1 files changed, 18 insertions, 8 deletions
diff --git a/activesupport/lib/active_support/inflector/transliterate.rb b/activesupport/lib/active_support/inflector/transliterate.rb
index edea142e82..103207fb63 100644
--- a/activesupport/lib/active_support/inflector/transliterate.rb
+++ b/activesupport/lib/active_support/inflector/transliterate.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'active_support/core_ext/string/multibyte'
 require 'active_support/i18n'
 
@@ -58,7 +57,7 @@ module ActiveSupport
     #   I18n.locale = :de
     #   transliterate('Jürgen')
     #   # => "Juergen"
-    def transliterate(string, replacement = "?")
+    def transliterate(string, replacement = "?".freeze)
       I18n.transliterate(ActiveSupport::Multibyte::Unicode.normalize(
         ActiveSupport::Multibyte::Unicode.tidy_bytes(string), :c),
           :replacement => replacement)
@@ -70,18 +69,29 @@ module ActiveSupport
     #   parameterize("Donald E. Knuth") # => "donald-e-knuth"
     #   parameterize("^trés|Jolie-- ")  # => "tres-jolie"
     def parameterize(string, sep = '-')
-      # replace accented chars with their ascii equivalents
+      # Replace accented chars with their ASCII equivalents.
       parameterized_string = transliterate(string)
-      # Turn unwanted chars into the separator
+
+      # Turn unwanted chars into the separator.
       parameterized_string.gsub!(/[^a-z0-9\-_]+/i, sep)
+
       unless sep.nil? || sep.empty?
-        re_sep = Regexp.escape(sep)
+        if sep == "-".freeze
+          re_duplicate_separator        = /-{2,}/
+          re_leading_trailing_separator = /^-|-$/i
+        else
+          re_sep = Regexp.escape(sep)
+          re_duplicate_separator        = /#{re_sep}{2,}/
+          re_leading_trailing_separator = /^#{re_sep}|#{re_sep}$/i
+        end
         # No more than one of the separator in a row.
-        parameterized_string.gsub!(/#{re_sep}{2,}/, sep)
+        parameterized_string.gsub!(re_duplicate_separator, sep)
         # Remove leading/trailing separator.
-        parameterized_string.gsub!(/^#{re_sep}|#{re_sep}$/i, '')
+        parameterized_string.gsub!(re_leading_trailing_separator, ''.freeze)
       end
-      parameterized_string.downcase
+
+      parameterized_string.downcase!
+      parameterized_string
     end
   end
 end