formparse package¶

Submodules¶

formparse.formula module¶

Formula that can be parsed and evaluated

class formparse.formula.Formula(formula: str)[source]¶

Bases: object

Simple formula, generated from a string input can it be evaluated with it .eval()`method. The currently supported operators are `+, -, * and /.

BIN_OPERATORS = {<class '_ast.Add'>: <built-in function add>, <class '_ast.Sub'>: <built-in function sub>, <class '_ast.Mult'>: <built-in function mul>, <class '_ast.Div'>: <built-in function truediv>, <class '_ast.Pow'>: <built-in function pow>}¶

EVALUATORS = {<class '_ast.Expression'>: '_eval_expression', <class '_ast.Constant'>: '_eval_constant', <class '_ast.Name'>: '_eval_name', <class '_ast.BinOp'>: '_eval_binop', <class '_ast.UnaryOp'>: '_eval_unaryop', <class '_ast.Call'>: '_eval_call'}¶

FUNCTIONS = {'abs': <built-in function abs>, 'max': <built-in function max>, 'min': <built-in function min>}¶

MAX_FORMULA_LENGTH = 255¶: Maximum length accepted for the formula, as is (incl. whitespaces, etc.)

MAX_RESULT_POTENCY = 18¶: Maximum maximum power of ten that is allowed for a expected result.

UN_OPERATORS = {<class '_ast.USub'>: <built-in function neg>}¶

classmethod estimate_result_size(node, args: dict | None = None) → int[source]¶

Estimate the result size based one the power of tens of its operands.

A more indepth explanation will follow.

Parameters:

node (ast.AST) – Node to estimate result size for.
args (Optional[dict], optional) – Parameters provided for
evaluation –
provided (if not) –
assigned (each variable is) –
None. (potency of 1. Defaults to) –

Raises:

FormulaComplexityError – If calculating the result size itself
is to expensive. –

Returns:

The maximum power to ten of the result.

Return type:

int

eval(args: dict | None = None) → float[source]¶

Evaluate the formula for a set if given arguments

Parameters:

args (Optional[dict], optional) – A dictionary with the arguments. Defaults to {}.

Raises:

FormulaRuntimeError – If the arguments are not a dictionary.
FormulaRuntimeError – If the evaluation fails for any other reason.

Returns:

The value of the result.

Return type:

float

classmethod parse_formula(formula: str) → AST[source]¶

Parse a given formula into an ast node.

Parameters:: formula (str) – Formula to parse.
Returns:: Parsed node.
Return type:: ast.AST

classmethod validate(node: AST) → Tuple[bool, str][source]¶

Check whether or not formula provided in node is valid.

NOTE: Formula.validate() does not check for length constraint but just for general validity. :param node: Formula to check, either as str or parsed ast Tree. :type node: ast.AST | str