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

Text.ParserCombinators.Poly.StateText

Synopsis

# 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 # # Methodsfmap :: (a -> b) -> Parser s a -> Parser s b #(<$) :: a -> Parser s b -> Parser s a # # Methodspure :: a -> Parser s a #(<*>) :: Parser s (a -> b) -> Parser s a -> Parser s b #(*>) :: Parser s a -> Parser s b -> Parser s b #(<*) :: Parser s a -> Parser s b -> Parser s a # # Methodsempty :: Parser s a #(<|>) :: Parser s a -> Parser s a -> Parser s a #some :: Parser s a -> Parser s [a] #many :: Parser s a -> Parser s [a] # # # Methodscommit :: Parser s a -> Parser s a #adjustErr :: Parser s a -> (String -> String) -> Parser s a #oneOf' :: [(String, Parser s a)] -> Parser s a # data Result z a # A return type like Either, that distinguishes not only between right and wrong answers, but also has commitment, so that a failure cannot be undone. This should only be used for writing very primitive parsers - really it is an internal detail of the library. The z type is the remaining unconsumed input. Constructors  Success z a Failure z String Committed (Result z a) Instances  # Methodsfmap :: (a -> b) -> Result z a -> Result z b #(<$) :: 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

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.