Initial commit

bundled/Basement/MutableBuilder.hs

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+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE RebindableSyntax #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+module Basement.MutableBuilder
+    ( Builder(..)
+    , BuildingState(..)
+    ) where
+
+import           Basement.Compat.Base
+import           Basement.Compat.MonadTrans
+import           Basement.Types.OffsetSize
+import           Basement.Monad
+
+newtype Builder collection mutCollection step state err a = Builder
+    { runBuilder :: State (Offset step, BuildingState collection mutCollection step (PrimState state), Maybe err) state a }
+    deriving (Functor, Applicative, Monad)
+
+-- | The in-progress state of a building operation.
+--
+-- The previous buffers are in reverse order, and
+-- this contains the current buffer and the state of
+-- progress packing the elements inside.
+data BuildingState collection mutCollection step state = BuildingState
+    { prevChunks     :: [collection]
+    , prevChunksSize :: !(CountOf step)
+    , curChunk       :: mutCollection state
+    , chunkSize      :: !(CountOf step)
+    }
+
+instance Monad state => MonadFailure (Builder collection mutCollection step state err) where
+    type Failure (Builder collection mutCollection step state err) = err
+    mFail builderError = Builder $ State $ \(offset, bs, _)  ->
+        return ((), (offset, bs, Just builderError))