src/lib/image_filename_sorter.cc

   1 /*
   2     Copyright (C) 2015 Carl Hetherington <cth@carlh.net>
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 */
  19
  20 #include <iostream>
  21 #include <boost/filesystem.hpp>
  22 #include <boost/optional.hpp>
  23 #include "raw_convert.h"
  24
  25 class ImageFilenameSorter
  26 {
  27 public:
  28         bool operator() (boost::filesystem::path a, boost::filesystem::path b)
  29         {
  30                 boost::optional<int> na = extract_number (a);
  31                 boost::optional<int> nb = extract_number (b);
  32                 if (!na || !nb) {
  33                         return a.string() < b.string();
  34                 }
  35
  36                 return na.get() < nb.get();
  37         }
  38
  39 private:
  40         boost::optional<int> extract_number (boost::filesystem::path p)
  41         {
  42                 p = p.leaf ();
  43
  44                 std::list<std::string> numbers;
  45
  46                 std::string current;
  47                 for (size_t i = 0; i < p.string().size(); ++i) {
  48                         if (isdigit (p.string()[i])) {
  49                                 current += p.string()[i];
  50                         } else {
  51                                 if (!current.empty ()) {
  52                                         numbers.push_back (current);
  53                                         current.clear ();
  54                                 }
  55                         }
  56                 }
  57
  58                 if (!current.empty ()) {
  59                         numbers.push_back (current);
  60                 }
  61
  62                 std::string longest;
  63                 for (std::list<std::string>::const_iterator i = numbers.begin(); i != numbers.end(); ++i) {
  64                         if (i->length() > longest.length()) {
  65                                 longest = *i;
  66                         }
  67                 }
  68
  69                 if (longest.empty ()) {
  70                         return boost::optional<int> ();
  71                 }
  72
  73                 return raw_convert<int> (longest);
  74         }
  75 };