Question

I need to parse text lists:

1 List name

1 item
2 item
3 item

2 List name

1 item
2 item
3 item

3 List name

1 item
2 item
3 item

I was trying to use regular expression to split first level list:

import re
def re_show(pat, s):
 print re.compile(pat, re.S).sub("{\g<0>}", s),'\n'

s = '''
1 List name

1 item
2 item
3 item

2 List name

1 item
2 item
3 item

3 List name

1 item
2 item
3 item
'''

re_show('\n\d+.*?(?=\n\n\d+.*?\n\n)', s)

But it doesn’t work. Instead of this:

{
1 List name

1 item
2 item
3 item}
{
2 List name

1 item
2 item
3 item}
{
3 List name

1 item
2 item
3 item}

I’ve got this:

{
1 List name}
{
1 item
2 item
3 item}
{
2 List name}
{
1 item
2 item
3 item}

3 List name

1 item
2 item
3 item

What would you recommend to solve this task?

Thanks for your answers. I’ve learned many new features of Python.

I think, I will use “state machine” approach as described here

Answer 1

class ListParser:

 def __init__(self, s):
  self.str = s.split("\n")
  print self.str
  self.answer = []

 def parse(self):
  self.nextLine()
  self.topList()
  return

 def topList(self):
  while(len(self.str) > 0):
   self.topListItem()

 def topListItem(self):
  l = self.nextLine()
  print "TOP: " + l
  l = self.nextLine()
  if l != '':
   raise Exception("expected blank line but found '%s'" % l)
  sub = self.sublist()

 def nextLine(self):
  return self.str.pop(0)

 def sublist(self):
  while True:
   l = self.nextLine()
   if l == '':
    return # end of sublist marked by blank line
   else:
    print "SUB: " + l

parser = ListParser(s)
parser.parse() 
print "done"

prints

TOP: 1 List name
SUB: 1 item
SUB: 2 item
SUB: 3 item
TOP: 2 List name
SUB: 1 item
SUB: 2 item
SUB: 3 item
TOP: 3 List name
SUB: 1 item
SUB: 2 item
SUB: 3 item
done