start from first page if previous container is empty

src/ssiv/widget/container.py

@@ -17,6 +17,13 @@ from ..co import OrderedDict
 
 __all__=['Containers']
 
+def _relocate(lst,pos,step):
+    # change from current position with step from pos in lst, return new position
+    assert isinstance(step,int)
+    if not (lst and step):return 0
+    pos+=step
+    return min(max(0,pos),len(lst)-1)
+
 class Containers(OrderedDict):
 
     __slots__=(
@@ -42,13 +49,6 @@ class Containers(OrderedDict):
             filenames.sort(key=self.sortkey,reverse=self.revsort)
         self._fnpos=self[container].index(filename)
 
-    def _relocate(self,lst,pos,step):
-        # change from current position with step from pos in lst, return new position
-        assert isinstance(step,int)
-        if not step:return
-        pos+=step
-        return min(max(0,pos),len(lst)-1)
-
     @property
     def sortkey(self):
         # 'key' argument that used in sorting filenames
@@ -106,13 +106,12 @@ class Containers(OrderedDict):
         assert isinstance(step,int)
         if not step:return
         oldpos=self._fnpos
-        while True:
-            try:
-                self._fnpos=self._relocate(self.getvalue(self._pos),self._fnpos,step)
-                break
-            except IndexError:
-                if not self.cross(-1):
-                    return False
+        try:
+            filenames=self.getvalue(self._pos)
+        except IndexError:
+            return self.cross(-1)
+        else:
+            self._fnpos=_relocate(filenames,self._fnpos,step)
         return self._fnpos!=oldpos
 
     def cross(self,step=1,/):