1 """Read and cache directory listings.

     2 

     3 The listdir() routine returns a sorted list of the files in a directory,

     4 using a cache to avoid reading the directory more often than necessary.

     5 The annotate() routine appends slashes to directories."""

     6 

     7 import os

     8 

     9 __all__ = ["listdir", "opendir", "annotate", "reset"]

    10 

    11 cache = {}

    12 

    13 def reset():

    14     """Reset the cache completely."""

    15     global cache

    16     cache = {}

    17 

    18 def listdir(path):

    19     """List directory contents, using cache."""

    20     try:

    21         cached_mtime, list = cache[path]

    22         del cache[path]

    23     except KeyError:

    24         cached_mtime, list = -1, []

    25     mtime = os.stat(path).st_mtime

    26     if mtime != cached_mtime:

    27         list = os.listdir(path)

    28         list.sort()

    29     cache[path] = mtime, list

    30     return list

    31 

    32 opendir = listdir # XXX backward compatibility

    33 

    34 def annotate(head, list):

    35     """Add '/' suffixes to directories."""

    36     for i in range(len(list)):

    37         if os.path.isdir(os.path.join(head, list[i])):

    38             list[i] = list[i] + '/'