Parses a disposition code from a tail. We can use the regular
fixed-field DispositionField.scan() method; the
disposition code is always exactly one character.
See Section 69.1, “DispositionField.scanField()”.
# - - - B a s e E n c o u n t e r . t a i l D i s p o s i t i o n
def tailDisposition(self, scan):
'''Parse a disposition code in a tail field.
[ scan is a Scan object ->
if scan starts with a disposition code ->
scan := scan advanced past that code
self.(DISPOSITION_ATTR) := a Disposition object
representing that code
else ->
Log() +:= error message(s)
raise SyntaxError ]
'''
DispositionField.scanField(self, scan, DISPOSITION_ATTR)