{-# LANGUAGE DeriveFoldable #-}
{-# LANGUAGE DeriveFunctor #-}
{-# OPTIONS_HADDOCK show-extensions #-}
-- |
-- Module : Yi.Syntax.Paren
-- License : GPL-2
-- Maintainer : yi-devel@googlegroups.com
-- Stability : experimental
-- Portability : portable
--
-- Parser for Haskell that only cares about parenthesis and layout.
module Yi.Syntax.Paren where
import Prelude hiding (elem)
import Control.Applicative (Alternative ((<|>), many))
import Data.Foldable (elem, toList)
import Data.Maybe (listToMaybe)
import Data.Monoid (Endo (Endo, appEndo), (<>))
import Yi.IncrementalParse (P, Parser, eof, lookNext, recoverWith, symbol)
import Yi.Lexer.Alex hiding (tokenToStyle)
import Yi.Lexer.Haskell
import Yi.Style (StyleName, errorStyle, hintStyle)
import Yi.Syntax (Point, Scanner, Span)
import Yi.Syntax.Layout (State, layoutHandler)
import Yi.Syntax.Tree
indentScanner :: Scanner (AlexState lexState) TT
-> Scanner (Yi.Syntax.Layout.State Token lexState) TT
indentScanner = layoutHandler startsLayout [(Special '(', Special ')'),
(Special '[', Special ']'),
(Special '{', Special '}')] ignoredToken
(Special '<', Special '>', Special '.') isBrace
-- HACK: We insert the Special '<', '>', '.', that don't occur in normal haskell
-- parsing.
isBrace :: TT -> Bool
isBrace (Tok b _ _) = Special '{' == b
ignoredToken :: TT -> Bool
ignoredToken (Tok t _ _) = isComment t || t == CppDirective
isNoise :: Token -> Bool
isNoise (Special c) = c `elem` (";,`" :: String)
isNoise _ = True
type Expr t = [Tree t]
data Tree t
= Paren t (Expr t) t -- A parenthesized expression (maybe with [ ] ...)
| Block ([Tree t]) -- A list of things separated by layout (as in do; etc.)
| Atom t
| Error t
| Expr [Tree t]
deriving (Show, Foldable, Functor)
instance IsTree Tree where
emptyNode = Expr []
uniplate (Paren l g r) = (g,\g' -> Paren l g' r)
uniplate (Expr g) = (g,Expr)
uniplate (Block s) = (s,Block)
uniplate t = ([],const t)
-- | Search the given list, and return the 1st tree after the given
-- point on the given line. This is the tree that will be moved if
-- something is inserted at the point. Precondition: point is in the
-- given line.
-- TODO: this should be optimized by just giving the point of the end
-- of the line
getIndentingSubtree :: Tree TT -> Point -> Int -> Maybe (Tree TT)
getIndentingSubtree root offset line =
listToMaybe [t | (t,posn) <- takeWhile ((<= line) . posnLine . snd) allSubTreesPosn,
-- it's very important that we do a linear search
-- here (takeWhile), so that the tree is evaluated
-- lazily and therefore parsing it can be lazy.
posnOfs posn > offset, posnLine posn == line]
where allSubTreesPosn = [(t',posn) | t'@(Block _) <-filter (not . null . toList) (getAllSubTrees root),
let (tok:_) = toList t',
let posn = tokPosn tok]
-- | Given a tree, return (first offset, number of lines).
getSubtreeSpan :: Tree TT -> (Point, Int)
getSubtreeSpan tree = (posnOfs first, lastLine - firstLine)
where bounds@[first, _last] = fmap (tokPosn . assertJust) [getFirstElement tree, getLastElement tree]
[firstLine, lastLine] = fmap posnLine bounds
assertJust (Just x) = x
assertJust _ = error "assertJust: Just expected"
-- dropWhile' f = foldMap (\x -> if f x then mempty else Endo (x :))
--
-- isBefore l (Atom t) = isBefore' l t
-- isBefore l (Error t) = isBefore l t
-- isBefore l (Paren l g r) = isBefore l r
-- isBefore l (Block s) = False
--
-- isBefore' l (Tok {tokPosn = Posn {posnLn = l'}}) =
parse :: P TT (Tree TT)
parse = Expr <$> parse' tokT tokFromT
parse' :: (TT -> Token) -> (Token -> TT) -> P TT [Tree TT]
parse' toTok _ = pExpr <* eof
where
-- parse a special symbol
sym c = symbol (isSpecial [c] . toTok)
pleaseSym c = recoverWith errTok <|> sym c
pExpr :: P TT (Expr TT)
pExpr = many pTree
pBlocks = (Expr <$> pExpr) `sepBy1` sym '.' -- the '.' is generated by the layout, see HACK above
-- note that we can have empty statements, hence we use sepBy1.
pTree :: P TT (Tree TT)
pTree = (Paren <$> sym '(' <*> pExpr <*> pleaseSym ')')
<|> (Paren <$> sym '[' <*> pExpr <*> pleaseSym ']')
<|> (Paren <$> sym '{' <*> pExpr <*> pleaseSym '}')
<|> (Block <$> (sym '<' *> pBlocks <* sym '>')) -- see HACK above
<|> (Atom <$> symbol (isNoise . toTok))
<|> (Error <$> recoverWith (symbol (isSpecial "})]" . toTok)))
-- note that, by construction, '<' and '>' will always be matched, so
-- we don't try to recover errors with them.
getStrokes :: Point -> Point -> Point -> Tree TT -> [Stroke]
getStrokes point _begin _end t0 = -- trace (show t0)
result
where getStrokes' (Atom t) = one (ts t)
getStrokes' (Error t) = one (modStroke errorStyle (ts t)) -- paint in red
getStrokes' (Block s) = getStrokesL s
getStrokes' (Expr g) = getStrokesL g
getStrokes' (Paren l g r)
| isErrorTok $ tokT r = one (modStroke errorStyle (ts l)) <> getStrokesL g
-- left paren wasn't matched: paint it in red.
-- note that testing this on the "Paren" node actually forces the parsing of the
-- right paren, undermining online behaviour.
| posnOfs (tokPosn l) == point || posnOfs (tokPosn r) == point - 1
= one (modStroke hintStyle (ts l)) <> getStrokesL g <> one (modStroke hintStyle (ts r))
| otherwise = one (ts l) <> getStrokesL g <> one (ts r)
getStrokesL = foldMap getStrokes'
ts = tokenToStroke
result = appEndo (getStrokes' t0) []
one x = Endo (x :)
tokenToStroke :: TT -> Stroke
tokenToStroke = fmap tokenToStyle . tokToSpan
modStroke :: StyleName -> Stroke -> Stroke
modStroke f = fmap (f `mappend`)
tokenToAnnot :: TT -> Maybe (Span String)
tokenToAnnot = sequenceA . tokToSpan . fmap tokenToText
-- | Create a special error token. (e.g. fill in where there is no correct token to parse)
-- Note that the position of the token has to be correct for correct computation of
-- node spans.
errTok :: Parser (Tok t) (Tok Token)
errTok = mkTok <$> curPos
where curPos = tB <$> lookNext
tB Nothing = maxBound
tB (Just x) = tokBegin x
mkTok p = Tok (Special '!') 0 (startPosn {posnOfs = p})