xapian-applications/omega/sort.cc

   1 /* @file sort.cc
   2  * @brief OmegaScript $sort function
   3  */
   4 /* Copyright (C) 2018 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
  19  * USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include "sort.h"
  25
  26 #include <algorithm>
  27 #include <string>
  28 #include <vector>
  29
  30 using namespace std;
  31
  32 void
  33 omegascript_sort(const vector<string>& args,
  34                  string& value)
  35 {
  36     const string &list = args[0];
  37     if (list.empty()) return;
  38
  39     bool uniq = false;
  40     bool rev = false;
  41     if (args.size() > 1) {
  42         for (auto opt_ch : args[1]) {
  43             switch (opt_ch) {
  44                 case 'r':
  45                     rev = true;
  46                     break;
  47                 case 'u':
  48                     uniq = true;
  49                     break;
  50                 default:
  51                     throw string("Unknown $sort option: ") + opt_ch;
  52             }
  53         }
  54     }
  55     vector<string> items;
  56     string::size_type split = 0, split2;
  57     do {
  58         split2 = list.find('\t', split);
  59         items.emplace_back(list, split, split2 - split);
  60         split = split2 + 1;
  61     } while (split2 != string::npos);
  62
  63     if (!rev) {
  64         sort(items.begin(), items.end());
  65     } else {
  66         sort(items.begin(), items.end(),
  67              [](const string& a, const string& b) {
  68                  return a > b;
  69              });
  70     }
  71
  72     value.reserve(list.size());
  73     bool tab = false;
  74     const string* prev = nullptr;
  75     for (auto&& item : items) {
  76         // Skip duplicates if "u" flag specified.
  77         if (prev && *prev == item) {
  78             continue;
  79         }
  80         if (uniq) {
  81             prev = &item;
  82         }
  83
  84         if (tab) {
  85             value += '\t';
  86         } else {
  87             tab = true;
  88         }
  89         value += item;
  90     }
  91 }