iostreams/filter/grep.hpp

0001 /*
0002  * Distributed under the Boost Software License, Version 1.0.(See accompanying
0003  * file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
0004  *
0005  * See http://www.boost.org/libs/iostreams for documentation.
0006
0007  * File:        boost/iostreams/filter/grep.hpp
0008  * Date:        Mon May 26 17:48:45 MDT 2008
0009  * Copyright:   2008 CodeRage, LLC
0010  * Author:      Jonathan Turkanis
0011  * Contact:     turkanis at coderage dot com
0012  *
0013  * Defines the class template basic_grep_filter and its specializations
0014  * grep_filter and wgrep_filter.
0015  */
0016
0017 #ifndef BOOST_IOSTREAMS_GREP_FILTER_HPP_INCLUDED
0018 #define BOOST_IOSTREAMS_GREP_FILTER_HPP_INCLUDED
0019
0020 #if defined(_MSC_VER)
0021 # pragma once
0022 #endif
0023
0024 #include <iostream>
0025
0026 #include <memory>  // allocator.
0027 #include <boost/iostreams/char_traits.hpp>
0028 #include <boost/iostreams/filter/line.hpp>
0029 #include <boost/iostreams/pipeline.hpp>
0030 #include <boost/regex.hpp>
0031
0032 namespace boost { namespace iostreams {
0033
0034 namespace grep {
0035
0036 const int invert      = 1;
0037 const int whole_line  = invert << 1;
0038
0039 } // End namespace grep.
0040
0041 template< typename Ch,
0042           typename Tr = regex_traits<Ch>,
0043           typename Alloc = std::allocator<Ch> >
0044 class basic_grep_filter : public basic_line_filter<Ch, Alloc> {
0045 private:
0046     typedef basic_line_filter<Ch, Alloc>               base_type;
0047 public:
0048     typedef typename base_type::char_type              char_type;
0049     typedef typename base_type::category               category;
0050     typedef char_traits<char_type>                     traits_type;
0051     typedef typename base_type::string_type            string_type;
0052     typedef basic_regex<Ch, Tr>                        regex_type;
0053     typedef regex_constants::match_flag_type           match_flag_type;
0054     basic_grep_filter( const regex_type& re,
0055                        match_flag_type match_flags =
0056                            regex_constants::match_default,
0057                        int options = 0 );
0058     int count() const { return count_; }
0059
0060     template<typename Sink>
0061     void close(Sink& snk, BOOST_IOS::openmode which)
0062     {
0063         base_type::close(snk, which);
0064         options_ &= ~f_initialized;
0065     }
0066 private:
0067     virtual string_type do_filter(const string_type& line)
0068     {
0069         if ((options_ & f_initialized) == 0) {
0070             options_ |= f_initialized;
0071             count_ = 0;
0072         }
0073         bool matches = (options_ & grep::whole_line) ?
0074             regex_match(line, re_, match_flags_) :
0075             regex_search(line, re_, match_flags_);
0076         if (options_ & grep::invert)
0077             matches = !matches;
0078         if (matches)
0079             ++count_;
0080         return matches ? line + traits_type::newline() : string_type();
0081     }
0082
0083     // Private flags bitwise OR'd with constants from namespace grep
0084     enum flags_ {
0085         f_initialized = 65536
0086     };
0087
0088     regex_type       re_;
0089     match_flag_type  match_flags_;
0090     int              options_;
0091     int              count_;
0092 };
0093 BOOST_IOSTREAMS_PIPABLE(basic_grep_filter, 3)
0094
0095 typedef basic_grep_filter<char>     grep_filter;
0096 typedef basic_grep_filter<wchar_t>  wgrep_filter;
0097
0098 //------------------Implementation of basic_grep_filter-----------------------//
0099
0100 template<typename Ch, typename Tr, typename Alloc>
0101 basic_grep_filter<Ch, Tr, Alloc>::basic_grep_filter
0102     (const regex_type& re, match_flag_type match_flags, int options)
0103     : base_type(true), re_(re), match_flags_(match_flags),
0104       options_(options), count_(0)
0105     { }
0106
0107 } } // End namespaces iostreams, boost.
0108
0109 #endif      // #ifndef BOOST_IOSTREAMS_REGEX_FILTER_HPP_INCLUDED