7770ccf0e3
...alongside a small REPL to quickly test the functionality. Change-Id: I3c2b3f060d82cd49488e00dec9b72f7b23e2b666 Reviewed-on: https://cl.tvl.fyi/c/depot/+/5337 Reviewed-by: wpcarro <wpcarro@gmail.com> Autosubmit: wpcarro <wpcarro@gmail.com> Tested-by: BuildkiteCI
27 lines
661 B
Python
27 lines
661 B
Python
# According to Crafting Interpreters, the only two primitives that a
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# scanner/lexer needs are peek and advance; other functions (e.g. match) are
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# nice-to-haves.
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class Scanner(object):
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def __init__(self, source):
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self.i = 0
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self.source = source
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def exhausted(self):
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return self.i >= len(self.source)
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def peek(self, n=0):
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return self.source[self.i + n] if self.i + n < len(self.source) else '\0'
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def advance(self):
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result = self.peek()
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self.i += 1
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return result
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def match(self, x):
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if self.exhausted():
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return False
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if self.peek() == x:
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self.advance()
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return True
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else:
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return False
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