unwarper: remove an obsolete functionality for a block splitting

ljd/ast/unwarper.py

@@ -238,15 +238,16 @@ def _split_by_slot_use(statements, min_i, warp, slot):
 	split_i = min_i
 
 	for i, statement in enumerate(statements):
-		sets, _uses = _extract_statement_slots(statement)
+		if isinstance(statement, nodes.Assignment):
+			sets = _extract_destination_slots(statement)
 
-		if i < min_i:
-			known_slots |= sets
-		else:
-			known_slots -= sets
+			if i < min_i:
+				known_slots |= sets
+			else:
+				known_slots -= sets
 
-		if len(known_slots) == 0:
-			break
+			if len(known_slots) == 0:
+				break
 
 		split_i = i + 1
 
@@ -262,33 +263,17 @@ def _split_by_slot_use(statements, min_i, warp, slot):
 	return split_i
 
 
-def _extract_statement_slots(statement):
+def _extract_destination_slots(statement):
 	sets = set()
-	uses = set()
 
-	if isinstance(statement, nodes.Assignment):
-		for node in statement.destinations.contents:
-			if isinstance(node, nodes.Identifier):
-				if node.type == nodes.Identifier.T_SLOT:
-					sets.add(node.slot)
-			else:
-				# Anything else is a use action, not a set action
-				uses.update(_gather_slots(node))
-
-		uses.update(_gather_slots(statement.expressions))
-	elif isinstance(statement, (nodes.IteratorFor, nodes.NumericFor)):
-		uses = _gather_slots(statement.expressions)
-	elif isinstance(statement, nodes.Return):
-		uses = _gather_slots(statement.returns)
-	elif isinstance(statement, nodes.BlackHole):
-		uses = _gather_slots(statement.contents)
-	elif isinstance(statement, nodes.FunctionCall):
-		uses = _gather_slots(statement.arguments)
-		uses.update(_gather_slots(statement.function))
-	elif isinstance(statement, nodes.While):
-		uses = _gather_slots(statement.expression)
-
-	return sets, uses
+	for node in statement.destinations.contents:
+		if not isinstance(node, nodes.Identifier):
+			continue
+
+		if node.type == nodes.Identifier.T_SLOT:
+			sets.add(node.slot)
+
+	return sets
 
 
 def _gather_slots(node):