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242 lines
7.8 KiB
242 lines
7.8 KiB
6 years ago
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# Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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"""Module which provides compatibility with older Python versions."""
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import collections
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import functools
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import os
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import sys
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__all__ = ["PY3", "long", "xrange", "unicode", "basestring", "u", "b",
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"lru_cache", "which"]
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PY3 = sys.version_info[0] == 3
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if PY3:
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long = int
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xrange = range
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unicode = str
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basestring = str
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def u(s):
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return s
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def b(s):
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return s.encode("latin-1")
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else:
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long = long
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xrange = xrange
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unicode = unicode
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basestring = basestring
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def u(s):
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return unicode(s, "unicode_escape")
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def b(s):
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return s
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# --- stdlib additions
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# py 3.2 functools.lru_cache
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# Taken from: http://code.activestate.com/recipes/578078
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# Credit: Raymond Hettinger
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try:
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from functools import lru_cache
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except ImportError:
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try:
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from threading import RLock
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except ImportError:
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from dummy_threading import RLock
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_CacheInfo = collections.namedtuple(
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"CacheInfo", ["hits", "misses", "maxsize", "currsize"])
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class _HashedSeq(list):
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__slots__ = 'hashvalue'
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def __init__(self, tup, hash=hash):
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self[:] = tup
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self.hashvalue = hash(tup)
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def __hash__(self):
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return self.hashvalue
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def _make_key(args, kwds, typed,
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kwd_mark=(object(), ),
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fasttypes=set((int, str, frozenset, type(None))),
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sorted=sorted, tuple=tuple, type=type, len=len):
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key = args
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if kwds:
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sorted_items = sorted(kwds.items())
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key += kwd_mark
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for item in sorted_items:
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key += item
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if typed:
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key += tuple(type(v) for v in args)
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if kwds:
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key += tuple(type(v) for k, v in sorted_items)
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elif len(key) == 1 and type(key[0]) in fasttypes:
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return key[0]
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return _HashedSeq(key)
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def lru_cache(maxsize=100, typed=False):
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"""Least-recently-used cache decorator, see:
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http://docs.python.org/3/library/functools.html#functools.lru_cache
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"""
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def decorating_function(user_function):
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cache = dict()
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stats = [0, 0]
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HITS, MISSES = 0, 1
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make_key = _make_key
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cache_get = cache.get
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_len = len
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lock = RLock()
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root = []
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root[:] = [root, root, None, None]
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nonlocal_root = [root]
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PREV, NEXT, KEY, RESULT = 0, 1, 2, 3
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if maxsize == 0:
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def wrapper(*args, **kwds):
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result = user_function(*args, **kwds)
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stats[MISSES] += 1
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return result
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elif maxsize is None:
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def wrapper(*args, **kwds):
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key = make_key(args, kwds, typed)
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result = cache_get(key, root)
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if result is not root:
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stats[HITS] += 1
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return result
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result = user_function(*args, **kwds)
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cache[key] = result
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stats[MISSES] += 1
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return result
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else:
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def wrapper(*args, **kwds):
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if kwds or typed:
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key = make_key(args, kwds, typed)
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else:
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key = args
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lock.acquire()
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try:
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link = cache_get(key)
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if link is not None:
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root, = nonlocal_root
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link_prev, link_next, key, result = link
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link_prev[NEXT] = link_next
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link_next[PREV] = link_prev
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last = root[PREV]
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last[NEXT] = root[PREV] = link
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link[PREV] = last
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link[NEXT] = root
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stats[HITS] += 1
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return result
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finally:
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lock.release()
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result = user_function(*args, **kwds)
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lock.acquire()
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try:
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root, = nonlocal_root
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if key in cache:
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pass
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elif _len(cache) >= maxsize:
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oldroot = root
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oldroot[KEY] = key
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oldroot[RESULT] = result
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root = nonlocal_root[0] = oldroot[NEXT]
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oldkey = root[KEY]
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root[KEY] = root[RESULT] = None
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del cache[oldkey]
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cache[key] = oldroot
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else:
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last = root[PREV]
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link = [last, root, key, result]
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last[NEXT] = root[PREV] = cache[key] = link
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stats[MISSES] += 1
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finally:
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lock.release()
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return result
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def cache_info():
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"""Report cache statistics"""
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lock.acquire()
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try:
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return _CacheInfo(stats[HITS], stats[MISSES], maxsize,
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len(cache))
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finally:
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lock.release()
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def cache_clear():
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"""Clear the cache and cache statistics"""
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lock.acquire()
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try:
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cache.clear()
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root = nonlocal_root[0]
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root[:] = [root, root, None, None]
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stats[:] = [0, 0]
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finally:
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lock.release()
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wrapper.__wrapped__ = user_function
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wrapper.cache_info = cache_info
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wrapper.cache_clear = cache_clear
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return functools.update_wrapper(wrapper, user_function)
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return decorating_function
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# python 3.3
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try:
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from shutil import which
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except ImportError:
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def which(cmd, mode=os.F_OK | os.X_OK, path=None):
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"""Given a command, mode, and a PATH string, return the path which
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conforms to the given mode on the PATH, or None if there is no such
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file.
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`mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
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of os.environ.get("PATH"), or can be overridden with a custom search
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path.
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"""
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def _access_check(fn, mode):
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return (os.path.exists(fn) and os.access(fn, mode) and
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not os.path.isdir(fn))
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if os.path.dirname(cmd):
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if _access_check(cmd, mode):
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return cmd
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return None
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if path is None:
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path = os.environ.get("PATH", os.defpath)
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if not path:
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return None
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path = path.split(os.pathsep)
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if sys.platform == "win32":
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if os.curdir not in path:
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path.insert(0, os.curdir)
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pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
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if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
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files = [cmd]
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else:
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files = [cmd + ext for ext in pathext]
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else:
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files = [cmd]
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seen = set()
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for dir in path:
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normdir = os.path.normcase(dir)
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if normdir not in seen:
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seen.add(normdir)
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for thefile in files:
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name = os.path.join(dir, thefile)
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if _access_check(name, mode):
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return name
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return None
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