match-nested.py

#!/usr/bin/python

# Find patterns in a text an remove then, along with everything that follows in
# curly braces ({}). The matched pattern may as well contain nested curly brances.
# Patterns may spread across multiple lines.

import sys 
import fileinput

def strip_first(s, pattern, count):
    out = ""

    try:
        i = 0

        if count == 0:
            i = s.index(pattern)
            out = s[:i]
            i += len(pattern)

        while True:
            if i >= len(s):
                break

            if s[i] == '{':
                count += 1

            if s[i] == '}':
                count -= 1

            i += 1

            if count == 0:
                break

        if count == 0:
            sub, count = strip_first(s[i:], pattern, count)
            out += sub

    except ValueError:
        out = s

    return (out, count)

pattern = sys.argv[1]
count = 0

for line in sys.stdin:
    out, count = strip_first(line, pattern, count)

    if len(out) > 0:
        sys.stdout.write(out)