29 lines
702 B
Python
29 lines
702 B
Python
#!/usr/bin/env python3
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"""calc CLI — evaluate an arithmetic expression given as a single argument."""
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import sys
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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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expr = sys.argv[1]
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try:
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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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tokens = tokenize(expr)
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ast = parse(tokens)
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result = evaluate(ast)
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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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