87 lines
2.5 KiB
Haskell
87 lines
2.5 KiB
Haskell
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{- GHC File system encoding support for Aeson.
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-
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- Import instead of Data.Aeson
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-
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- Copyright 2018 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# LANGUAGE FlexibleInstances, TypeSynonymInstances #-}
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module Utility.Aeson (
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module X,
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ToJSON'(..),
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encode,
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packString,
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) where
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import Data.Aeson as X hiding (ToJSON, toJSON, encode)
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import Data.Aeson hiding (encode)
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import qualified Data.Aeson
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import qualified Data.Text as T
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import qualified Data.Text.Encoding as T
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import qualified Data.ByteString.Lazy as L
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import qualified Data.ByteString as S
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import qualified Data.Set
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import qualified Data.Vector
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import Prelude
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import Utility.FileSystemEncoding
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-- | Use this instead of Data.Aeson.encode to make sure that the
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-- below String instance is used.
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encode :: ToJSON' a => a -> L.ByteString
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encode = Data.Aeson.encode . toJSON'
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-- | Aeson has an unfortunate ToJSON instance for Char and [Char]
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-- which does not support Strings containing UTF8 characters
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-- encoded using the filesystem encoding when run in a non-utf8 locale.
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--
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-- Since we can't replace that with a instance that does the right
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-- thing, instead here's a new class that handles String right.
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class ToJSON' a where
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toJSON' :: a -> Value
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instance ToJSON' String where
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toJSON' = toJSON . packString
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-- | Pack a String to Text, correctly handling the filesystem encoding.
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--
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-- Use this instead of Data.Text.pack.
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--
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-- Note that if the string contains invalid UTF8 characters not using
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-- the FileSystemEncoding, this is the same as Data.Text.pack.
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packString :: String -> T.Text
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packString s = case T.decodeUtf8' (S.concat $ L.toChunks $ encodeBS s) of
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Right t -> t
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Left _ -> T.pack s
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-- | An instance for lists cannot be included as it would overlap with
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-- the String instance. Instead, you can use a Vector.
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instance ToJSON' s => ToJSON' (Data.Vector.Vector s) where
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toJSON' = toJSON . map toJSON' . Data.Vector.toList
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-- Aeson generates the same JSON for a Set as for a list.
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instance ToJSON' s => ToJSON' (Data.Set.Set s) where
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toJSON' = toJSON . map toJSON' . Data.Set.toList
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instance (ToJSON' a, ToJSON a) => ToJSON' (Maybe a) where
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toJSON' (Just a) = toJSON (Just (toJSON' a))
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toJSON' v@Nothing = toJSON v
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instance (ToJSON' a, ToJSON a, ToJSON' b, ToJSON b) => ToJSON' (a, b) where
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toJSON' (a, b) = toJSON ((toJSON' a, toJSON' b))
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instance ToJSON' Bool where
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toJSON' = toJSON
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instance ToJSON' Integer where
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toJSON' = toJSON
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instance ToJSON' Object where
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toJSON' = toJSON
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instance ToJSON' Value where
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toJSON' = toJSON
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