Introduce splaytree.KeyNotFoundError and use it for reporting

issues when removing non-existing nodes from a SplayTree.
Review URL: http://codereview.chromium.org/42599

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1609 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/splaytree.py

@@ -36,6 +36,13 @@ class Node(object):
     self.right = None
 
 
+class KeyNotFoundError(Exception):
+  """KeyNotFoundError is raised when removing a non-existing node."""
+
+  def __init__(self, key):
+    self.key = key
+
+
 class SplayTree(object):
   """The splay tree itself is just a reference to the root of the tree."""
 
@@ -75,12 +82,12 @@ class SplayTree(object):
     """Remove the node with the given key from the SplayTree."""
     # Raise exception for key that is not found if the tree is empty.
     if self.IsEmpty():
-      raise Exception('KeyNotFound')
+      raise KeyNotFoundError(key)
     # Splay on the key to move the node with the given key to the top.
     self.Splay(key)
     # Raise exception for key that is not found.
     if self.root.key != key:
-      raise Exception('KeyNotFound')
+      raise KeyNotFoundError(key)
     removed = self.root
     # Link out the root node.
     if not self.root.left:

tools/tickprocessor.py

@@ -235,14 +235,14 @@ class TickProcessor(object):
       removed_node = self.js_entries.Remove(from_addr)
       removed_node.value.SetStartAddress(to_addr);
       self.js_entries.Insert(to_addr, removed_node.value)
-    except 'KeyNotFound':
+    except splaytree.KeyNotFoundError:
       print('Code move event for unknown code: 0x%x' % from_addr)
 
   def ProcessCodeDelete(self, from_addr):
     try:
       removed_node = self.js_entries.Remove(from_addr)
       self.deleted_code.append(removed_node.value)
-    except 'KeyNotFound':
+    except splaytree.KeyNotFoundError:
       print('Code delete event for unknown code: 0x%x' % from_addr)
 
   def ProcessBeginCodeRegion(self, id, assm, start, name):