38 lines
1,009 B
Python
38 lines
1,009 B
Python
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class Parser(object):
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def __init__(self, tokens):
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self.tokens = tokens
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self.i = 0
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def prev(self):
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return self.tokens[self.i - 1]
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def curr(self):
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return self.tokens[self.i]
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def next(self):
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return self.tokens[self.i + 1]
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def consume(self):
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if not self.exhausted():
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self.i += 1
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return self.prev()
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def match(self, xs):
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if not self.exhausted() and self.curr() in xs:
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self.consume()
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return True
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return False
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def expect(self, xs):
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if not self.match(xs):
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raise Exception("Expected token \"{}\" but received \"{}\"".format(xs, self.curr()))
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return self.prev()
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def expect_predicate(self, predicate):
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if predicate(self.curr()):
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return self.consume()
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raise Exception("Expected token \"{}\" to pass predicate, but it did not".format(self.curr()))
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def exhausted(self):
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return self.i >= len(self.tokens)
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