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{- git-annex deferred parse values
-
- Copyright 2015-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE FlexibleInstances #-}
module Types.DeferredParse where
import Annex
import Options.Applicative
import qualified Data.Semigroup as Sem
import Prelude
-- Some values cannot be fully parsed without performing an action.
-- The action may be expensive, so it's best to call finishParse on such a
-- value before using getParsed repeatedly.
data DeferredParse a = DeferredParse (Annex a) | ReadyParse a
class DeferredParseClass a where
finishParse :: a -> Annex a
getParsed :: DeferredParse a -> Annex a
getParsed (DeferredParse a) = a
getParsed (ReadyParse a) = pure a
instance DeferredParseClass (DeferredParse a) where
finishParse (DeferredParse a) = ReadyParse <$> a
finishParse (ReadyParse a) = pure (ReadyParse a)
instance DeferredParseClass (Maybe (DeferredParse a)) where
finishParse Nothing = pure Nothing
finishParse (Just v) = Just <$> finishParse v
instance DeferredParseClass [DeferredParse a] where
finishParse v = mapM finishParse v
type AnnexOption = Parser AnnexSetter
-- Used for options that can modify Annex state by running
-- an arbitrary action in it, and can also set up AnnexRead.
data AnnexSetter = AnnexSetter
{ annexStateSetter :: Annex ()
, annexReadSetter :: AnnexRead -> AnnexRead
}
instance Sem.Semigroup AnnexSetter where
a <> b = AnnexSetter
{ annexStateSetter = annexStateSetter a >> annexStateSetter b
, annexReadSetter = annexReadSetter b . annexReadSetter a
}
instance Monoid AnnexSetter where
mempty = AnnexSetter (return ()) id
|
