23 lines
610 B
Python
23 lines
610 B
Python
"""calc.py — command-line calculator: string → tokens → AST → number."""
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import sys
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from calc.lexer import tokenize, LexError
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from calc.parser import parse, ParseError
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from calc.evaluator import evaluate, EvalError
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def main() -> None:
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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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expr = sys.argv[1]
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try:
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result = evaluate(parse(tokenize(expr)))
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except (LexError, ParseError, EvalError) as e:
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print(f"error: {e}", file=sys.stderr)
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sys.exit(1)
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print(result)
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if __name__ == "__main__":
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main()
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