Allow returning remaining-non-childcommand input

more specifically, the part of the input that is not part of any
successfully parsed subcommand invocation. "remaining" is not
completely accurate because this works even when all input
is processed.

src/UI/Butcher/Monadic/Core.hs

@@ -29,7 +29,9 @@ module UI.Butcher.Monadic.Core
   , reorderStop
   , cmdCheckParser
   , cmdRunParser
+  , cmdRunParserExt
   , cmdRunParserA
+  , cmdRunParserAExt
   )
 where
 
@@ -319,6 +321,9 @@ cmdCheckParser mTopLevel cmdParser
     monadMisuseError = error "CmdParser definition error - used Monad powers where only Applicative/Arrow is allowed"
 
 
+newtype PastCommandInput = PastCommandInput Input
+
+
 cmdRunParser
   :: Maybe String
   -> Input
@@ -328,6 +333,14 @@ cmdRunParser mTopLevel inputInitial cmdParser
   = runIdentity
   $ cmdRunParserA mTopLevel inputInitial cmdParser
 
+cmdRunParserExt
+  :: Maybe String
+  -> Input
+  -> CmdParser Identity out ()
+  -> (CommandDesc (), Input, Either ParsingError (CommandDesc out))
+cmdRunParserExt mTopLevel inputInitial cmdParser
+  = runIdentity
+  $ cmdRunParserAExt mTopLevel inputInitial cmdParser
 
 cmdRunParserA :: forall f out
                . Applicative f
@@ -337,7 +350,16 @@ cmdRunParserA :: forall f out
               -> f ( CommandDesc ()
                    , Either ParsingError (CommandDesc out)
                    )
-cmdRunParserA mTopLevel inputInitial cmdParser
+cmdRunParserA mTopLevel inputInitial cmdParser =
+  (\(x, _, z) -> (x, z)) <$> cmdRunParserAExt mTopLevel inputInitial cmdParser
+
+cmdRunParserAExt
+  :: forall f out . Applicative f
+  => Maybe String
+  -> Input
+  -> CmdParser f out ()
+  -> f (CommandDesc (), Input, Either ParsingError (CommandDesc out))
+cmdRunParserAExt mTopLevel inputInitial cmdParser
     = runIdentity
     $ MultiRWSS.runMultiRWSTNil
     $ (<&> captureFinal)
@@ -345,15 +367,17 @@ cmdRunParserA mTopLevel inputInitial cmdParser
     $ MultiRWSS.withMultiStateA cmdParser
     $ MultiRWSS.withMultiStateSA (StackBottom [])
     $ MultiRWSS.withMultiStateSA inputInitial
+    $ MultiRWSS.withMultiStateSA (PastCommandInput inputInitial)
     $ MultiRWSS.withMultiStateSA initialCommandDesc
     $ processMain cmdParser
   where
     initialCommandDesc = emptyCommandDesc
       { _cmd_mParent = mTopLevel <&> \n -> (n, emptyCommandDesc) }
-    captureFinal :: ([String], (CmdDescStack, (Input, (CommandDesc out, f()))))
-                 -> f (CommandDesc (), Either ParsingError (CommandDesc out))
-    captureFinal (errs, (descStack, (inputRest, (cmd, act)))) =
-        act $> (() <$ cmd', res)
+    captureFinal
+      :: ([String], (CmdDescStack, (Input, (PastCommandInput, (CommandDesc out, f())))))
+      -> f (CommandDesc (), Input, Either ParsingError (CommandDesc out))
+    captureFinal (errs, (descStack, (inputRest, (PastCommandInput pastCmdInput, (cmd, act))))) =
+        act $> (() <$ cmd', pastCmdInput, res)
       where
         errs' = errs ++ inputErrs ++ stackErrs
         inputErrs = case inputRest of
@@ -372,7 +396,7 @@ cmdRunParserA mTopLevel inputInitial cmdParser
                 -> MultiRWSS.MultiRWS
                      '[]
                      '[[String]]
-                     '[CommandDesc out, Input, CmdDescStack, CmdParser f out ()]
+                     '[CommandDesc out, PastCommandInput, Input, CmdDescStack, CmdParser f out ()]
                      (f ())
     processMain = \case
       Pure () -> return $ pure $ ()
@@ -492,10 +516,16 @@ cmdRunParserA mTopLevel inputInitial cmdParser
         case mRest of
           Nothing -> do
             cmd :: CommandDesc out <- mGet
-            subCmd <- MultiRWSS.withMultiStateS (emptyCommandDesc :: CommandDesc out)
-                    $ MultiRWSS.withMultiStateA (StackBottom [])
-                    $ iterM processCmdShallow sub
-            mSet $ cmd { _cmd_children = (cmdStr, subCmd) : _cmd_children cmd }
+            let (subCmd, subStack)
+                  = runIdentity
+                  $ MultiRWSS.runMultiRWSTNil
+                  $ MultiRWSS.withMultiStateSA (emptyCommandDesc :: CommandDesc out)
+                  $ MultiRWSS.withMultiStateS (StackBottom [])
+                  $ iterM processCmdShallow sub
+            mSet $ cmd
+              { _cmd_children = (cmdStr, postProcessCmd subStack subCmd)
+                              : _cmd_children cmd
+              }
             processMain next
           Just rest -> do
             iterM processCmdShallow f
@@ -504,6 +534,7 @@ cmdRunParserA mTopLevel inputInitial cmdParser
               prevStack :: CmdDescStack <- mGet
               return $ postProcessCmd prevStack c
             mSet $ rest
+            mSet $ PastCommandInput rest
             mSet $ (emptyCommandDesc :: CommandDesc out)
               { _cmd_mParent = Just (cmdStr, cmd)
               }