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

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006 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 2, 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 COPYING.  If not, write to
  18 // the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
  19 // MA 02111-1307, USA.
  20
  21 // As a special exception, you may use this file as part of a free
  22 // software library without restriction.  Specifically, if other files
  23 // instantiate templates or use macros or inline functions from this
  24 // file, or you compile this file and link it with other files to
  25 // produce an executable, this file does not by itself cause the
  26 // resulting executable to be covered by the GNU General Public
  27 // License.  This exception does not however invalidate any other
  28 // reasons why the executable file might be covered by the GNU General
  29 // Public License.
  30
  31 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  32
  33 // Permission to use, copy, modify, sell, and distribute this software
  34 // is hereby granted without fee, provided that the above copyright
  35 // notice appears in all copies, and that both that copyright notice
  36 // and this permission notice appear in supporting documentation. None
  37 // of the above authors, nor IBM Haifa Research Laboratories, make any
  38 // representation about the suitability of this software for any
  39 // purpose. It is provided "as is" without express or implied
  40 // warranty.
  41
  42 /**
  43  * @file trie_prefix_search_example.cpp
  44  * An example showing how to use a trie for searching
  45  *    for words with a given prefix.
  46  */
  47
  48 /**
  49  * This example shows how to use a PATRICIA trie for searching
  50  * for words with a given prefix.
  51  */
  52
  53 #include <cassert>
  54 #include <iostream>
  55 #include <ext/pb_ds/assoc_container.hpp>
  56 #include <ext/pb_ds/trie_policy.hpp>
  57 #include <ext/pb_ds/tag_and_trait.hpp>
  58
  59 using namespace std;
  60 using namespace __gnu_pbds;
  61
  62 // A PATRICIA trie with a prefix-search node-updator type. Note that
  63 // since the node updator is trie_prefix_search_node_update, then the
  64 // container includes its method prefix_range.
  65 typedef null_mapped_type                mapped_type;
  66 typedef string_trie_e_access_traits<>   cmp_fn;
  67 typedef pat_trie_tag                    tag_type;
  68
  69 typedef trie<string, mapped_type, cmp_fn, tag_type,
  70              trie_prefix_search_node_update> trie_type;
  71
  72 // The following helper function takes a trie object and r_key, a
  73 // const reference to a string, and prints all entries whose key
  74 // includes r_key as a prefix.
  75 void
  76 print_prefix_match(const trie_type& t, const string& key)
  77 {
  78   typedef trie_type::const_iterator             const_iterator;
  79   typedef pair<const_iterator, const_iterator>  pair_type;
  80
  81   cout << "All keys whose prefix matches \"" << key << "\":" << endl;
  82
  83   const pair_type match_range = t.prefix_range(key);
  84   for (const_iterator it = match_range.first; it != match_range.second; ++it)
  85     cout << *it << ' ';
  86   cout << endl;
  87 }
  88
  89 int main()
  90 {
  91   trie_type t;
  92
  93   // Insert some entries.
  94   assert(t.insert("I").second == true);
  95   assert(t.insert("wish").second == true);
  96   assert(t.insert("that").second == true);
  97   assert(t.insert("I").second == false);
  98   assert(t.insert("could").second == true);
  99   assert(t.insert("ever").second == true);
 100   assert(t.insert("see").second == true);
 101   assert(t.insert("a").second == true);
 102   assert(t.insert("poem").second == true);
 103   assert(t.insert("lovely").second == true);
 104   assert(t.insert("as").second == true);
 105   assert(t.insert("a").second == false);
 106   assert(t.insert("trie").second == true);
 107
 108   // Now search for prefixes.
 109   print_prefix_match(t, "");
 110   print_prefix_match(t, "a");
 111   print_prefix_match(t, "as");
 112   print_prefix_match(t, "ad");
 113   print_prefix_match(t, "t");
 114   print_prefix_match(t, "tr");
 115   print_prefix_match(t, "trie");
 116   print_prefix_match(t, "zzz");
 117
 118   return 0;
 119 }
 120