Distribution.Compat.Parsec

Cabal-2.1.0.0: A framework for packaging Haskell software

Safe Haskell | None
Language | Haskell2010

Distribution.Compat.Parsec

Contents

- Combinators
- Char

Synopsis

- type Parsec s u = ParsecT s u Identity
- data ParsecT s u (m :: * -> *) a :: * -> * -> (* -> *) -> * -> *
- class Monad m => Stream s (m :: * -> *) t | s -> t
- (<?>) :: ParsecT s u m a -> String -> ParsecT s u m a
- runParser :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a
- between :: Stream s m t => ParsecT s u m open -> ParsecT s u m close -> ParsecT s u m a -> ParsecT s u m a
- option :: Stream s m t => a -> ParsecT s u m a -> ParsecT s u m a
- optional :: Stream s m t => ParsecT s u m a -> ParsecT s u m ()
- optionMaybe :: Stream s m t => ParsecT s u m a -> ParsecT s u m (Maybe a)
- try :: ParsecT s u m a -> ParsecT s u m a
- sepBy :: Stream s m t => ParsecT s u m a -> ParsecT s u m sep -> ParsecT s u m [a]
- sepBy1 :: Stream s m t => ParsecT s u m a -> ParsecT s u m sep -> ParsecT s u m [a]
- choice :: Stream s m t => [ParsecT s u m a] -> ParsecT s u m a
- eof :: (Stream s m t, Show t) => ParsecT s u m ()
- integral :: (Stream s m Char, Integral a) => ParsecT s u m a
- char :: Stream s m Char => Char -> ParsecT s u m Char
- anyChar :: Stream s m Char => ParsecT s u m Char
- satisfy :: Stream s m Char => (Char -> Bool) -> ParsecT s u m Char
- space :: Stream s m Char => ParsecT s u m Char
- spaces :: Stream s m Char => ParsecT s u m ()
- skipSpaces1 :: Stream s m Char => ParsecT s u m ()
- string :: Stream s m Char => String -> ParsecT s u m String
- munch :: Stream s m Char => (Char -> Bool) -> ParsecT s u m String
- munch1 :: Stream s m Char => (Char -> Bool) -> ParsecT s u m String
- oneOf :: Stream s m Char => [Char] -> ParsecT s u m Char

# Documentation

type Parsec s u = ParsecT s u Identity Source #

data ParsecT s u (m :: * -> *) a :: * -> * -> (* -> *) -> * -> * Source #

ParserT monad transformer and Parser type

`ParsecT s u m a` is a parser with stream type `s`, user state type `u`, underlying monad `m` and return type `a`. Parsec is strict in the user state. If this is undesirable, simply used a data type like `data Box a = Box a` and the state type `Box YourStateType` to add a level of indirection.

Instances

MonadState s m => MonadState s (ParsecT s' u m) |
Instance details Methods get :: ParsecT s' u m s Source # put :: s -> ParsecT s' u m () Source # state :: (s -> (a, s)) -> ParsecT s' u m a Source #
MonadReader r m => MonadReader r (ParsecT s u m) |
Instance details Methods ask :: ParsecT s u m r Source # local :: (r -> r) -> ParsecT s u m a -> ParsecT s u m a Source # reader :: (r -> a) -> ParsecT s u m a Source #
MonadError e m => MonadError e (ParsecT s u m) |
Instance details Methods throwError :: e -> ParsecT s u m a Source # catchError :: ParsecT s u m a -> (e -> ParsecT s u m a) -> ParsecT s u m a Source #
MonadTrans (ParsecT s u) |
Instance details Methods lift :: Monad m => m a -> ParsecT s u m a Source #
Monad (ParsecT s u m) |
Instance details Methods (>>=) :: ParsecT s u m a -> (a -> ParsecT s u m b) -> ParsecT s u m b Source # (>>) :: ParsecT s u m a -> ParsecT s u m b -> ParsecT s u m b Source # return :: a -> ParsecT s u m a Source # fail :: String -> ParsecT s u m a Source #
Functor (ParsecT s u m) |
Instance details Methods fmap :: (a -> b) -> ParsecT s u m a -> ParsecT s u m b Source # (<$) :: a -> ParsecT s u m b -> ParsecT s u m a Source #
MonadFail (ParsecT s u m) |
Instance details Methods fail :: String -> ParsecT s u m a Source #
Applicative (ParsecT s u m) |
Instance details Methods pure :: a -> ParsecT s u m a Source # (<*>) :: ParsecT s u m (a -> b) -> ParsecT s u m a -> ParsecT s u m b Source # liftA2 :: (a -> b -> c) -> ParsecT s u m a -> ParsecT s u m b -> ParsecT s u m c Source # (*>) :: ParsecT s u m a -> ParsecT s u m b -> ParsecT s u m b Source # (<*) :: ParsecT s u m a -> ParsecT s u m b -> ParsecT s u m a Source #
MonadIO m => MonadIO (ParsecT s u m) |
Instance details Methods liftIO :: IO a -> ParsecT s u m a Source #
Alternative (ParsecT s u m) |
Instance details Methods empty :: ParsecT s u m a Source # (<|>) :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a Source # some :: ParsecT s u m a -> ParsecT s u m [a] Source # many :: ParsecT s u m a -> ParsecT s u m [a] Source #
MonadPlus (ParsecT s u m) |
Instance details Methods mzero :: ParsecT s u m a Source # mplus :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a Source #
MonadCont m => MonadCont (ParsecT s u m) |
Instance details Methods callCC :: ((a -> ParsecT s u m b) -> ParsecT s u m a) -> ParsecT s u m a Source #

class Monad m => Stream s (m :: * -> *) t | s -> t Source #

An instance of `Stream` has stream type `s`, underlying monad `m` and token type `t` determined by the stream

Some rough guidelines for a "correct" instance of Stream:

- unfoldM uncons gives the [t] corresponding to the stream
- A `Stream` instance is responsible for maintaining the "position within the stream" in the stream state `s`. This is trivial unless you are using the monad in a non-trivial way.

Minimal complete definition

uncons

Instances

Monad m => Stream ByteString m Char |
Instance details Methods uncons :: ByteString -> m (Maybe (Char, ByteString)) Source #
Monad m => Stream ByteString m Char |
Instance details Methods uncons :: ByteString -> m (Maybe (Char, ByteString)) Source #
Monad m => Stream Text m Char |
Instance details Methods uncons :: Text -> m (Maybe (Char, Text)) Source #
Monad m => Stream Text m Char |
Instance details Methods uncons :: Text -> m (Maybe (Char, Text)) Source #
Monad m => Stream [tok] m tok |
Instance details Methods uncons :: [tok] -> m (Maybe (tok, [tok])) Source #

(<?>) :: ParsecT s u m a -> String -> ParsecT s u m a infix 0 Source #

The parser `p <?> msg` behaves as parser `p`, but whenever the parser `p` fails without consuming any input, it replaces expect error messages with the expect error message `msg`.

This is normally used at the end of a set alternatives where we want to return an error message in terms of a higher level construct rather than returning all possible characters. For example, if the `expr` parser from the `try` example would fail, the error message is: '...: expecting expression'. Without the `(<?>)` combinator, the message would be like '...: expecting "let" or letter', which is less friendly.

runParser :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a Source #

The most general way to run a parser over the Identity monad. `runParser p state filePath input` runs parser `p` on the input list of tokens `input`, obtained from source `filePath` with the initial user state `st`. The `filePath` is only used in error messages and may be the empty string. Returns either a `ParseError` (`Left`) or a value of type `a` (`Right`).

     parseFromFile p fname
       = do{ input <- readFile fname
           ; return (runParser p () fname input)
           }

# Combinators

between :: Stream s m t => ParsecT s u m open -> ParsecT s u m close -> ParsecT s u m a -> ParsecT s u m a Source #

`between open close p` parses `open`, followed by `p` and `close`. Returns the value returned by `p`.

     braces  = between (symbol "{") (symbol "}")

option :: Stream s m t => a -> ParsecT s u m a -> ParsecT s u m a Source #

`option x p` tries to apply parser `p`. If `p` fails without consuming input, it returns the value `x`, otherwise the value returned by `p`.

     priority  = option 0 (do{ d <- digit
                             ; return (digitToInt d)
                             })

optional :: Stream s m t => ParsecT s u m a -> ParsecT s u m () Source #

`optional p` tries to apply parser `p`. It will parse `p` or nothing. It only fails if `p` fails after consuming input. It discards the result of `p`.

optionMaybe :: Stream s m t => ParsecT s u m a -> ParsecT s u m (Maybe a) Source #

`optionMaybe p` tries to apply parser `p`. If `p` fails without consuming input, it return `Nothing`, otherwise it returns `Just` the value returned by `p`.

try :: ParsecT s u m a -> ParsecT s u m a Source #

The parser `try p` behaves like parser `p`, except that it pretends that it hasn't consumed any input when an error occurs.

This combinator is used whenever arbitrary look ahead is needed. Since it pretends that it hasn't consumed any input when `p` fails, the (`<|>`) combinator will try its second alternative even when the first parser failed while consuming input.

The `try` combinator can for example be used to distinguish identifiers and reserved words. Both reserved words and identifiers are a sequence of letters. Whenever we expect a certain reserved word where we can also expect an identifier we have to use the `try` combinator. Suppose we write:

     expr        = letExpr <|> identifier <?> "expression"

     letExpr     = do{ string "let"; ... }
     identifier  = many1 letter

If the user writes "lexical", the parser fails with: `unexpected 'x', expecting 't' in "let"`. Indeed, since the (`<|>`) combinator only tries alternatives when the first alternative hasn't consumed input, the `identifier` parser is never tried (because the prefix "le" of the `string "let"` parser is already consumed). The right behaviour can be obtained by adding the `try` combinator:

     expr        = letExpr <|> identifier <?> "expression"

     letExpr     = do{ try (string "let"); ... }
     identifier  = many1 letter

sepBy :: Stream s m t => ParsecT s u m a -> ParsecT s u m sep -> ParsecT s u m [a] Source #

`sepBy p sep` parses zero or more occurrences of `p`, separated by `sep`. Returns a list of values returned by `p`.

     commaSep p  = p `sepBy` (symbol ",")

sepBy1 :: Stream s m t => ParsecT s u m a -> ParsecT s u m sep -> ParsecT s u m [a] Source #

`sepBy1 p sep` parses one or more occurrences of `p`, separated by `sep`. Returns a list of values returned by `p`.

choice :: Stream s m t => [ParsecT s u m a] -> ParsecT s u m a Source #

`choice ps` tries to apply the parsers in the list `ps` in order, until one of them succeeds. Returns the value of the succeeding parser.

eof :: (Stream s m t, Show t) => ParsecT s u m () Source #

This parser only succeeds at the end of the input. This is not a primitive parser but it is defined using `notFollowedBy`.

     eof  = notFollowedBy anyToken <?> "end of input"

# Char

integral :: (Stream s m Char, Integral a) => ParsecT s u m a Source #

char :: Stream s m Char => Char -> ParsecT s u m Char Source #

`char c` parses a single character `c`. Returns the parsed character (i.e. `c`).

     semiColon  = char ';'

anyChar :: Stream s m Char => ParsecT s u m Char Source #

This parser succeeds for any character. Returns the parsed character.

satisfy :: Stream s m Char => (Char -> Bool) -> ParsecT s u m Char Source #

The parser `satisfy f` succeeds for any character for which the supplied function `f` returns `True`. Returns the character that is actually parsed.

space :: Stream s m Char => ParsecT s u m Char Source #

Parses a white space character (any character which satisfies `isSpace`) Returns the parsed character.

spaces :: Stream s m Char => ParsecT s u m () Source #

Skips zero or more white space characters. See also `skipMany`.

skipSpaces1 :: Stream s m Char => ParsecT s u m () Source #

string :: Stream s m Char => String -> ParsecT s u m String Source #

`string s` parses a sequence of characters given by `s`. Returns the parsed string (i.e. `s`).

     divOrMod    =   string "div"
                 <|> string "mod"

munch :: Stream s m Char => (Char -> Bool) -> ParsecT s u m String Source #

Greedely munch characters while predicate holds. Always succeeds.

munch1 :: Stream s m Char => (Char -> Bool) -> ParsecT s u m String Source #

Greedily munch characters while predicate holds. Require at least one character.

oneOf :: Stream s m Char => [Char] -> ParsecT s u m Char Source #

`oneOf cs` succeeds if the current character is in the supplied list of characters `cs`. Returns the parsed character. See also `satisfy`.

      vowel  = oneOf "aeiou"