Add support for // and //=.

Avoid if/elif/elif/else tests where the final else is supposed to
handle exactly one case instead of all other cases.  When the list of
operators is extended, the catchall else treats all new operators as
the last operator in the set of tests.  Instead, raise an exception if
an unexpected operator occurs.

Lib/compiler/transformer.py

@@ -588,9 +588,11 @@ class Transformer:
             if nodelist[i-1][0] == token.LEFTSHIFT:
                 node = LeftShift([node, right])
                 node.lineno = nodelist[1][2]
-            else:
+            elif nodelist[i-1][0] == token.RIGHTSHIFT:
                 node = RightShift([node, right])
                 node.lineno = nodelist[1][2]
+            else:
+                raise ValueError, "unexpected token: %s" % nodelist[i-1][0]
         return node
 
     def arith_expr(self, nodelist):
@@ -600,9 +602,11 @@ class Transformer:
             if nodelist[i-1][0] == token.PLUS:
                 node = Add([node, right])
                 node.lineno = nodelist[1][2]
-            else:
+            elif nodelist[i-1][0] == token.MINUS:
                 node = Sub([node, right])
                 node.lineno = nodelist[1][2]
+            else:
+                raise ValueError, "unexpected token: %s" % nodelist[i-1][0]
         return node
 
     def term(self, nodelist):
@@ -614,8 +618,12 @@ class Transformer:
                 node = Mul([node, right])
             elif t == token.SLASH:
                 node = Div([node, right])
-            else:
+            elif t == token.PERCENT:
                 node = Mod([node, right])
+            elif t == token.DOUBLESLASH:
+                node = FloorDiv([node, right])
+            else:
+                raise ValueError, "unexpected token: %s" % t
             node.lineno = nodelist[1][2]
         return node
 
@@ -750,10 +758,13 @@ class Transformer:
 
                 if i < len(nodelist):
                     # should be DOUBLESTAR or STAR STAR
-                    if nodelist[i][0] == token.DOUBLESTAR:
+                    t = nodelist[i][0]
+                    if t == token.DOUBLESTAR:
                         node = nodelist[i+1]
-                    else:
+                    elif t == token.STARSTAR:
                         node = nodelist[i+2]
+                    else:
+                        raise ValueError, "unexpected token: %s" % t
                     names.append(node[1])
                     flags = flags | CO_VARKEYWORDS
 

Tools/compiler/compiler/transformer.py

@@ -588,9 +588,11 @@ class Transformer:
             if nodelist[i-1][0] == token.LEFTSHIFT:
                 node = LeftShift([node, right])
                 node.lineno = nodelist[1][2]
-            else:
+            elif nodelist[i-1][0] == token.RIGHTSHIFT:
                 node = RightShift([node, right])
                 node.lineno = nodelist[1][2]
+            else:
+                raise ValueError, "unexpected token: %s" % nodelist[i-1][0]
         return node
 
     def arith_expr(self, nodelist):
@@ -600,9 +602,11 @@ class Transformer:
             if nodelist[i-1][0] == token.PLUS:
                 node = Add([node, right])
                 node.lineno = nodelist[1][2]
-            else:
+            elif nodelist[i-1][0] == token.MINUS:
                 node = Sub([node, right])
                 node.lineno = nodelist[1][2]
+            else:
+                raise ValueError, "unexpected token: %s" % nodelist[i-1][0]
         return node
 
     def term(self, nodelist):
@@ -614,8 +618,12 @@ class Transformer:
                 node = Mul([node, right])
             elif t == token.SLASH:
                 node = Div([node, right])
-            else:
+            elif t == token.PERCENT:
                 node = Mod([node, right])
+            elif t == token.DOUBLESLASH:
+                node = FloorDiv([node, right])
+            else:
+                raise ValueError, "unexpected token: %s" % t
             node.lineno = nodelist[1][2]
         return node
 
@@ -750,10 +758,13 @@ class Transformer:
 
                 if i < len(nodelist):
                     # should be DOUBLESTAR or STAR STAR
-                    if nodelist[i][0] == token.DOUBLESTAR:
+                    t = nodelist[i][0]
+                    if t == token.DOUBLESTAR:
                         node = nodelist[i+1]
-                    else:
+                    elif t == token.STARSTAR:
                         node = nodelist[i+2]
+                    else:
+                        raise ValueError, "unexpected token: %s" % t
                     names.append(node[1])
                     flags = flags | CO_VARKEYWORDS