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--
-- | Generate C methods that process message dealing with the structs
-- defined in a header file.
--
-- This module contains the pure conversion from CStructs into C code.
-- Normally, this module would be implemented as a conversion between C ASTs,
-- but we want to add comments to the generated code, which are not
-- representable in the abstract syntax tree.
module Language.Trans.CStructs2MsgHandlers where

-- Internal imports: C AST representation.
import qualified Language.C.AbsC as C ( TranslationUnit (MkTranslationUnit) )

-- Internal imports: Copilot's own CStruct representation.
import Language.Copilot.CStruct ( CStruct (cStructName) )

import Language.Trans.CStruct2CopilotStruct ( camelCaseTypeName, mkCStruct )

-- | Generate a C methods that process message dealing with the structs
-- defined in a header file.
cstructs2MsgHandlers :: C.TranslationUnit -> Either String String
cstructs2MsgHandlers (C.MkTranslationUnit gs) =
  unlines <$> mapM (fmap cstruct2MsgHandler . mkCStruct) gs

-- | Generate a C method that processes one message dealing with one
-- kind of struct.
cstruct2MsgHandler :: CStruct -> String
cstruct2MsgHandler cstruct = unlines
    [ nameCStruct ++ " " ++ nameLocalVar ++ ";"
    , ""
    , "/**"
    , "* Make ICAROUS data available to Copilot and run monitors."
    , "*/"
    , "void COPILOT_Process" ++ nameVar ++ "Monitor(void)"
    , "{"
    , "  " ++ nameCStruct ++ "* msg;"
    , "  msg = (" ++ nameCStruct  ++ "*) COPILOTMsgPtr;"
    , "  " ++ nameLocalVar ++ " = *msg;"
    , ""
    , "  // Run all copilot monitors."
    , "  step();"
    , "}"
    ]
  where
    nameCStruct  = cStructName cstruct
    nameVar      = camelCaseTypeName nameCStruct
    nameLocalVar = 'm' : 'y' : camelCaseTypeName nameCStruct