Merge branch '212-process-tree-to-powl-converter-utility' into 'integration'

[priority 2] Process tree to POWL converter utility

Closes #212

See merge request process-mining/pm4py/pm4py-core!1212

Author: fit-humam-kourani

pm4py/objects/conversion/process_tree/converter.py

@@ -1,6 +1,7 @@
 from pm4py.objects.conversion.process_tree.variants import to_petri_net
 from pm4py.objects.conversion.process_tree.variants import to_petri_net_transition_bordered
 from pm4py.objects.conversion.process_tree.variants import to_bpmn
+from pm4py.objects.conversion.process_tree.variants import to_powl
 from pm4py.util import exec_utils
 from enum import Enum
 
@@ -9,6 +10,7 @@ class Variants(Enum):
     TO_PETRI_NET = to_petri_net
     TO_PETRI_NET_TRANSITION_BORDERED = to_petri_net_transition_bordered
     TO_BPMN = to_bpmn
+    TO_POWL = to_powl
 
 
 def apply(tree, parameters=None, variant=Variants.TO_PETRI_NET):

pm4py/objects/conversion/process_tree/variants/to_powl.py

@@ -0,0 +1,53 @@
+from pm4py.objects.process_tree.obj import ProcessTree, Operator as PTOperator
+from pm4py.objects.powl.obj import POWL, StrictPartialOrder, OperatorPOWL, Transition, SilentTransition
+from typing import Optional, Dict, Any
+
+
+def apply_recursive(tree: ProcessTree, rec_depth=0) -> POWL:
+    """
+    Internal method
+    """
+    nodes = []
+
+    for c in tree.children:
+        nodes.append(apply_recursive(c, rec_depth+1))
+
+    if tree.operator is None:
+        if tree.label is not None:
+            powl = Transition(label=tree.label)
+        else:
+            powl = SilentTransition()
+    elif tree.operator == PTOperator.OR:
+        raise Exception("conversion of process trees containing OR nodes is not supported!")
+    elif tree.operator == PTOperator.XOR:
+        powl = OperatorPOWL(PTOperator.XOR, nodes)
+    elif tree.operator == PTOperator.LOOP:
+        powl = OperatorPOWL(PTOperator.LOOP, nodes)
+    else:
+        powl = StrictPartialOrder(nodes=nodes)
+
+    if tree.operator == PTOperator.SEQUENCE:
+        for i in range(len(nodes)-1):
+            powl.order.add_edge(nodes[i], nodes[i+1])
+
+    return powl
+
+
+def apply(tree: ProcessTree, parameters: Optional[Dict[Any, Any]] = None) -> POWL:
+    """
+    Converts a process tree model to a POWL model
+
+    Parameters
+    ---------------
+    tree
+        Process tree
+
+    Returns
+    ---------------
+    powl_model
+        POWL model
+    """
+    if parameters is None:
+        parameters = {}
+
+    return apply_recursive(tree)