24 lines
609 B
Python
24 lines
609 B
Python
#!/usr/bin/env python3
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"""calc — evaluate an arithmetic expression from the command line."""
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import sys
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from calc.lexer import LexError, tokenize
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from calc.parser import ParseError, parse
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from calc.evaluator import EvalError, evaluate
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def main():
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if len(sys.argv) != 2:
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print("usage: calc.py <expression>", file=sys.stderr)
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sys.exit(1)
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try:
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result = evaluate(parse(tokenize(sys.argv[1])))
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print(result)
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except (LexError, ParseError, EvalError) as exc:
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print(f"error: {exc}", file=sys.stderr)
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sys.exit(1)
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if __name__ == "__main__":
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main()
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