normalize.rb: trivial optimizations

* lib/unicode_normalize/normalize.rb (nfc_one, normalize): trivial
  optimizations.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48309 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/unicode_normalize/normalize.rb

@@ -116,7 +116,7 @@ module UnicodeNormalize
       if last_class<accent_class and composite = COMPOSITION_TABLE[start+accent]
         start = composite
       else
-        accents += accent
+        accents << accent
         last_class = accent_class
       end
     end
@@ -125,7 +125,8 @@ module UnicodeNormalize
 
   def self.normalize(string, form = :nfc)
     encoding = string.encoding
-    if encoding == Encoding::UTF_8
+    case encoding
+    when Encoding::UTF_8
       case form
       when :nfc then
         string.gsub REGEXP_C, NF_HASH_C
@@ -138,9 +139,9 @@ module UnicodeNormalize
       else
         raise ArgumentError, "Invalid normalization form #{form}."
       end
-    elsif encoding == Encoding::US_ASCII
+    when Encoding::US_ASCII
       string
-    elsif  UNICODE_ENCODINGS.include? encoding
+    when *UNICODE_ENCODINGS
       normalize(string.encode(Encoding::UTF_8), form).encode(encoding)
     else
       raise Encoding::CompatibilityError, "Unicode Normalization not appropriate for #{encoding}"