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module Text.Hakyll.Page
( Page
, fromContext
, getValue
, getBody
, readPage
) where
import qualified Data.Map as M
import qualified Data.List as L
import Data.Maybe (fromMaybe)
import Control.Parallel.Strategies (rdeepseq, ($|))
import Control.Monad.Reader (liftIO)
import System.FilePath (takeExtension)
import System.IO
import Text.Pandoc
import Text.Hakyll.Hakyll (Hakyll)
import Text.Hakyll.File
import Text.Hakyll.Util (trim)
import Text.Hakyll.Context (Context)
import Text.Hakyll.Renderable
import Text.Hakyll.Regex (substituteRegex, matchesRegex)
-- | A Page is basically key-value mapping. Certain keys have special
-- meanings, like for example url, body and title.
data Page = Page Context
-- | Create a Page from a key-value mapping.
fromContext :: Context -> Page
fromContext = Page
-- | Obtain a value from a page. Will resturn an empty string when nothing is
-- found.
getValue :: String -> Page -> String
getValue str (Page page) = fromMaybe [] $ M.lookup str page
-- | Get the URL for a certain page. This should always be defined. If
-- not, it will error.
getPageURL :: Page -> String
getPageURL (Page page) = fromMaybe (error "No page url") $ M.lookup "url" page
-- | Get the original page path.
getPagePath :: Page -> String
getPagePath (Page page) =
fromMaybe (error "No page path") $ M.lookup "path" page
-- | Get the body for a certain page. When not defined, the body will be
-- empty.
getBody :: Page -> String
getBody (Page page) = fromMaybe [] $ M.lookup "body" page
-- | The default reader options for pandoc parsing.
readerOptions :: ParserState
readerOptions = defaultParserState { stateSmart = True }
-- | The default writer options for pandoc rendering.
writerOptions :: WriterOptions
writerOptions = defaultWriterOptions
-- | Get a render function for a given extension.
getRenderFunction :: String -> (String -> String)
getRenderFunction ".html" = id
getRenderFunction ext = writeHtmlString writerOptions
. readFunction ext readerOptions
where
readFunction ".rst" = readRST
readFunction ".tex" = readLaTeX
readFunction _ = readMarkdown
-- | Split a page into sections.
splitAtDelimiters :: [String] -> [[String]]
splitAtDelimiters [] = []
splitAtDelimiters ls@(x:xs)
| isDelimiter x = let (content, rest) = break isDelimiter xs
in (x : content) : splitAtDelimiters rest
| otherwise = [ls]
-- | Check if the given string is a metadata delimiter.
isDelimiter :: String -> Bool
isDelimiter = L.isPrefixOf "---"
-- | Used for caching of files.
cachePage :: Page -> Hakyll ()
cachePage page@(Page mapping) = do
makeDirectories destination
liftIO writePageToCache
where
(sectionMetaData, simpleMetaData) = M.partition (elem '\n')
(M.delete "body" mapping)
writePageToCache = do
handle <- openFile destination WriteMode
hPutStrLn handle "---"
mapM_ (writePair handle) $ M.toList simpleMetaData
mapM_ (writeSection handle) $ M.toList sectionMetaData
hPutStrLn handle "---"
hPutStrLn handle $ getBody page
hClose handle
writePair h (k, v) = do hPutStr h $ k ++ ": " ++ v
hPutStrLn h ""
writeSection h (k, v) = do hPutStrLn h $ "--- " ++ k
hPutStrLn h v
destination = toCache $ getURL page
-- | Read one section of a page.
readSection :: (String -> String) -- ^ Render function.
-> Bool -- ^ If this section is the first section in the page.
-> [String] -- ^ Lines in the section.
-> [(String, String)] -- ^ Key-values extracted.
readSection _ _ [] = []
readSection renderFunction isFirst ls
| not isDelimiter' = body ls
| isNamedDelimiter = readSectionMetaData ls
| isFirst = readSimpleMetaData (tail ls)
| otherwise = body (tail ls)
where
isDelimiter' = isDelimiter (head ls)
isNamedDelimiter = (head ls) `matchesRegex` "----* *[a-zA-Z][a-zA-Z]*"
body ls' = [("body", renderFunction $ unlines ls')]
readSimpleMetaData = map readPair
readPair = (trimPair . break (== ':'))
trimPair (key, value) = (trim key, trim $ tail value)
readSectionMetaData [] = []
readSectionMetaData (header:value) =
let key = substituteRegex "[^a-zA-Z]" "" header
in [(key, renderFunction $ unlines value)]
-- | Read a page from a file. Metadata is supported, and if the filename
-- has a @.markdown@ extension, it will be rendered using pandoc.
readPage :: FilePath -> Hakyll Page
readPage pagePath = do
-- Check cache.
getFromCache <- isCacheValid cacheFile [pagePath]
let path = if getFromCache then cacheFile else pagePath
renderFunction = getRenderFunction $ takeExtension path
sectionFunctions = map (readSection renderFunction)
(True : repeat False)
-- Read file.
handle <- liftIO $ openFile path ReadMode
sections <- fmap (splitAtDelimiters . lines )
(liftIO $ hGetContents handle)
let context = concat $ zipWith ($) sectionFunctions sections
page = fromContext $ M.fromList $
[ ("url", url)
, ("path", pagePath)
] ++ context
seq (($|) id rdeepseq context) $ liftIO $ hClose handle
-- Cache if needed
if getFromCache then return () else cachePage page
return page
where
url = toURL pagePath
cacheFile = toCache url
-- Make pages renderable.
instance Renderable Page where
getDependencies = (:[]) . getPagePath
getURL = getPageURL
toContext (Page page) = return page
|
