Performance test on http://apidock.com/rails/Inflector/demodulize vs http://apidock.com/rails/ActiveSupport/Inflector/deconstantize

demodulize_deconstantize.rb

require 'benchmark'

# $ ruby -v 
# => ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-darwin12.2.0]
#
#     N.times { |i| RINDEX.deconstantize(A::B::C::D.name) }
#                     user     system      total        real
# rindex          0.160000   0.000000   0.160000 (  0.164055)
# gsub            0.580000   0.010000   0.590000 (  0.683018)
#
#     N.times { |i| RINDEX.deconstantize(D.name) }
#                     user     system      total        real
# rindex          0.160000   0.000000   0.160000 (  0.175646)
# gsub            0.160000   0.000000   0.160000 (  0.201934)
#
#     N.times { |i| RINDEX.demodulize(A::B::C::D.name) }
#                     user     system      total        real
# rindex          0.160000   0.000000   0.160000 (  0.189615)
# gsub            0.590000   0.010000   0.600000 (  0.740444)
#
#     N.times { |i| RINDEX.demodulize(D.name) }
#                     user     system      total        real
# rindex          0.090000   0.000000   0.090000 (  0.099179)
# gsub            0.160000   0.000000   0.160000 (  0.184077)


module RINDEX
  def self.demodulize(path)
    path = path.to_s
    if i = path.rindex('::')
      path[(i+2)..-1]
    else
      path
    end
  end

  def self.deconstantize(path)
    path.to_s[0...(path.rindex('::') || 0)] # implementation based on the one in facets' Module#spacename
  end
end

module GSUB
  def self.demodulize(path)
    path.to_s.gsub(/^.*::/, '')
  end

  def self.deconstantize(path)
    path.to_s.gsub(/::.*/, '')
  end
end

N = 100000
module A
  module B
    module C
      class D; end
    end
  end
end

class D; end

puts "    N.times { |i| RINDEX.deconstantize(A::B::C::D.name) }\n"
Benchmark.bm(13) do |x|
  x.report("rindex") {
    N.times { |i| RINDEX.deconstantize(A::B::C::D.name) }
  }

  x.report("gsub") {
    N.times { |i| GSUB.deconstantize(A::B::C::D.name) }
  }
end

puts "    N.times { |i| RINDEX.deconstantize(D.name) }\n"
Benchmark.bm(13) do |x|
  x.report("rindex") {
    N.times { |i| RINDEX.deconstantize(D.name) }
  }

  x.report("gsub") {
    N.times { |i| GSUB.deconstantize(D.name) }
  }
end

puts "    N.times { |i| RINDEX.demodulize(A::B::C::D.name) }\n"
Benchmark.bm(13) do |x|
  x.report("rindex") {
    N.times { |i| RINDEX.demodulize(A::B::C::D.name) }
  }

  x.report("gsub") {
    N.times { |i| GSUB.demodulize(A::B::C::D.name) }
  }
end

puts "    N.times { |i| RINDEX.demodulize(D.name) }\n"
Benchmark.bm(13) do |x|
  x.report("rindex") {
    N.times { |i| RINDEX.demodulize(D.name) }
  }

  x.report("gsub") {
    N.times { |i| GSUB.demodulize(D.name) }
  }
end