-- |
-- Module : Text.Subtitles.SRT
-- Copyright : Ruben Astudillo 2012
-- License : BSD3
--
-- Maintainer : ruben.astud@gmail.com
-- Portability : unknown
--
-- A basic parser for .srt files (subtitles) based on 'Attoparsec' and 'Text'
module Text.Subtitles.SRT
(
-- * Terminology of the module
-- $example
-- * Re-exported Datatypes
module Text.Subtitles.SRT.Datatypes,
-- * Main parsers
parseSRT,
parseSingleLine
) where
import Prelude hiding (takeWhile)
import Control.Applicative
import Data.Attoparsec.Text
import qualified Data.Text as T
-- in project modules
import Text.Subtitles.SRT.Datatypes
-- $example
--
-- All the sections of a Line have their corresponding ADT in
-- "Text.Subtitles.SRT.Datatypes"
--
-- >2
-- >00:00:50,050 --> 00:00:52,217
-- >Drama here
--
-- The whole Line is represented in the 'Line' ADT which constructors
-- represented by different ADTs
--
-- * The first line is called index, which is the first constructor of
-- 'Line'.
--
-- * The second one is called 'Range', which correspond to two separated 'Time'.
--
-- * The last one is the 'subs'. which is just Text and correspond to the third
-- constructor of 'Line'.
-- |Main Parser, gives you a list of all the Lines of the subtitle. It fails if
-- the subtitle doesn't have any Lines.
parseSRT :: Parser Subtitles
parseSRT = many1 parseSingleLine
-- |The individual Line parser. given the upper example return the
-- corresponding Line representation
parseSingleLine :: Parser Line
parseSingleLine =
Line <$> parseIndex <*> parseRange <* eol <*> parseDialog T.empty
parseIndex :: Parser Int
parseIndex = decimal <* eol
eol :: Parser ()
eol = endOfLine
{- Is clear that this just aplies parseTime breaking down the "-->" string -}
parseRange :: Parser Range
parseRange = Range <$> parseTime <* arrowString <*> parseTime
where
arrowString :: Parser Text
arrowString = string (T.pack " --> ")
parseTime :: Parser Time
parseTime = Time <$> numDot <*> numDot <*> decimal <* char ',' <*> decimal
where
numDot :: Parser Int
numDot = decimal <* char ':'
{- return the dialog checking for newlines that could be in there. that why is
- written in a monad instead of applicative. more efficient version welcome -}
parseDialog :: Text -> Parser Text
parseDialog t = do
line <- takeWhile1 (not . isEndOfLine)
endOfLine
let lineState = T.append t (T.snoc line '\n')
next <- anyChar
case next of
'\n' -> return lineState
_ -> parseDialog (T.snoc lineState next)