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Using the author's Scan instance for parsing
an input stream, this static method looks for a simple or
compound bird code.
# - - - B i r d I d . s c a n - - -
def scan ( txny, scan ):
"""Scan a simple or compound bird code.
"""
First we check to see if the beginning of the line
matches the regular expression RE_ABBR.
If not, we can fail right away.
#-- 1 --
# [ if scan starts with a simple bird code ->
# scan := scan advanced past matching characters
# abbr := matching characters
# rel := None
# abbr2 := None
# else ->
# scan +:= error message
# raise ValueError ]
abbr = BirdId.scanAbbr ( txny, scan )
rel = abbr2 = None
If the next character is a relationship code, it must be followed by a second simple bird code.
#-- 2 --
# [ if scan starts with a relationship code followed by
# a valid simple bird code ->
# scan := scan advanced past all that
# rel := the relationship code
# abbr2 := the simple bird code
# else if scan starts with a relationship code not
# followed by a valid simple bird code ->
# scan +:= error message
# raise ValueError
# else -> I ]
m = scan.tabReMatch ( RE_REL )
if m is not None:
#-- 2.1 --
# [ if scan starts with a valid simple bird code ->
# rel := matched string from m
# scan := scan advanced past the bird code
# else ->
# scan +:= error message
# raise ValueError ]
rel = m.group()
abbr2 = BirdId.scanAbbr ( txny, scan )
The next character may be "?"; in that case set
the q attribute to that string.
#-- 3 --
# [ if scan starts with "?" ->
# scan := scan advanced 1
# q := "?"
# else ->
# q := "" ]
if scan.tabMatch ( "?" ):
q = "?"
else:
q = ""
Finally we bundle all the parts together as a BirdId instance.
#-- 4 --
return BirdId ( txny, abbr, rel, abbr2, q )
The next line is necessary to make this method static.
scan = staticmethod(scan)