Match series of (non-nested) balanced parentheses at end of string

Question

How can I match one or more parenthetical expressions appearing at the end of string?

Input:

'hello (i) (m:foo)'

Desired output:

['i', 'm:foo']

Intended for a python script. Paren marks cannot appear inside of each other (no nesting), and the parenthetical expressions may be separated by whitespace.

It's harder than it might seem at first glance, at least so it seems to me.

Answer 1

You don't need to use regex:

def splitter(input):
    return [ s.rstrip(" \t)") for s in input.split("(") ][1:]
print splitter('hello (i) (m:foo)')

Note: this solution only works if your input is already known to be valid. See MizardX's solution that will work on any input.

Answer 2

paren_pattern = re.compile(r"\(([^()]*)\)(?=(?:\s*\([^()]*\))*\s*$)")

def getParens(s):
  return paren_pattern.findall(s)

or even shorter:

getParens = re.compile(r"\(([^()]*)\)(?=(?:\s*\([^()]*\))*\s*$)").findall

explaination:

\(                     # opening paren
([^()]*)               # content, captured into group 1
\)                     # closing paren
(?=                    # look ahead for...
  (?:\s*\([^()]*\))*   #   a series of parens, separated by whitespace
  \s*                  #   possibly more whitespace after
  $                    #   end of string
)                      # end of look ahead