Fix typo in grammar.

Add lexertl.

inc/lexertl/partition/charset.hpp

@@ -0,0 +1,73 @@
+// charset.hpp
+// Copyright (c) 2005-2012 Ben Hanson (http://www.benhanson.net/)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file licence_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef LEXERTL_CHARSET_HPP
+#define LEXERTL_CHARSET_HPP
+
+#include <algorithm>
+#include <iterator>
+#include <set>
+#include "../size_t.hpp"
+#include "../string_token.hpp"
+
+namespace lexertl
+{
+namespace detail
+{
+template<typename char_type, typename id_type>
+struct basic_charset
+{
+    typedef basic_string_token<char_type> token;
+    typedef std::set<id_type> index_set;
+
+    token _token;
+    index_set _index_set;
+
+    basic_charset () :
+        _token (),
+        _index_set ()
+    {
+    }
+
+    basic_charset (const token &token_, const std::size_t index_) :
+        _token (token_),
+        _index_set ()
+    {
+        _index_set.insert (index_);
+    }
+
+    bool empty () const
+    {
+        return _token.empty () && _index_set.empty ();
+    }
+
+    void intersect (basic_charset &rhs_, basic_charset &overlap_)
+    {
+        _token.intersect (rhs_._token, overlap_._token);
+
+        if (!overlap_._token.empty ())
+        {
+            std::merge (_index_set.begin (), _index_set.end (),
+                rhs_._index_set.begin (), rhs_._index_set.end (),
+                std::inserter (overlap_._index_set,
+                overlap_._index_set.end ()));
+
+            if (_token.empty ())
+            {
+                _index_set.clear ();
+            }
+
+            if (rhs_._token.empty ())
+            {
+                rhs_._index_set.clear ();
+            }
+        }
+    }
+};
+}
+}
+
+#endif