libstdc++-v3/testsuite/ext/pb_ds/example/trie_prefix_search.cc

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 3, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License
  17 // along with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20
  21 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  22
  23 // Permission to use, copy, modify, sell, and distribute this software
  24 // is hereby granted without fee, provided that the above copyright
  25 // notice appears in all copies, and that both that copyright notice
  26 // and this permission notice appear in supporting documentation. None
  27 // of the above authors, nor IBM Haifa Research Laboratories, make any
  28 // representation about the suitability of this software for any
  29 // purpose. It is provided "as is" without express or implied
  30 // warranty.
  31
  32 /**
  33  * @file trie_prefix_search_example.cpp
  34  * An example showing how to use a trie for searching
  35  *    for words with a given prefix.
  36  */
  37
  38 /**
  39  * This example shows how to use a PATRICIA trie for searching
  40  * for words with a given prefix.
  41  */
  42
  43 #include <cassert>
  44 #include <iostream>
  45 #include <ext/pb_ds/assoc_container.hpp>
  46 #include <ext/pb_ds/trie_policy.hpp>
  47 #include <ext/pb_ds/tag_and_trait.hpp>
  48
  49 using namespace std;
  50 using namespace __gnu_pbds;
  51
  52 // A PATRICIA trie with a prefix-search node-updator type. Note that
  53 // since the node updator is trie_prefix_search_node_update, then the
  54 // container includes its method prefix_range.
  55 typedef null_mapped_type                mapped_type;
  56 typedef string_trie_e_access_traits<>   cmp_fn;
  57 typedef pat_trie_tag                    tag_type;
  58
  59 typedef trie<string, mapped_type, cmp_fn, tag_type,
  60              trie_prefix_search_node_update> trie_type;
  61
  62 // The following helper function takes a trie object and r_key, a
  63 // const reference to a string, and prints all entries whose key
  64 // includes r_key as a prefix.
  65 void
  66 print_prefix_match(const trie_type& t, const string& key)
  67 {
  68   typedef trie_type::const_iterator             const_iterator;
  69   typedef pair<const_iterator, const_iterator>  pair_type;
  70
  71   cout << "All keys whose prefix matches \"" << key << "\":" << endl;
  72
  73   const pair_type match_range = t.prefix_range(key);
  74   for (const_iterator it = match_range.first; it != match_range.second; ++it)
  75     cout << *it << ' ';
  76   cout << endl;
  77 }
  78
  79 int main()
  80 {
  81   trie_type t;
  82
  83   // Insert some entries.
  84   assert(t.insert("I").second == true);
  85   assert(t.insert("wish").second == true);
  86   assert(t.insert("that").second == true);
  87   assert(t.insert("I").second == false);
  88   assert(t.insert("could").second == true);
  89   assert(t.insert("ever").second == true);
  90   assert(t.insert("see").second == true);
  91   assert(t.insert("a").second == true);
  92   assert(t.insert("poem").second == true);
  93   assert(t.insert("lovely").second == true);
  94   assert(t.insert("as").second == true);
  95   assert(t.insert("a").second == false);
  96   assert(t.insert("trie").second == true);
  97
  98   // Now search for prefixes.
  99   print_prefix_match(t, "");
 100   print_prefix_match(t, "a");
 101   print_prefix_match(t, "as");
 102   print_prefix_match(t, "ad");
 103   print_prefix_match(t, "t");
 104   print_prefix_match(t, "tr");
 105   print_prefix_match(t, "trie");
 106   print_prefix_match(t, "zzz");
 107
 108   return 0;
 109 }
 110