35 lines
1005 B
Python
35 lines
1005 B
Python
from calc.parser import Num, BinOp, Unary, Node
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class EvalError(Exception):
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pass
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def evaluate(node: 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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v = evaluate(node.operand)
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if node.op == '-':
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return -v
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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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l = evaluate(node.left)
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r = evaluate(node.right)
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if node.op == '+':
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result = l + r
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elif node.op == '-':
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result = l - r
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elif node.op == '*':
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result = l * r
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elif node.op == '/':
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if r == 0:
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raise EvalError("division by zero")
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result = l / r
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else:
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raise EvalError(f"unknown binary op {node.op!r}")
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if isinstance(result, float) and result == int(result):
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return int(result)
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return result
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raise EvalError(f"unknown node type {type(node)!r}")
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