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Modularise the server input and output
The goal here is to make the `Control` module as boring and dispensible as possible, so that users can put the pieces together as they like. Thisi s a step in that direction, tackling the server in/out threads.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| {-# LANGUAGE OverloadedStrings #-} | ||
| {-# LANGUAGE RankNTypes #-} | ||
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| module Language.LSP.Server.IO (serverOut, serverIn, LspIoLog) where | ||
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| import Colog.Core (LogAction (..), WithSeverity (..), Severity (..), (<&)) | ||
| import Control.Monad | ||
| import qualified Data.Aeson as J | ||
| import qualified Data.Attoparsec.ByteString as Attoparsec | ||
| import Data.Attoparsec.ByteString.Char8 | ||
| import qualified Data.ByteString as BS | ||
| import qualified Data.ByteString.Lazy as BSL | ||
| import qualified Data.Text as T | ||
| import qualified Data.Text.Encoding as T | ||
| import Data.Text.Prettyprint.Doc | ||
| import Data.List | ||
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| data LspIoLog = | ||
| HeaderParseFail [String] String | ||
| | BodyParseFail String | ||
| | RecvMsg BS.ByteString | ||
| | SendMsg BS.ByteString | ||
| | EOF | ||
| deriving (Show) | ||
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| instance Pretty LspIoLog where | ||
| pretty (HeaderParseFail ctxs err) = | ||
| vsep [ | ||
| "Failed to parse message header:" | ||
| , pretty (intercalate " > " ctxs) <> ": " <+> pretty err | ||
| ] | ||
| pretty (BodyParseFail err) = | ||
| vsep [ | ||
| "Failed to parse message body:" | ||
| , pretty err | ||
| ] | ||
| pretty (RecvMsg msg) = "---> " <> pretty (T.decodeUtf8 msg) | ||
| pretty (SendMsg msg) = "<--- " <> pretty (T.decodeUtf8 msg) | ||
| pretty EOF = "Got EOF" | ||
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| -- | Process which receives messages and sends them. Output queue of messages ensures they are serialised. | ||
| serverIn :: | ||
| LogAction IO (WithSeverity LspIoLog) | ||
| -> (J.Value -> IO ()) -- ^ Channel to send out messages on. | ||
| -> IO BS.ByteString -- ^ Action to pull in new messages (e.g. from a handle). | ||
| -> IO () | ||
| serverIn logger msgOut clientIn = do | ||
| bs <- clientIn | ||
| loop (parse parser bs) | ||
| where | ||
| loop :: Result BS.ByteString -> IO () | ||
| loop (Fail _ ctxs err) = do | ||
| logger <& HeaderParseFail ctxs err `WithSeverity` Error | ||
| pure () | ||
| loop (Partial c) = do | ||
| bs <- clientIn | ||
| if BS.null bs | ||
| then do | ||
| logger <& EOF `WithSeverity` Error | ||
| pure () | ||
| else loop (c bs) | ||
| loop (Done remainder parsed) = do | ||
| logger <& RecvMsg parsed `WithSeverity` Debug | ||
| case J.eitherDecode (BSL.fromStrict parsed) of | ||
| -- Note: this is recoverable, because we can just discard the | ||
| -- message and keep going, whereas a header parse failure is | ||
| -- not recoverable | ||
| Left err -> logger <& BodyParseFail err `WithSeverity` Error | ||
| Right msg -> msgOut msg | ||
| loop (parse parser remainder) | ||
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| parser = do | ||
| _ <- string "Content-Length: " | ||
| len <- decimal | ||
| _ <- string _TWO_CRLF | ||
| Attoparsec.take len | ||
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| -- | Process which receives messages and sends them. Input queue of messages ensures they are serialised. | ||
| serverOut | ||
| :: LogAction IO (WithSeverity LspIoLog) | ||
| -> IO J.Value -- ^ Channel to receive messages on. | ||
| -> (BS.ByteString -> IO ()) -- ^ Action to send messages out on (e.g. via a handle). | ||
| -> IO () | ||
| serverOut logger msgIn clientOut = forever $ do | ||
| msg <- msgIn | ||
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| -- We need to make sure we only send over the content of the message, | ||
| -- and no other tags/wrapper stuff | ||
| let str = J.encode msg | ||
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| let out = BS.concat | ||
| [ T.encodeUtf8 $ T.pack $ "Content-Length: " ++ show (BSL.length str) | ||
| , _TWO_CRLF | ||
| , BSL.toStrict str ] | ||
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| clientOut out | ||
| logger <& SendMsg out `WithSeverity` Debug | ||
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| _TWO_CRLF :: BS.ByteString | ||
| _TWO_CRLF = "\r\n\r\n" |
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