PO Box (Post office box) regular expression in ruby.

po_box_regex.rb

po_box_regex = /\A\b(?:p[.\s]?o?[.\s]?b?[.\s]?)\b(?:box)?|post{1}\s(?:office)?\s?(:?box|bin){1}\z/i

# Matches
#
# P. O. Box
# P.O.Box
# Post Box
# Post Office Box
# P.O.B
# P.O.B.
# POB
# Post Office Bin
# P O Box DesMoines1000
# P O Box Des Moines 1000
# Post Office Box
# Post Box
# PO
# P.O.
# P.B.

# Does NOT match
#
# Post Office
# Bin
# Box
# 12 Box
# Post
# Postal Code
# Portsmouth
# Campbell
# Raspberry
# Polonium
# Polar beer.

it will fail when Po Shau Centre, Kwun Tong, Hong Kong