63 lines
1.7 KiB
Haskell
63 lines
1.7 KiB
Haskell
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-- | Module providing a function to parse a page from a file
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--
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module Hakyll.Web.Page.Read
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( readPage
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) where
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import Control.Applicative ((<$>), (<*>))
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import Control.Arrow (second, (***))
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import Control.Monad.State
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import Data.List (isPrefixOf)
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import Data.Map (Map)
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import qualified Data.Map as M
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import Hakyll.Web.Page
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import Hakyll.Web.Util.String
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-- | We're using a simple state monad as parser
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--
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type LineParser = State [String]
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-- | Check if the given string is a metadata delimiter.
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--
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isPossibleDelimiter :: String -> Bool
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isPossibleDelimiter = isPrefixOf "---"
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-- | Read the metadata section from a page
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--
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parseMetadata :: LineParser (Map String String)
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parseMetadata = get >>= \content -> case content of
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-- No lines means no metadata
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[] -> return M.empty
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-- Check if the file begins with a delimiter
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(l : ls) -> if not (isPossibleDelimiter l)
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then -- No delimiter means no body
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return M.empty
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else do -- Break the metadata section
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let (metadata, rest) = second (drop 1) $ break (== l) ls
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-- Put the rest back
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put rest
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-- Parse the metadata
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return $ M.fromList $ map parseMetadata' metadata
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where
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parseMetadata' :: String -> (String, String)
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parseMetadata' = (trim *** trim . drop 1) . break (== ':')
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-- | Read the body section of a page
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--
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parseBody :: LineParser String
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parseBody = do
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body <- get
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put []
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return $ unlines body
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-- | Read an entire page
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--
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parsePage :: LineParser (Page String)
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parsePage = Page <$> parseMetadata <*> parseBody
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-- | Read a page from a string
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--
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readPage :: String -> Page String
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readPage = evalState parsePage . lines
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