Optimize URI#hostname and URI#hostname=

Author: lzap

lib/uri/generic.rb

@@ -643,7 +643,7 @@ def host=(v)
     #
     def hostname
       v = self.host
-      /\A\[(.*)\]\z/ =~ v ? $1 : v
+      v&.start_with?('[') && v.end_with?(']') ? v[1..-2] : v
     end
 
     # Sets the host part of the URI as the argument with brackets for IPv6 addresses.
@@ -659,7 +659,7 @@ def hostname
     # it is wrapped with brackets.
     #
     def hostname=(v)
-      v = "[#{v}]" if /\A\[.*\]\z/ !~ v && /:/ =~ v
+      v = "[#{v}]" if !(v&.start_with?('[') && v&.end_with?(']')) && v&.index(':')
       self.host = v
     end
 

test/uri/test_generic.rb

@@ -799,8 +799,12 @@ def test_ipv6
 
     u = URI("http://foo/bar")
     assert_equal("http://foo/bar", u.to_s)
+    u.hostname = "[::1]"
+    assert_equal("http://[::1]/bar", u.to_s)
     u.hostname = "::1"
     assert_equal("http://[::1]/bar", u.to_s)
+    u.hostname = ""
+    assert_equal("http:///bar", u.to_s)
   end
 
   def test_build