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 the returned value) or failure (with the parse error), and parser state at the end of parsing.

See also: Consumption, Result.

Constructors

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

data Consumption

Whether the input has been consumed or not.

See also: Result, Reply.

Constructors

Consumed

Some part of input stream was consumed

Virgin

No input was consumed

data Result s e a

Whether the parser has failed or not. On success we include the resulting value, on failure we include a ParseError.

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 e -> (a -> State s e -> Hints (Token s) -> m b) -> (ParseError s e -> State s e -> m b) -> (a -> State s e -> Hints (Token s) -> m b) -> (ParseError s e -> State s e -> m b) -> m b

Instances

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

Defined in Text.Megaparsec.Internal

Methods

parseError :: ParseError s 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 e)

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

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.

Note: strictly speaking, this instance is unlawful. The right identity law does not hold, e.g. in general this is not true:

v >> mzero = mero

However the following holds:

try v >> mzero = mzero

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 a ParseError record into Hints.

withHints

Arguments

:: Stream s

=> Hints (Token s)

Hints to use

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

Continuation to influence

-> ParseError s e

First argument of resulting continuation

-> State s e

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 e -> Hints t -> m b)

An “OK” continuation to alter

-> a -> State s e -> 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 the label primitive.

runParsecT

Arguments

:: Monad m

=> ParsecT e s m a

Parser to run

-> State s e

Initial state

-> m (Reply e s a)

Low-level unpacking of the ParsecT type.

withParsecT

Arguments

:: forall e e' s m a. (Monad m, Ord e')

=> (e -> e')

-> ParsecT e s m a

Inner parser

-> ParsecT e' s m a

Outer parser

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

Note that the inner parser will start with an empty collection of “delayed” ParseErrors. Any delayed ParseErrors produced in the inner parser will be lifted by applying the provided function and added to the collection of delayed parse errors of the outer parser.

Since: 7.0.0