re = /(?>([^(]*?)\s*([(]([^()]*|(?R))*[)])([^)]*?)\s*)/
str = 'SU 3180 and
(CMG 3200 or SU 3210 or
(CMG 3200 or
(CMG 3200 or SU 3210 and
(CMG 3200 or SU 3210)
)
)
)'
# Print the match result
str.scan(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html