Text.Trifecta.Parser

Documentation

newtype Parser a

The type of a trifecta parser

The first four arguments are behavior continuations:

• epsilon success: the parser has consumed no input and has a result as well as a possible Err; the position and chunk are unchanged (see pure)
• epsilon failure: the parser has consumed no input and is failing with the given Err; the position and chunk are unchanged (see empty)
• committed success: the parser has consumed input and is yielding the result, set of expected strings that would have permitted this parse to continue, new position, and residual chunk to the continuation.
• committed failure: the parser has consumed input and is failing with a given ErrInfo (user-facing error message)

The remaining two arguments are

• the current position
• the chunk of input currently under analysis

Parser is an Alternative; trifecta's backtracking behavior encoded as <|> is to behave as the leftmost parser which yields a value (regardless of any input being consumed) or which consumes input and fails. That is, a choice of parsers will only yield an epsilon failure if *all* parsers in the choice do. If that is not the desired behavior, see try, which turns a committed parser failure into an epsilon failure (at the cost of error information).

Constructors

Parser

Fields

• unparser :: forall r. (a -> Err -> It Rope r) -> (Err -> It Rope r) -> (a -> Set String -> Delta -> ByteString -> It Rope r) -> (ErrInfo -> It Rope r) -> Delta -> ByteString -> It Rope r

Instances

MonadFail Parser

Defined in Text.Trifecta.Parser

Methods

fail :: String -> Parser a

Alternative Parser

Defined in Text.Trifecta.Parser

Methods

empty :: Parser a

(<|>) :: Parser a -> Parser a -> Parser a

some :: Parser a -> Parser [a]

many :: Parser a -> Parser [a]

Applicative Parser

Defined in Text.Trifecta.Parser

Methods

pure :: a -> Parser a

(<*>) :: Parser (a -> b) -> Parser a -> Parser b

liftA2 :: (a -> b -> c) -> Parser a -> Parser b -> Parser c

(*>) :: Parser a -> Parser b -> Parser b

(<*) :: Parser a -> Parser b -> Parser a

Functor Parser

Defined in Text.Trifecta.Parser

Methods

fmap :: (a -> b) -> Parser a -> Parser b

(<$) :: a -> Parser b -> Parser a

Monad Parser

Defined in Text.Trifecta.Parser

Methods

(>>=) :: Parser a -> (a -> Parser b) -> Parser b

(>>) :: Parser a -> Parser b -> Parser b

return :: a -> Parser a

MonadPlus Parser

Defined in Text.Trifecta.Parser

Methods

mzero :: Parser a

mplus :: Parser a -> Parser a -> Parser a

CharParsing Parser

Defined in Text.Trifecta.Parser

Methods

satisfy :: (Char -> Bool) -> Parser Char

char :: Char -> Parser Char

notChar :: Char -> Parser Char

anyChar :: Parser Char

string :: String -> Parser String

text :: Text -> Parser Text

Parsing Parser

Defined in Text.Trifecta.Parser

Methods

try :: Parser a -> Parser a

(<?>) :: Parser a -> String -> Parser a

skipMany :: Parser a -> Parser ()

skipSome :: Parser a -> Parser ()

unexpected :: String -> Parser a

eof :: Parser ()

notFollowedBy :: Show a => Parser a -> Parser ()

LookAheadParsing Parser

Defined in Text.Trifecta.Parser

Methods

lookAhead :: Parser a -> Parser a

TokenParsing Parser

Defined in Text.Trifecta.Parser

Methods

someSpace :: Parser ()

nesting :: Parser a -> Parser a

semi :: Parser Char

highlight :: Highlight -> Parser a -> Parser a

token :: Parser a -> Parser a

DeltaParsing Parser

Defined in Text.Trifecta.Parser

Methods

line :: Parser ByteString

position :: Parser Delta

slicedWith :: (a -> ByteString -> r) -> Parser a -> Parser r

rend :: Parser Rendering

restOfLine :: Parser ByteString

Errable Parser

Defined in Text.Trifecta.Parser

Methods

raiseErr :: Err -> Parser a

MarkParsing Delta Parser

Defined in Text.Trifecta.Parser

Methods

mark :: Parser Delta

release :: Delta -> Parser ()

(Semigroup a, Monoid a) => Monoid (Parser a)

Defined in Text.Trifecta.Parser

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mempty :: Parser a

mappend :: Parser a -> Parser a -> Parser a

mconcat :: [Parser a] -> Parser a

Semigroup a => Semigroup (Parser a)

Defined in Text.Trifecta.Parser

Methods

(<>) :: Parser a -> Parser a -> Parser a

sconcat :: NonEmpty (Parser a) -> Parser a

stimes :: Integral b => b -> Parser a -> Parser a

manyAccum :: (a -> [a] -> [a]) -> Parser a -> Parser [a]

Feeding a parser more more input

data Step a

A Step allows for incremental parsing, since the parser

• can be done with a final result
• have errored
• can have yielded a partial result with possibly more to come

Constructors

StepDone !Rope a

Parsing is done and has converted the Rope to a final result

StepFail !Rope ErrInfo

Parsing the Rope has failed with an error

StepCont !Rope (Result a) (Rope -> Step a)

The Rope has been partially consumed and already yielded a Result, and if more input is provided, more results can be produced.

One common scenario for this is to parse log files: after parsing a single line, that data can already be worked with, but there may be more lines to come.

Instances

Functor Step

Defined in Text.Trifecta.Parser

Methods

fmap :: (a -> b) -> Step a -> Step b

(<$) :: a -> Step b -> Step a

Show a => Show (Step a)

Defined in Text.Trifecta.Parser

Methods

showsPrec :: Int -> Step a -> ShowS

show :: Step a -> String

showList :: [Step a] -> ShowS

feed :: Reducer t Rope => t -> Step r -> Step r

Feed some additional input to a Step to continue parsing a bit further.

starve :: Step a -> Result a

Assume all possible input has been given to the parser, execute it to yield a final result.

stepParser

Arguments

:: Parser a

-> Delta

Starting cursor position. Usually mempty for the beginning of the file.

-> Step a

Incremental parsing. A Step can be supplied with new input using feed, the final Result is obtained using starve.

stepResult :: Rope -> Result a -> Step a

stepIt :: It Rope a -> Step a

Parsing

runParser

Arguments

:: Reducer t Rope

=> Parser a

-> Delta

Starting cursor position. Usually mempty for the beginning of the file.

-> t

-> Result a

Run a Parser on input that can be reduced to a Rope, e.g. String, or ByteString. See also the monomorphic versions parseString and parseByteString.

parseFromFile :: MonadIO m => Parser a -> String -> m (Maybe a)

(parseFromFile p filePath) runs a parser p on the input read from filePath using readFile. All diagnostic messages emitted over the course of the parse attempt are shown to the user on the console.

main = do
  result <- parseFromFile numbers "digits.txt"
  case result of
    Nothing -> return ()
    Just a  -> print $ sum a

parseFromFileEx :: MonadIO m => Parser a -> String -> m (Result a)

(parseFromFileEx p filePath) runs a parser p on the input read from filePath using readFile. Returns all diagnostic messages emitted over the course of the parse and the answer if the parse was successful.

main = do
  result <- parseFromFileEx (many number) "digits.txt"
  case result of
    Failure xs -> displayLn xs
    Success a  -> print (sum a)

parseString

Arguments

:: Parser a

-> Delta

Starting cursor position. Usually mempty for the beginning of the file.

-> String

-> Result a

Fully parse a String to a Result.

parseByteString p delta i runs a parser p on i.

parseByteString

Arguments

:: Parser a

-> Delta

Starting cursor position. Usually mempty for the beginning of the file.

-> ByteString

-> Result a

Fully parse a ByteString to a Result.

parseByteString p delta i runs a parser p on i.

parseTest :: (MonadIO m, Show a) => Parser a -> String -> m ()