`AND` statements not flattened in dedup()

[AyanSinhaMahapatra]

For example licensing.dedup() should have simplified the following expression:

(gpl AND mit) AND mit AND (gpl OR mit) -> gpl AND mit AND (gpl OR mit)

But currently it does not flatten AND statements in parenthesis, but it should.

This can be done either by:

1. licensing.dedup(str(expression.flatten())) (?)
2. By replacing OR statements by one symbol, simplifying and then getting the OR statements back by using substitution tables.

[stefan6419846]

I recently stumbled upon this as well when investigating #124. Has there been any progress on this?

licensing.dedup(str(expression.flatten()))

This only works partially when the base expression is AND or OR. Additionally, it does not resolve for nested setups as far as I could tell from some basic testing.

The following snippet seems to work for nested expressions:

def flatten_expression(expression: LicenseExpression) -> LicenseExpression:
    if isinstance(expression, (AND, OR)):
        flat_arguments = [flatten_expression(argument) for argument in expression.args]
        expression_cls = type(expression)
        return expression_cls(*flat_arguments).flatten()

    return expression