Add an Ord instance for Cidr and use it to implement Eq.

[hath.git] / src / Cidr.hs

diff --git a/src/Cidr.hs b/src/Cidr.hs
index d071586036a17cd90bb32c2da6b0eccc14129869..e353406d9eaa7303d6ba437d99d79083ffa1f586 100644 (file)
--- a/src/Cidr.hs
+++ b/src/Cidr.hs
@@ -61,12 +61,14 @@ instance Eq Cidr where
   -- | Two CIDRs are equal if they have the same network bits and if
   --   their masks are the same. In other words, if they are the same
   --   after normalization.
-  cidr1 == cidr2 = addr1 == addr2 && mask1 == mask2
+  cidr1 == cidr2 = (cidr1 <= cidr2) && (cidr2 <= cidr1)
+
+instance Ord Cidr where
+  cidr1 <= cidr2 = if addr1 == addr2 then mask1 <= mask2 else addr1 <= addr2
     where
       Cidr addr1 mask1 = normalize cidr1
       Cidr addr2 mask2 = normalize cidr2
 
-
 -- | Returns the mask portion of a CIDR address. That is, everything
 --   after the trailing slash.
 maskbits_from_cidr_string :: String -> Maybe Maskbits
@@ -300,7 +302,8 @@ cidr_properties =
   testGroup "CIDR Properties" [
       prop_all_cidrs_contain_themselves,
       prop_contains_proper_antisymmetric,
-      prop_normalize_idempotent ]
+      prop_normalize_idempotent,
+      prop_normalize_preserves_equality ]
 
 
 -- HUnit Tests
@@ -549,3 +552,11 @@ prop_normalize_idempotent =
   where
     prop :: Cidr -> Bool
     prop cidr = (normalize cidr) == (normalize (normalize cidr))
+
+-- Normalization should not affect equality of two CIDRs.
+prop_normalize_preserves_equality :: TestTree
+prop_normalize_preserves_equality =
+  testProperty "The CIDR \"normalize\" function preserves equality " prop
+  where
+    prop :: Cidr -> Cidr -> Bool
+    prop cidr1 cidr2 = (cidr1 == cidr2) == (normalize cidr1 == normalize cidr2)