Completion.hs

{-# OPTIONS_HADDOCK hide #-}

{-

This file is part of the package byline. It is subject to the license
terms in the LICENSE file found in the top-level directory of this
distribution and at git://pmade.com/byline/LICENSE. No part of the
byline package, including this file, may be copied, modified,
propagated, or distributed except according to the terms contained in
the LICENSE file.

-}

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-- | Internal completion operations.
module System.Console.Byline.Internal.Completion
       ( CompletionFunc
       , Completion (..)
       , runCompletionFunction
       ) where

--------------------------------------------------------------------------------
-- Library imports:
import Data.IORef
import qualified Data.Text as Text
import qualified System.Console.Haskeline.Completion as H

--------------------------------------------------------------------------------
-- Byline imports:
import System.Console.Byline.Completion

--------------------------------------------------------------------------------
-- | Convert a Byline completion result into a Haskeline completion result.
convertCompletion :: Completion -> H.Completion
convertCompletion (Completion r d i) =
  H.Completion { H.replacement = Text.unpack r
               , H.display     = Text.unpack d
               , H.isFinished  = i
               }

--------------------------------------------------------------------------------
-- | Helper function that allows Byline to swap out the completion function.
runCompletionFunction :: IORef (Maybe CompletionFunc) -> H.CompletionFunc IO
runCompletionFunction compref (left, right) = do
  comp <- readIORef compref

  case comp of
    Nothing -> H.completeFilename (left, right)

    Just f -> do
      (output, completions) <-
        f (Text.reverse $ Text.pack left, Text.pack right)

      return (Text.unpack $ Text.reverse output,
              map convertCompletion completions)