Boolean text which returns a list prepared for a binary tree structure.

boolean_parser.py

def parse(expr):

    expr = expr.replace('(', ' ( ').replace(')', ' ) ')
    brac_just_opened = False

    def _listify(iter):
        nonlocal brac_just_opened
        items = []
        for item in iter:
            if item == '(':
                brac_just_opened = True
                result, closeparen = _listify(iter)
                items.append(result)
            elif item == ')':
                if len(items) == 1:
                    return items[0], True
                else:
                    return items, True
            elif item == 'NOT':
                if brac_just_opened:
                    result, closeparen = _listify(iter)
                    items.append(['NOT', result])
                else:
                    result, closeparen = _listify(iter)
                    items.extend(['NOT', result])
            else:
                items.append(item)
        if len(items) == 1:
            return items[0], False
        else:
            return items, False

    listified_expr = _listify(iter(expr.split()))[0]

    def _prefixify(lst):
        if len(lst) > 1:
            if len(lst) == 2:
                return lst
            if len(lst) % 2 == 1:
                odds = lst[1::2]
                if odds.count(odds[0]) == len(odds):
                    return [odds[0]] + lst[0::2]
                else:
                    return 'ERROR'

    def _convert_to_prefix_notation(lst):
        res = []
        prefix_lst = _prefixify(lst)
        list_idxs = [i for i in range(len(prefix_lst)) if isinstance(prefix_lst[i], list)]
        if len(list_idxs) > 0:
            for i in range(len(prefix_lst)):
                if i in list_idxs:
                    res.append(_convert_to_prefix_notation(prefix_lst[i]))
                else:
                    res.append(prefix_lst[i])
                if i == len(prefix_lst) - 1:
                    return res
        else:
            return prefix_lst

    if isinstance(listified_expr, list):
        return _convert_to_prefix_notation(listified_expr)
    else:
        return [listified_expr]