Use existing constant-related functions

RASP_support/DrawCompFlow.py

@@ -465,10 +465,10 @@ def __init__(self, depth, d_heads, d_ffs, add_tokens_on_ff=False):
 		ff_parents = list(set(ff_parents))
 		ff_parents = [p for p in ff_parents if not guarded_contains(d_ffs, p)]
 		# in the trivial case (no parents and only one ff), the ff is marked as
-		# constant
-		if not ff_parents and len(d_ffs) == 1 and d_ffs[0]._constant:
-			# switch the parents and ffs to label the trivial ff as 'X'
-			ff_parents, d_ffs = d_ffs, ff_parents
+		# constant and should be labelled as 'X'
+		for x in [ff for ff in d_ffs if ff.is_constant()]:
+			d_ffs.remove(x)
+			ff_parents.append(x)
 		rows_by_type = {RES: d_ffs, VVAR: ff_parents}
 		rowtype_order = [VVAR, RES]
 		if add_tokens_on_ff and not contains_tokens(ff_parents):

RASP_support/analyse.py

@@ -186,9 +186,9 @@ def __init__(self, select, sequences, comp_depth):
 		# filter out non-ffs in the non-trivial case
 		all_ffs = [m for m in all_ffs if m.from_zipmap]
 	else:
-		# mark the sequence as constant (indices / tokens) in the trivial case
+		# mark the sequence as constant in the case of trivial indices or tokens
 		for ff in all_ffs:
-			ff._constant = True
+			ff.mark_as_constant()
 	if remove_minors:
 		all_ffs = [ff for ff in all_ffs if not ff.is_minor]