Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Click here to view the latest version of this page.


 * Copyright (c) 1998-2002
 * John Maddock
 * Use, modification and distribution are subject to the 
 * Boost Software License, Version 1.0. (See accompanying file 
 * LICENSE_1_0.txt or copy at

  *   LOCATION:    see for most recent version.
  *   FILE         regex_replace_example.cpp
  *   VERSION      see <boost/version.hpp>
  *   DESCRIPTION: regex_replace example:
  *                converts a C++ file to syntax highlighted HTML.

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <iterator>
#include <boost/regex.hpp>
#include <fstream>
#include <iostream>

// purpose:
// takes the contents of a file and transform to
// syntax highlighted code in html format

boost::regex e1, e2;
extern const char* expression_text;
extern const char* format_string;
extern const char* pre_expression;
extern const char* pre_format;
extern const char* header_text;
extern const char* footer_text;

void load_file(std::string& s, std::istream& is)
   if(is.bad()) return;
   char c;
      if(s.capacity() == s.size())
         s.reserve(s.capacity() * 3);
      s.append(1, c);

int main(int argc, const char** argv)
   for(int i = 1; i < argc; ++i)
      std::cout << "Processing file " << argv[i] << std::endl;
      std::ifstream fs(argv[i]);
      std::string in;
      load_file(in, fs);
      std::string out_name = std::string(argv[i]) + std::string(".htm");
      std::ofstream os(out_name.c_str());
      os << header_text;
      // strip '<' and '>' first by outputting to a
      // temporary string stream
      std::ostringstream t(std::ios::out | std::ios::binary);
      std::ostream_iterator<char> oi(t);
      boost::regex_replace(oi, in.begin(), in.end(), e2, pre_format, boost::match_default | boost::format_all);
      // then output to final output stream
      // adding syntax highlighting:
      std::string s(t.str());
      std::ostream_iterator<char> out(os);
      boost::regex_replace(out, s.begin(), s.end(), e1, format_string, boost::match_default | boost::format_all);
      os << footer_text;
   { return -1; }
   return 0;

const char* pre_expression = "(<)|(>)|(&)|\\r";
const char* pre_format = "(?1&lt;)(?2&gt;)(?3&amp;)";

const char* expression_text = // preprocessor directives: index 1
                              // comment: index 2
                              // literals: index 3
                              // string literals: index 4
                              // keywords: index 5

const char* format_string = "(?1<font color=\"#008040\">$&</font>)"
                            "(?2<I><font color=\"#000080\">$&</font></I>)"
                            "(?3<font color=\"#0000A0\">$&</font>)"
                            "(?4<font color=\"#0000FF\">$&</font>)"

const char* header_text = "<HTML>\n<HEAD>\n"
                          "<TITLE>Auto-generated html formated source</TITLE>\n"
                          "<META HTTP-EQUIV=\"Content-Type\" CONTENT=\"text/html; charset=windows-1252\">\n"
                          "<BODY LINK=\"#0000ff\" VLINK=\"#800080\" BGCOLOR=\"#ffffff\">\n"
                          "<P> </P>\n<PRE>";

const char* footer_text = "</PRE>\n</BODY>\n\n";