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.

Preprocessor State

data HppState

Dynamic state of the preprocessor engine.

Instances

Monad m => HasEnv (StateT HppState m)

Methods

getEnv :: StateT HppState m Env

setEnv :: Env -> StateT HppState m ()

Monad m => HasHppState (StateT HppState m)

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

Methods

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

Monad m => Monad (HppT m)

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)

Methods

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

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

Monad m => Applicative (HppT m)

Methods

pure :: a -> HppT m a

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

(*>) :: 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]