-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Print current MPD song and status as JSON
--
-- Print currently playing MPD's song metadata and status as JSON
@package mpd-current-json
@version 1.5.0.1
module Network.MPD.Parse
-- | Extract a field from the returned MPD.Status data record.
--
-- Helper to extract a specific field from the Network.MPD.Status
-- data record by providing the corresponding field label. If the input
-- status "st" is not Right a, indicating an
-- error, or the field label function is not applicable, it returns
-- Nothing.
--
-- Example:
--
--
-- ghci> import qualified Network.MPD as MPD
-- ghci> st <- MPD.withMPD MPD.status
-- ghci> getStatusField st MPD.stVolume
--
--
-- Just (Just 100)
getStatusField :: Response Status -> (Status -> a) -> Maybe a
-- | Go a level deeper than getStatusField. For nested Maybe
-- a fields from Status.
--
-- Example:
--
--
-- ghci> import qualified Network.MPD as MPD
-- ghci> st <- MPD.withMPD MPD.status
-- ghci> getStatusFieldElement st MPD.stVolume
--
--
-- Just 100
getStatusFieldElement :: Response Status -> (Status -> Maybe a) -> Maybe a
-- | Either check for the returned value of currentSong,
-- then call processSong or return Nothing.
getTag :: Metadata -> Either a (Maybe Song) -> Maybe String
-- | Use sgGetTag to extract a tag from a song,
-- safely get only the head item of the returned Maybe list,
-- then safely convert it to a string.
processSong :: Metadata -> Maybe Song -> Maybe String
-- | Get the current Song relative path with sgFilePath
maybePathCurrentSong :: Response (Maybe Song) -> Maybe String
-- | Get the next song's relative path in the current playlist.
--
-- Using sgFilePath from the returned Response
-- [Song].
maybePathNextPlaylistSong :: Response [Song] -> Maybe String
-- | Safely get the head of a list. Same as Safe.headMay.
headMay :: [a] -> Maybe a
-- | Convert Value to String within a Maybe
-- context.
--
-- This Value is from MPD and is basically the same as a
-- String but used internally to store metadata values.
--
-- Example:
--
--
-- processSong :: Metadata -> Maybe Song -> Maybe String
-- processSong _ Nothing = Nothing
-- processSong tag (Just song) = do
-- let tagVal = MPD.sgGetTag tag song
-- valueToStringMay =<< (headMay =<< tagVal)
--
--
-- sgGetTag returns a Maybe [Value]. libmpd also
-- provides toString that can convert, along other types, a
-- Value to a String.
valueToStringMay :: Value -> Maybe String
-- | Check if Maybe v exists and is of type expected by
-- object as defined in Value, if it is return both the
-- key and value within the Maybe context tied
-- with .=. This gives support to 'optional' fields using
-- catMaybes that discard Nothing values and is meant to
-- prevent creating JSON key/value pairs with null values, e.g.:
--
--
-- jsonTags = object . catMaybes $
-- [ "artist" .=? artist
-- , "album" .=? album
-- , "title" .=? title
-- ]
--
--
-- Where if a value on the right is Nothing that key/value pair
-- will not be included in object because of catMaybes.
(.=?) :: (KeyValue e a, ToJSON v) => Key -> Maybe v -> Maybe a
-- | Helper function for creating an JSON object where
-- catMaybes won't include items from the '[Maybe Pair]' list that
-- return Nothing.
objectJson :: [Maybe Pair] -> Value
-- | Extracts the Int value from an Id within Status,
-- if present and the Either value is a Right.
getStatusIdInt :: (Status -> Maybe Id) -> Either MPDError Status -> Maybe Int