ruby-boost-regex

Wraps the Boost.Regex library to provide Boost regexes. Why? Why not! (Plus, it's worth seeing if it's faster.)

I'm trying to match the API to be at least completely compatible with normal Regexps, and then add Boost features. So far...

Features

Matches set global special variables like $`, $1-$9, $&, and so on
Supports =~ operator, === operator (for case...when)
Supports #match method as in normal Regexps, returning the same type of object (MatchData).
Spiffy monkey patch (see below)

Cool monkey patch

So monkey patching is bad, right? Right. And rubyists monkey patch all the time, which makes us bad people. Well, this module adds a new, alternate regex, but Ruby has a syntax for regexes already:

reg = /\d{3}/

This is nice because we don't have to escape the backslashes, plus it looks really nice with syntax highlighting. With these boost regexes, you'll either have to do

reg = Boost::Regexp.new("\\d{3}")
# or
reg = Boost::Regexp.new(/\d{3}/)

Why do all that typing? We have a literal regex syntax! But it creates normal regexes. So, we have a compromise:

Boost::Regexp.enable_monkey_patch! # only have to do this once
reg = /\d{3}/.boost!
reg.class # ==> Boost::Regexp

Cool, eh?

Of course, Boost gives us lots of crazy flags:

reg = /abc(def)/.boost!(Boost::Regexp::NO_SUBS & Boost::Regexp::IGNORECASE)
reg =~ "zzzABCDEF" # ==> 3
puts $1  # ==> nil

Benchmarks

I adapted the ruby-benchmark-suite's bm_regex_dna benchmark, which is used in the Computer Language Shootout. However, it uses str.scan(), which will fail if confronted with a non-standard Regexp. So I had to write my own, which is less optimized. The benchmark code is free to be scrutinized! It uses the standard benchmark module because lifting the spiffy one from ruby-benchmark-suite proved to be too much of a hassle for now.

Anyway, here's some results:

DNA-Matching (Computer Language Shootout)
=========================================
Rehearsal ------------------------------------------------
Normal regex  17.190000   0.020000  17.210000 ( 17.278168)
Boost regex   12.120000   0.030000  12.150000 ( 12.213959)
-------------------------------------- total: 29.360000sec

                   user     system      total        real
Normal regex  17.050000   0.020000  17.070000 ( 17.082539)
Boost regex   12.000000   0.030000  12.030000 ( 12.040932)

Failing to match a phone number in a big string of text
=======================================================
Rehearsal ------------------------------------------------
Normal regex   0.070000   0.000000   0.070000 (  0.070072)
Boost regex    0.030000   0.000000   0.030000 (  0.034858)
--------------------------------------- total: 0.100000sec

                   user     system      total        real
Normal regex   0.070000   0.000000   0.070000 (  0.070087)
Boost regex    0.040000   0.000000   0.040000 (  0.035052)

Usage

Don't have it as a gem yet. Sorry! But you could do this in theory:

r = Boost::Regexp.new("(\\d{3})-(\\d{3})-(\\d{4})")
r =~ "555-123-4567"
p $1 # ==> "555"
matches = r.match("123-456-7890")
p matches[2] # ==> "456"

Note on Patches/Pull Requests