt;
143#include &lt;boost/regex.hpp&gt;
144#include &lt;fstream&gt;
145#include &lt;iostream&gt;
146</FONT>
147<FONT color=#000080><I>// purpose:
148// takes the contents of a file and transform to
149// syntax highlighted code in html format
150</I></FONT>
151boost::regex e1, e2;
152<B>extern</B> <B>const</B> <B>char</B>* expression_text;
153<B>extern</B> <B>const</B> <B>char</B>* format_string;
154<B>extern</B> <B>const</B> <B>char</B>* pre_expression;
155<B>extern</B> <B>const</B> <B>char</B>* pre_format;
156<B>extern</B> <B>const</B> <B>char</B>* header_text;
157<B>extern</B> <B>const</B> <B>char</B>* footer_text;
158
159<B>void</B> load_file(std::string&amp; s, std::istream&amp; is)
160{
161   s.erase();
162   s.reserve(is.rdbuf()-&gt;in_avail());
163   <B>char</B> c;
164   <B>while</B>(is.get(c))
165   {
166      <B>if</B>(s.capacity() == s.size())
167         s.reserve(s.capacity() * <FONT color=#000080>3</FONT>);
168      s.append(<FONT color=#000080>1</FONT>, c);
169   }
170}
171
172<B>int</B> main(<B>int</B> argc, <B>const</B> <B>char</B>** argv)
173{
174   try{
175   e1.assign(expression_text);
176   e2.assign(pre_expression);
177   <B>for</B>(<B>int</B> i = <FONT color=#000080>1</FONT>; i &lt; argc; ++i)
178   {
179      std::cout &lt;&lt; <FONT color=#0000ff>"Processing file "</FONT> &lt;&lt; argv[i] &lt;&lt; std::endl;
180      std::ifstream fs(argv[i]);
181      std::string in;
182      load_file(in, fs);
183      std::string out_name(std::string(argv[i]) + std::string(<FONT color=#0000ff>".htm"</FONT>));
184      std::ofstream os(out_name.c_str());
185      os &lt;&lt; header_text;
186      <FONT color=#000080><I>// strip '&lt;' and '&gt;' first by outputting to a
187</I></FONT>      <FONT color=#000080><I>// temporary string stream
188</I></FONT>      std::ostringstream t(std::ios::out | std::ios::binary);
189      std::ostream_iterator&lt;<B>char</B>, <B>char</B>&gt; oi(t);
190      boost::regex_replace(oi, in.begin(), in.end(),
191      e2, pre_format, boost::match_default | boost::format_all);
192      <FONT color=#000080><I>// then output to final output stream
193</I></FONT>      <FONT color=#000080><I>// adding syntax highlighting:
194</I></FONT>      std::string s(t.str());
195      std::ostream_iterator&lt;<B>char</B>, <B>char</B>&gt; out(os);
196      boost::regex_replace(out, s.begin(), s.end(),
197      e1, format_string, boost::match_default | boost::format_all);
198      os &lt;&lt; footer_text;
199   }
200   }
201   <STRONG>catch</STRONG>(...)
202   { <STRONG>return</STRONG> -1; }
203   <B>return</B> <FONT color=#000080>0</FONT>;
204}
205
206<B>extern</B> <B>const</B> <B>char</B>* pre_expression = <FONT color=#0000ff>"(&lt;)|(&gt;)|\\r"</FONT>;
207<B>extern</B> <B>const</B> <B>char</B>* pre_format = <FONT color=#0000ff>"(?1&lt;)(?2&gt;)"</FONT>;
208
209
210<B>const</B> <B>char</B>* expression_text = <FONT color=#000080><I>// preprocessor directives: index 1
211</I></FONT>                              <FONT color=#0000ff>"(^[[:blank:]]*#(?:[^\\\\\\n]|\\\\[^\\n[:punct:][:word:]]*[\\n[:punct:][:word:]])*)|"
212</FONT>                              <FONT color=#000080><I>// comment: index 2
213</I></FONT>                              <FONT color=#0000ff>"(//[^\\n]*|/\\*.*?\\*/)|"
214</FONT>                              <FONT color=#000080><I>// literals: index 3
215</I></FONT>                              <FONT color=#0000ff>"\\&lt;([+-]?(?:(?:0x[[:xdigit:]]+)|(?:(?:[[:digit:]]*\\.)?[[:digit:]]+(?:[eE][+-]?[[:digit:]]+)?))u?(?:(?:int(?:8|16|32|64))|L)?)\\&gt;|"
216</FONT>                              <FONT color=#000080><I>// string literals: index 4
217</I></FONT>                              <FONT color=#0000ff>"('(?:[^\\\\']|\\\\.)*'|\"(?:[^\\\\\"]|\\\\.)*\")|"
218</FONT>                              <FONT color=#000080><I>// keywords: index 5
219</I></FONT>                              <FONT color=#0000ff>"\\&lt;(__asm|__cdecl|__declspec|__export|__far16|__fastcall|__fortran|__import"
220</FONT>                              <FONT color=#0000ff>"|__pascal|__rtti|__stdcall|_asm|_cdecl|__except|_export|_far16|_fastcall"
221</FONT>                              <FONT color=#0000ff>"|__finally|_fortran|_import|_pascal|_stdcall|__thread|__try|asm|auto|bool"
222</FONT>                              <FONT color=#0000ff>"|break|case|catch|cdecl|char|class|const|const_cast|continue|default|delete"
223</FONT>                              <FONT color=#0000ff>"|do|double|dynamic_cast|else|enum|explicit|extern|false|float|for|friend|goto"
224</FONT>                              <FONT color=#0000ff>"|if|inline|int|long|mutable|namespace|new|operator|pascal|private|protected"
225</FONT>                              <FONT color=#0000ff>"|public|register|reinterpret_cast|return|short|signed|sizeof|static|static_cast"
226</FONT>                              <FONT color=#0000ff>"|struct|switch|template|this|throw|true|try|typedef|typeid|typename|union|unsigned"
227</FONT>                              <FONT color=#0000ff>"|using|virtual|void|volatile|wchar_t|while)\\&gt;"
228</FONT>                              ;
229
230<B>const</B> <B>char</B>* format_string = <FONT color=#0000ff>"(?1&lt;font color=\"#008040\"&gt;$&amp;&lt;/font&gt;)"
231</FONT>                            <FONT color=#0000ff>"(?2&lt;I&gt;&lt;font color=\"#000080\"&gt;$&amp;&lt;/font&gt;&lt;/I&gt;)"
232</FONT>                            <FONT color=#0000ff>"(?3&lt;font color=\"#0000A0\"&gt;$&amp;&lt;/font&gt;)"
233</FONT>                            <FONT color=#0000ff>"(?4&lt;font color=\"#0000FF\"&gt;$&amp;&lt;/font&gt;)"
234</FONT>                            <FONT color=#0000ff>"(?5&lt;B&gt;$&amp;&lt;/B&gt;)"</FONT>;
235
236<B>const</B> <B>char</B>* header_text = <FONT color=#0000ff>"&lt;HTML&gt;\n&lt;HEAD&gt;\n"
237</FONT>                          <FONT color=#0000ff>"&lt;TITLE&gt;Auto-generated html formated source&lt;/TITLE&gt;\n"
238</FONT>                          <FONT color=#0000ff>"&lt;META HTTP-EQUIV=\"Content-Type\" CONTENT=\"text/html; charset=windows-1252\"&gt;\n"
239</FONT>                          <FONT color=#0000ff>"&lt;/HEAD&gt;\n"
240</FONT>                          <FONT color=#0000ff>"&lt;BODY LINK=\"#0000ff\" VLINK=\"#800080\" BGCOLOR=\"#ffffff\"&gt;\n"
241</FONT>                          <FONT color=#0000ff>"&lt;P&gt; &lt;/P&gt;\n&lt;PRE&gt;"</FONT>;
242
243<B>const</B> <B>char</B>* footer_text = <FONT color=#0000ff>"&lt;/PRE&gt;\n&lt;/BODY&gt;\n\n"</FONT>;
244      </PRE>
245      <HR>
246      <p>Revised&nbsp; 
247         <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> 
248         26 June 2004&nbsp; 
249         <!--webbot bot="Timestamp" endspan i-checksum="39359" --></p>
250      <p><i>© Copyright John Maddock&nbsp;1998-
251            <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y" startspan -->  2004<!--webbot bot="Timestamp" endspan i-checksum="39359" --></i></p>
252      <P><I>Use, modification and distribution are subject to the Boost Software License,
253            Version 1.0. (See accompanying file <A href="../../../LICENSE_1_0.txt">LICENSE_1_0.txt</A>
254            or copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)</I></P>
255   </body>
256</html>
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