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|
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{- |
Module : Text.Pandoc.Readers.Metadata
Copyright : Copyright (C) 2006-2021 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
Parse YAML/JSON metadata to 'Pandoc' 'Meta'.
-}
module Text.Pandoc.Readers.Metadata (
yamlBsToMeta,
yamlBsToRefs,
yamlMetaBlock,
yamlMap ) where
import Control.Monad.Except (throwError)
import qualified Data.ByteString as B
import qualified Data.Map as M
import Data.Text (Text)
import qualified Data.Text as T
import qualified Data.Yaml as Yaml
import Data.Aeson (Value(..), Object, Result(..), fromJSON, (.:?), withObject)
import Data.Aeson.Types (parse)
import Text.Pandoc.Shared (tshow)
import Text.Pandoc.Class.PandocMonad (PandocMonad (..))
import Text.Pandoc.Definition hiding (Null)
import Text.Pandoc.Error
import Text.Pandoc.Parsing hiding (tableWith, parse)
import qualified Text.Pandoc.UTF8 as UTF8
yamlBsToMeta :: (PandocMonad m, HasLastStrPosition st)
=> ParserT Sources st m (Future st MetaValue)
-> B.ByteString
-> ParserT Sources st m (Future st Meta)
yamlBsToMeta pMetaValue bstr = do
case Yaml.decodeAllEither' bstr of
Right (Object o:_) -> fmap Meta <$> yamlMap pMetaValue o
Right [Null] -> return . return $ mempty
Right _ -> Prelude.fail "expected YAML object"
Left err' -> do
throwError $ PandocParseError
$ T.pack $ Yaml.prettyPrintParseException err'
-- Returns filtered list of references.
yamlBsToRefs :: (PandocMonad m, HasLastStrPosition st)
=> ParserT Sources st m (Future st MetaValue)
-> (Text -> Bool) -- ^ Filter for id
-> B.ByteString
-> ParserT Sources st m (Future st [MetaValue])
yamlBsToRefs pMetaValue idpred bstr =
case Yaml.decodeEither' bstr of
Right (Object m) -> do
let isSelected (String t) = idpred t
isSelected _ = False
let hasSelectedId (Object o) =
case parse (withObject "ref" (.:? "id")) (Object o) of
Success (Just id') -> isSelected id'
_ -> False
hasSelectedId _ = False
case parse (withObject "metadata" (.:? "references")) (Object m) of
Success (Just refs) -> sequence <$>
mapM (yamlToMetaValue pMetaValue) (filter hasSelectedId refs)
_ -> return $ return []
Right _ -> return . return $ []
Left err' -> do
throwError $ PandocParseError
$ T.pack $ Yaml.prettyPrintParseException err'
normalizeMetaValue :: (PandocMonad m, HasLastStrPosition st)
=> ParserT Sources st m (Future st MetaValue)
-> Text
-> ParserT Sources st m (Future st MetaValue)
normalizeMetaValue pMetaValue x =
-- Note: a standard quoted or unquoted YAML value will
-- not end in a newline, but a "block" set off with
-- `|` or `>` will.
if "\n" `T.isSuffixOf` T.dropWhileEnd isSpaceChar x -- see #6823
then parseFromString' pMetaValue (x <> "\n")
else parseFromString' asInlines x
where asInlines = fmap b2i <$> pMetaValue
b2i (MetaBlocks [Plain ils]) = MetaInlines ils
b2i (MetaBlocks [Para ils]) = MetaInlines ils
b2i bs = bs
isSpaceChar ' ' = True
isSpaceChar '\t' = True
isSpaceChar _ = False
yamlToMetaValue :: (PandocMonad m, HasLastStrPosition st)
=> ParserT Sources st m (Future st MetaValue)
-> Value
-> ParserT Sources st m (Future st MetaValue)
yamlToMetaValue pMetaValue v =
case v of
String t -> normalizeMetaValue pMetaValue t
Bool b -> return $ return $ MetaBool b
Number d -> normalizeMetaValue pMetaValue $
case fromJSON v of
Success (x :: Int) -> tshow x
_ -> tshow d
Null -> return $ return $ MetaString ""
Array{} -> do
case fromJSON v of
Error err' -> throwError $ PandocParseError $ T.pack err'
Success xs -> fmap MetaList . sequence <$>
mapM (yamlToMetaValue pMetaValue) xs
Object o -> fmap MetaMap <$> yamlMap pMetaValue o
yamlMap :: (PandocMonad m, HasLastStrPosition st)
=> ParserT Sources st m (Future st MetaValue)
-> Object
-> ParserT Sources st m (Future st (M.Map Text MetaValue))
yamlMap pMetaValue o = do
case fromJSON (Object o) of
Error err' -> throwError $ PandocParseError $ T.pack err'
Success (m' :: M.Map Text Value) -> do
let kvs = filter (not . ignorable . fst) $ M.toList m'
fmap M.fromList . sequence <$> mapM toMeta kvs
where
ignorable t = "_" `T.isSuffixOf` t
toMeta (k, v) = do
fv <- yamlToMetaValue pMetaValue v
return $ do
v' <- fv
return (k, v')
-- | Parse a YAML metadata block using the supplied 'MetaValue' parser.
yamlMetaBlock :: (HasLastStrPosition st, PandocMonad m)
=> ParserT Sources st m (Future st MetaValue)
-> ParserT Sources st m (Future st Meta)
yamlMetaBlock parser = try $ do
string "---"
blankline
notFollowedBy blankline -- if --- is followed by a blank it's an HRULE
rawYamlLines <- manyTill anyLine stopLine
-- by including --- and ..., we allow yaml blocks with just comments:
let rawYaml = T.unlines ("---" : (rawYamlLines ++ ["..."]))
optional blanklines
yamlBsToMeta parser $ UTF8.fromText rawYaml
stopLine :: Monad m => ParserT Sources st m ()
stopLine = try $ (string "---" <|> string "...") >> blankline >> return ()
|
