mikz: does anyway have better way of converting whatever/string/like/this to [['whatever'], ['whatever', 'string'], ['whatever', 'string', 'like'], ['whatever', 'string', 'like', 'this']] than: str.split('/').reduce([]){ |acc, v| acc.push(([acc.last].compact + [v]).flatten) }

benchmark.rb

require 'benchmark'

loops = 1_000_000

str = 'whatever/string/like/this'

Benchmark.bm do |x|
  x.report 'michal1' do
    loops.times do
      str.split('/').reduce([]){ |acc, v| acc.push(([acc.last].compact + [v]).flatten) }
    end
  end
  x.report 'rgrau1' do
    loops.times do
      acc = [[]]; str.split('/').map { |elem| acc << (acc[-1] + [elem]).flatten }; acc
    end
  end
  x.report 'alex1' do
    loops.times do
      str.split('/').inject([]) { |acc, v| acc << ((acc.last || []) + [v]) }
    end
  end
  x.report 'michal2' do
    loops.times do
      str.split('/').reduce([[]]){ |acc, v| acc.push(acc.last.push(v).dup) }.uniq
    end
  end
  x.report 'alex2' do
    loops.times do
      [].tap { |w| a=str.split('/'); a.size.times { |i| w << a[0..i] } }
    end
  end
end

alex@inxs:~/dev/3scale/core$ ruby bm.rb
user system total real
michal1 7.160000 0.000000 7.160000 ( 7.165719)
rgrau1 5.910000 0.000000 5.910000 ( 5.901147)
alex1 2.910000 0.000000 2.910000 ( 2.909804)
michal2 14.310000 0.000000 14.310000 ( 14.305894)
alex2 2.820000 0.000000 2.820000 ( 2.819322)