Performance benchmarks on `ActiveSupport`'s `String#camelize` and `String#underscore`

test_acronym_fixes.rb

#!/usr/bin/env ruby
#
# This script has been adapted from a similar script by Dave Gynn (@dgynn):
#
#   - https://gist.github.com/dgynn/bd54e970f8942ce2ca532e4adc3fd30a
#
# This can be run against a local version of ActiveSupport or the latest
# release for comparison (ideally, you would put this in your `rails/`
# dir locally and run against local changes from there)
#
# Run at least once with --install-gems to ensure all required Gems are installed
#
#   ruby ./test_acronym_fixes.rb --install-gems
#
# If you wish to change gems (based on options, see below), you must re-run
# with --install-gems
#
#
#
# To run against local code
#
#   ruby ./test_acronym_fixes.rb --local
#
# To run against latest release
#
#   ruby ./test_acronym_fixes.rb
#

begin
  require "bundler/inline"
  require "optparse"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end


### Option Parsing ###

options = { :install_gems => false, :local => false }

ARGV.options do |opts|
  opts.banner = "Usage: #{File.basename $PROGRAM_NAME} [options]"

  opts.on("--install-gems", "Bundle install the gems. Run with this flag once.") do |install|
    options[:install_gems] = install
  end

  opts.on("--local", "Run against local code rather than installed gem") do |local|
    options[:local] = local
  end

  opts.on("--silent-bundler", "Don't display bundler output") do
    require "bundler"
    options[:ui] = Bundler::UI::Silent.new
  end

  opts.on("-h", "--help", "Show this help") { puts opts; exit }
  opts.parse!
end


### Dependency Handling ###

gemfile(options[:install_gems], :ui => options[:ui]) do
  source "https://rubygems.org"

  if options[:local]
    gem "activesupport", :path => "./activesupport"
  else
    gem "activesupport"
  end

  gem "memory_profiler"
  gem "get_process_mem"
end


### Main Script ###

require "benchmark"
require "active_support/inflector"

capitals = ("A".."Z").to_a
lowers   = ("a".."z").to_a
string   = "AbcDef"
output   = StringIO.new

report = nil
benchmark = Benchmark.measure do
  report  = MemoryProfiler.report(:color_output => true) do
    10_000.times do
      string.gsub!(/[A-Z]/) {|char| capitals[(capitals.index(char) + 1) % 26] }
            .gsub!(/[a-z]/) {|char| lowers[(lowers.index(char) + 1) % 26] }
            .underscore
            .camelize
    end
  end
end


### Benchmark Output ###

report.pretty_print(output)

output.rewind
20.times { puts output.readline }
puts


real_seconds = benchmark.real % 60
user_seconds = benchmark.utime % 60
sys_seconds  = benchmark.stime % 60
cu_seconds   = benchmark.cutime % 60
cs_seconds   = benchmark.cstime % 60

puts ""
puts "Timings"
puts "-------"
puts "real    %dm%.3fs" % [(benchmark.real - real_seconds) / 60,  real_seconds]
puts "user    %dm%.3fs" % [(benchmark.utime - user_seconds) / 60, user_seconds]
puts "sys     %dm%.3fs" % [(benchmark.stime - sys_seconds) / 60,  sys_seconds]
puts "cuser   %dm%.3fs" % [(benchmark.cutime - cu_seconds) / 60,  cu_seconds]
puts "csys    %dm%.3fs" % [(benchmark.cstime - cs_seconds) / 60,  cs_seconds]
puts

puts "Memory used MB: #{GetProcessMem.new.mb}"