Text.ParserCombinators.Poly.StateText

polyparse-1.12: A variety of alternative parser combinator libraries.

Safe Haskell | Safe
Language | Haskell98

Text.ParserCombinators.Poly.StateText

Contents

- The Parser datatype
  - Basic parsers
  - Derived parsers (but implemented more efficiently)
  - State-handling
  - Re-parsing
- Re-export all more general combinators

Synopsis

- newtype Parser s a = P (s -> Text -> Result (Text, s) a)
- data Result z a
  - = Success z a
  - | Failure z String
  - | Committed (Result z a)
- runParser :: Parser s a -> s -> Text -> (Either String a, s, Text)
- next :: Parser s Char
- eof :: Parser s ()
- satisfy :: (Char -> Bool) -> Parser s Char
- onFail :: Parser s a -> Parser s a -> Parser s a
- manySatisfy :: (Char -> Bool) -> Parser s Text
- many1Satisfy :: (Char -> Bool) -> Parser s Text
- stUpdate :: (s -> s) -> Parser s ()
- stQuery :: (s -> a) -> Parser s a
- stGet :: Parser s s
- reparse :: Text -> Parser s ()
- module Text.ParserCombinators.Poly.Base
- module Control.Applicative

# The Parser datatype

newtype Parser s a #

This `Parser` datatype is a specialised parsing monad with error reporting. Whereas the standard version can be used for arbitrary token types, this version is specialised to Text input only.

Constructors

P (s -> Text -> Result (Text, s) a) |

Instances

Monad (Parser s) # |
Methods (>>=) :: Parser s a -> (a -> Parser s b) -> Parser s b # (>>) :: Parser s a -> Parser s b -> Parser s b # return :: a -> Parser s a # fail :: String -> Parser s a #
Functor (Parser s) # |
Methods fmap :: (a -> b) -> Parser s a -> Parser s b # (<$) :: a -> Parser s b -> Parser s a #
Applicative (Parser s) # |
Methods pure :: a -> Parser s a # (<*>) :: Parser s (a -> b) -> Parser s a -> Parser s b # (*>) :: Parser s a -> Parser s b -> Parser s b # (<*) :: Parser s a -> Parser s b -> Parser s a #
Alternative (Parser s) # |
Methods empty :: Parser s a # (<|>) :: Parser s a -> Parser s a -> Parser s a # some :: Parser s a -> Parser s [a] # many :: Parser s a -> Parser s [a] #
PolyParse (Parser s) # |
Commitment (Parser s) # |
Methods commit :: Parser s a -> Parser s a # adjustErr :: Parser s a -> (String -> String) -> Parser s a # oneOf' :: [(String, Parser s a)] -> Parser s a #

data Result z a #

A return type like Either, that distinguishes not only between right and wrong answers, but also has commitment, so that a failure cannot be undone. This should only be used for writing very primitive parsers - really it is an internal detail of the library. The z type is the remaining unconsumed input.

Constructors

Success z a |
Failure z String |
Committed (Result z a) |

Instances

Functor (Result z) # |
Methods fmap :: (a -> b) -> Result z a -> Result z b # (<$) :: a -> Result z b -> Result z a #

runParser :: Parser s a -> s -> Text -> (Either String a, s, Text) #

Apply a parser to an input token sequence.

## Basic parsers

next :: Parser s Char #

Simply return the next token in the input tokenstream.

eof :: Parser s () #

Succeed if the end of file/input has been reached, fail otherwise.

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

Return the next token if it satisfies the given predicate.

onFail :: Parser s a -> Parser s a -> Parser s a #

`p `onFail` q` means parse p, unless p fails, in which case parse q instead. Can be chained together to give multiple attempts to parse something. (Note that q could itself be a failing parser, e.g. to change the error message from that defined in p to something different.) However, a severe failure in p cannot be ignored.

## Derived parsers (but implemented more efficiently)

manySatisfy :: (Char -> Bool) -> Parser s Text #

`manySatisfy p` is a more efficient fused version of `many (satisfy p)`

many1Satisfy :: (Char -> Bool) -> Parser s Text #

`many1Satisfy p` is a more efficient fused version of `many1 (satisfy p)`

## State-handling

stUpdate :: (s -> s) -> Parser s () #

Update the internal state.

stQuery :: (s -> a) -> Parser s a #

Query the internal state.

stGet :: Parser s s #

Deliver the entire internal state.

## Re-parsing

reparse :: Text -> Parser s () #

Push some tokens back onto the front of the input stream and reparse. This is useful e.g. for recursively expanding macros. When the user-parser recognises a macro use, it can lookup the macro expansion from the parse state, lex it, and then stuff the lexed expansion back down into the parser.

# Re-export all more general combinators

module Text.ParserCombinators.Poly.Base

module Control.Applicative