1 files changed, 41 insertions, 0 deletions
diff --git a/lib/rubygems/text.rb b/lib/rubygems/text.rb
index c694e8a9c0..ddf1e820a7 100644
--- a/lib/rubygems/text.rb
+++ b/lib/rubygems/text.rb
@@ -1,3 +1,9 @@
+######################################################################
+# This file is imported from the rubygems project.
+# DO NOT make modifications in this repo. They _will_ be reverted!
+# File a patch instead and assign it to Ryan Davis or Eric Hodel.
+######################################################################
+
 require 'rubygems'
 
 ##
@@ -26,5 +32,40 @@ module Gem::Text
     result.join("\n").gsub(/^/, " " * indent)
   end
 
+  # This code is based directly on the Text gem implementation
+  # Returns a value representing the "cost" of transforming str1 into str2
+  def levenshtein_distance str1, str2
+    s = str1
+    t = str2
+    n = s.length
+    m = t.length
+    max = n/2
+
+    return m if (0 == n)
+    return n if (0 == m)
+    return n if (n - m).abs > max
+
+    d = (0..m).to_a
+    x = nil
+
+    n.times do |i|
+      e = i+1
+
+      m.times do |j|
+        cost = (s[i] == t[j]) ? 0 : 1
+        x = [
+             d[j+1] + 1, # insertion
+             e + 1,      # deletion
+             d[j] + cost # substitution
+            ].min
+        d[j] = e
+        e = x
+      end
+
+      d[m] = x
+    end
+
+    return x
+  end
 end