regexp/pattern_time_limits_parens.rb

tests/_examples/regexp/pattern_time_limits_parens.rb in the metorex repository.

# A pattern can be given a limit on how long one match may run. A match that
# passes the limit raises Regexp::TimeoutError rather than running on.
p(Regexp.timeout)

# A limit written on a pattern of its own stands in place of the one the
# class names, and reading it back answers what was set.
slow = Regexp.new("(a*)*b", timeout: 0.5)
p(slow.timeout)
p(slow.source)

# A pattern built without one has none of its own, whatever the class says.
plain = Regexp.new("(c*)*d")
p(plain.timeout)

# The limit has to be a positive number of seconds.
held = begin
  Regexp.new("x", timeout: 0)
rescue ArgumentError => error
  error.message
end
p(held)

held = begin
  Regexp.timeout = -1
rescue ArgumentError => error
  error.message
end
p(held)

# The class names a limit for every pattern written without one, read back
# as a number of seconds.
Regexp.timeout = 5
p(Regexp.timeout)
p(plain.timeout)
p(/(a+)b/.match("aaab")[1])

# Clearing it takes the limit off again.
Regexp.timeout = nil
p(Regexp.timeout)
p(Regexp::TimeoutError.superclass)

Output:

nil
0.5
"(a*)*b"
nil
"invalid timeout: 0"
"invalid timeout: -1"
5.0
nil
"aaa"
nil
RegexpError