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|
-----------------------------------------------------------------------------
-- |
-- Copyright : (C) 2015 Dimitri Sabadie
-- License : BSD3
--
-- Maintainer : Dimitri Sabadie <dimitri.sabadie@gmail.com>
-- Stability : experimental
-- Portability : portable
--
-----------------------------------------------------------------------------
module Codec.Wavefront.Lexer where
import Codec.Wavefront.Element
import Codec.Wavefront.Face
import Codec.Wavefront.Line
import Codec.Wavefront.Location
import Codec.Wavefront.Normal
import Codec.Wavefront.Point
import Codec.Wavefront.Token
import Codec.Wavefront.TexCoord
import Data.DList ( DList, append, empty, fromList, snoc )
import Data.Text ( Text )
import Control.Monad.State ( State, execState, gets, modify )
import Data.Foldable ( traverse_ )
import Numeric.Natural ( Natural )
-- |The lexer context. The result of lexing a stream of tokens is this exact type.
data Ctxt = Ctxt {
-- |Locations.
ctxtLocations :: DList Location
-- |Texture coordinates.
, ctxtTexCoords :: DList TexCoord
-- |Normals.
, ctxtNormals :: DList Normal
-- |Points.
, ctxtPoints :: DList (Element Point)
-- |Lines.
, ctxtLines :: DList (Element Line)
-- |Faces.
, ctxtFaces :: DList (Element Face)
-- |Current object.
, ctxtCurrentObject :: Maybe Text
-- |Current groups.
, ctxtCurrentGroups :: [Text]
-- |Current material.
, ctxtCurrentMtl :: Maybe Text
-- |Material libraries.
, ctxtMtlLibs :: DList Text
-- |Current smoothing group.
, ctxtCurrentSmoothingGroup :: Natural
} deriving (Eq,Show)
-- |The empty 'Ctxt'. Such a context exists at the beginning of the token stream and gets altered
-- as we consume tokens.
emptyCtxt :: Ctxt
emptyCtxt = Ctxt {
ctxtLocations = empty
, ctxtTexCoords = empty
, ctxtNormals = empty
, ctxtPoints = empty
, ctxtLines = empty
, ctxtFaces = empty
, ctxtCurrentObject = Nothing
, ctxtCurrentGroups = ["default"]
, ctxtCurrentMtl = Nothing
, ctxtMtlLibs = empty
, ctxtCurrentSmoothingGroup = 0
}
-- |The lexer function, consuming tokens and yielding a 'Ctxt'.
lexer :: TokenStream -> Ctxt
lexer stream = execState (traverse_ consume stream) emptyCtxt
where
consume tk = case tk of
TknV v -> do
locations <- gets ctxtLocations
modify $ \ctxt -> ctxt { ctxtLocations = locations `snoc` v }
TknVN vn -> do
normals <- gets ctxtNormals
modify $ \ctxt -> ctxt { ctxtNormals = normals `snoc` vn }
TknVT vt -> do
texCoords <- gets ctxtTexCoords
modify $ \ctxt -> ctxt { ctxtTexCoords = texCoords `snoc` vt }
TknP p -> do
(pts,element) <- prepareElement ctxtPoints
modify $ \ctxt -> ctxt { ctxtPoints = pts `append` fmap element (fromList p) }
TknL l -> do
(lns,element) <- prepareElement ctxtLines
modify $ \ctxt -> ctxt { ctxtLines = lns `append` fmap element (fromList l) }
TknF f -> do
(fcs,element) <- prepareElement ctxtFaces
modify $ \ctxt -> ctxt { ctxtFaces = fcs `snoc` element f }
TknG g -> modify $ \ctxt -> ctxt { ctxtCurrentGroups = g }
TknO o -> modify $ \ctxt -> ctxt { ctxtCurrentObject = Just o }
TknMtlLib l -> do
libs <- gets ctxtMtlLibs
modify $ \ctxt -> ctxt { ctxtMtlLibs = libs `append` fromList l }
TknUseMtl mtl -> modify $ \ctxt -> ctxt { ctxtCurrentMtl = Just mtl }
TknS sg -> modify $ \ctxt -> ctxt { ctxtCurrentSmoothingGroup = sg }
-- Prepare to create a new 'Element' by retrieving its associated list.
prepareElement :: (Ctxt -> DList (Element a)) -> State Ctxt (DList (Element a),a -> Element a)
prepareElement field = do
(aList,obj,grp,mtl,sg) <- gets $ (\ctxt -> (field ctxt,ctxtCurrentObject ctxt,ctxtCurrentGroups ctxt,ctxtCurrentMtl ctxt,ctxtCurrentSmoothingGroup ctxt))
pure (aList,Element obj grp mtl sg)
|
