136 lines
3.6 KiB
Haskell
136 lines
3.6 KiB
Haskell
{-|
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Module : SubFix
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Description : core functions for subfix
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Copyright : (C) Jonathan Lamothe
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License : GPL-3
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Maintainer : jonathan@jlamothe.net
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at
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your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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-}
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{-# LANGUAGE LambdaCase, RecordWildCards #-}
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module SubFix (
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-- * Data Types
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Caption (..),
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-- * Functions
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convert,
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decode,
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encode,
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) where
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import Control.Monad.Trans.Class (lift)
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import Control.Monad.Trans.State (StateT, evalStateT, get, put)
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import Data.Char (chr)
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import SubFix.Internal (decodeTime)
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-- | Defines a caption group
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data Caption = Caption
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{ capID :: Int
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-- ^ The caption identifier
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, capStart :: Integer
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-- ^ The caption start time (in milliseconds)
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, capEnd :: Integer
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-- ^ The caption end time (in milliseconds)
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, capText :: String
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-- ^ The caption text
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} deriving (Eq, Show)
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-- | Applies the transformations to a caption group
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convert :: Caption -> Caption
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convert c = c { capText = editText $ capText c }
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-- | Decodes the text of a subtitle file
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decode
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:: String
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-- ^ The encoded text
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-> Either String [Caption]
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-- ^ The resulting caption list, or a message describing the error
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-- that occured.
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decode = evalStateT decodeLoop . lines
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-- | Encodes a list of caption groups
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encode :: [Caption] -> String
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encode = undefined
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editText :: String -> String
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editText = checkCaret . checkNotes
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checkCaret :: String -> String
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checkCaret ('^' : str) = "{\\an8}" ++ str
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checkCaret str = str
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checkNotes :: String -> String
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checkNotes "" = ""
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checkNotes ('#' : '#' : str) = chr 0x2669 : checkNotes str
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checkNotes (ch : str) = ch : checkNotes str
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decodeLoop :: StateT [String] (Either String) [Caption]
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decodeLoop = get >>= \case
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[] -> return []
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_ -> do
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caption <- decodeNextCaption
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captions <- decodeLoop
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return $ caption : captions
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decodeNextCaption :: StateT [String] (Either String) Caption
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decodeNextCaption = do
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capID <- decodeID
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(capStart, capEnd) <- decodeTimes
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capText <- decodeText
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return $ Caption {..}
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decodeID :: StateT [String] (Either String) Int
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decodeID = do
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line <- nextLine
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case reads line of
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[(val, "")] -> return val
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_ -> lift $ Left "invalid caption ID"
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decodeTimes :: StateT [String] (Either String) (Integer, Integer)
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decodeTimes = do
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line <- nextLine
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case words line of
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[startStr, "-->", endStr] -> do
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start <- case decodeTime startStr of
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Just (val, "") -> return val
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_ -> lift $ Left "invalid start time"
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end <- case decodeTime endStr of
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Just (val, "") -> return val
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_ -> lift $ Left "invalid end time"
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return (start, end)
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_ -> lift $ Left "invalid time signature"
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decodeText :: StateT [String] (Either String) String
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decodeText = get >>= \case
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[] -> return ""
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_ -> do
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line <- nextLine
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if line == ""
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then return ""
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else do
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next <- decodeText
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return $ line ++ "\n" ++ next
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nextLine :: StateT [String] (Either String) String
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nextLine = get >>= \case
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(line : remaining) -> do
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put remaining
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return line
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[] -> lift $ Left "missing line"
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--jl
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