Spaces:
Sleeping
Sleeping
| import ast | |
| import operator | |
| from typing import Any, Dict | |
| _ALLOWED_OPERATORS = { | |
| ast.Add: operator.add, | |
| ast.Sub: operator.sub, | |
| ast.Mult: operator.mul, | |
| ast.Div: operator.truediv, | |
| ast.FloorDiv: operator.floordiv, | |
| ast.Mod: operator.mod, | |
| ast.Pow: operator.pow, | |
| ast.USub: operator.neg, | |
| ast.UAdd: operator.pos, | |
| } | |
| def _evaluate(node: ast.AST) -> float: | |
| if isinstance(node, ast.Expression): | |
| return _evaluate(node.body) | |
| if isinstance(node, ast.Constant): | |
| if isinstance(node.value, (int, float)): | |
| return node.value | |
| raise ValueError("Only numeric constants are allowed.") | |
| if isinstance(node, ast.BinOp): | |
| operator_type = type(node.op) | |
| if operator_type not in _ALLOWED_OPERATORS: | |
| raise ValueError( | |
| f"Operator {operator_type.__name__} is not allowed." | |
| ) | |
| left = _evaluate(node.left) | |
| right = _evaluate(node.right) | |
| return _ALLOWED_OPERATORS[operator_type](left, right) | |
| if isinstance(node, ast.UnaryOp): | |
| operator_type = type(node.op) | |
| if operator_type not in _ALLOWED_OPERATORS: | |
| raise ValueError( | |
| f"Operator {operator_type.__name__} is not allowed." | |
| ) | |
| value = _evaluate(node.operand) | |
| return _ALLOWED_OPERATORS[operator_type](value) | |
| raise ValueError( | |
| f"Unsupported expression element: {type(node).__name__}" | |
| ) | |
| def calculator(expression: str) -> Dict[str, Any]: | |
| """ | |
| Safely evaluate a basic mathematical expression. | |
| Supported operations: | |
| +, -, *, /, //, %, **, unary +, unary - | |
| """ | |
| if not isinstance(expression, str): | |
| raise TypeError("expression must be a string.") | |
| expression = expression.strip() | |
| if not expression: | |
| raise ValueError("expression cannot be empty.") | |
| if len(expression) > 200: | |
| raise ValueError("expression is too long.") | |
| try: | |
| parsed = ast.parse(expression, mode="eval") | |
| result = _evaluate(parsed) | |
| except ZeroDivisionError as exc: | |
| raise ValueError("Division by zero is not allowed.") from exc | |
| except SyntaxError as exc: | |
| raise ValueError("Invalid mathematical expression.") from exc | |
| return { | |
| "expression": expression, | |
| "result": result, | |
| } |