refactor and make reversed(range()) optimisation apply only to known bounds, not any non-NameNode

Cython/Compiler/Optimize.py

@@ -663,13 +663,16 @@ class IterationTransform(Visitor.EnvTransform):
             if step_value < 0:
                 step_value = -step_value
             if step_value != 1:
-                if isinstance(bound1, ExprNodes.NameNode) or isinstance(bound2, ExprNodes.NameNode): 
+                begin_value = bound1.constant_result
+                end_value = bound2.constant_result
+                if isinstance(begin_value, (int, long)) and isinstance(end_value, (int, long)):
+                    bound1_value = step_value * ((begin_value - end_value - 1) // step_value) + end_value + 1
+                    bound1 = ExprNodes.IntNode(
+                        bound1.pos, value=str(bound1_value), constant_result=bound1_value,
+                        type=PyrexTypes.widest_numeric_type(bound1.type, bound2.type))
+                else:
                     # FIXME: Optimize when variable is in range (e.g. reversed(range(x, y, 3)))
                     return node
-                else:
-                    end_value = int(bound2.value)
-                    begin_value = int(bound1.value)
-                    bound1.value = str(step_value*((begin_value-end_value-1) // step_value) + end_value+1)
         else:
             if step_value < 0:
                 step_value = -step_value

tests/run/reversed_iteration.pyx

@@ -133,12 +133,39 @@ def reversed_range_step_neg(int a, int b):
         result.append(i)
     return result, i
 
+
+#cython.test_assert_path_exists('//ForFromStatNode')
+def reversed_range_step3(int a, int b):
+    """
+    >>> [ i for i in _reversed(range(-5, 0, 3)) ]
+    [-2, -5]
+    >>> reversed_range_step3(-5, 0)
+    ([-2, -5], -5)
+
+    >>> [ i for i in _reversed(range(0, 5, 3)) ]
+    [3, 0]
+    >>> reversed_range_step3(0, 5)
+    ([3, 0], 0)
+
+    >>> [ i for i in _reversed(range(5, 0, 3)) ]
+    []
+    >>> reversed_range_step3(5, 0)
+    ([], 99)
+    """
+    cdef int i = 99
+    result = []
+    for i in reversed(range(a, b, 3)):
+        result.append(i)
+    return result, i
+
+
 @cython.test_assert_path_exists('//ForFromStatNode')
-def reversed_range_step4():
+@cython.test_fail_if_path_exists('//ForInStatNode')
+def reversed_range_constant():
     """
     >>> [ i for i in _reversed(range(-12, -2, 4)) ]
     [-4, -8, -12]
-    >>> reversed_range_step4()
+    >>> reversed_range_constant()
     ([-4, -8, -12], -12)
     """
     cdef int i = 99
@@ -207,29 +234,6 @@ def reversed_range_step4():
         result.append(i)
     return result, i
 
-#cython.test_assert_path_exists('//ForFromStatNode')
-def reversed_range_step3(int a, int b):
-    """
-    >>> [ i for i in _reversed(range(-5, 0, 3)) ]
-    [-2, -5]
-    >>> reversed_range_step3(-5, 0)
-    ([-2, -5], -5)
-
-    >>> [ i for i in _reversed(range(0, 5, 3)) ]
-    [3, 0]
-    >>> reversed_range_step3(0, 5)
-    ([3, 0], 0)
-
-    >>> [ i for i in _reversed(range(5, 0, 3)) ]
-    []
-    >>> reversed_range_step3(5, 0)
-    ([], 99)
-    """
-    cdef int i = 99
-    result = []
-    for i in reversed(range(a, b, 3)):
-        result.append(i)
-    return result, i
 
 unicode_string = u"abcDEF"