37 lines
1.1 KiB
Python
37 lines
1.1 KiB
Python
from calc.parser import Num, BinOp, Unary
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class EvalError(Exception):
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pass
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def evaluate(node) -> "int | float":
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if isinstance(node, Num):
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return node.value
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if isinstance(node, Unary):
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if node.op == '-':
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return -evaluate(node.operand)
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raise EvalError(f"unknown unary op: {node.op!r}")
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if isinstance(node, BinOp):
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left = evaluate(node.left)
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right = evaluate(node.right)
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if node.op == '+':
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return left + right
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if node.op == '-':
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return left - right
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if node.op == '*':
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return left * right
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if node.op == '/':
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if right == 0:
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raise EvalError("division by zero")
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return left / right
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raise EvalError(f"unknown binary op: {node.op!r}")
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raise EvalError(f"unknown node type: {type(node).__name__}")
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def format_result(value) -> str:
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"""Whole-valued results print without .0; non-whole as float."""
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if isinstance(value, float) and value == int(value):
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return str(int(value))
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return str(value)
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