From 4c31714a251ad4f656bb58fb4a2f0b6612747e74 Mon Sep 17 00:00:00 2001
From: Michael Snoyman <michael@snoyman.com>
Date: Tue, 24 Jun 2014 08:46:08 +0300
Subject: [PATCH] Special support for key-value pairs in route attributes #762

---
 yesod-routes/Yesod/Routes/Parse.hs | 18 +++++++++++++++++-
 yesod-routes/test/Hierarchy.hs     |  6 ++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/yesod-routes/Yesod/Routes/Parse.hs b/yesod-routes/Yesod/Routes/Parse.hs
index f230e7ff..d71afef1 100644
--- a/yesod-routes/Yesod/Routes/Parse.hs
+++ b/yesod-routes/Yesod/Routes/Parse.hs
@@ -19,6 +19,8 @@ import qualified System.IO as SIO
 import Yesod.Routes.TH
 import Yesod.Routes.Overlap (findOverlapNames)
 import Data.List (foldl')
+import Data.Maybe (mapMaybe)
+import qualified Data.Set as Set
 
 -- | A quasi-quoter to parse a string into a list of 'Resource's. Checks for
 -- overlapping routes, failing if present; use 'parseRoutesNoCheck' to skip the
@@ -107,7 +109,21 @@ addAttrs attrs =
     goTree (ResourceLeaf res) = ResourceLeaf (goRes res)
     goTree (ResourceParent x y z) = ResourceParent x y (map goTree z)
 
-    goRes res = res { resourceAttrs = attrs ++ resourceAttrs res }
+    goRes res =
+        res { resourceAttrs = noDupes ++ resourceAttrs res }
+      where
+        usedKeys = Set.fromList $ map fst $ mapMaybe toPair $ resourceAttrs res
+        used attr =
+            case toPair attr of
+                Nothing -> False
+                Just (key, _) -> key `Set.member` usedKeys
+        noDupes = filter (not . used) attrs
+
+    toPair s =
+        case break (== '=') s of
+            (x, '=':y) -> Just (x, y)
+            _ -> Nothing
+
 
 -- | Take attributes out of the list and put them in the first slot in the
 -- result tuple.
diff --git a/yesod-routes/test/Hierarchy.hs b/yesod-routes/test/Hierarchy.hs
index 9bcd796a..dfd2d871 100644
--- a/yesod-routes/test/Hierarchy.hs
+++ b/yesod-routes/test/Hierarchy.hs
@@ -99,8 +99,8 @@ do
     /post       Post3         POST
 --    /#Int       Delete3            DELETE
 
-/afterwards AfterR:
-  /             After     GET
+/afterwards AfterR !parent !key=value1:
+  /             After     GET !child !key=value2
 
 -- /trailing-nest TrailingNestR:
 --  /foo TrailingFooR GET
@@ -204,3 +204,5 @@ hierarchy = describe "hierarchy" $ do
         parseRoute (["admin!", "5"], []) @?= (Nothing :: Maybe (Route Hierarchy))
     it "inherited attributes" $ do
         routeAttrs (NestR SpacedR) @?= Set.fromList ["NestingAttr", "NonNested"]
+    it "pair attributes" $
+        routeAttrs (AfterR After) @?= Set.fromList ["parent", "child", "key=value2"]