Benchmarking ways to insert a separator at every 80 characters of a string

gistfile1.rb

# Benchmarking ways to insert a separator at every 80 characters of a string
#
# Original question asked here:
# http://www.nabble.com/Cut-a-string-each-80-character-td22343923.html
#
# This version based on improvements suggested by Robert Klemme

require 'benchmark'

S = ('0123456789' * (80 * 100)).freeze
R = '<br/>'.freeze
GS = "\\&#{R}".freeze
SANE = '<br/>0123456789'.freeze
DELTA = 80 + R.length
REP = 500


def with_scan s
  s = s.scan(/.{80}/).join(R)
  raise 'with_scan failed' unless s[-85..-71] == SANE
end

def with_gsub s
  s = s.gsub!(/.{80}/, GS).chomp!(R)
  raise 'with_gsub failed' unless s[-85..-71] == SANE
end

def with_insert s
  i = 80
  while i < s.length
    s.insert i, R
    i += DELTA
  end
  raise 'with_insert failed' unless s[-85..-71] == SANE
end


Benchmark.bmbm do |bm|
  bm.report('with_scan  ') { REP.times { with_scan   S.dup }}
  bm.report('with_gsub  ') { REP.times { with_gsub   S.dup }}
  bm.report('with_insert') { REP.times { with_insert S.dup }}
end

=begin
ruby 1.8.7 (2008-08-11 patchlevel 72) [i686-darwin8]
Rehearsal -----------------------------------------------
with_scan     4.790000   0.240000   5.030000 (  5.147447)
with_gsub     4.860000   0.270000   5.130000 (  5.279766)
with_insert  10.350000   0.170000  10.520000 ( 10.688951)
------------------------------------- total: 20.680000sec
                  user     system      total        real
with_scan     4.770000   0.230000   5.000000 (  5.086956)
with_gsub     4.790000   0.250000   5.040000 (  5.138912)
with_insert  10.360000   0.170000  10.530000 ( 10.780026)

ruby 1.8.7 (2008-08-11 patchlevel 72) [i686-darwin8]
Rehearsal -----------------------------------------------
with_scan     4.800000   0.250000   5.050000 (  5.295321)
with_gsub     4.870000   0.280000   5.150000 (  5.271513)
with_insert  10.370000   0.180000  10.550000 ( 10.851188)
------------------------------------- total: 20.750000sec

                  user     system      total        real
with_scan     4.780000   0.230000   5.010000 (  5.135472)
with_gsub     4.800000   0.260000   5.060000 (  5.213397)
with_insert  10.380000   0.190000  10.570000 ( 10.953337)
=end