gistfile1.rb

## Original
def orig_reverse_sql_order(order_query)
  order_query.join(', ').split(',').collect { |s|
    if s.match(/\s(asc|ASC)$/)
      s.gsub(/\s(asc|ASC)$/, ' DESC')
    elsif s.match(/\s(desc|DESC)$/)
      s.gsub(/\s(desc|DESC)$/, ' ASC')
    else
      s + ' DESC'
    end
  }
end

## Modified
def mod1_reverse_sql_order(order_query)
  order_query.join(', ').split(',').collect { |s|
    if s.match(/\s(asc|ASC)$/)
      s.gsub!(/\s(asc|ASC)$/, ' DESC')
    elsif s.match(/\s(desc|DESC)$/)
      s.gsub!(/\s(desc|DESC)$/, ' ASC')
    else
      s.concat(' DESC')
    end

    s
  }
end

## Modified - don't create match object
def mod2_reverse_sql_order(order_query)
  order_query.join(', ').split(',').collect { |s|
    if s =~ /\s(asc|ASC)$/
      s.gsub!(/\s(asc|ASC)$/, ' DESC')
    elsif s =~ /\s(desc|DESC)$/
      s.gsub!(/\s(desc|DESC)$/, ' ASC')
    else
      s.concat(' DESC')
    end

    s
  }
end

## Modified - case?
def mod3_reverse_sql_order(order_query)
  order_query.join(', ').split(',').collect { |s|
    case s
    when /\s(asc|ASC)$/
      s.gsub!(/\s(asc|ASC)$/, ' DESC')
    when /\s(desc|DESC)$/
      s.gsub!(/\s(desc|DESC)$/, ' ASC')
    else
      s.concat(' DESC')
    end

    s
  }
end

## Lazy gsub?
def lazy_reverse_sql_order(order_query)
  order_query.join(', ').split(',').collect do |s|
    s.gsub!(/\sasc\Z/i, ' DESC') || s.gsub!(/\sdesc\Z/i, ' ASC') || s.concat(' DESC')
  end
end

order_query = ['created_at ASC, updated_at desc, id']
require 'benchmark'
include Benchmark
bm do |x|
  x.report('orig:'){ 100000.times { orig_reverse_sql_order(order_query)} }
  x.report('mod1:'){ 100000.times { mod1_reverse_sql_order(order_query)} }
  x.report('mod2:'){ 100000.times { mod2_reverse_sql_order(order_query)} }
  x.report('mod3:'){ 100000.times { mod3_reverse_sql_order(order_query)} }
  x.report('lazy:'){ 100000.times { lazy_reverse_sql_order(order_query)} }
end
__END__
      user     system      total        real
orig:  1.660000   0.040000   1.700000 (  1.689658)
mod1:  1.650000   0.030000   1.680000 (  1.693604)
mod2:  1.370000   0.030000   1.400000 (  1.395524)
mod3:  1.340000   0.020000   1.360000 (  1.358895)
lazy:  0.930000   0.030000   0.960000 (  0.954206)