ruby の正規表現の ^$ と \A\z の速度比較

r.rb

require 'benchmark'
Benchmark.bmbm do |x|
  n = 1000000
  x.report('^$   0  ') { n.times { 0.class.to_s =~ /^(Integer|Fixnum|FalseClass|TrueClass|NilClass)$/ } }
  x.report('\A\z 0  ') { n.times { 0.class.to_s =~ /\A(Integer|Fixnum|FalseClass|TrueClass|NilClass)\z/ } }
  x.report('^$   nil') { n.times { nil.class.to_s =~ /^(Integer|Fixnum|FalseClass|TrueClass|NilClass)$/ } }
  x.report('\A\z nil') { n.times { nil.class.to_s =~ /\A(Integer|Fixnum|FalseClass|TrueClass|NilClass)\z/ } }
  x.report('^$   x  ') { n.times { x.class.to_s =~ /^(Integer|Fixnum|FalseClass|TrueClass|NilClass)$/ } }
  x.report('\A\z x  ') { n.times { x.class.to_s =~ /\A(Integer|Fixnum|FalseClass|TrueClass|NilClass)\z/ } }
end

result.txt

Rehearsal --------------------------------------------
^$   0     0.420000   0.010000   0.430000 (  0.431502)
\A\z 0     0.430000   0.000000   0.430000 (  0.431883)
^$   nil   0.480000   0.000000   0.480000 (  0.478276)
\A\z nil   0.470000   0.000000   0.470000 (  0.470363)
^$   x     0.420000   0.000000   0.420000 (  0.419455)
\A\z x     0.390000   0.000000   0.390000 (  0.389344)
----------------------------------- total: 2.620000sec

               user     system      total        real
^$   0     0.410000   0.010000   0.420000 (  0.422920)
\A\z 0     0.400000   0.000000   0.400000 (  0.402938)
^$   nil   0.440000   0.010000   0.450000 (  0.459061)
\A\z nil   0.460000   0.000000   0.460000 (  0.459551)
^$   x     0.420000   0.000000   0.420000 (  0.421417)
\A\z x     0.400000   0.000000   0.400000 (  0.400294)


Rehearsal --------------------------------------------
^$   0     0.410000   0.000000   0.410000 (  0.416605)
\A\z 0     0.380000   0.000000   0.380000 (  0.379546)
^$   nil   0.420000   0.000000   0.420000 (  0.423058)
\A\z nil   0.420000   0.000000   0.420000 (  0.422661)
^$   x     0.470000   0.000000   0.470000 (  0.463877)
\A\z x     0.420000   0.000000   0.420000 (  0.426670)
----------------------------------- total: 2.520000sec

               user     system      total        real
^$   0     0.380000   0.000000   0.380000 (  0.379946)
\A\z 0     0.390000   0.000000   0.390000 (  0.392950)
^$   nil   0.410000   0.000000   0.410000 (  0.415787)
\A\z nil   0.420000   0.000000   0.420000 (  0.430581)
^$   x     0.440000   0.000000   0.440000 (  0.445779)
\A\z x     0.430000   0.000000   0.430000 (  0.425383)


Rehearsal --------------------------------------------
^$   0     0.400000   0.000000   0.400000 (  0.399049)
\A\z 0     0.380000   0.000000   0.380000 (  0.389624)
^$   nil   0.420000   0.000000   0.420000 (  0.418071)
\A\z nil   0.430000   0.000000   0.430000 (  0.438361)
^$   x     0.400000   0.000000   0.400000 (  0.397920)
\A\z x     0.380000   0.000000   0.380000 (  0.382451)
----------------------------------- total: 2.410000sec

               user     system      total        real
^$   0     0.380000   0.010000   0.390000 (  0.382801)
\A\z 0     0.370000   0.000000   0.370000 (  0.373419)
^$   nil   0.420000   0.000000   0.420000 (  0.416101)
\A\z nil   0.420000   0.000000   0.420000 (  0.426962)
^$   x     0.400000   0.000000   0.400000 (  0.404458)
\A\z x     0.370000   0.000000   0.370000 (  0.371693)