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|
import string
class EBNF:
IDENT = 0
LITERAL = 2
LPAREN = 3
LBRAK = 4
LBRACE = 5
BAR = 6
EQL = 7
RPAREN = 8
RBRAK = 9
RBRACE = 10
PERIOD = 11
OTHER = 12
__input__ = None
__char__ = None
__symbol__ = None
__data__ = None
def __init__(self, input):
self.__input__ = input
self.__get_char__()
def __get_char__(self):
self.__char__ = self.__input__.read(1)
if self.__char__ == '':
raise EOFError
return self.__char__
def __get_sym__(self):
self.__data__ = None
while self.__char__ in string.whitespace:
self.__get_char__()
if self.__char__ in string.letters + "_":
self.__symbol__ = self.IDENT
self.__data__ = self.__char__
while self.__get_char__() in string.letters + "_":
self.__data__ += self.__char__
return
elif self.__char__ == '"':
self.__symbol__ = self.LITERAL
self.__data__ = ""
while self.__get_char__() != '"':
self.__data__ += self.__char__
elif self.__char__ == '=':
self.__symbol__ = self.EQL
elif self.__char__ == '(':
self.__symbol__ = self.LPAREN
elif self.__char__ == ')':
self.__symbol__ = self.RPAREN
elif self.__char__ == '[':
self.__symbol__ = self.LBRAK
elif self.__char__ == ']':
self.__symbol__ = self.RBRAK
elif self.__char__ == '{':
self.__symbol__ = self.LBRACE
elif self.__char__ == '}':
self.__symbol__ = self.RBRACE
elif self.__char__ == '|':
self.__symbol__ = self.BAR
elif self.__char__ == '.':
self.__symbol__ = self.PERIOD
else:
self.__symbol__ = self.OTHER
self.__get_char__()
def __error__(self, num):
pos = self.__input__.tell()
if pos > self.__lastpos__ + 2:
print "ERROR: pos=%d, err=%d, sym=%d" % (pos, num, self.__symbol__)
self.__lastpos__ = pos
def __expression__(self):
self.__term__()
while self.__symbol__ == self.BAR:
self.__get_sym__()
self.__term__()
def __term__(self):
self.__factor__()
while self.__symbol__ < self.BAR:
self.__factor__()
def __factor__(self):
if self.__symbol__ == self.IDENT:
print "record(TO, '%s', 1)" % (self.__data__,)
self.__get_sym__()
elif self.__symbol__ == self.LITERAL:
print "record(T1, '%s', 0)" % (self.__data__,)
self.__get_sym__()
elif self.__symbol__ == self.LPAREN:
self.__get_sym__()
self.__expression__()
if self.__symbol__ == self.RPAREN:
self.__get_sym__()
else:
self.__error__(2)
elif self.__symbol__ == self.LBRAK:
self.__get_sym__()
self.__expression__()
if self.__symbol__ == self.RBRAK:
self.__get_sym__()
else:
self.__error__(3)
elif self.__symbol__ == self.LBRACE:
self.__get_sym__()
self.__expression__()
if self.__symbol__ == self.RBRACE:
self.__get_sym__()
else:
self.__error__(4)
else:
self.__error__(5)
def __production__(self):
self.__get_sym__()
if self.__symbol__ == self.EQL:
self.__get_sym__()
else:
self.__error__(7)
self.__expression__()
if self.__symbol__ == self.PERIOD:
self.__get_sym__()
else:
self.__error__(8)
def __syntax__(self):
while self.__symbol__ == self.IDENT:
self.__production__()
def compile(self):
try:
self.__lastpos__ = 0
self.__get_sym__()
self.__syntax__()
except EOFError:
return
if __name__ == '__main__':
import sys
ebnf = EBNF(sys.stdin)
ebnf.compile()
|
