Hpp

Front-end interface to the pre-processor.

Running the Preprocessor

preprocess :: Monad m => [ByteString] -> HppT m ()

Preprocess lines of input.

runHpp :: MonadIO m => HppState -> HppT m a -> ExceptT Error m (HppOutput, HppState)

Run a preprocessor action with some initial state. Returns the result of preprocessing as well as an updated preprocessor state representation.

streamHpp :: MonadIO m => HppState -> ([ByteString] -> m ()) -> HppT m a -> ExceptT Error m ([FilePath], HppState)

streamHpp state sink action runs a preprocessor action with some initial state. Output is streamed to the caller-provided output sink as it is generated. The list of files read during preprocessing is returned along with an updated preprocessor state representation.

expand :: HppState -> HppT (State ([ByteString] -> [ByteString])) a -> Except Error (HppOutput, HppState)

Like runHpp, but does not access the filesystem. Run a preprocessor action with some initial state. Returns the result of preprocessing as well as an updated preprocessor state representation. Since this operation performs no IO, #include directives are ignored in terms of the generated output lines, but the files named in those directive are available in the HppOutput value returned.

Preprocessor State

data HppState

Dynamic state of the preprocessor engine.

Instances

Show HppState

Defined in Hpp.Types

Methods

showsPrec :: Int -> HppState -> ShowS

show :: HppState -> String

showList :: [HppState] -> ShowS

Monad m => HasEnv (StateT HppState m)

Defined in Hpp.Types

Methods

getEnv :: StateT HppState m Env

setEnv :: Env -> StateT HppState m ()

Monad m => HasHppState (StateT HppState m)

Defined in Hpp.Types

Methods

getState :: StateT HppState m HppState

setState :: HppState -> StateT HppState m ()

emptyHppState :: HppState

An HppState containing no macro definitions, and default values for the starting configuration: the name of the current file is "NoFile", there are no paths to be searched for included files, etc. See Config for more information on available configuration.

initHppState :: Config -> Env -> HppState

Create a HppState with the given Config and Env.

Adding Definitions

parseDefinition :: ByteString -> ByteString -> Maybe (ByteString, Macro)

Lower level parsing of macro definitions. Will typically be used with insertPair for manual construction of a Env binding environment.

addDefinition :: ByteString -> ByteString -> HppState -> Maybe HppState

addDefinition name expression adds a binding of name to expression in the preprocessor’s internal state.

Core Types

data HppT m a

The type of preprocessor actions. Created with preprocess and executed with runHpp or streamHpp.

Instances

MonadTrans HppT

Defined in Hpp

Methods

lift :: Monad m => m a -> HppT m a

Monad m => Monad (HppT m)

Defined in Hpp

Methods

(>>=) :: HppT m a -> (a -> HppT m b) -> HppT m b

(>>) :: HppT m a -> HppT m b -> HppT m b

return :: a -> HppT m a

fail :: String -> HppT m a

Functor m => Functor (HppT m)

Defined in Hpp

Methods

fmap :: (a -> b) -> HppT m a -> HppT m b

(<$) :: a -> HppT m b -> HppT m a

Monad m => Applicative (HppT m)

Defined in Hpp

Methods

pure :: a -> HppT m a

(<*>) :: HppT m (a -> b) -> HppT m a -> HppT m b

liftA2 :: (a -> b -> c) -> HppT m a -> HppT m b -> HppT m c

(*>) :: HppT m a -> HppT m b -> HppT m b

(<*) :: HppT m a -> HppT m b -> HppT m a

data HppOutput

The result of running hpp

Constructors

HppOutput

Fields

• hppFilesRead :: [FilePath]
• hppOutput :: [ByteString]