Fixing constraint problem with next()/previous() (#26)

formats/folia.py

@@ -2135,6 +2135,7 @@ def next(self, Class=True, scope=True, reverse=False):
                 returnnext = False
                 for e in order(parent):
                     if e is child:
+                        #we found the current item, next item will be the one to return
                         returnnext = True
                     elif returnnext and e.auth and not isinstance(e,AbstractAnnotationLayer) and (not structural or (structural and (not isinstance(e,(AbstractTokenAnnotation,TextContent)) ) )):
                         if structural and isinstance(e,Correction):
@@ -2159,7 +2160,7 @@ def next(self, Class=True, scope=True, reverse=False):
 
             #generational iteration
             child = parent
-            if scope is not None and child in scope:
+            if scope is not None and child.__class__ in scope:
                 #you shall not pass!
                 break
             parent = parent.parent

tests/folia.py

@@ -506,6 +506,12 @@ def test021b_previousword_noscope(self):
         self.assertTrue( isinstance(prevw, folia.Word) )
         self.assertEqual( prevw.text(),  "." )
 
+    def test021c_previousword_constrained(self):
+        """Sanity Check - Obtaining non-existing previous word with scope constraint"""
+        w = self.doc['WR-P-E-J-0000000001.p.1.s.4.w.1']
+        prevw = w.previous(folia.Word, [folia.Sentence])
+        self.assertEqual(prevw, None)
+
     def test022_nextword(self):
         """Sanity Check - Obtaining next word"""
         w = self.doc['WR-P-E-J-0000000001.p.1.s.2.w.7']