Source code for pm4py.objects.process_tree.utils.regex

'''
    PM4Py – A Process Mining Library for Python
Copyright (C) 2024 Process Intelligence Solutions UG (haftungsbeschränkt)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see this software project's root or
visit <https://www.gnu.org/licenses/>.

Website: https://processintelligence.solutions
Contact: info@processintelligence.solutions
'''
from pm4py.objects.process_tree import obj as pt_operator
from pm4py.util.regex import SharedObj, get_new_char

from pm4py.util import constants
import warnings

if constants.SHOW_INTERNAL_WARNINGS:
    warnings.warn("The regex package will be removed in a future release.")




def pt_to_regex(tree, rec_depth=0, shared_obj=None, parameters=None):
    """
    Transforms a process tree to a regular expression

    NB: The conversion is not yet working with trees containing an AND and/or an OR operator!

    Parameters
    ------------
    tree
        Process tree
    parameters
        Possible parameters of the algorithm
    """
    if parameters is None:
        parameters = {}

    if shared_obj is None:
        shared_obj = SharedObj()

    stru = ""

    if tree.operator is not None:
        contains_tau = (
            len(
                list(
                    child
                    for child in tree.children
                    if child.operator is None and child.label is None
                )
            )
            > 0
        )
        children_rep = []
        for child in tree.children:
            rep, shared_obj = pt_to_regex(
                child,
                rec_depth=rec_depth + 1,
                shared_obj=shared_obj,
                parameters=parameters,
            )
            children_rep.append(rep)
        if tree.operator == pt_operator.Operator.SEQUENCE:
            children_rep = [x for x in children_rep if x is not None]
            stru = "(" + "".join(children_rep) + ")"
        elif tree.operator == pt_operator.Operator.XOR:
            children_rep = [x for x in children_rep if x is not None]
            stru = "(" + "|".join(children_rep) + ")"
            if contains_tau:
                stru = "(" + stru + "?)"
        elif tree.operator == pt_operator.Operator.LOOP:
            children_rep = [x for x in children_rep if x is not None]
            if len(children_rep) == 1:
                stru = "(" + children_rep[0] + ")+"
            else:
                stru = "(" + "".join(children_rep) + ")*" + children_rep[0]
        elif tree.operator == pt_operator.Operator.PARALLEL:
            raise Exception(
                "the conversion is not yet working with trees containing an AND and/or an OR operator!"
            )
        elif tree.operator == pt_operator.Operator.OR:
            raise Exception(
                "the conversion is not yet working with trees containing an AND and/or an OR operator!"
            )

    elif tree.label is not None:
        if tree.label not in shared_obj.mapping_dictio:
            get_new_char(tree.label, shared_obj)
        stru = shared_obj.mapping_dictio[tree.label]
    elif tree.label is None:
        return None, shared_obj

    if rec_depth == 0:
        ret = "^" + stru + "$", shared_obj.mapping_dictio
        # print(ret)
        return ret

    return stru, shared_obj