Append current line to previous line

I'm trying to parse .ldif file but failed to get desired output. Any help is much appreciated.

Here's is what I'm doing using python:

lines = open("use.ldif", "r").read().split("\n")
for i, line in enumerate(lines):
   if not line.find(":"):
      lines[i-1] = lines[-1].strip() + line
      lines.pop(i)

open("user_modified.ldif", "w").write("\n".join(lines)+"\n")

use.ldif (input file)

dn: cnh
changetype: add
objectclass: inetOrgPerson
objectclass: cdsUser
objectclass: organizationalPerson
objectclass: Person
objectclass: n
objectclass: Top
objectclass: cd
objectclass: D
objectclass: nshd shdghsf shgdhfjh jhghhghhgh
 hjgfhgfghfhg
street: shgdhgf

dn: cnh
changetype: add
objectclass: inetOrgPerson
objectclass: hjgfhgfghfhg
street: shgdhgf kjsgdhgsjhg shdghsgjfhsfsf
 jgsdhsh
company: xyz

user_modified.ldif (Output from my code)

I am getting the same output, nothing is modified. I feel it's because I'm doing split("\n") but I'm not getting an idea of what else can be done.

desired output

dn: cnh
changetype: add
objectclass: inetOrgPerson
objectclass: cdsUser
objectclass: organizationalPerson
objectclass: Person
objectclass: n
objectclass: Top
objectclass: cd
objectclass: D
objectclass: nshd shdghsf shgdhfjh jhghhghhghhjgfhgfghfhg
street: shgdhgf

dn: cnh
changetype: add
objectclass: inetOrgPerson
objectclass: hjgfhgfghfhg
street: shgdhgf kjsgdhgsjhg shdghsgjfhsfsfjgsdhsh
company: xyz

As you can see in my output file user_modified.ldif the object class in first entry and street in second entry gets to the next line. How can I have them in same line, like in the desired output.

Thanks in advance

Solution

Okey here my approach:

import re

pattern = re.compile(r"(\w+):(.*)")

with open("use.ldif", "r") as f:
    new_lines = []

    for line in f:
        if line.endswith('\n'):
            line = line[:-1]

        if line == "":
            new_lines.append(line)
            continue

        l = pattern.search(line)
        if l:
            new_lines.append(line)
        else:
            new_lines[-1] += line

with open("user_modified.ldif", "wt") as f:
    f.write("\n".join(new_lines))

Looking a bit your code I suggest you to get documented a bit about iterating over files. Maybe you are still beginner with Python, but in your code shows you are processing whole file 3 times, at read(), at split('\n') and finally at the for statement. When you open a file, what you get is called descriptor, and as you can see in my code you can use it to iterate over the file getting a line on each step. For larger files this will become a important performance trick.