"""Read and cache directory listings.+
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+
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The listdir() routine returns a sorted list of the files in a directory,+
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using a cache to avoid reading the directory more often than necessary.+
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The annotate() routine appends slashes to directories."""+
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+
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import os+
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+
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__all__ = ["listdir", "opendir", "annotate", "reset"]+
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+
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cache = {}+
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+
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def reset():+
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    """Reset the cache completely."""+
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    global cache+
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    cache = {}+
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+
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def listdir(path):+
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    """List directory contents, using cache."""+
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    try:+
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        cached_mtime, list = cache[path]+
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        del cache[path]+
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    except KeyError:+
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        cached_mtime, list = -1, []+
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    mtime = os.stat(path).st_mtime+
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    if mtime != cached_mtime:+
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        list = os.listdir(path)+
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        list.sort()+
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    cache[path] = mtime, list+
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    return list+
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+
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opendir = listdir # XXX backward compatibility+
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+
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def annotate(head, list):+
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    """Add '/' suffixes to directories."""+
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    for i in range(len(list)):+
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        if os.path.isdir(os.path.join(head, list[i])):+
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            list[i] = list[i] + '/'+
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