From 72042fc36f503894741ea4086bb89076b58542dc Mon Sep 17 00:00:00 2001
From: Walter Bender <walter.bender@gmail.com>
Date: Mon, 09 Jul 2012 21:13:32 +0000
Subject: fix problem with nested while loops

---
diff --git a/TurtleArt/tabasics.py b/TurtleArt/tabasics.py
index 06b8d1c..56a2fd1 100644
--- a/TurtleArt/tabasics.py
+++ b/TurtleArt/tabasics.py
@@ -785,6 +785,7 @@ boolean operators from Numbers palette'))
                           help_string=_('if-then-else operator that uses \
 boolean operators from Numbers palette'))
 
+        # Deprecated
         palette.add_block('hspace',
                           style='flow-style-tail',
                           hidden=True,
diff --git a/TurtleArt/tablock.py b/TurtleArt/tablock.py
index 7e48d43..dd1ac04 100644
--- a/TurtleArt/tablock.py
+++ b/TurtleArt/tablock.py
@@ -49,6 +49,12 @@ class Blocks:
         else:
             return(self.list[i])
 
+    def swap(self, blk1, blk2):
+        i1 = self.list.index(blk1)
+        i2 = self.list.index(blk2)
+        self.list[i1] = blk2
+        self.list[i2] = blk1
+
     def length_of_list(self):
         return(len(self.list))
 
diff --git a/TurtleArt/talogo.py b/TurtleArt/talogo.py
index 3e8fb0f..8d957bc 100644
--- a/TurtleArt/talogo.py
+++ b/TurtleArt/talogo.py
@@ -803,8 +803,6 @@ class LogoCode:
         # into trouble if any of these block types (forever, while,
         # until. ifelse, stopstack, or stack) is changed in tablock.py
 
-        # TODO: Detect nesting, e.g., forever while
-
         if b.name == 'while':
             while_blk = True
         else:
@@ -819,7 +817,7 @@ class LogoCode:
             self.save_blocks = blocks[:]
 
         # Create an action block that will jump to the new stack
-        action_name = '#s_forever %d' % (len(self.save_while_blks) + 1)
+        action_name = '_forever %d' % (len(self.save_while_blks) + 1)
         action_blk = HiddenBlock('stack')
         action_label_blk = HiddenBlock('string', value=action_name)
 
@@ -841,7 +839,7 @@ class LogoCode:
 
         # Create action block(s) to run the code inside the forever loop
         if until_blk and whileflow is not None:  # run until flow at least once
-            action_flow_name = '#s_flow %d' % (len(self.save_while_blks) + 1)
+            action_flow_name = '_flow %d' % (len(self.save_while_blks) + 1)
             action_first = HiddenBlock('stack')
             first_label_blk = HiddenBlock('string', value=action_flow_name)
 
diff --git a/TurtleArt/tautils.py b/TurtleArt/tautils.py
index bd7309f..676c4ca 100644
--- a/TurtleArt/tautils.py
+++ b/TurtleArt/tautils.py
@@ -657,13 +657,15 @@ def find_group(blk):
     return group
 
 
-def find_blk_below(blk, name):
+def find_blk_below(blk, namelist):
     ''' Find a specific block below this block. '''
     if blk == None or len(blk.connections) == 0:
         return
+    if type(namelist) != list:
+        namelist = [namelist]
     group = find_group(blk)
     for gblk in group:
-        if gblk.name == name:
+        if gblk.name in namelist:
             return gblk
     return None
 
diff --git a/TurtleArt/tawindow.py b/TurtleArt/tawindow.py
index d187580..ad0f0db 100644
--- a/TurtleArt/tawindow.py
+++ b/TurtleArt/tawindow.py
@@ -2592,12 +2592,39 @@ class TurtleArtWindow():
         # If we are in an expandable flow, expand it...
         if best_destination is not None:
             self._resize_parent_clamps(best_destination)
-            '''
-            blk, dockn = self._expandable_flow_above(best_destination)
-            while blk is not None:
-                self._resize_clamp(blk, blk.connections[dockn], dockn=dockn)
-                blk, dockn = self._expandable_flow_above(blk)
-            '''
+        # Check for while nesting
+        if best_destination is not None:
+            while_blk = self._while_in_drag_group(self.drag_group[0])
+            if while_blk is not None:
+                self._check_while_nesting(best_destination,
+                                          self.drag_group[0], while_blk)
+
+    def _while_in_drag_group(self, blk):
+        ''' Is there a contained while or until block? '''
+        if blk.name in ['while', 'until']:
+            return blk
+        return find_blk_below(blk, ['while', 'until'])
+
+    def _check_while_nesting(self, blk, dock_blk, while_blk):
+        ''' Is there a containing while or until block? If so, swap them '''
+        if blk.name in ['while', 'until']:
+            if blk.connections[2] == dock_blk:
+                self._swap_while_blocks(blk, while_blk)
+        while blk.connections[-1] is not None:
+            blk = blk.connections[-1]
+            if blk.name in ['while', 'until']:
+                if blk.connections[2] == dock_blk:
+                    self._swap_while_blocks(blk, while_blk)
+            dock_blk = blk
+
+    def _swap_while_blocks(self, blk1, blk2):
+        ''' Swap postion in block list of nested while blocks '''
+        # Check to see if blk1 comes before blk2 in the block list.
+        # If so, swap them.
+        i1 = self.just_blocks().index(blk1)
+        i2 = self.just_blocks().index(blk2)
+        if i1 < i2:
+            self.block_list.swap(blk1, blk2)
 
     def _disconnect(self, blk):
         ''' Disconnect block from stack above it. '''
--
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