228 lines
8.3 KiB
Haskell
228 lines
8.3 KiB
Haskell
{-# LANGUAGE LambdaCase #-}
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{-# LANGUAGE NoImplicitPrelude #-}
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module Language.Haskell.Brittany.Internal.Layouters.Pattern where
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import Language.Haskell.Brittany.Internal.Prelude
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import Language.Haskell.Brittany.Internal.PreludeUtils
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import qualified Data.Foldable as Foldable
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import qualified Data.Sequence as Seq
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import qualified Data.Text as Text
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import qualified GHC.OldList as List
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import Language.Haskell.Brittany.Internal.Types
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import Language.Haskell.Brittany.Internal.LayouterBasics
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import GHC ( GenLocated(L)
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, ol_val
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)
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import GHC.Hs
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import GHC.Types.Basic
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import {-# SOURCE #-} Language.Haskell.Brittany.Internal.Layouters.Expr
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import Language.Haskell.Brittany.Internal.Layouters.Type
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-- | layouts patterns (inside function bindings, case alternatives, let
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-- bindings or do notation). E.g. for input
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-- > case computation of
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-- > (warnings, Success a b) -> ..
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-- This part ^^^^^^^^^^^^^^^^^^^^^^^ of the syntax tree is layouted by
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-- 'layoutPat'. Similarly for
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-- > func abc True 0 = []
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-- ^^^^^^^^^^ this part
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-- We will use `case .. of` as the imagined prefix to the examples used in
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-- the different cases below.
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layoutPat :: LPat GhcPs -> ToBriDocM (Seq BriDocNumbered)
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layoutPat lpat@(L _ pat) = docWrapNode lpat $ case pat of
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WildPat _ -> fmap Seq.singleton $ docLit $ Text.pack "_"
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-- _ -> expr
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VarPat _ n ->
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fmap Seq.singleton $ docLit $ lrdrNameToText n
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-- abc -> expr
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LitPat _ lit ->
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fmap Seq.singleton $ allocateNode $ litBriDoc lit
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-- 0 -> expr
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ParPat _ inner -> do
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-- (nestedpat) -> expr
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left <- docLit $ Text.pack "("
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right <- docLit $ Text.pack ")"
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innerDocs <- colsWrapPat =<< layoutPat inner
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return $ Seq.empty Seq.|> left Seq.|> innerDocs Seq.|> right
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-- return $ (left Seq.<| innerDocs) Seq.|> right
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-- case Seq.viewl innerDocs of
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-- Seq.EmptyL -> fmap return $ docLit $ Text.pack "()" -- this should never occur..
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-- x1 Seq.:< rest -> case Seq.viewr rest of
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-- Seq.EmptyR ->
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-- fmap return $ docSeq
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-- [ docLit $ Text.pack "("
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-- , return x1
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-- , docLit $ Text.pack ")"
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-- ]
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-- middle Seq.:> xN -> do
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-- x1' <- docSeq [docLit $ Text.pack "(", return x1]
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-- xN' <- docSeq [return xN, docLit $ Text.pack ")"]
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-- return $ (x1' Seq.<| middle) Seq.|> xN'
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ConPat _ lname (PrefixCon args) -> do
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-- Abc a b c -> expr
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nameDoc <- lrdrNameToTextAnn lname
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argDocs <- layoutPat `mapM` args
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if null argDocs
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then return <$> docLit nameDoc
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else do
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x1 <- appSep (docLit nameDoc)
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xR <- fmap Seq.fromList
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$ sequence
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$ spacifyDocs
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$ fmap colsWrapPat argDocs
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return $ x1 Seq.<| xR
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ConPat _ lname (InfixCon left right) -> do
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-- a :< b -> expr
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nameDoc <- lrdrNameToTextAnn lname
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leftDoc <- appSep . colsWrapPat =<< layoutPat left
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rightDoc <- colsWrapPat =<< layoutPat right
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middle <- appSep $ docLit nameDoc
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return $ Seq.empty Seq.|> leftDoc Seq.|> middle Seq.|> rightDoc
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ConPat _ lname (RecCon (HsRecFields [] Nothing)) -> do
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-- Abc{} -> expr
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let t = lrdrNameToText lname
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fmap Seq.singleton $ docLit $ t <> Text.pack "{}"
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ConPat _ lname (RecCon (HsRecFields fs@(_:_) Nothing)) -> do
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-- Abc { a = locA, b = locB, c = locC } -> expr1
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-- Abc { a, b, c } -> expr2
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let t = lrdrNameToText lname
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fds <- fs `forM` \(L _ (HsRecField (L _ fieldOcc) fPat pun)) -> do
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let FieldOcc _ lnameF = fieldOcc
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fExpDoc <- if pun
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then return Nothing
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else Just <$> docSharedWrapper layoutPat fPat
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return (lrdrNameToText lnameF, fExpDoc)
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Seq.singleton <$> docSeq
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[ appSep $ docLit t
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, appSep $ docLit $ Text.pack "{"
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, docSeq $ List.intersperse docCommaSep
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$ fds <&> \case
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(fieldName, Just fieldDoc) -> docSeq
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[ appSep $ docLit fieldName
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, appSep $ docLit $ Text.pack "="
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, fieldDoc >>= colsWrapPat
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]
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(fieldName, Nothing) -> docLit fieldName
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, docSeparator
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, docLit $ Text.pack "}"
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]
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ConPat _ lname (RecCon (HsRecFields [] (Just (L _ 0)))) -> do
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-- Abc { .. } -> expr
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let t = lrdrNameToText lname
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Seq.singleton <$> docSeq
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[ appSep $ docLit t
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, docLit $ Text.pack "{..}"
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]
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ConPat _ lname (RecCon (HsRecFields fs@(_:_) (Just (L _ dotdoti)))) | dotdoti == length fs -> do
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-- Abc { a = locA, .. }
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let t = lrdrNameToText lname
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fds <- fs `forM` \(L _ (HsRecField (L _ fieldOcc) fPat pun)) -> do
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let FieldOcc _ lnameF = fieldOcc
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fExpDoc <- if pun
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then return Nothing
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else Just <$> docSharedWrapper layoutPat fPat
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return (lrdrNameToText lnameF, fExpDoc)
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Seq.singleton <$> docSeq
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[ appSep $ docLit t
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, appSep $ docLit $ Text.pack "{"
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, docSeq $ fds >>= \case
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(fieldName, Just fieldDoc) ->
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[ appSep $ docLit fieldName
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, appSep $ docLit $ Text.pack "="
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, fieldDoc >>= colsWrapPat
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, docCommaSep
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]
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(fieldName, Nothing) -> [docLit fieldName, docCommaSep]
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, docLit $ Text.pack "..}"
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]
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TuplePat _ args boxity -> do
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-- (nestedpat1, nestedpat2, nestedpat3) -> expr
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-- (#nestedpat1, nestedpat2, nestedpat3#) -> expr
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case boxity of
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Boxed -> wrapPatListy args "()" docParenL docParenR
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Unboxed -> wrapPatListy args "(##)" docParenHashLSep docParenHashRSep
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AsPat _ asName asPat -> do
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-- bind@nestedpat -> expr
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wrapPatPrepend asPat (docLit $ lrdrNameToText asName <> Text.pack "@")
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SigPat _ pat1 (HsPS _ ty1) -> do
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-- i :: Int -> expr
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patDocs <- layoutPat pat1
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tyDoc <- docSharedWrapper layoutType ty1
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case Seq.viewr patDocs of
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Seq.EmptyR -> error "cannot happen ljoiuxoasdcoviuasd"
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xR Seq.:> xN -> do
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xN' <- -- at the moment, we don't support splitting patterns into
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-- multiple lines. but we cannot enforce pasting everything
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-- into one line either, because the type signature will ignore
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-- this if we overflow sufficiently.
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-- In order to prevent syntactically invalid results in such
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-- cases, we need the AddBaseY here.
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-- This can all change when patterns get multiline support.
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docAddBaseY BrIndentRegular $ docSeq
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[ appSep $ return xN
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, appSep $ docLit $ Text.pack "::"
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, docForceSingleline tyDoc
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]
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return $ xR Seq.|> xN'
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ListPat _ elems ->
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-- [] -> expr1
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-- [nestedpat1, nestedpat2, nestedpat3] -> expr2
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wrapPatListy elems "[]" docBracketL docBracketR
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BangPat _ pat1 -> do
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-- !nestedpat -> expr
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wrapPatPrepend pat1 (docLit $ Text.pack "!")
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LazyPat _ pat1 -> do
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-- ~nestedpat -> expr
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wrapPatPrepend pat1 (docLit $ Text.pack "~")
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NPat _ llit@(L _ ol) mNegative _ -> do
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-- -13 -> expr
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litDoc <- docWrapNode llit $ allocateNode $ overLitValBriDoc $ GHC.ol_val ol
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negDoc <- docLit $ Text.pack "-"
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pure $ case mNegative of
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Just{} -> Seq.fromList [negDoc, litDoc]
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Nothing -> Seq.singleton litDoc
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_ -> return <$> briDocByExactInlineOnly "some unknown pattern" lpat
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colsWrapPat :: Seq BriDocNumbered -> ToBriDocM BriDocNumbered
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colsWrapPat = docCols ColPatterns . fmap return . Foldable.toList
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wrapPatPrepend
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:: LPat GhcPs
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-> ToBriDocM BriDocNumbered
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-> ToBriDocM (Seq BriDocNumbered)
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wrapPatPrepend pat prepElem = do
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patDocs <- layoutPat pat
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case Seq.viewl patDocs of
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Seq.EmptyL -> return Seq.empty
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x1 Seq.:< xR -> do
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x1' <- docSeq [prepElem, return x1]
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return $ x1' Seq.<| xR
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wrapPatListy
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:: [LPat GhcPs]
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-> String
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-> ToBriDocM BriDocNumbered
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-> ToBriDocM BriDocNumbered
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-> ToBriDocM (Seq BriDocNumbered)
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wrapPatListy elems both start end = do
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elemDocs <- Seq.fromList elems `forM` (layoutPat >=> colsWrapPat)
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case Seq.viewl elemDocs of
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Seq.EmptyL -> fmap Seq.singleton $ docLit $ Text.pack both
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x1 Seq.:< rest -> do
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sDoc <- start
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eDoc <- end
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rest' <- rest `forM` \bd -> docSeq
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[ docCommaSep
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, return bd
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]
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return $ (sDoc Seq.<| x1 Seq.<| rest') Seq.|> eDoc
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