Advanced Regex features in Ruby (my presentation from our local Ruby meetups)

presentation.rb

############
# GROUPING #
############

def Given(*) end

Given(/There (is|are) some links?/) { } # ERROR

Given(/There (?:is|are) some links?/) { }


##############
# REPETITION #
##############

/<.+>/.match "<a><b>" # => #<MatchData "<a><b>">

/<.+?>/.match "<a><b>" # => #<MatchData "<a>">


###########
# ANCHORS #
###########

/^[\w ]+$/ === "John Smith\nUPDATE users SET admin = true" # => true

/\A[\w ]+\Z/ === "John Smith\nUPDATE users SET admin = true" # => false


# positive lookahead (?=) & lookbehind (?<=)
"ScheduledEvent"
  .split(/(?=[A-Z])/) # => ["Scheduled", "Event"]
  .map(&:downcase).join("_") # => "scheduled_event"

# negative lookahead (?!) & lookbehind (?<!)
(<<-EOS).scan(/[a-zA-Z0-9 ]+? (?!LAME)/) # => ["Film ", "Film ", "2 "]
Film 1
Film 2   LAME
EOS


###########
# OPTIONS #
###########

/pattern/i # ignore case
/pattern/m # extend "." to match newline
/pattern/x # free-spacing mode
/pattern/o # perform #{} interpolation only once

/pattern/mi

/a(?i:b)c/ === "aBc" # => true

/a(?-i:b)c/i === "ABC" # => false

/(?i-mx:a)/


###########
# UNICODE #
###########

("a".."z").to_a # => ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

("┌".."╋").to_a # => ["┌", "┍", "┎", "┏", "┐", "┑", "┒", "┓", "└", "┕", "┖", "┗", "┘", "┙", "┚", "┛", "├", "┝", "┞", "┟", "┠", "┡", "┢", "┣", "┤", "┥", "┦", "┧", "┨", "┩", "┪", "┫", "┬", "┭", "┮", "┯", "┰", "┱", "┲", "┳", "┴", "┵", "┶", "┷", "┸", "┹", "┺", "┻", "┼", "┽", "┾", "┿", "╀", "╁", "╂", "╃", "╄", "╅", "╆", "╇", "╈", "╉", "╊", "╋"]

/[┌-╋]/ === "┣" # => true

/[\u{250C}-\u{254B}]/ === "┣"


#####################
# CHARACTER CLASSES #
#####################

/^[a-zA-Z]+$/ === "Ryan" # => true

/^[a-zA-Z]+$/ === "Krleža" # => false

/^\w+$/ === "Krleža" # => false

/^[[:alpha:]8]+$/ === "8Krleža" # => true

/^[[:alpha:]]+$/ === "象形字" # => true

/^[[:upper:]]+$/
/^[[:lower:]]+$/

/^[^[:punct:]]+$/ === ".,;'-" # => false


/^\p{Alpha}+$/

/^\p{ASCII}+$/

/^\p{Arabic}+$/ === "غظضخثت" # => true

/^\p{Sc}+$/ === "$£" # => true

/^\p{^P}+$/

Regexp.union("foo", /bar/, /baz/i) # => /foo|(?-mix:bar)|(?i-mx:baz)/


`ri Regexp`