## result
                          user     system      total        real
apeiros:              0.460000   0.010000   0.470000 (  0.470928)
nullie:               0.510000   0.000000   0.510000 (  0.512677)
Loaded suite compare_segments
Started
..
Finished in 0.003989 seconds.

2 tests, 30 assertions, 0 failures, 0 errors


## code
require 'benchmark'
require 'test/unit'

$n = 1e3
$tests = [
	["/", "/", "/"],
	["/", "/segment1", "/"],
	["/segment1", "/", "/"],
	["/segment1", "/segment1", "/segment1"],
	["/segment1", "/segment2", "/"],
	["/segment1/segment2", "/segment1/segment2", "/segment1/segment2"],
	["/segment1/segment2", "/segment1/segment2/", "/segment1/segment2"],
	["/segment1/segment2/", "/segment1/segment2", "/segment1/segment2"],
	["/segment1/segment2/", "/segment1/segment2/", "/segment1/segment2"],
	["/segment1/segment2", "/segmentX/segmentY/", "/"],
	["/segment1/segment2/segment3/segment4", "/segment1/segment2/segmentX/segmentY", "/segment1/segment2"],
	["/segment1/segment2/segment3/segment4", "/segment1/segment2/segment3x/segment4", "/segment1/segment2"],
	["/segment1/segment2/segment3/segment4", "/segment1/segment2", "/segment1/segment2"],
	["/segment1/segment2/segment3/segment4", "/segment1/segment2/", "/segment1/segment2"],
	[
		"/longsegment1/longsegment2/longsegment3/longsegment4/longsegment5/longsegment6/longsegment7/longsegment8/longsegment9",
		"/longsegment1/longsegment2/longsegment3/longsegment4/longsegment5/longsegment6/longsegment7/longsegment8/longsegment9",
		"/longsegment1/longsegment2/longsegment3/longsegment4/longsegment5/longsegment6/longsegment7/longsegment8/longsegment9",
	]
]

def cs_apeiros(s1,s2)
	s1 = s1[1,s1.length].split(/\//)
	s2 = s2[1,s2.length].split(/\//)
	same = []
	s1.length.times { |i| break unless s1[i] == s2[i]; same << s1[i] }
	"/"+same.join("/")
end

def cs_apeiros(s1,s2)
	result    = ""
	offset    = 0
	offset2   = nil
	s1        = s1.chomp("/")
	s1_length = s1.length
	s2_length = s2.length
	while offset < s1_length
		offset2 = s1.index("/", offset+1) || s1_length
		length  = offset2-offset
		segment = s1[offset,length]
		break unless (s2[offset,length] == segment && (s2_length == offset2 || s2[offset2] == 47))
		result << segment
		offset  = offset2
	end
	result == "" ? "/" : result
end

def cs_nullie(s1,s2)
	s1 = s1[1,s1.length].split(/\//)
	s2 = s2[1,s2.length].split(/\//)
	r = []
	s1.each {|x| break unless x == s2.shift; r << x}
	"/"+r.join("/")
end

Benchmark.bm(20) { |bm|
	bm.report("apeiros:") { $n.to_i.times { $tests.each { |(a,b,r)| cs_apeiros(a,b) } } }
	bm.report("nullie:") { $n.to_i.times { $tests.each { |(a,b,r)| cs_nullie(a,b) } } }
}

class TestImplementations < Test::Unit::TestCase
	def test_apeiros
		$tests.each { |(a,b,r)|
			assert_equal(r, cs_apeiros(a,b), "#{r} epected for #{a}, #{b}")
		}
	end

	def test_nullie
		$tests.each { |(a,b,r)|
			assert_equal(r, cs_nullie(a,b))
		}
	end
end