#! /usr/bin/env python

# Update a bunch of files according to a script.

# The input file contains lines of the form <filename>:<lineno>:<text>,

# meaning that the given line of the given file is to be replaced

# by the given text.  This is useful for performing global substitutions

# on grep output:

import os

import sys

import re

pat = '^([^: \t\n]+):([1-9][0-9]*):'

prog = re.compile(pat)

class FileObj:

    def __init__(self, filename):

        self.filename = filename

        self.changed = 0

        try:

            self.lines = open(filename, 'r').readlines()

        except IOError, msg:

            print '*** Can\'t open "%s":' % filename, msg

            self.lines = None

            return

        print 'diffing', self.filename

    def finish(self):

        if not self.changed:

            print 'no changes to', self.filename

            return

        try:

            os.rename(self.filename, self.filename + '~')

            fp = open(self.filename, 'w')

        except (os.error, IOError), msg:

            print '*** Can\'t rewrite "%s":' % self.filename, msg

            return

        print 'writing', self.filename

        for line in self.lines:

            fp.write(line)

        fp.close()

        self.changed = 0

    def process(self, lineno, rest):

        if self.lines is None:

            print '(not processed): %s:%s:%s' % (

                      self.filename, lineno, rest),

            return

        i = eval(lineno) - 1

        if not 0 <= i < len(self.lines):

            print '*** Line number out of range: %s:%s:%s' % (

                      self.filename, lineno, rest),

            return

        if self.lines[i] == rest:

            print '(no change): %s:%s:%s' % (

                      self.filename, lineno, rest),

            return

        if not self.changed:

            self.changed = 1

        print '%sc%s' % (lineno, lineno)

        print '<', self.lines[i],

        print '---'

        self.lines[i] = rest

        print '>', self.lines[i],

def main():

    if sys.argv[1:]:

        try:

            fp = open(sys.argv[1], 'r')

        except IOError, msg:

            print 'Can\'t open "%s":' % sys.argv[1], msg

            sys.exit(1)

    else:

        fp = sys.stdin

    curfile = None

    while 1:

        line = fp.readline()

        if not line:

            if curfile: curfile.finish()

            break

        n = prog.match(line)

        if n < 0:

            print 'Funny line:', line,

            continue

        filename, lineno = prog.group(1, 2)

        if not curfile or filename <> curfile.filename:

            if curfile: curfile.finish()

            curfile = FileObj(filename)

        curfile.process(lineno, line[n:])

if __name__ == "__main__":

    main()