--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+
+// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
+
+// Permission to use, copy, modify, sell, and distribute this software
+// is hereby granted without fee, provided that the above copyright
+// notice appears in all copies, and that both that copyright notice
+// and this permission notice appear in supporting documentation. None
+// of the above authors, nor IBM Haifa Research Laboratories, make any
+// representation about the suitability of this software for any
+// purpose. It is provided "as is" without express or implied
+// warranty.
+
+/**
+ * @file trie_prefix_search_example.cpp
+ * An example showing how to use a trie for searching
+ * for words with a given prefix.
+ */
+
+/**
+ * This example shows how to use a PATRICIA trie for searching
+ * for words with a given prefix.
+ */
+
+#include <cassert>
+#include <iostream>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/trie_policy.hpp>
+#include <ext/pb_ds/tag_and_trait.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+// A PATRICIA trie with a prefix-search node-updator type. Note that
+// since the node updator is trie_prefix_search_node_update, then the
+// container includes its method prefix_range.
+typedef null_mapped_type mapped_type;
+typedef string_trie_e_access_traits<> cmp_fn;
+typedef pat_trie_tag tag_type;
+
+typedef trie<string, mapped_type, cmp_fn, tag_type,
+ trie_prefix_search_node_update> trie_type;
+
+// The following helper function takes a trie object and r_key, a
+// const reference to a string, and prints all entries whose key
+// includes r_key as a prefix.
+void
+print_prefix_match(const trie_type& t, const string& key)
+{
+ typedef trie_type::const_iterator const_iterator;
+ typedef pair<const_iterator, const_iterator> pair_type;
+
+ cout << "All keys whose prefix matches \"" << key << "\":" << endl;
+
+ const pair_type match_range = t.prefix_range(key);
+ for (const_iterator it = match_range.first; it != match_range.second; ++it)
+ cout << *it << ' ';
+ cout << endl;
+}
+
+int main()
+{
+ trie_type t;
+
+ // Insert some entries.
+ assert(t.insert("I").second == true);
+ assert(t.insert("wish").second == true);
+ assert(t.insert("that").second == true);
+ assert(t.insert("I").second == false);
+ assert(t.insert("could").second == true);
+ assert(t.insert("ever").second == true);
+ assert(t.insert("see").second == true);
+ assert(t.insert("a").second == true);
+ assert(t.insert("poem").second == true);
+ assert(t.insert("lovely").second == true);
+ assert(t.insert("as").second == true);
+ assert(t.insert("a").second == false);
+ assert(t.insert("trie").second == true);
+
+ // Now search for prefixes.
+ print_prefix_match(t, "");
+ print_prefix_match(t, "a");
+ print_prefix_match(t, "as");
+ print_prefix_match(t, "ad");
+ print_prefix_match(t, "t");
+ print_prefix_match(t, "tr");
+ print_prefix_match(t, "trie");
+ print_prefix_match(t, "zzz");
+
+ return 0;
+}
+