From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 19 Aug 2013 12:24:29 +0000 (-0400)
Subject: Replace cidr_from_string with a Read instance.
X-Git-Tag: 0.0.4~4
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=a5dfa1fd4dde2d79f42c606a56b4aea303d273e8;p=hath.git

Replace cidr_from_string with a Read instance.
---

diff --git a/src/Cidr.hs b/src/Cidr.hs
index d6acdcf..dc2b556 100644
--- a/src/Cidr.hs
+++ b/src/Cidr.hs
@@ -2,7 +2,6 @@
 --   with the CIDR type.
 module Cidr
 ( Cidr(..),
-  cidr_from_string,
   cidr_properties,
   cidr_tests,
   combine_all,
@@ -23,7 +22,7 @@ module Cidr
 
 import Data.List (nubBy)
 import Data.List.Split (splitOneOf)
-import Data.Maybe (catMaybes, fromJust, mapMaybe)
+import Data.Maybe (catMaybes, mapMaybe)
 
 import Test.HUnit (assertEqual)
 import Test.Framework (Test, testGroup)
@@ -43,7 +42,6 @@ data Cidr = Cidr { ipv4address :: IPv4Address,
                    maskbits :: Maskbits }
 
 
-
 instance Show Cidr where
     show cidr = (show (ipv4address cidr)) ++ "/" ++ (show (maskbits cidr))
 
@@ -79,21 +77,22 @@ maskbits_from_cidr_string s
 --   of its octets (as Ints).
 octets_from_cidr_string :: String -> [Octet]
 octets_from_cidr_string s =
-  mapMaybe readMaybe (take 4 (splitOneOf "./" s))
-
-
--- | Return Nothing if we can't parse both maskbits and octets from
---   the string.
-cidr_from_string :: String -> Maybe Cidr
-cidr_from_string s =
-  case (octets_from_cidr_string s) of
-    [oct1, oct2, oct3, oct4] ->
-      case (maskbits_from_cidr_string s) of
-        Just mbits ->
-          Just $ Cidr (IPv4Address oct1 oct2 oct3 oct4) mbits
-        _ -> Nothing
-    _ -> Nothing
+  case parts of
+    (p1:p2:p3:p4:_) -> mapMaybe readMaybe [p1,p2,p3,p4]
+    _ -> []
+  where
+    parts = splitOneOf "./" s
 
+instance Read Cidr where
+  -- | Parse everything or nothing.
+  readsPrec _ = \s ->
+    case (octets_from_cidr_string s) of
+      [oct1, oct2, oct3, oct4] ->
+        case (maskbits_from_cidr_string s) of
+          Just mbits ->
+            [(Cidr (IPv4Address oct1 oct2 oct3 oct4) mbits, "")]
+          _ -> []
+      _ -> []
 
 
 -- | Given a CIDR, return the minimum valid IPv4 address contained
@@ -309,7 +308,7 @@ test_enumerate =
     addr3 = mk_ip $ toEnum 242
     addr4 = mk_ip $ toEnum 243
     expected = [addr1, addr2, addr3, addr4]
-    actual = enumerate $ fromJust $ cidr_from_string "192.168.0.240/30"
+    actual = enumerate $ read "192.168.0.240/30"
 
 test_min_host1 :: Test
 test_min_host1 =
@@ -319,7 +318,7 @@ test_min_host1 =
     actual
   where
     desc = "The minimum host in 10.0.0.0/24 is 10.0.0.0"
-    actual = show $ min_host (fromJust $ cidr_from_string "10.0.0.0/24")
+    actual = show $ min_host (read "10.0.0.0/24")
     expected = "10.0.0.0"
 
 
@@ -331,7 +330,7 @@ test_max_host1 =
     actual
   where
     desc = "The maximum host in 10.0.0.0/24 is 10.0.0.255"
-    actual = show $ max_host (fromJust $ cidr_from_string "10.0.0.0/24")
+    actual = show $ max_host (read "10.0.0.0/24")
     expected = "10.0.0.255"
 
 
@@ -344,7 +343,7 @@ test_equality1 =
     (cidr1 == cidr1)
   where
     desc = "10.1.1.0/23 equals itself"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
+    cidr1 = read "10.1.1.0/23" :: Cidr
 
 
 test_contains1 :: Test
@@ -356,8 +355,8 @@ test_contains1 =
     (cidr1 `contains` cidr2)
   where
     desc = "10.1.1.0/23 contains 10.1.1.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
-    cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
+    cidr1 = read "10.1.1.0/23"
+    cidr2 = read "10.1.1.0/24"
 
 
 test_contains2 :: Test
@@ -369,7 +368,7 @@ test_contains2 =
     (cidr1 `contains` cidr1)
   where
     desc = "10.1.1.0/23 contains itself"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
+    cidr1 = read "10.1.1.0/23"
 
 
 test_contains_proper1 :: Test
@@ -381,8 +380,8 @@ test_contains_proper1 =
     (cidr1 `contains_proper` cidr2)
   where
     desc = "10.1.1.0/23 contains 10.1.1.0/24 properly"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
-    cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
+    cidr1 = read "10.1.1.0/23"
+    cidr2 = read "10.1.1.0/24"
 
 
 test_contains_proper2 :: Test
@@ -394,7 +393,7 @@ test_contains_proper2 =
     (cidr1 `contains_proper` cidr1)
   where
     desc = "10.1.1.0/23 does not contain itself properly"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
+    cidr1 = read "10.1.1.0/23"
 
 
 test_adjacent1 :: Test
@@ -406,8 +405,8 @@ test_adjacent1 =
     (cidr1 `adjacent` cidr2)
   where
     desc = "10.1.0.0/24 is adjacent to 10.1.1.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.1.0.0/24"
-    cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
+    cidr1 = read "10.1.0.0/24"
+    cidr2 = read "10.1.1.0/24"
 
 
 test_adjacent2 :: Test
@@ -419,8 +418,8 @@ test_adjacent2 =
     (cidr1 `adjacent` cidr2)
   where
     desc = "10.1.0.0/23 is not adjacent to 10.1.0.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.1.0.0/23"
-    cidr2 = fromJust $ cidr_from_string "10.1.0.0/24"
+    cidr1 = read "10.1.0.0/23"
+    cidr2 = read "10.1.0.0/24"
 
 
 test_adjacent3 :: Test
@@ -432,8 +431,8 @@ test_adjacent3 =
     (cidr1 `adjacent` cidr2)
   where
     desc = "10.1.0.0/24 is not adjacent to 10.2.5.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.1.0.0/24"
-    cidr2 = fromJust $ cidr_from_string "10.2.5.0/24"
+    cidr1 = read "10.1.0.0/24"
+    cidr2 = read "10.2.5.0/24"
 
 
 test_adjacent4 :: Test
@@ -445,8 +444,8 @@ test_adjacent4 =
     (cidr1 `adjacent` cidr2)
   where
     desc = "10.1.1.0/24 is not adjacent to 10.1.2.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.1.1.0/24"
-    cidr2 = fromJust $ cidr_from_string "10.1.2.0/24"
+    cidr1 = read "10.1.1.0/24"
+    cidr2 = read "10.1.2.0/24"
 
 
 test_combine_contained1 :: Test
@@ -458,9 +457,9 @@ test_combine_contained1 =
     (combine_contained test_cidrs)
   where
     desc = "10.0.0.0/8, 10.1.0.0/16, and 10.1.1.0/24 combine to 10.0.0.0/8"
-    cidr1 = fromJust $ cidr_from_string "10.0.0.0/8"
-    cidr2 = fromJust $ cidr_from_string "10.1.0.0/16"
-    cidr3 = fromJust $ cidr_from_string "10.1.1.0/24"
+    cidr1 = read "10.0.0.0/8"
+    cidr2 = read "10.1.0.0/16"
+    cidr3 = read "10.1.1.0/24"
     expected_cidrs = [cidr1]
     test_cidrs = [cidr1, cidr2, cidr3]
 
@@ -474,8 +473,8 @@ test_combine_contained2 =
     (combine_contained [cidr1, cidr2])
   where
     desc = "192.168.3.0/23 does not contain 192.168.1.0/24"
-    cidr1 = fromJust $ cidr_from_string "192.168.3.0/23"
-    cidr2 = fromJust $ cidr_from_string "192.168.1.0/24"
+    cidr1 = read "192.168.3.0/23"
+    cidr2 = read "192.168.1.0/24"
 
 
 test_combine_all1 :: Test
@@ -488,12 +487,12 @@ test_combine_all1 =
   where
     desc = "10.0.0.0/24 is adjacent to 10.0.1.0/24 "
            ++ "and 10.0.3.0/23 contains 10.0.2.0/24"
-    cidr1 = fromJust $ cidr_from_string "10.0.0.0/24"
-    cidr2 = fromJust $ cidr_from_string "10.0.1.0/24"
-    cidr3 = fromJust $ cidr_from_string "10.0.2.0/24"
-    cidr4 = fromJust $ cidr_from_string "10.0.3.0/23"
-    cidr5 = fromJust $ cidr_from_string "10.0.0.0/23"
-    expected_cidrs = [fromJust $ cidr_from_string "10.0.0.0/22"]
+    cidr1 = read "10.0.0.0/24"
+    cidr2 = read "10.0.1.0/24"
+    cidr3 = read "10.0.2.0/24"
+    cidr4 = read "10.0.3.0/23"
+    cidr5 = read "10.0.0.0/23"
+    expected_cidrs = [read "10.0.0.0/22"]
     test_cidrs = [cidr1, cidr2, cidr3, cidr4, cidr5]
 
 
@@ -506,7 +505,7 @@ test_combine_all2 =
       (combine_all test_cidrs)
     where
       desc = "127.0.0.1/32 combines with itself recursively"
-      cidr1 = fromJust $ cidr_from_string "127.0.0.1/32"
+      cidr1 = read "127.0.0.1/32"
       expected_cidrs = [cidr1]
       test_cidrs = [cidr1, cidr1, cidr1, cidr1, cidr1]
 
@@ -521,11 +520,11 @@ test_combine_all3 =
   where
     desc = "10.0.0.16, 10.0.0.17, 10.0.0.18, and "
            ++ "10.0.0.19 get combined into 10.0.0.16/30"
-    cidr1 = fromJust $ cidr_from_string "10.0.0.16/32"
-    cidr2 = fromJust $ cidr_from_string "10.0.0.17/32"
-    cidr3 = fromJust $ cidr_from_string "10.0.0.18/32"
-    cidr4 = fromJust $ cidr_from_string "10.0.0.19/32"
-    expected_cidrs = [fromJust $ cidr_from_string "10.0.0.16/30"]
+    cidr1 = read "10.0.0.16/32"
+    cidr2 = read "10.0.0.17/32"
+    cidr3 = read "10.0.0.18/32"
+    cidr4 = read "10.0.0.19/32"
+    expected_cidrs = [read "10.0.0.16/30"]
     test_cidrs = [cidr1, cidr2, cidr3, cidr4]
 
 
diff --git a/src/Main.hs b/src/Main.hs
index 5b034ba..f567400 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -11,10 +11,10 @@ import Data.Maybe (catMaybes, isNothing)
 import Data.String.Utils (splitWs)
 import System.Exit (ExitCode(..), exitSuccess, exitWith)
 import System.IO (stderr, hPutStrLn)
+import Text.Read (readMaybe)
 
 import Cidr (
   Cidr(..),
-  cidr_from_string,
   combine_all,
   enumerate,
   max_octet1,
@@ -115,7 +115,7 @@ main = do
   input <- inputfunc
 
   let cidr_strings = splitWs input
-  let cidrs = map cidr_from_string cidr_strings
+  let cidrs = map readMaybe cidr_strings
 
   when (any isNothing cidrs) $ do
     putStrLn "Error: not valid CIDR notation."