Handle precedence in routing example.

tests/RouteTests.elm

@@ -1,6 +1,7 @@
 module RouteTests exposing (..)
 
 import Expect
+import List.Extra
 import Regex
 import Test exposing (Test, describe, test)
 
@@ -38,22 +39,104 @@ all =
                                         Nothing
                         }
                     |> Expect.equal (Cats__Name__ { name = Nothing } |> Just)
+        , test "multiple matchers" <|
+            \() ->
+                "/slide/123"
+                    |> firstMatch exampleMatchers
+                    |> Expect.equal (Slide__Number_ { number = "123" } |> Just)
+        , test "hardcoded routes have precedence over dynamic segments" <|
+            \() ->
+                "/post/create"
+                    |> firstMatch postPrecedenceExample
+                    |> Expect.equal (Post__Create {} |> Just)
+        , test "dynamic segments match when they are not overshadowed by a hardcoded route" <|
+            \() ->
+                "/post/update"
+                    |> firstMatch postPrecedenceExample
+                    |> Expect.equal (Post__Slug_ { slug = "update" } |> Just)
         ]
 
 
+exampleMatchers : List (Matcher Route)
+exampleMatchers =
+    [ { pattern = "^cats(?:\\/([^/]+))?$"
+      , toRoute =
+            \matches ->
+                case matches of
+                    [ name ] ->
+                        Cats__Name__ { name = name } |> Just
+
+                    _ ->
+                        Nothing
+      }
+    , { pattern = "^slide\\/(?:([^/]+))$"
+      , toRoute =
+            \matches ->
+                case matches of
+                    [ Just number ] ->
+                        Slide__Number_ { number = number } |> Just
+
+                    _ ->
+                        Nothing
+      }
+    ]
+
+
+postPrecedenceExample : List (Matcher Route)
+postPrecedenceExample =
+    [ { pattern = "^post\\/create$"
+      , toRoute =
+            \_ ->
+                Just (Post__Create {})
+      }
+    , { pattern = "^post\\/(?:([^/]+))$"
+      , toRoute =
+            \matches ->
+                case matches of
+                    [ Just slug ] ->
+                        Post__Slug_ { slug = slug } |> Just
+
+                    _ ->
+                        Nothing
+      }
+    ]
+
+
+firstMatch : List (Matcher Route) -> String -> Maybe Route
+firstMatch matchers path =
+    List.Extra.findMap
+        (\matcher ->
+            if Regex.contains (matcher.pattern |> toRegex) (normalizePath path) then
+                tryMatch matcher path
+
+            else
+                Nothing
+        )
+        matchers
+
+
+toRegex : String -> Regex.Regex
+toRegex pattern =
+    Regex.fromString pattern
+        |> Maybe.withDefault Regex.never
+
+
+type alias Matcher route =
+    { pattern : String, toRoute : List (Maybe String) -> Maybe route }
+
+
 tryMatch : { pattern : String, toRoute : List (Maybe String) -> Maybe Route } -> String -> Maybe Route
 tryMatch { pattern, toRoute } path =
     path
         |> normalizePath
-        |> submatches "^cats(?:\\/([^/]+))?$"
+        |> submatches pattern
         |> toRoute
 
 
 submatches : String -> String -> List (Maybe String)
 submatches pattern path =
     Regex.find
-        (Regex.fromString
-            "^cats(?:\\/([^/]+))?$"
+        (Regex.fromString pattern
             |> Maybe.withDefault Regex.never
         )
         path
@@ -89,3 +172,5 @@ type Route
     = Slide {}
     | Cats__Name__ { name : Maybe String }
     | Slide__Number_ { number : String }
+    | Post__Create {}
+    | Post__Slug_ { slug : String }