+# Copyright (C) 2013 Martin A. Hansen.
+
+# This program 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 2
+# of the License, or (at your option) any later version.
+
+# This program 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 program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+
+# http://www.gnu.org/copyleft/gpl.html
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+
+# This software is part of the Biopieces framework (www.biopieces.org).
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+
+require 'inline'
+
+class Levenshtein
+ BYTES_IN_INT = 4
+
+ def self.distance(s, t)
+ return 0 if s == t;
+ return t.length if s.length == 0;
+ return s.length if t.length == 0;
+
+ v0 = "\0" * (t.length + 1) * BYTES_IN_INT
+ v1 = "\0" * (t.length + 1) * BYTES_IN_INT
+
+ l = self.new
+ l.distance_C(s, t, s.length, t.length, v0, v1)
+ end
+
+ def initialize
+ end
+
+ # >>>>>>>>>>>>>>> RubyInline C code <<<<<<<<<<<<<<<
+
+ inline do |builder|
+ builder.prefix %{
+ unsigned int min(unsigned int a, unsigned int b, unsigned int c)
+ {
+ unsigned int m = a;
+
+ if (m > b) m = b;
+ if (m > c) m = c;
+
+ return m;
+ }
+ }
+
+ builder.c %{
+ VALUE distance_C(
+ VALUE _s,
+ VALUE _t,
+ VALUE _s_len,
+ VALUE _t_len,
+ VALUE _v0,
+ VALUE _v1
+ )
+ {
+ char *s = (char *) StringValuePtr(_s);
+ char *t = (char *) StringValuePtr(_t);
+ unsigned int s_len = FIX2UINT(_s_len);
+ unsigned int t_len = FIX2UINT(_t_len);
+ unsigned int *v0 = (unsigned int *) StringValuePtr(_v0);
+ unsigned int *v1 = (unsigned int *) StringValuePtr(_v1);
+
+ unsigned int i = 0;
+ unsigned int j = 0;
+ unsigned int cost = 0;
+
+ for (i = 0; i < t_len + 1; i++)
+ v0[i] = i;
+
+ for (i = 0; i < s_len; i++)
+ {
+ v1[0] = i + 1;
+
+ for (j = 0; j < t_len; j++)
+ {
+ cost = (s[i] == t[j]) ? 0 : 1;
+ v1[j + 1] = min(v1[j] + 1, v0[j + 1] + 1, v0[j] + cost);
+ }
+
+ for (j = 0; j < t_len + 1; j++)
+ v0[j] = v1[j];
+ }
+
+ return UINT2NUM(v1[t_len]);
+ }
+ }
+ end
+end
+
+# >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+
+
+__END__