bgneal@64: Key lists
bgneal@64: ---------
bgneal@64: 
bgneal@64: Key lists are represented as a named tuple called ``KeyList``.
bgneal@64: 
bgneal@64: .. class:: m209.keylist.KeyList(indicator, lugs, pin_list, letter_check)
bgneal@64: 
bgneal@64:    As a named tuple, ``KeyList`` has the following attributes:
bgneal@64: 
bgneal@64:    * ``indicator`` - the string name for the ``KeyList``; must be 2 letters in
bgneal@64:      the range ``AA`` - ``ZZ``
bgneal@64:    * ``lugs`` - a string representing the drum lug settings; see below
bgneal@64:    * ``pin_list`` - a list of six strings which represent key wheel pin
bgneal@64:      settings; see below
bgneal@64:    * ``letter_check`` - a string representing the letter check used to verify
bgneal@64:      operator settings; if unknown this can be ``None`` or an empty string
bgneal@64:    
bgneal@65: .. _lug-settings:
bgneal@65: 
bgneal@64: Lug settings format
bgneal@64: ~~~~~~~~~~~~~~~~~~~
bgneal@64: 
bgneal@64: Drum lug settings are often conveniently represented as strings consisting of
bgneal@64: at most 27 whitespace-separated pairs of integers separated by dashes. For
bgneal@64: example::
bgneal@64: 
bgneal@64:    lugs = '1-0 2-0 2-0 0-3 0-5 0-5 0-5 0-6 2-4 3-6'
bgneal@64: 
bgneal@64: Each integer pair must be in the form ``m-n`` where m & n are integers
bgneal@64: between 0 and 6, inclusive. Each integer represents a lug position where
bgneal@64: 0 is a neutral position, and 1-6 correspond to key wheel positions. If
bgneal@64: m & n are both non-zero, they cannot be equal.
bgneal@64: 
bgneal@64: If a string has less than 27 pairs, it is assumed all remaining bars have both
bgneal@64: lugs in the neutral (0) positions.
bgneal@64: 
bgneal@64: Order of the pairs within the string does not matter.
bgneal@64: 
bgneal@64: To reduce typing and to aid in readability, an alternate shortcut notation is
bgneal@64: supported::
bgneal@64: 
bgneal@64:    lugs = '1-0 2-0*2 0-3 0-5*3 0-6 2-4 3-6'
bgneal@64: 
bgneal@64: Any pair that is suffixed by ``*k``, where k is a positive integer, means there
bgneal@64: are ``k`` copies of the preceeding lug pair combination. For example, these two
bgneal@64: strings describe identical drum configurations::
bgneal@64: 
bgneal@64:    lugs1 = '2-4 2-4 2-4 0-1 0-1'
bgneal@64:    lugs2 = '2-4*3 0-1*2'
bgneal@64: 
bgneal@65: .. _pin-settings:
bgneal@65: 
bgneal@64: Key wheel pin settings
bgneal@64: ~~~~~~~~~~~~~~~~~~~~~~
bgneal@64: 
bgneal@64: Key wheel pin settings are represented as iterables of letters whose pins are
bgneal@64: slid to the "effective" position (to the right). Letters not appearing in this
bgneal@64: sequence are considered to be in the "ineffective" position (to the left). If
bgneal@64: None or empty, all pins are set to be ineffective.
bgneal@64: 
bgneal@64: Examples::
bgneal@64: 
bgneal@64:    all_ineffective = ''
bgneal@64:    wheel1 = 'ABDEFHIJMQSUXZ'
bgneal@64:    wheel2 = 'EINPQRTVXZ'
bgneal@64:    wheel3 = 'DEFGIKNOSUX'
bgneal@64:    wheel4 = 'BFGJKRS'
bgneal@64:    wheel5 = 'ABCDFGHIJMPS'
bgneal@64:    wheel6 = 'ADEFHIJKN'
bgneal@64: 
bgneal@64: Key list example
bgneal@64: ~~~~~~~~~~~~~~~~
bgneal@64: 
bgneal@64: An example of using the :class:`~m209.keylist.KeyList` is:
bgneal@64: 
bgneal@64: .. code-block:: python
bgneal@64: 
bgneal@64:    from m209.keylist import KeyList
bgneal@64: 
bgneal@64:    key_list1 = KeyList(
bgneal@64:           indicator='AA',
bgneal@64:           lugs='0-4 0-5*4 0-6*6 1-0*5 1-2 1-5*4 3-0*3 3-4 3-6 5-6',
bgneal@64:           pin_list=[
bgneal@64:               'FGIKOPRSUVWYZ',
bgneal@64:               'DFGKLMOTUY',
bgneal@64:               'ADEFGIORTUVX',
bgneal@64:               'ACFGHILMRSU',
bgneal@64:               'BCDEFJKLPS',
bgneal@64:               'EFGHIJLMNP'
bgneal@64:           ],
bgneal@64:           letter_check='QLRRN TPTFU TRPTN MWQTV JLIJE J')
bgneal@64: 
bgneal@64: Key list file I/O
bgneal@64: ~~~~~~~~~~~~~~~~~
bgneal@64: 
bgneal@64: Key lists can be stored in files in config file ("INI") style format using
bgneal@64: functions found in the ``m209.keylist.config`` module.
bgneal@64: 
bgneal@64: .. function:: m209.keylist.config.read_key_list(fname[, indicator=None])
bgneal@64: 
bgneal@64:     Reads key list information from the file given by ``fname``.
bgneal@64: 
bgneal@64:     Searches the config file for the key list with the given indicator. If
bgneal@64:     found, returns a :class:`~m209.keylist.KeyList` object. Returns ``None`` if
bgneal@64:     not found.
bgneal@64: 
bgneal@64:     If ``indicator`` is ``None``, a key list is chosen from the file at random.
bgneal@64: 
bgneal@64: .. function:: m209.keylist.config.write(fname, key_lists)
bgneal@64: 
bgneal@64:     Writes the key lists to the file named ``fname`` in config file format.
bgneal@64: 
bgneal@64:     ``key_lists`` must be an iterable of :class:`~m209.keylist.KeyList` objects.
bgneal@64: 
bgneal@64: Key list file format
bgneal@64: ++++++++++++++++++++
bgneal@64: 
bgneal@64: An example key list file in config file format is presented below. The label
bgneal@64: for each section of the file is the key list indicator.
bgneal@64: 
bgneal@64: ::
bgneal@64: 
bgneal@64:    [CA]
bgneal@64:    lugs = 0-5*5 0-6*2 1-0*7 1-2 1-3*3 1-6 2-0 3-0*3 3-5*2 3-6 4-5
bgneal@64:    wheel1 = ABCDFGHJLOPRVWYZ
bgneal@64:    wheel2 = BCDEIJKPQSUVX
bgneal@64:    wheel3 = ACDGLNQRSTUV
bgneal@64:    wheel4 = FGHIJNQRSU
bgneal@64:    wheel5 = DEIJOQS
bgneal@64:    wheel6 = BCDEILMNOP
bgneal@64:    check = RGPRO RTYOO TWYSN GXTPF PNWIH P
bgneal@64: 
bgneal@64:    [CD]
bgneal@64:    lugs = 0-4*4 0-5 1-0*7 1-2*2 1-4*3 2-0*2 2-4*2 2-6*2 3-0*4
bgneal@64:    wheel1 = AEFHIKMPQRSUVZ
bgneal@64:    wheel2 = ABFGHINORSUVZ
bgneal@64:    wheel3 = BDEHJKLMNOQRSU
bgneal@64:    wheel4 = CDEFGHJKMRU
bgneal@64:    wheel5 = FGHIJOQS
bgneal@64:    wheel6 = EGIJKLP
bgneal@64:    check = ZRLWL YRMIZ RZOPN UWMVZ DVGPM H
bgneal@64: 
bgneal@64: Generating key lists
bgneal@64: ~~~~~~~~~~~~~~~~~~~~
bgneal@64: 
bgneal@64: The ``m209`` library contains a function to pseudo-randomly generate a key list
bgneal@64: that is based on the procedure described in the 1944 M-209 manual.
bgneal@64: 
bgneal@64: .. function:: m209.keylist.generate.generate_key_list(indicator[, lug_selection=None, max_lug_attempts=MAX_LUG_ATTEMPTS, max_pin_attempts=MAX_PIN_ATTEMPTS])
bgneal@64: 
bgneal@64:    The only required parameter is ``indicator``, the two-letter indicator for
bgneal@64:    the key list.
bgneal@64: 
bgneal@64:    If successful, a :class:`~m209.keylist.KeyList` object is returned.
bgneal@64: 
bgneal@64:    If a :class:`~m209.keylist.KeyList` could not be generated
bgneal@64:    a ``KeyListGenError`` exception is raised.
bgneal@64: 
bgneal@64:    The algorithm is heuristic-based and makes random decisions based upon the
bgneal@64:    1944 procedure. The actual procedure is loosely specified in the manual, and
bgneal@64:    much is left up to the human operator. It is possible that the algorithm
bgneal@64:    cannot find a solution to meet the key list requirements specified in the
bgneal@64:    manual, in which case it simply tries again up to some set of limits. These
bgneal@64:    limits can be tweaked using the optional parameters to the algorithm. If no
bgneal@64:    solution is found after exhausting the limits, a ``KeyListGenError`` is
bgneal@64:    raised.
bgneal@64: 
bgneal@64:    The optional parameters are:
bgneal@64: 
bgneal@64:    * ``lug_selection`` - a list of 6 integers used to drive the lug settings
bgneal@64:      portion of the algorithm. If not supplied, a list of 6 integers is chosen
bgneal@64:      from data tables that appear in the 1944 manual. For more information on
bgneal@64:      the requirements for these integers, see the manual.
bgneal@64: 
bgneal@64:    * ``max_lug_attempts`` - the maximum number of times to attempt to create
bgneal@64:      lug settings before giving up
bgneal@64: 
bgneal@64:    * ``max_pin_attempts`` - the maximum number of times to attempt to generate
bgneal@64:      key wheel pin settings before giving up
bgneal@64: