89e1a05a8f
As long as all code imports Utility.Aeson rather than Data.Aeson, and no Strings that may contain utf-8 characters are used for eg, object keys via T.pack, this is guaranteed to fix the problem everywhere that git-annex generates json. It's kind of annoying to need to wrap ToJSON with a ToJSON', especially since every data type that has a ToJSON instance has to be ported over. However, that only took 50 lines of code, which is worth it to ensure full coverage. I initially tried an alternative approach of a newtype FileEncoded, which had to be used everywhere a String was fed into aeson, and chasing down all the sites would have been far too hard. Did consider creating an intentionally overlapping instance ToJSON String, and letting ghc fail to build anything that passed in a String, but am not sure that wouldn't pollute some library that git-annex depends on that happens to use ToJSON String internally. This commit was supported by the NSF-funded DataLad project.
86 lines
2.5 KiB
Haskell
86 lines
2.5 KiB
Haskell
{- 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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