Text.Megaparsec.Internal

Internal definitions. Versioning rules do not apply here. Please do not rely on these unless you really know what you're doing.

Since: 6.5.0

Data types

newtype Hints t

Hints represent a collection of ErrorItems to be included into ParseError (when it's a TrivialError) as “expected” message items when a parser fails without consuming input right after successful parser that produced the hints.

For example, without hints you could get:

>>> parseTest (many (char 'r') <* eof) "ra"
1:2:
unexpected 'a'
expecting end of input

We're getting better error messages with the help of hints:

>>> parseTest (many (char 'r') <* eof) "ra"
1:2:
unexpected 'a'
expecting 'r' or end of input

Constructors

Hints [Set (ErrorItem t)]

Instances

Semigroup (Hints t)

Defined in Text.Megaparsec.Internal

Methods

(<>) :: Hints t -> Hints t -> Hints t

sconcat :: NonEmpty (Hints t) -> Hints t

stimes :: Integral b => b -> Hints t -> Hints t

Monoid (Hints t)

Defined in Text.Megaparsec.Internal

Methods

mempty :: Hints t

mappend :: Hints t -> Hints t -> Hints t

mconcat :: [Hints t] -> Hints t

data Reply e s a

All information available after parsing. This includes consumption of input, success (with returned value) or failure (with parse error), and parser state at the end of parsing.

See also: Consumption, Result.

Constructors

Reply (State s) Consumption (Result s e a)

data Consumption

This data structure represents an aspect of result of parser's work.

See also: Result, Reply.

Constructors

Consumed

Some part of input stream was consumed

Virgin

No input was consumed

data Result s e a

This data structure represents an aspect of result of parser's work.

See also: Consumption, Reply.

Constructors

OK a

Parser succeeded

Error (ParseError s e)

Parser failed

newtype ParsecT e s m a

ParsecT e s m a is a parser with custom data component of error e, stream type s, underlying monad m and return type a.

Constructors

ParsecT

Fields

• unParser :: forall b. State s -> (a -> State s -> Hints (Token s) -> m b) -> (ParseError s e -> State s -> m b) -> (a -> State s -> Hints (Token s) -> m b) -> (ParseError s e -> State s -> m b) -> m b

Instances

(Ord e, Stream s) => MonadParsec e s (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

failure :: Maybe (ErrorItem (Token s)) -> Set (ErrorItem (Token s)) -> ParsecT e s m a

fancyFailure :: Set (ErrorFancy e) -> ParsecT e s m a

label :: String -> ParsecT e s m a -> ParsecT e s m a

hidden :: ParsecT e s m a -> ParsecT e s m a

try :: ParsecT e s m a -> ParsecT e s m a

lookAhead :: ParsecT e s m a -> ParsecT e s m a

notFollowedBy :: ParsecT e s m a -> ParsecT e s m ()

withRecovery :: (ParseError s e -> ParsecT e s m a) -> ParsecT e s m a -> ParsecT e s m a

observing :: ParsecT e s m a -> ParsecT e s m (Either (ParseError s e) a)

eof :: ParsecT e s m ()

token :: (Token s -> Maybe a) -> Set (ErrorItem (Token s)) -> ParsecT e s m a

tokens :: (Tokens s -> Tokens s -> Bool) -> Tokens s -> ParsecT e s m (Tokens s)

takeWhileP :: Maybe String -> (Token s -> Bool) -> ParsecT e s m (Tokens s)

takeWhile1P :: Maybe String -> (Token s -> Bool) -> ParsecT e s m (Tokens s)

takeP :: Maybe String -> Int -> ParsecT e s m (Tokens s)

getParserState :: ParsecT e s m (State s)

updateParserState :: (State s -> State s) -> ParsecT e s m ()

(Stream s, MonadState st m) => MonadState st (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

get :: ParsecT e s m st

put :: st -> ParsecT e s m ()

state :: (st -> (a, st)) -> ParsecT e s m a

(Stream s, MonadReader r m) => MonadReader r (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

ask :: ParsecT e s m r

local :: (r -> r) -> ParsecT e s m a -> ParsecT e s m a

reader :: (r -> a) -> ParsecT e s m a

(Stream s, MonadError e' m) => MonadError e' (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

throwError :: e' -> ParsecT e s m a

catchError :: ParsecT e s m a -> (e' -> ParsecT e s m a) -> ParsecT e s m a

MonadTrans (ParsecT e s)

Defined in Text.Megaparsec.Internal

Methods

lift :: Monad m => m a -> ParsecT e s m a

Stream s => Monad (ParsecT e s m)

return returns a parser that succeeds without consuming input.

Defined in Text.Megaparsec.Internal

Methods

(>>=) :: ParsecT e s m a -> (a -> ParsecT e s m b) -> ParsecT e s m b

(>>) :: ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m b

return :: a -> ParsecT e s m a

fail :: String -> ParsecT e s m a

Functor (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

fmap :: (a -> b) -> ParsecT e s m a -> ParsecT e s m b

(<$) :: a -> ParsecT e s m b -> ParsecT e s m a

(Stream s, MonadFix m) => MonadFix (ParsecT e s m)

Since: 6.0.0

Defined in Text.Megaparsec.Internal

Methods

mfix :: (a -> ParsecT e s m a) -> ParsecT e s m a

Stream s => MonadFail (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

fail :: String -> ParsecT e s m a

Stream s => Applicative (ParsecT e s m)

pure returns a parser that succeeds without consuming input.

Defined in Text.Megaparsec.Internal

Methods

pure :: a -> ParsecT e s m a

(<*>) :: ParsecT e s m (a -> b) -> ParsecT e s m a -> ParsecT e s m b

liftA2 :: (a -> b -> c) -> ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m c

(*>) :: ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m b

(<*) :: ParsecT e s m a -> ParsecT e s m b -> ParsecT e s m a

(Stream s, MonadIO m) => MonadIO (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

liftIO :: IO a -> ParsecT e s m a

(Ord e, Stream s) => Alternative (ParsecT e s m)

empty is a parser that fails without consuming input.

Defined in Text.Megaparsec.Internal

Methods

empty :: ParsecT e s m a

(<|>) :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a

some :: ParsecT e s m a -> ParsecT e s m [a]

many :: ParsecT e s m a -> ParsecT e s m [a]

(Ord e, Stream s) => MonadPlus (ParsecT e s m)

mzero is a parser that fails without consuming input.

Defined in Text.Megaparsec.Internal

Methods

mzero :: ParsecT e s m a

mplus :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a

(Stream s, MonadCont m) => MonadCont (ParsecT e s m)

Defined in Text.Megaparsec.Internal

Methods

callCC :: ((a -> ParsecT e s m b) -> ParsecT e s m a) -> ParsecT e s m a

(a ~ Tokens s, IsString a, Eq a, Stream s, Ord e) => IsString (ParsecT e s m a)

Since: 6.3.0

Defined in Text.Megaparsec.Internal

Methods

fromString :: String -> ParsecT e s m a

(Stream s, Semigroup a) => Semigroup (ParsecT e s m a)

Since: 5.3.0

Defined in Text.Megaparsec.Internal

Methods

(<>) :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a

sconcat :: NonEmpty (ParsecT e s m a) -> ParsecT e s m a

stimes :: Integral b => b -> ParsecT e s m a -> ParsecT e s m a

(Stream s, Monoid a) => Monoid (ParsecT e s m a)

Since: 5.3.0

Defined in Text.Megaparsec.Internal

Methods

mempty :: ParsecT e s m a

mappend :: ParsecT e s m a -> ParsecT e s m a -> ParsecT e s m a

mconcat :: [ParsecT e s m a] -> ParsecT e s m a

Helper functions

toHints

Arguments

:: Stream s

=> Int

Current offset in input stream

-> ParseError s e

Parse error to convert

-> Hints (Token s)

Convert ParseError record into Hints.

withHints

Arguments

:: Stream s

=> Hints (Token s)

Hints to use

-> (ParseError s e -> State s -> m b)

Continuation to influence

-> ParseError s e

First argument of resulting continuation

-> State s

Second argument of resulting continuation

-> m b

withHints hs c makes “error” continuation c use given hints hs.

Note that if resulting continuation gets ParseError that has custom data in it, hints are ignored.

accHints

Arguments

:: Hints t

Hints to add

-> (a -> State s -> Hints t -> m b)

An “OK” continuation to alter

-> a -> State s -> Hints t -> m b

Altered “OK” continuation

accHints hs c results in “OK” continuation that will add given hints hs to third argument of original continuation c.

refreshLastHint :: Hints t -> Maybe (ErrorItem t) -> Hints t

Replace the most recent group of hints (if any) with the given ErrorItem (or delete it if Nothing is given). This is used in label primitive.

runParsecT

Arguments

:: Monad m

=> ParsecT e s m a

Parser to run

-> State s

Initial state

-> m (Reply e s a)

Low-level unpacking of the ParsecT type.

withParsecT :: (Monad m, Ord e') => (e -> e') -> ParsecT e s m a -> ParsecT e' s m a

Transform any custom errors thrown by the parser using the given function. Similar in function and purpose to withExceptT.

Since: 7.0.0