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--------------------------------------------------------------------------------
-- | Module containing the template data structure
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Hakyll.Web.Template.Internal
( Template (..)
, TemplateElement (..)
) where
--------------------------------------------------------------------------------
import Control.Applicative (pure, (<$>), (<*>))
import Data.Binary (Binary, get, getWord8, put, putWord8)
import Data.Typeable (Typeable)
--------------------------------------------------------------------------------
import Hakyll.Core.Writable
--------------------------------------------------------------------------------
-- | Datatype used for template substitutions.
newtype Template = Template
{ unTemplate :: [TemplateElement]
} deriving (Show, Eq, Binary, Typeable)
--------------------------------------------------------------------------------
instance Writable Template where
-- Writing a template is impossible
write _ _ = return ()
--------------------------------------------------------------------------------
-- | Elements of a template.
data TemplateElement
= Chunk String
| Key String
| Escaped
| If String Template (Maybe Template) -- key, then branch, else branch
| For String Template (Maybe Template) -- key, body, separator
| Partial String -- filename
deriving (Show, Eq, Typeable)
--------------------------------------------------------------------------------
instance Binary TemplateElement where
put (Chunk string) = putWord8 0 >> put string
put (Key key) = putWord8 1 >> put key
put (Escaped) = putWord8 2
put (If key t f) = putWord8 3 >> put key >> put t >> put f
put (For key b s) = putWord8 4 >> put key >> put b >> put s
put (Partial p) = putWord8 5 >> put p
get = getWord8 >>= \tag -> case tag of
0 -> Chunk <$> get
1 -> Key <$> get
2 -> pure Escaped
3 -> If <$> get <*> get <*> get
4 -> For <$> get <*> get <*> get
5 -> Partial <$> get
_ -> error $
"Hakyll.Web.Template.Internal: Error reading cached template"
|
