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Main.hs
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Main.hs
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{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE OverloadedStrings #-}
module Main where
import Control.Applicative ((<|>), optional)
import Control.Exception (SomeException)
import Data.Aeson (Value)
import Data.Monoid ((<>))
import Data.Version (showVersion)
import Dhall.JSON (Conversion, SpecialDoubleMode(..))
import Options.Applicative (Parser, ParserInfo)
import qualified Control.Exception
import qualified Data.Aeson
import qualified Data.Aeson.Encode.Pretty
import qualified Data.ByteString.Lazy
import qualified Data.Text.IO as Text.IO
import qualified Dhall
import qualified Dhall.JSON
import qualified GHC.IO.Encoding
import qualified Options.Applicative as Options
import qualified Paths_dhall_json as Meta
import qualified System.Exit
import qualified System.IO
data Options
= Options
{ explain :: Bool
, pretty :: Bool
, omission :: Value -> Value
, conversion :: Conversion
, approximateSpecialDoubles :: Bool
, file :: Maybe FilePath
, output :: Maybe FilePath
}
| Version
parseOptions :: Parser Options
parseOptions =
( Options
<$> parseExplain
<*> parsePretty
<*> Dhall.JSON.parsePreservationAndOmission
<*> Dhall.JSON.parseConversion
<*> parseApproximateSpecialDoubles
<*> optional parseFile
<*> optional parseOutput
)
<|> parseVersion
where
parseExplain =
Options.switch
( Options.long "explain"
<> Options.help "Explain error messages in detail"
)
parsePretty =
prettyFlag <|> compactFlag <|> defaultBehavior
where
prettyFlag =
Options.flag'
True
( Options.long "pretty"
<> Options.help "Deprecated, will be removed soon. Pretty print generated JSON"
)
compactFlag =
Options.flag'
False
( Options.long "compact"
<> Options.help "Render JSON on one line"
)
defaultBehavior =
pure True
parseVersion =
Options.flag'
Version
( Options.long "version"
<> Options.help "Display version"
)
parseApproximateSpecialDoubles =
Options.switch
( Options.long "approximate-special-doubles"
<> Options.help "Use approximate representation for NaN/±Infinity"
)
parseFile =
Options.strOption
( Options.long "file"
<> Options.help "Read expression from a file instead of standard input"
<> Options.metavar "FILE"
)
parseOutput =
Options.strOption
( Options.long "output"
<> Options.help "Write JSON to a file instead of standard output"
<> Options.metavar "FILE"
)
parserInfo :: ParserInfo Options
parserInfo =
Options.info
(Options.helper <*> parseOptions)
( Options.fullDesc
<> Options.progDesc "Compile Dhall to JSON"
)
main :: IO ()
main = do
GHC.IO.Encoding.setLocaleEncoding GHC.IO.Encoding.utf8
options <- Options.execParser parserInfo
case options of
Version -> do
putStrLn (showVersion Meta.version)
Options {..} -> do
handle $ do
let config = Data.Aeson.Encode.Pretty.Config
{ Data.Aeson.Encode.Pretty.confIndent = Data.Aeson.Encode.Pretty.Spaces 2
, Data.Aeson.Encode.Pretty.confCompare = compare
, Data.Aeson.Encode.Pretty.confNumFormat = Data.Aeson.Encode.Pretty.Generic
, Data.Aeson.Encode.Pretty.confTrailingNewline = False }
let encode =
if pretty
then Data.Aeson.Encode.Pretty.encodePretty' config
else Data.Aeson.encode
let explaining = if explain then Dhall.detailed else id
let specialDoubleMode =
if approximateSpecialDoubles
then ApproximateWithinJSON
else ForbidWithinJSON
text <- case file of
Nothing -> Text.IO.getContents
Just path -> Text.IO.readFile path
json <- omission <$> explaining (Dhall.JSON.codeToValue conversion specialDoubleMode file text)
let write =
case output of
Nothing -> Data.ByteString.Lazy.putStr
Just file_ -> Data.ByteString.Lazy.writeFile file_
write (encode json <> "\n")
handle :: IO a -> IO a
handle = Control.Exception.handle handler
where
handler :: SomeException -> IO a
handler e = do
System.IO.hPutStrLn System.IO.stderr ""
System.IO.hPrint System.IO.stderr e
System.Exit.exitFailure