Prefer string patterns for gsub

https://github.com/ruby/ruby/pull/579 - there is a new optimization
since ruby 2.2

Previously regexp patterns were faster (since a string was converted to
regexp underneath anyway). But now string patterns are faster and
better reflect the purpose.

  Benchmark.ips do |bm|
    bm.report('regexp') { 'this is ::a random string'.gsub(/::/, '/') }
    bm.report('string') { 'this is ::a random string'.gsub('::', '/') }
    bm.compare!
  end
  # string: 753724.4 i/s
  # regexp: 501443.1 i/s - 1.50x slower

5 files changed, 6 insertions, 6 deletions

diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index fe8a2ac9ba..6c58009efc 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -73,7 +73,7 @@ module ActiveSupport
         string = string.sub(/^(?:#{inflections.acronym_regex}(?=\b|[A-Z_])|\w)/) { $&.downcase }
       end
       string.gsub!(/(?:_|(\/))([a-z\d]*)/i) { "#{$1}#{inflections.acronyms[$2] || $2.capitalize}" }
-      string.gsub!(/\//, '::')
+      string.gsub!('/', '::')
       string
     end
 
@@ -90,7 +90,7 @@ module ActiveSupport
     #   camelize(underscore('SSLError'))  # => "SslError"
     def underscore(camel_cased_word)
       return camel_cased_word unless camel_cased_word =~ /[A-Z-]|::/
-      word = camel_cased_word.to_s.gsub(/::/, '/')
+      word = camel_cased_word.to_s.gsub('::', '/')
       word.gsub!(/(?:(?<=([A-Za-z\d]))|\b)(#{inflections.acronym_regex})(?=\b|[^a-z])/) { "#{$1 && '_'}#{$2.downcase}" }
       word.gsub!(/([A-Z\d]+)([A-Z][a-z])/,'\1_\2')
       word.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
diff --git a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
index ce03700de1..202d94356e 100644
--- a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
@@ -13,7 +13,7 @@ module ActiveSupport
         end
 
         rounded_number = NumberToRoundedConverter.convert(number, options)
-        format.gsub(/%n/, rounded_number).gsub(/%u/, options[:unit])
+        format.gsub('%n', rounded_number).gsub('%u', options[:unit])
       end
 
       private
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
index 6940beb318..273ca4cb48 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
@@ -23,7 +23,7 @@ module ActiveSupport
         unit = determine_unit(units, exponent)
 
         rounded_number = NumberToRoundedConverter.convert(number, options)
-        format.gsub(/%n/, rounded_number).gsub(/%u/, unit).strip
+        format.gsub('%n', rounded_number).gsub('%u', unit).strip
       end
 
       private
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
index 78d2c9ae6e..67023ca5a6 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
@@ -20,7 +20,7 @@ module ActiveSupport
           human_size = number / (base ** exponent)
           number_to_format = NumberToRoundedConverter.convert(human_size, options)
         end
-        conversion_format.gsub(/%n/, number_to_format).gsub(/%u/, unit)
+        conversion_format.gsub('%n', number_to_format).gsub('%u', unit)
       end
 
       private
diff --git a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
index 1af294a03e..eafe2844f7 100644
--- a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
@@ -5,7 +5,7 @@ module ActiveSupport
 
       def convert
         rounded_number = NumberToRoundedConverter.convert(number, options)
-        options[:format].gsub(/%n/, rounded_number)
+        options[:format].gsub('%n', rounded_number)
       end
     end
   end