问简单的正则表达式，用于从带有嵌套偏误的字符串中提取字符

EN

s = "a(b,c(d,e(f,g),h(i)))"

import re

level = 0
for tok in re.finditer(r"\w+|[()]", s):
    tok = tok.group()
    if tok == "(":
        level += 1
    elif tok == ")":
        level -= 1
    else:
        print "%s%s" % (" "*level, tok)

a
 b
 c
  d
  e
   f
   g
  h
   i

>>> s = "a(b,c(d,e(f,g),h(i))),a(b,c(d,e(f,g),h(i)))"
>>> from pyparsing import nestedExpr,Word,alphas,Literal
>>> result = nestedExpr(content=Word(alphas)).ignore(Literal(',')).parseString('('+s+')')
>>> print(results.asList())
[['a', ['b', 'c', ['d', 'e', ['f', 'g'], 'h', ['i']]], 'a', ['b', 'c', ['d', 'e', ['f', 'g'], 'h', ['i']]]]]
>>> def dump(lst,indent=''):
...   for i in lst:
...      if isinstance(i,list):
...        dump(i,indent+' ')
...      else:
...        print (indent,i)
...
>>> dump(result.asList())
  a
   b
   c
    d
    e
     f
     g
    h
     i
  a
   b
   c
    d
    e
     f
     g
    h
     i