#18 & massive structure overhaul

lib/RPGEngine/Internals/Input.hs

@@ -0,0 +1,56 @@
+-- Allows to create a massive inputHandler that can handle anything
+-- after you specify what you want it to do.
+
+module RPGEngine.Internals.Input
+( InputHandler(..)
+, composeInputHandlers
+, handle
+, handleKey
+, handleAnyKey
+) where
+
+import Graphics.Gloss.Interface.IO.Game
+
+----------------------------- Constants ------------------------------
+
+type InputHandler a = Event -> (a -> a)
+
+----------------------------------------------------------------------
+
+-- Compose multiple InputHandlers into one InputHandler that handles
+-- all of them.
+composeInputHandlers :: [InputHandler a] -> InputHandler a
+composeInputHandlers []       ev a = a
+composeInputHandlers (ih:ihs) ev a = composeInputHandlers ihs ev (ih ev a)
+
+-- Handle any event
+handle :: Event -> (a -> a) -> InputHandler a
+handle (EventKey key _ _ _) = handleKey key
+-- handle (EventMotion _)      = undefined
+-- handle (EventResize _)      = undefined
+handle _                    = const (const id)
+
+-- Handle a event by pressing a key
+handleKey :: Key -> (a -> a) -> InputHandler a
+handleKey (SpecialKey  sk) = handleSpecialKey sk
+handleKey (Char        c ) = handleCharKey c
+handleKey (MouseButton _ ) = const (const id)
+
+-- Handle any key, equivalent to "Press any key to start"
+handleAnyKey :: (a -> a) -> InputHandler a
+handleAnyKey f (EventKey _ Down _ _) = f
+handleAnyKey _ _                     = id
+
+----------------------------------------------------------------------
+
+handleCharKey :: Char -> (a -> a) -> InputHandler a
+handleCharKey c1 f (EventKey (Char c2) Down _ _)
+    | c1 == c2  = f
+    | otherwise = id
+handleCharKey _  _ _ = id
+
+handleSpecialKey :: SpecialKey -> (a -> a) -> InputHandler a
+handleSpecialKey sk1 f (EventKey (SpecialKey sk2) Down _ _)
+    | sk1 == sk2 = f
+    | otherwise  = id
+handleSpecialKey _   _ _ = id