requestion regarding regular expression

[Scott David Daniels]

BartlebyScrivener wrote:
> That's it. Thank you! Very instructive.
> 
> Final:
> 
> path = "d:/emacs files/emacsinit.txt"
> lines = open(path).readlines()
> # next two lines all on one
> starts = [i for i, line in enumerate(lines) if
> line.startswith('(defun')]
> for i, start in enumerate(starts):
>     while start > 0 and lines[start-1].startswith(';'):
>         starts[i] = start = start-1
>         print starts
> 
If you don't want to hold the whole file in memory, this gets the
starts a result at a time:

     def starts(source):
         prelude = None
         for number, line in enumerate(source): # read and number a line
             if line[0] == ';':
                 if prelude is None:
                     prelude = number  # Start of commented region
                 # else: this line just extends previous prelude
             else:
                 if line.startswith('(defun'):
                     # You could append to a result here, but yield lets
                     # the first found one get out straightaway.
                     if prelude is None:
                         yield number
                     else:
                         yield prelude
                 prelude = None


     path = "d:/emacs files/emacsinit.txt"
     source = open(path)
     try:
         for line in starts(source):
             print line,
         # could just do: print list(starts(source))
     finally:
         source.close()
     print

-- 
-Scott David Daniels
scott.daniels at acm.org