diff options
Diffstat (limited to 'haddock-library/src/Documentation/Haddock/Parser/Monad.hs')
| -rw-r--r-- | haddock-library/src/Documentation/Haddock/Parser/Monad.hs | 97 |
1 files changed, 77 insertions, 20 deletions
diff --git a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs index a5664aa8..fa46f536 100644 --- a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs +++ b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs @@ -4,15 +4,32 @@ {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE BangPatterns #-} {-# LANGUAGE TypeSynonymInstances #-} +-- | +-- Module : Documentation.Haddock.Parser.Monad +-- Copyright : (c) Alec Theriault 2018-2019, +-- License : BSD-like +-- +-- Maintainer : haddock@projects.haskell.org +-- Stability : experimental +-- Portability : portable +-- +-- Defines the Parsec monad over which all parsing is done and also provides +-- more efficient versions of the usual parsec combinator functions (but +-- specialized to 'Text'). module Documentation.Haddock.Parser.Monad where import qualified Text.Parsec.Char as Parsec import qualified Text.Parsec as Parsec +import Text.Parsec.Pos ( updatePosChar ) +import Text.Parsec ( State(..) + , getParserState, setParserState ) import qualified Data.Text as T import Data.Text ( Text ) +import Control.Monad ( mfilter ) +import Data.Functor ( ($>) ) import Data.String ( IsString(..) ) import Data.Bits ( Bits(..) ) import Data.Char ( ord ) @@ -20,7 +37,11 @@ import Data.List ( foldl' ) import Control.Applicative as App import Documentation.Haddock.Types ( Version ) +import Prelude hiding (takeWhile) +-- | The only bit of information we really care about truding along with us +-- through parsing is the version attached to a @\@since@ annotation - if +-- the doc even contained one. newtype ParserState = ParserState { parserStateSince :: Maybe Version } deriving (Eq, Show) @@ -29,7 +50,7 @@ initialParserState :: ParserState initialParserState = ParserState Nothing setSince :: Version -> Parser () -setSince since = Parsec.modifyState (\st -> st {parserStateSince = Just since}) +setSince since = Parsec.modifyState (\st -> st{ parserStateSince = Just since }) type Parser = Parsec.Parsec Text ParserState @@ -44,38 +65,74 @@ parseOnly p t = case Parsec.runParser p' initialParserState "<haddock>" t of -- | Always succeeds, but returns 'Nothing' if at the end of input. Does not -- consume input. +-- +-- Equivalent to @Parsec.optionMaybe . Parsec.lookAhead $ Parsec.anyChar@, but +-- more efficient. peekChar :: Parser (Maybe Char) -peekChar = Parsec.optionMaybe . Parsec.try . Parsec.lookAhead $ Parsec.anyChar +peekChar = headOpt . stateInput <$> getParserState + where headOpt t | T.null t = Nothing + | otherwise = Just (T.head t) +{-# INLINE peekChar #-} -- | Fails if at the end of input. Does not consume input. +-- +-- Equivalent to @Parsec.lookAhead Parsec.anyChar@, but more efficient. peekChar' :: Parser Char -peekChar' = Parsec.lookAhead Parsec.anyChar +peekChar' = headFail . stateInput =<< getParserState + where headFail t | T.null t = Parsec.parserFail "peekChar': reached EOF" + | otherwise = App.pure (T.head t) +{-# INLINE peekChar' #-} -- | Parses the given string. Returns the parsed string. +-- +-- Equivalent to @Parsec.string (T.unpack t) $> t@, but more efficient. string :: Text -> Parser Text -string t = Parsec.string (T.unpack t) *> App.pure t +string t = do + s@State{ stateInput = inp, statePos = pos } <- getParserState + case T.stripPrefix t inp of + Nothing -> Parsec.parserFail "string: Failed to match the input string" + Just inp' -> + let pos' = T.foldl updatePosChar pos t + s' = s{ stateInput = inp', statePos = pos' } + in setParserState s' $> t + +-- | Keep matching characters as long as the predicate function holds (and +-- return them). +-- +-- Equivalent to @fmap T.pack . Parsec.many@, but more efficient. +takeWhile :: (Char -> Bool) -> Parser Text +takeWhile f = do + s@State{ stateInput = inp, statePos = pos } <- getParserState + let (t, inp') = T.span f inp + pos' = T.foldl updatePosChar pos t + s' = s{ stateInput = inp', statePos = pos' } + setParserState s' $> t + +-- | Like 'takeWhile', but fails if no characters matched. +-- +-- Equivalent to @fmap T.pack . Parsec.many1@, but more efficient. +takeWhile1 :: (Char -> Bool) -> Parser Text +takeWhile1 = mfilter (not . T.null) . takeWhile -- | Scan the input text, accumulating characters as long as the scanning -- function returns true. scan :: (s -> Char -> Maybe s) -- ^ scan function -> s -- ^ initial state -> Parser Text -scan f = fmap T.pack . go - where go s1 = do { cOpt <- peekChar - ; case cOpt >>= f s1 of - Nothing -> pure "" - Just s2 -> (:) <$> Parsec.anyChar <*> go s2 - } - --- | Apply a parser for a character zero or more times and collect the result in --- a string. -takeWhile :: Parser Char -> Parser Text -takeWhile = fmap T.pack . Parsec.many - --- | Apply a parser for a character one or more times and collect the result in --- a string. -takeWhile1 :: Parser Char -> Parser Text -takeWhile1 = fmap T.pack . Parsec.many1 +scan f st = do + s@State{ stateInput = inp, statePos = pos } <- getParserState + go inp st pos 0 $ \inp' pos' n -> + let s' = s{ Parsec.stateInput = inp', Parsec.statePos = pos' } + in setParserState s' $> T.take n inp + where + go inp s !pos !n cont + = case T.uncons inp of + Nothing -> cont inp pos n -- ran out of input + Just (c, inp') -> + case f s c of + Nothing -> cont inp pos n -- scan function failed + Just s' -> go inp' s' (updatePosChar pos c) (n+1) cont + -- | Parse a decimal number. decimal :: Integral a => Parser a |