Use Text instead of String in pathTo for better performance (#2226)

* Use Text instead of String in pathTo for better performance

Add actionPrefixText and stripActionSuffixText functions that use
efficient Text operations (Text.isPrefixOf, Text.stripSuffix, Text.breakOn)
instead of recursive char-by-char String traversal. Update pathTo to use
these Text functions, reducing Text.pack calls in the hot path.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Remove actionPrefix and stripActionSuffixString

Replace usages of actionPrefix with Text.encodeUtf8 (actionPrefixText ...)
and delete the old String-based functions that are no longer needed.
Also removes unused Data.Char import.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: mpscholten

ihp/IHP/RouterSupport.hs

@@ -59,7 +59,6 @@ import Unsafe.Coerce
 import IHP.HaskellSupport hiding (get)
 import qualified Data.Typeable as Typeable
 import qualified Data.ByteString.Char8 as ByteString
-import qualified Data.Char as Char
 import Control.Monad.Fail
 import Data.String.Conversions (ConvertibleStrings (convertString), cs)
 import qualified Text.Blaze.Html5 as Html5
@@ -345,7 +344,7 @@ class Data controller => AutoRoute controller where
             parseAction :: Constr -> Parser controller
             parseAction constr = let
                     prefix :: ByteString
-                    prefix = ByteString.pack (actionPrefix @controller)
+                    prefix = Text.encodeUtf8 (actionPrefixText @controller)
 
                     actionName = ByteString.pack (showConstr constr)
 
@@ -412,49 +411,50 @@ class Data controller => AutoRoute controller where
 -- All controllers defined in the `Web/` directory don't have a prefix at all.
 --
 -- E.g. controllers in the `Admin/` directory are prefixed with @/admin/@.
-actionPrefix :: forall (controller :: Type). Typeable controller => String
-actionPrefix =
-        case moduleName of
-            ('W':'e':'b':'.':_) -> "/"
-            ('I':'H':'P':'.':_) -> "/"
-            ("") -> "/"
-            moduleName -> "/" <> let prefix = getPrefix "" moduleName in map Char.toLower prefix <> "/"
+actionPrefixText :: forall (controller :: Type). Typeable controller => Text
+actionPrefixText
+    | "Web." `Text.isPrefixOf` moduleName = "/"
+    | "IHP." `Text.isPrefixOf` moduleName = "/"
+    | Text.null moduleName = "/"
+    | otherwise = "/" <> Text.toLower (getPrefix moduleName) <> "/"
     where
-        moduleName :: String
-        moduleName = Typeable.typeOf (error "unreachable" :: controller)
+        moduleName :: Text
+        moduleName = Text.pack $ Typeable.typeOf (error "unreachable" :: controller)
                 |> Typeable.typeRepTyCon
                 |> Typeable.tyConModule
 
-        -- E.g. getPrefix "" "Admin.User" == "Admin"
-        getPrefix prefix ('.':_) = prefix
-        getPrefix prefix (x:xs) = getPrefix (prefix <> [x]) xs
-        getPrefix prefix [] = prefix
+        getPrefix :: Text -> Text
+        getPrefix t = fst (Text.breakOn "." t)
+{-# INLINE actionPrefixText #-}
 
-{-# INLINE actionPrefix #-}
-
--- | Strips the "Action" at the end of action names
+-- | Strips the "Action" suffix from action names
 --
--- >>> stripActionSuffixString "ShowUserAction"
+-- >>> stripActionSuffixByteString "ShowUserAction"
 -- "ShowUser"
 --
--- >>> stripActionSuffixString "UsersAction"
+-- >>> stripActionSuffixByteString "UsersAction"
 -- "UsersAction"
 --
--- >>> stripActionSuffixString "User"
+-- >>> stripActionSuffixByteString "User"
 -- "User"
-stripActionSuffixString :: String -> String
-stripActionSuffixString string =
-    case string of
-        "Action" -> ""
-        (x:xs) -> x : stripActionSuffixString xs
-        "" -> ""
-{-# INLINE stripActionSuffixString #-}
-
--- | Like 'stripActionSuffixString' but for ByteStrings
 stripActionSuffixByteString :: ByteString -> ByteString
 stripActionSuffixByteString actionName = fromMaybe actionName (ByteString.stripSuffix "Action" actionName)
 {-# INLINE stripActionSuffixByteString #-}
 
+-- | Strips the "Action" suffix from action names
+--
+-- >>> stripActionSuffixText "ShowUserAction"
+-- "ShowUser"
+--
+-- >>> stripActionSuffixText "UsersAction"
+-- "UsersAction"
+--
+-- >>> stripActionSuffixText "User"
+-- "User"
+stripActionSuffixText :: Text -> Text
+stripActionSuffixText actionName = fromMaybe actionName (Text.stripSuffix "Action" actionName)
+{-# INLINE stripActionSuffixText #-}
+
 
 -- | Returns the create action for a given controller.
 -- Example: `createAction @UsersController == Just CreateUserAction`
@@ -529,13 +529,13 @@ instance QueryParam a => QueryParam [a] where
 
 instance {-# OVERLAPPABLE #-} (Show controller, AutoRoute controller) => HasPath controller where
     {-# INLINABLE pathTo #-}
-    pathTo !action = Text.pack (appPrefix <> actionName <> arguments)
+    pathTo !action = appPrefix <> actionName <> Text.pack arguments
         where
-            appPrefix :: String
-            !appPrefix = actionPrefix @controller
+            appPrefix :: Text
+            !appPrefix = actionPrefixText @controller
 
-            actionName :: String
-            !actionName = stripActionSuffixString $! showConstr constructor
+            actionName :: Text
+            !actionName = stripActionSuffixText $! Text.pack (showConstr constructor)
 
             constructor = toConstr action
 
@@ -804,7 +804,7 @@ webSocketAppWithCustomPathAndHTTPFallback path = do
 
 -- | Defines the start page for a router (when @\/@ is requested).
 startPage :: forall action application. (Controller action, InitControllerContext application, ?application::application, ?request :: Request, ?respond :: Respond, Typeable application, Typeable action) => action -> Parser Application
-startPage action = get (ByteString.pack (actionPrefix @action)) action
+startPage action = get (Text.encodeUtf8 (actionPrefixText @action)) action
 {-# INLINABLE startPage #-}
 
 withPrefix prefix routes = string prefix >> choice (map (\r -> r <* endOfInput) routes)
@@ -876,7 +876,7 @@ parseRouteWithId = do
 
 catchAll :: forall action application. (?request :: Request, ?respond :: Respond, Controller action, InitControllerContext application, Typeable action, ?application :: application, Typeable application, Data action) => action -> Parser Application
 catchAll action = do
-    string (ByteString.pack (actionPrefix @action))
+    string (Text.encodeUtf8 (actionPrefixText @action))
     _ <- takeByteString
     pure (runAction' @application action)
 {-# INLINABLE catchAll #-}