{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE PackageImports #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Text.Templating.Heist.Internal where
------------------------------------------------------------------------------
import Control.Applicative
import Control.Exception (SomeException)
import Control.Monad.CatchIO
import "monads-fd" Control.Monad.RWS.Strict
import qualified Data.Attoparsec.Char8 as AP
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B
import qualified Data.ByteString.Lazy as L
import Data.Either
import qualified Data.Foldable as F
import Data.List
import qualified Data.Map as Map
import Data.Maybe
import Prelude hiding (catch)
import System.Directory.Tree hiding (name)
import System.FilePath
import Text.XML.Expat.Format
import qualified Text.XML.Expat.Tree as X
------------------------------------------------------------------------------
import Text.Templating.Heist.Constants
import Text.Templating.Heist.Types
------------------------------------------------------------------------------
-- | Restores the components of TemplateState that can get modified in
-- template calls. You should use this function instead of @putTS@ to restore
-- an old state. Thas was needed because doctypes needs to be in a "global
-- scope" as opposed to the template call "local scope" of state items such
-- as recursionDepth, curContext, and spliceMap.
restoreState :: Monad m => TemplateState m -> TemplateMonad m ()
restoreState ts1 =
modifyTS (\ts2 -> ts2
{ _recursionDepth = _recursionDepth ts1
, _curContext = _curContext ts1
, _spliceMap = _spliceMap ts1
})
------------------------------------------------------------------------------
-- | Mappends a doctype to the state.
addDoctype :: Monad m => [ByteString] -> TemplateMonad m ()
addDoctype dt = do
modifyTS (\s -> s { _doctypes = _doctypes s `mappend` dt })
------------------------------------------------------------------------------
-- TemplateState functions
------------------------------------------------------------------------------
------------------------------------------------------------------------------
-- | Adds an on-load hook to a `TemplateState`.
addOnLoadHook :: (Monad m) =>
(Template -> IO Template)
-> TemplateState m
-> TemplateState m
addOnLoadHook hook ts = ts { _onLoadHook = _onLoadHook ts >=> hook }
------------------------------------------------------------------------------
-- | Adds a pre-run hook to a `TemplateState`.
addPreRunHook :: (Monad m) =>
(Template -> m Template)
-> TemplateState m
-> TemplateState m
addPreRunHook hook ts = ts { _preRunHook = _preRunHook ts >=> hook }
------------------------------------------------------------------------------
-- | Adds a post-run hook to a `TemplateState`.
addPostRunHook :: (Monad m) =>
(Template -> m Template)
-> TemplateState m
-> TemplateState m
addPostRunHook hook ts = ts { _postRunHook = _postRunHook ts >=> hook }
------------------------------------------------------------------------------
-- | Bind a new splice declaration to a tag name within a 'TemplateState'.
bindSplice :: Monad m =>
ByteString -- ^ tag name
-> Splice m -- ^ splice action
-> TemplateState m -- ^ source state
-> TemplateState m
bindSplice n v ts = ts {_spliceMap = Map.insert n v (_spliceMap ts)}
------------------------------------------------------------------------------
-- | Convenience function for looking up a splice.
lookupSplice :: Monad m =>
ByteString
-> TemplateState m
-> Maybe (Splice m)
lookupSplice nm ts = Map.lookup nm $ _spliceMap ts
------------------------------------------------------------------------------
-- | Converts a path into an array of the elements in reverse order. If the
-- path is absolute, we need to remove the leading slash so the split doesn't
-- leave @\"\"@ as the last element of the TPath.
--
-- FIXME @\"..\"@ currently doesn't work in paths, the solution is non-trivial
splitPathWith :: Char -> ByteString -> TPath
splitPathWith s p = if B.null p then [] else (reverse $ B.split s path)
where
path = if B.head p == s then B.tail p else p
-- | Converts a path into an array of the elements in reverse order using the
-- path separator of the local operating system. See 'splitPathWith' for more
-- details.
splitLocalPath :: ByteString -> TPath
splitLocalPath = splitPathWith pathSeparator
-- | Converts a path into an array of the elements in reverse order using a
-- forward slash (/) as the path separator. See 'splitPathWith' for more
-- details.
splitTemplatePath :: ByteString -> TPath
splitTemplatePath = splitPathWith '/'
------------------------------------------------------------------------------
-- | Does a single template lookup without cascading up.
singleLookup :: TemplateMap
-> TPath
-> ByteString
-> Maybe (InternalTemplate, TPath)
singleLookup tm path name = fmap (\a -> (a,path)) $ Map.lookup (name:path) tm
------------------------------------------------------------------------------
-- | Searches for a template by looking in the full path then backing up into each
-- of the parent directories until the template is found.
traversePath :: TemplateMap
-> TPath
-> ByteString
-> Maybe (InternalTemplate, TPath)
traversePath tm [] name = fmap (\a -> (a,[])) (Map.lookup [name] tm)
traversePath tm path name =
singleLookup tm path name `mplus`
traversePath tm (tail path) name
------------------------------------------------------------------------------
-- | Convenience function for looking up a template.
lookupTemplate :: Monad m =>
ByteString
-> TemplateState m
-> Maybe (InternalTemplate, TPath)
lookupTemplate nameStr ts =
f (_templateMap ts) path name
where (name:p) = case splitTemplatePath nameStr of
[] -> [""]
ps -> ps
path = p ++ (_curContext ts)
f = if '/' `B.elem` nameStr
then singleLookup
else traversePath
------------------------------------------------------------------------------
-- | Sets the templateMap in a TemplateState.
setTemplates :: Monad m => TemplateMap -> TemplateState m -> TemplateState m
setTemplates m ts = ts { _templateMap = m }
------------------------------------------------------------------------------
-- | Adds a template to the template state.
insertTemplate :: Monad m =>
TPath
-> InternalTemplate
-> TemplateState m
-> TemplateState m
insertTemplate p t st =
setTemplates (Map.insert p t (_templateMap st)) st
------------------------------------------------------------------------------
-- | Adds a template to the template state.
addTemplate :: Monad m =>
ByteString
-> InternalTemplate
-> TemplateState m
-> TemplateState m
addTemplate n t st = insertTemplate (splitTemplatePath n) t st
------------------------------------------------------------------------------
-- | Stops the recursive processing of splices. Consider the following
-- example:
--
-- >
-- >
-- > ...
-- >
-- >
--
-- Assume that @\"foo\"@ is bound to a splice procedure. Running the @foo@
-- splice will result in a list of nodes @L@. Normally @foo@ will recursively
-- scan @L@ for splices and run them. If @foo@ calls @stopRecursion@, @L@
-- will be included in the output verbatim without running any splices.
stopRecursion :: Monad m => TemplateMonad m ()
stopRecursion = modifyTS (\st -> st { _recurse = False })
------------------------------------------------------------------------------
-- | Sets the current context
setContext :: Monad m => TPath -> TemplateMonad m ()
setContext c = modifyTS (\st -> st { _curContext = c })
------------------------------------------------------------------------------
-- | Gets the current context
getContext :: Monad m => TemplateMonad m TPath
getContext = getsTS _curContext
------------------------------------------------------------------------------
-- | Performs splice processing on a single node.
runNode :: Monad m => Node -> Splice m
runNode n@(X.Text _) = return [n]
runNode n@(X.Element nm at ch) = do
s <- liftM (lookupSplice nm) getTS
maybe runChildren (recurseSplice n) s
where
runChildren = do
newKids <- runNodeList ch
newAtts <- mapM attSubst at
return [X.Element nm newAtts newKids]
------------------------------------------------------------------------------
-- | Helper function for substituting a parsed attribute into an attribute
-- tuple.
attSubst :: (Monad m) => (t, ByteString) -> TemplateMonad m (t, ByteString)
attSubst (n,v) = do
v' <- parseAtt v
return (n,v')
------------------------------------------------------------------------------
-- | Parses an attribute for any identifier expressions and performs
-- appropriate substitution.
parseAtt :: (Monad m) => ByteString -> TemplateMonad m ByteString
parseAtt bs = do
let ast = case AP.feed (AP.parse attParser bs) "" of
(AP.Fail _ _ _) -> []
(AP.Done _ res) -> res
(AP.Partial _) -> []
chunks <- mapM cvt ast
return $ B.concat chunks
where
cvt (Literal x) = return x
cvt (Ident x) = getAttributeSplice x
------------------------------------------------------------------------------
-- | AST to hold attribute parsing structure. This is necessary because
-- attoparsec doesn't support parsers running in another monad.
data AttAST = Literal ByteString |
Ident ByteString
deriving (Show)
------------------------------------------------------------------------------
-- | Parser for attribute variable substitution.
attParser :: AP.Parser [AttAST]
attParser = AP.many1 (identParser <|> litParser)
where
escChar = (AP.char '\\' *> AP.anyChar) <|>
AP.satisfy (AP.notInClass "\\$")
litParser = Literal <$> (B.pack <$> AP.many1 escChar)
identParser = AP.string "$(" *>
(Ident <$> AP.takeWhile (/=')')) <* AP.string ")"
------------------------------------------------------------------------------
-- | Get's the attribute value. If the splice's result list contains non-text
-- nodes, this will translate them into text nodes with textContent and
-- concatenate them together.
--
-- Originally, this only took the first node from the splices's result list,
-- and only if it was a text node. This caused problems when the splice's
-- result contained HTML entities, as they would split a text node. This was
-- then fixed to take the first consecutive bunch of text nodes, and return
-- their concatenation. This was seen as more useful than throwing an error,
-- and more intuitive than trying to render all the nodes as text.
--
-- However, it was decided in the end to render all the nodes as text, and
-- then concatenate them. If a splice returned
-- \"some \text\<\/b\> foobar\", the user would almost certainly want
-- \"some text foobar\" to be rendered, and Heist would probably seem
-- annoyingly limited for not being able to do this. If the user really did
-- want it to render \"some \", it would probably be easier for them to
-- accept that they were silly to pass more than that to be substituted than
-- it would be for the former user to accept that
-- \"some \text\<\/b\> foobar\" is being rendered as \"some \" because
-- it's \"more intuitive\".
getAttributeSplice :: Monad m => ByteString -> TemplateMonad m ByteString
getAttributeSplice name = do
s <- liftM (lookupSplice name) getTS
nodes <- maybe (return []) id s
return $ B.concat $ map X.textContent nodes
------------------------------------------------------------------------------
-- | Performs splice processing on a list of nodes.
runNodeList :: Monad m => [Node] -> Splice m
runNodeList nodes = liftM concat $ sequence (map runNode nodes)
------------------------------------------------------------------------------
-- | The maximum recursion depth. (Used to prevent infinite loops.)
mAX_RECURSION_DEPTH :: Int
mAX_RECURSION_DEPTH = 50
------------------------------------------------------------------------------
-- | Checks the recursion flag and recurses accordingly. Does not recurse
-- deeper than mAX_RECURSION_DEPTH to avoid infinite loops.
recurseSplice :: Monad m => Node -> Splice m -> Splice m
recurseSplice node splice = do
result <- localParamNode (const node) splice
ts' <- getTS
if _recurse ts' && _recursionDepth ts' < mAX_RECURSION_DEPTH
then do modRecursionDepth (+1)
res <- runNodeList result
restoreState ts'
return res
else return result
where
modRecursionDepth :: Monad m => (Int -> Int) -> TemplateMonad m ()
modRecursionDepth f =
modifyTS (\st -> st { _recursionDepth = f (_recursionDepth st) })
------------------------------------------------------------------------------
-- | Looks up a template name runs a TemplateMonad computation on it.
lookupAndRun :: Monad m
=> ByteString
-> ((InternalTemplate, TPath) -> TemplateMonad m (Maybe a))
-> TemplateMonad m (Maybe a)
lookupAndRun name k = do
ts <- getTS
maybe (return Nothing) k
(lookupTemplate name ts)
------------------------------------------------------------------------------
-- | Looks up a template name evaluates it by calling runNodeList.
evalTemplate :: Monad m
=> ByteString
-> TemplateMonad m (Maybe Template)
evalTemplate name = lookupAndRun name
(\(t,ctx) -> do
ts <- getTS
putTS (ts {_curContext = ctx})
res <- runNodeList $ _itNodes t
restoreState ts
return $ Just res)
------------------------------------------------------------------------------
-- | Looks up a template name evaluates it by calling runNodeList. This also
-- executes pre- and post-run hooks and adds the doctype.
evalWithHooks :: Monad m
=> ByteString
-> TemplateMonad m (Maybe Template)
evalWithHooks name = lookupAndRun name
(\(t,ctx) -> do
addDoctype $ maybeToList $ _itDoctype t
ts <- getTS
nodes <- lift $ _preRunHook ts $ _itNodes t
putTS (ts {_curContext = ctx})
res <- runNodeList nodes
restoreState ts
return . Just =<< lift (_postRunHook ts res))
------------------------------------------------------------------------------
-- | Binds a list of constant string splices
bindStrings :: Monad m
=> [(ByteString, ByteString)]
-> TemplateState m
-> TemplateState m
bindStrings pairs ts = foldr add ts pairs
where
add (n,v) = bindSplice n (return [X.Text v])
------------------------------------------------------------------------------
-- | Renders a template with the specified parameters. This is the function
-- to use when you want to "call" a template and pass in parameters from code.
callTemplate :: Monad m
=> ByteString -- ^ The name of the template
-> [(ByteString, ByteString)] -- ^ Association list of
-- (name,value) parameter pairs
-> TemplateMonad m (Maybe Template)
callTemplate name params = do
modifyTS $ bindStrings params
evalTemplate name
------------------------------------------------------------------------------
-- | Converts a Template to an InternalTemplate. This can only be done inside
-- TemplateMonad where the doctype is available.
toInternalTemplate :: Monad m => Template -> TemplateMonad m InternalTemplate
toInternalTemplate t = do
dts <- getsTS _doctypes
return $ InternalTemplate {
_itDoctype = listToMaybe dts,
_itNodes = t
}
------------------------------------------------------------------------------
-- | Renders an internal template by prepending the appropriate doctype.
renderInternal :: Monad m => InternalTemplate -> TemplateMonad m ByteString
renderInternal (InternalTemplate dt nodes) =
return $ maybe bs (flip B.append bs) dt
where
bs = formatList' nodes
------------------------------------------------------------------------------
-- | Renders a template from the specified TemplateState.
renderTemplate :: Monad m
=> TemplateState m
-> ByteString
-> m (Maybe ByteString)
renderTemplate ts name = do
evalTemplateMonad
(do mt <- evalWithHooks name
maybe (return Nothing)
(\t -> liftM Just $ renderInternal =<< toInternalTemplate t)
mt
) (X.Text "") ts
------------------------------------------------------------------------------
-- Template loading
------------------------------------------------------------------------------
-- | Turns an in-memory XML/XHTML bytestring into a (doctype,'[Node]') pair.
parseDoc :: ByteString -> IO (Either String (Maybe ByteString,[Node]))
parseDoc bs = do
let (doctype,rest) = extractDoctype bs
let wrap b = B.concat ["\n", b, "\n"]
return $
mapRight (\n -> (doctype,X.getChildren n)) $
mapLeft genErrorMsg $
X.parse' heistExpatOptions (wrap rest)
where
genErrorMsg (X.XMLParseError str loc) = locMsg loc ++ ": " ++ translate str
locMsg (X.XMLParseLocation line col _ _) =
"(line " ++ show (line-1) ++ ", col " ++ show col ++ ")"
translate "junk after document element" = "document must have a single root element"
translate s = s
-- | Reads an XML document from disk.
getDoc :: String -> IO (Either String InternalTemplate)
getDoc f = do
bs <- catch (liftM Right $ B.readFile f)
(\(e::SomeException) -> return $ Left $ show e)
d' <- either (return . Left)
parseDoc
bs
let d = mapLeft (\s -> f ++ " " ++ s) d'
return $ either Left
(\(doctype, nodes) -> Right $ InternalTemplate {
_itDoctype = doctype,
_itNodes = nodes
})
d
------------------------------------------------------------------------------
-- | Checks whether the bytestring has a doctype.
hasDoctype :: ByteString -> Bool
hasDoctype bs = " (Maybe ByteString, ByteString)
extractDoctype bs =
if hasDoctype bs
then (Just $ B.snoc (B.takeWhile p bs) '>',B.tail $ B.dropWhile p bs)
else (Nothing, bs)
where
p = (/='>')
------------------------------------------------------------------------------
mapLeft :: (a -> b) -> Either a c -> Either b c
mapLeft g = either (Left . g) Right
mapRight :: (b -> c) -> Either a b -> Either a c
mapRight g = either Left (Right . g)
------------------------------------------------------------------------------
-- | Loads a template with the specified path and filename. The
-- template is only loaded if it has a ".tpl" extension.
loadTemplate :: String -- ^ path of the template root
-> String -- ^ full file path (includes the template root)
-> IO [Either String (TPath, InternalTemplate)] --TemplateMap
loadTemplate templateRoot fname
| ".tpl" `isSuffixOf` fname = do
c <- getDoc fname
return [fmap (\t -> (splitLocalPath $ B.pack tName, t)) c]
| otherwise = return []
where -- tName is path relative to the template root directory
correction = if last templateRoot == '/' then 0 else 1
tName = drop ((length templateRoot)+correction) $
-- We're only dropping the template root, not the whole path
take ((length fname) - 4) fname
------------------------------------------------------------------------------
-- | Traverses the specified directory structure and builds a
-- TemplateState by loading all the files with a ".tpl" extension.
loadTemplates :: Monad m => FilePath -> TemplateState m -> IO (Either String (TemplateState m))
loadTemplates dir ts = do
d <- readDirectoryWith (loadTemplate dir) dir
let tlist = F.fold (free d)
errs = lefts tlist
case errs of
[] -> liftM Right $ foldM loadHook ts $ rights tlist
_ -> return $ Left $ unlines errs
------------------------------------------------------------------------------
-- | Reversed list of directories. This holds the path to the template
runHookInternal :: Monad m => (Template -> m Template)
-> InternalTemplate
-> m InternalTemplate
runHookInternal f t = do
n <- f $ _itNodes t
return $ t { _itNodes = n }
------------------------------------------------------------------------------
-- | Runs the onLoad hook on the template and returns the `TemplateState`
-- with the result inserted.
loadHook :: Monad m => TemplateState m -> (TPath, InternalTemplate) -> IO (TemplateState m)
loadHook ts (tp, t) = do
t' <- runHookInternal (_onLoadHook ts) t
return $ insertTemplate tp t' ts
------------------------------------------------------------------------------
-- These are here until we can get them into hexpat.
------------------------------------------------------------------------------
formatList :: (X.GenericXMLString tag, X.GenericXMLString text) =>
[X.Node tag text]
-> L.ByteString
formatList nodes = foldl L.append L.empty $ map formatNode nodes
formatList' :: (X.GenericXMLString tag, X.GenericXMLString text) =>
[X.Node tag text]
-> B.ByteString
formatList' = B.concat . L.toChunks . formatList