class MntEnt(object):
	__slots__ = [
			'mnt_fsname',
			'mnt_dir',
			'mnt_type',
			'mnt_opts',
			'mnt_freq',
			'mnt_passno',
	]

	@classmethod
	def from_string(cls, line):
		data = line.split(' ')
		mnt_fsname, mnt_dir, mnt_type, mnt_opts = [
				cls._decode_octal(_) for _ in data[0:4]
		]
		mnt_freq, mnt_passno = [
				int(_, 10) for _ in data[4:6]
		]
		return cls(mnt_fsname, mnt_dir, mnt_type, mnt_opts, mnt_freq, mnt_passno)

	def __init__(self, mnt_fsname, mnt_dir, mnt_type, mnt_opts, mnt_freq=0, mnt_passno=0):
		self.mnt_fsname = mnt_fsname
		self.mnt_dir = mnt_dir
		self.mnt_type = mnt_type
		self.mnt_opts = mnt_opts
		self.mnt_freq = mnt_freq
		self.mnt_passno = mnt_passno

	RE_DECODE_OCTAL = re.compile(r'\\([0-7]{3})')
	@classmethod
	def _decode_octal(cls, string):
		r"""
		>>> MntEnt._decode_octal(r'a\040b\011c\012d\134e')
		'a b\tc\nd\\e'
		"""
		return cls.RE_DECODE_OCTAL.sub(
				lambda match: chr(int(match.group(1), 8)),
				string
		)

	RE_ENCODE_OCTAL = re.compile(r'[\t\n \\]')
	@classmethod
	def _encode_octal(cls, string):
		r"""
		>>> MntEnt._encode_octal('a b\tc\nd\\e')
		'a\\040b\\011c\\012d\\134e'
		"""
		return cls.RE_ENCODE_OCTAL.sub(
				lambda match: r'\%03o' % (ord(match.group()),),
				string
		)

	def __str__(self):
		return ' '.join((
					self._encode_octal(self.mnt_fsname),
					self._encode_octal(self.mnt_dir),
					self._encode_octal(self.mnt_type),
					self._encode_octal(self.mnt_opts),
					'%d' % (self.mnt_freq,),
					'%d' % (self.mnt_passno,),
		))

	def __repr__(self):
		return '%s(%r, %r, %r, %r, mnt_freq=%d, mnt_passno=%d)' % (
				self.__class__.__name__,
				self.mnt_fsname,
				self.mnt_dir,
				self.mnt_type,
				self.mnt_opts,
				self.mnt_freq,
				self.mnt_passno,
		)


class Mounts(list):
	def __init__(self, filename='/proc/mounts'):
		list.__init__(self)
		for line in open(filename, 'rb'):
			self.append(MntEnt.from_string(line))

	def mounted_directories(self):
		for mnt in self:
			yield mnt.mnt_dir

	def mount_source(self, mount_point):  # unused
		for mnt in reversed(self):
			if mnt.mnt_dir == mount_point:
				return mnt.mnt_fsname
		raise KeyError(mount_point)