Ruby

Patch: https://github.com/ruby/ruby/pull/3369

casecmp? is a kind of performance trap as it's much slower than using a case insensitive regexp or just casecmp == 0.

str = "Connection" cmp = "connection" Benchmark.ips do |x| x.report('/\A\z/i.match?') { /\Afoo\Z/i.match?(str) } x.report('casecmp?') { cmp.casecmp?(str) } x.report('casecmp') { cmp.casecmp(str) == 0 } x.compare! end Calculating ------------------------------------- /\A\z/i.match? 11.447M (± 1.3%) i/s - 57.814M in 5.051489s casecmp? 6.197M (± 0.9%) i/s - 31.138M in 5.025252s casecmp 12.753M (± 1.2%) i/s - 64.636M in 5.069195s Comparison: casecmp: 12752791.6 i/s /\A\z/i.match?: 11446996.1 i/s - 1.11x (± 0.00) slower casecmp?: 6196886.0 i/s - 2.06x (± 0.00) slower 

This is because, unlike the others, it is sensitive to unicode case folding.

However, there are cases where fast case insensitive equality check of known ASCII strings is useful. For instance, matching HTTP headers.

This patch checks if both strings use a single byte encoding, and if so then does a simple iterative comparison with TOLOWER(). This makes casecmp? slightly faster than casecmp == 0 when both strings are ASCII.

| |compare-ruby|built-ruby| |:-----------------------|-----------:|---------:| |casecmp-1 | 11.618M| 10.757M| | | 1.08x| -| |casecmp-10 | 1.849M| 1.723M| | | 1.07x| -| |casecmp-100 | 204.490k| 186.798k| | | 1.09x| -| |casecmp-1000 | 20.413k| 20.184k| | | 1.01x| -| |casecmp-nonascii1 | 19.541M| 20.100M| | | -| 1.03x| |casecmp-nonascii10 | 19.489M| 19.914M| | | -| 1.02x| |casecmp-nonascii100 | 19.479M| 20.155M| | | -| 1.03x| |casecmp-nonascii1000 | 19.462M| 20.064M| | | -| 1.03x| |casecmp_p-1 | 2.214M| 12.030M| | | -| 5.43x| |casecmp_p-10 | 1.373M| 2.150M| | | -| 1.57x| |casecmp_p-100 | 249.292k| 231.041k| | | 1.08x| -| |casecmp_p-1000 | 16.173k| 23.592k| | | -| 1.46x| |casecmp_p-nonascii1 | 651.921k| 650.572k| | | 1.00x| -| |casecmp_p-nonascii10 | 108.253k| 109.006k| | | -| 1.01x| |casecmp_p-nonascii100 | 11.749k| 11.889k| | | -| 1.01x| |casecmp_p-nonascii1000 | 1.140k| 1.138k| |