Demo/scripts/update.py

   1 #! /usr/bin/env python
   2
   3 # Update a bunch of files according to a script.
   4 # The input file contains lines of the form <filename>:<lineno>:<text>,
   5 # meaning that the given line of the given file is to be replaced
   6 # by the given text.  This is useful for performing global substitutions
   7 # on grep output:
   8
   9 import os
  10 import sys
  11 import re
  12
  13 pat = '^([^: \t\n]+):([1-9][0-9]*):'
  14 prog = re.compile(pat)
  15
  16 class FileObj:
  17     def __init__(self, filename):
  18         self.filename = filename
  19         self.changed = 0
  20         try:
  21             self.lines = open(filename, 'r').readlines()
  22         except IOError, msg:
  23             print '*** Can\'t open "%s":' % filename, msg
  24             self.lines = None
  25             return
  26         print 'diffing', self.filename
  27
  28     def finish(self):
  29         if not self.changed:
  30             print 'no changes to', self.filename
  31             return
  32         try:
  33             os.rename(self.filename, self.filename + '~')
  34             fp = open(self.filename, 'w')
  35         except (os.error, IOError), msg:
  36             print '*** Can\'t rewrite "%s":' % self.filename, msg
  37             return
  38         print 'writing', self.filename
  39         for line in self.lines:
  40             fp.write(line)
  41         fp.close()
  42         self.changed = 0
  43
  44     def process(self, lineno, rest):
  45         if self.lines is None:
  46             print '(not processed): %s:%s:%s' % (
  47                       self.filename, lineno, rest),
  48             return
  49         i = eval(lineno) - 1
  50         if not 0 <= i < len(self.lines):
  51             print '*** Line number out of range: %s:%s:%s' % (
  52                       self.filename, lineno, rest),
  53             return
  54         if self.lines[i] == rest:
  55             print '(no change): %s:%s:%s' % (
  56                       self.filename, lineno, rest),
  57             return
  58         if not self.changed:
  59             self.changed = 1
  60         print '%sc%s' % (lineno, lineno)
  61         print '<', self.lines[i],
  62         print '---'
  63         self.lines[i] = rest
  64         print '>', self.lines[i],
  65
  66 def main():
  67     if sys.argv[1:]:
  68         try:
  69             fp = open(sys.argv[1], 'r')
  70         except IOError, msg:
  71             print 'Can\'t open "%s":' % sys.argv[1], msg
  72             sys.exit(1)
  73     else:
  74         fp = sys.stdin
  75     curfile = None
  76     while 1:
  77         line = fp.readline()
  78         if not line:
  79             if curfile: curfile.finish()
  80             break
  81         n = prog.match(line)
  82         if n < 0:
  83             print 'Funny line:', line,
  84             continue
  85         filename, lineno = prog.group(1, 2)
  86         if not curfile or filename <> curfile.filename:
  87             if curfile: curfile.finish()
  88             curfile = FileObj(filename)
  89         curfile.process(lineno, line[n:])
  90
  91 if __name__ == "__main__":
  92     main()