Modulemegaparsec-9.7.0Haskell2010

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.

5 types
6 values

Packagemegaparsec-9.7.0
Exports11
LanguageHaskell2010
LicenceBSD-2-Clause
SourceInternal.hs

Data types

5 declarations

newtypenewtype 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:

Example1 expression

>>> 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:

Example1 expression

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

Constructors

Hints (Set (ErrorItem t))

Instances2Semigroup, Monoid

Ord t => Semigroup (Hints t)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
Ord t => Monoid (Hints t)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal

datadata 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. Reply can also be used to resume parsing.

Constructors

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

Instances1Functor

Functor (Reply e s)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal

datadata Consumption

Whether the input has been consumed or not.

Constructors

Consumed
Some part of input stream was consumed
NotConsumed
No input was consumed

datadata Result s e a

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

Constructors

OK (Hints (Token s)) a
Parser succeeded (includes hints)
Error (ParseError s e)
Parser failed

Instances1Functor

Functor (Result s e)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal

newtypenewtype ParsecT e s (m :: Type -> Type) 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
- 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

Instances19MonadParsec, MonadParsecDbg, MonadError, MonadReader, MonadState, MonadWriter, …

(Ord e, Stream s) => MonadParsec e s (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(VisualStream s, ShowErrorComponent e) => MonadParsecDbg e s (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Debug
(Stream s, MonadError e' m) => MonadError e' (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, MonadReader r m) => MonadReader r (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, MonadState st m) => MonadState st (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, MonadWriter w m) => MonadWriter w (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
Stream s => MonadTrans (ParsecT e s)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
Stream s => Monad (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
return returns a parser that succeeds without consuming input.
Functor (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, MonadFix m) => MonadFix (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
Stream s => MonadFail (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
Stream s => Applicative (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
pure returns a parser that succeeds without consuming input.
(Ord e, Stream s) => Alternative (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
empty is a parser that fails without consuming input.
(Ord e, Stream s) => MonadPlus (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
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 = mzero
```
However the following holds:
```
try v >> mzero = mzero
```
(Stream s, MonadIO m) => MonadIO (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, MonadCont m) => MonadCont (ParsecT e s m)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(a ~ Tokens s, IsString a, Eq a, Stream s, Ord e) => IsString (ParsecT e s m a)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, Semigroup a) => Semigroup (ParsecT e s m a)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal
(Stream s, Monoid a) => Monoid (ParsecT e s m a)Defined in megaparsec-9.7.0 · Text.Megaparsec.Internal

Helper functions

6 declarations

valuetoHints

:: Stream s
=> Int
Current offset in input stream
-> ParseError s e
Parse error to convert
-> Hints (Token s)

Convert a ParseError record into Hints.

valuewithHints

:: 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.

valueaccHints

:: Stream s
=> Hints (Token s)
Hints to add
-> (a -> State s e -> Hints (Token s) -> m b)
An “OK” continuation to alter
-> a
Altered “OK” continuation
-> State s e
-> Hints (Token s)
-> m b

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

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

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

valuerunParsecT

:: 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.

valuewithParsecT

:: 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.