| Copyright | (c) Daan Leijen 1999-2001 (c) Paolo Martini 2007 | 
|---|---|
| License | BSD-style (see the LICENSE file) | 
| Maintainer | derek.a.elkins@gmail.com | 
| Stability | provisional | 
| Portability | portable | 
| Safe Haskell | Safe | 
| Language | Haskell2010 | 
Text.Parsec.Prim
Description
The primitive parser combinators.
Synopsis
- unknownError :: State s u -> ParseError
- sysUnExpectError :: String -> SourcePos -> Reply s u a
- unexpected :: Stream s m t => String -> ParsecT s u m a
- data ParsecT s u m a
- runParsecT :: Monad m => ParsecT s u m a -> State s u -> m (Consumed (m (Reply s u a)))
- mkPT :: Monad m => (State s u -> m (Consumed (m (Reply s u a)))) -> ParsecT s u m a
- type Parsec s u = ParsecT s u Identity
- data Consumed a
- data Reply s u a- = Ok a !(State s u) ParseError
- | Error ParseError
 
- data State s u = State {- stateInput :: s
- statePos :: !SourcePos
- stateUser :: !u
 
- parsecMap :: (a -> b) -> ParsecT s u m a -> ParsecT s u m b
- parserReturn :: a -> ParsecT s u m a
- parserBind :: ParsecT s u m a -> (a -> ParsecT s u m b) -> ParsecT s u m b
- mergeErrorReply :: ParseError -> Reply s u a -> Reply s u a
- parserFail :: String -> ParsecT s u m a
- parserZero :: ParsecT s u m a
- parserPlus :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a
- (<?>) :: ParsecT s u m a -> String -> ParsecT s u m a
- (<|>) :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a
- label :: ParsecT s u m a -> String -> ParsecT s u m a
- labels :: ParsecT s u m a -> [String] -> ParsecT s u m a
- lookAhead :: Stream s m t => ParsecT s u m a -> ParsecT s u m a
- class Monad m => Stream s m t | s -> t where
- tokens :: (Stream s m t, Eq t) => ([t] -> String) -> (SourcePos -> [t] -> SourcePos) -> [t] -> ParsecT s u m [t]
- try :: ParsecT s u m a -> ParsecT s u m a
- token :: Stream s Identity t => (t -> String) -> (t -> SourcePos) -> (t -> Maybe a) -> Parsec s u a
- tokenPrim :: Stream s m t => (t -> String) -> (SourcePos -> t -> s -> SourcePos) -> (t -> Maybe a) -> ParsecT s u m a
- tokenPrimEx :: Stream s m t => (t -> String) -> (SourcePos -> t -> s -> SourcePos) -> Maybe (SourcePos -> t -> s -> u -> u) -> (t -> Maybe a) -> ParsecT s u m a
- many :: ParsecT s u m a -> ParsecT s u m [a]
- skipMany :: ParsecT s u m a -> ParsecT s u m ()
- manyAccum :: (a -> [a] -> [a]) -> ParsecT s u m a -> ParsecT s u m [a]
- runPT :: Stream s m t => ParsecT s u m a -> u -> SourceName -> s -> m (Either ParseError a)
- runP :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a
- runParserT :: Stream s m t => ParsecT s u m a -> u -> SourceName -> s -> m (Either ParseError a)
- runParser :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a
- parse :: Stream s Identity t => Parsec s () a -> SourceName -> s -> Either ParseError a
- parseTest :: (Stream s Identity t, Show a) => Parsec s () a -> s -> IO ()
- getPosition :: Monad m => ParsecT s u m SourcePos
- getInput :: Monad m => ParsecT s u m s
- setPosition :: Monad m => SourcePos -> ParsecT s u m ()
- setInput :: Monad m => s -> ParsecT s u m ()
- getParserState :: Monad m => ParsecT s u m (State s u)
- setParserState :: Monad m => State s u -> ParsecT s u m (State s u)
- updateParserState :: (State s u -> State s u) -> ParsecT s u m (State s u)
- getState :: Monad m => ParsecT s u m u
- putState :: Monad m => u -> ParsecT s u m ()
- modifyState :: Monad m => (u -> u) -> ParsecT s u m ()
- setState :: Monad m => u -> ParsecT s u m ()
- updateState :: Monad m => (u -> u) -> ParsecT s u m ()
Documentation
unknownError :: State s u -> ParseError #
sysUnExpectError :: String -> SourcePos -> Reply s u a #
unexpected :: Stream s m t => String -> ParsecT s u m a #
The parser unexpected msg always fails with an unexpected error
 message msg without consuming any input.
The parsers fail, (<?>) and unexpected are the three parsers
 used to generate error messages. Of these, only (<?>) is commonly
 used. For an example of the use of unexpected, see the definition
 of notFollowedBy.
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 use a data type like data Box a = Box a and
 the state type Box YourStateType to add a level of indirection.
Instances
| MonadError e m => MonadError e (ParsecT s u m) # | |
| Defined in Text.Parsec.Prim 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 # | |
| MonadReader r m => MonadReader r (ParsecT s u m) # | |
| MonadState s m => MonadState s (ParsecT s' u m) # | |
| MonadTrans (ParsecT s u) # | |
| Defined in Text.Parsec.Prim | |
| MonadFail (ParsecT s u m) # | Since: parsec-3.1.12.0 | 
| MonadIO m => MonadIO (ParsecT s u m) # | |
| Alternative (ParsecT s u m) # | |
| Applicative (ParsecT s u m) # | |
| Defined in Text.Parsec.Prim 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 # | |
| Functor (ParsecT s u m) # | |
| Monad (ParsecT s u m) # | |
| MonadPlus (ParsecT s u m) # | |
| MonadCont m => MonadCont (ParsecT s u m) # | |
| (Monoid a, Semigroup (ParsecT s u m a)) => Monoid (ParsecT s u m a) # | The  Since: parsec-3.1.12 | 
| Semigroup a => Semigroup (ParsecT s u m a) # | The  (many $ char The above will parse a string like  (many $ char Since: parsec-3.1.12 | 
runParsecT :: Monad m => ParsecT s u m a -> State s u -> m (Consumed (m (Reply s u a))) #
Low-level unpacking of the ParsecT type. To run your parser, please look to runPT, runP, runParserT, runParser and other such functions.
mkPT :: Monad m => (State s u -> m (Consumed (m (Reply s u a)))) -> ParsecT s u m a #
Low-level creation of the ParsecT type. You really shouldn't have to do this.
Constructors
| Ok a !(State s u) ParseError | |
| Error ParseError | 
parserReturn :: a -> ParsecT s u m a #
parserBind :: ParsecT s u m a -> (a -> ParsecT s u m b) -> ParsecT s u m b #
mergeErrorReply :: ParseError -> Reply s u a -> Reply s u a #
parserFail :: String -> ParsecT s u m a #
parserZero :: ParsecT s u m a #
parserZero always fails without consuming any input. parserZero is defined
 equal to the mzero member of the MonadPlus class and to the empty member
 of the Alternative class.
parserPlus :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a #
(<?>) :: ParsecT s u m a -> String -> ParsecT s u m a infix 0 #
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.
(<|>) :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a infixr 1 #
This combinator implements choice. The parser p <|> q first
 applies p. If it succeeds, the value of p is returned. If p
 fails without consuming any input, parser q is tried. This
 combinator is defined equal to the mplus member of the MonadPlus
 class and the (<|>) member of Alternative.
The parser is called predictive since q is only tried when
 parser p didn't consume any input (i.e.. the look ahead is 1).
 This non-backtracking behaviour allows for both an efficient
 implementation of the parser combinators and the generation of good
 error messages.
label :: ParsecT s u m a -> String -> ParsecT s u m a #
A synonym for <?>, but as a function instead of an operator.
lookAhead :: Stream s m t => ParsecT s u m a -> ParsecT s u m a #
lookAhead p parses p without consuming any input.
If p fails and consumes some input, so does lookAhead. Combine with try
 if this is undesirable.
class Monad m => Stream s m t | s -> t where #
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 Streaminstance is responsible for maintaining the "position within the stream" in the stream states. This is trivial unless you are using the monad in a non-trivial way.
Instances
| Monad m => Stream ByteString m Char # | |
| Defined in Text.Parsec.Prim Methods uncons :: ByteString -> m (Maybe (Char, ByteString)) # | |
| Monad m => Stream ByteString m Char # | |
| Defined in Text.Parsec.Prim Methods uncons :: ByteString -> m (Maybe (Char, ByteString)) # | |
| Monad m => Stream Text m Char # | |
| Monad m => Stream Text m Char # | |
| Monad m => Stream [tok] m tok # | |
| Defined in Text.Parsec.Prim | |
tokens :: (Stream s m t, Eq t) => ([t] -> String) -> (SourcePos -> [t] -> SourcePos) -> [t] -> ParsecT s u m [t] #
try :: ParsecT s u m a -> ParsecT s u m a #
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 letterIf 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 letterArguments
| :: Stream s Identity t | |
| => (t -> String) | Token pretty-printing function. | 
| -> (t -> SourcePos) | Computes the position of a token. | 
| -> (t -> Maybe a) | Matching function for the token to parse. | 
| -> Parsec s u a | 
The parser token showTok posFromTok testTok accepts a token t
 with result x when the function testTok t returns Just xt should be returned by posFromTok t and
 the token can be shown using showTok t.
This combinator is expressed in terms of tokenPrim.
 It is used to accept user defined token streams. For example,
 suppose that we have a stream of basic tokens tupled with source
 positions. We can then define a parser that accepts single tokens as:
 mytoken x
   = token showTok posFromTok testTok
   where
     showTok (pos,t)     = show t
     posFromTok (pos,t)  = pos
     testTok (pos,t)     = if x == t then Just t else NothingArguments
| :: Stream s m t | |
| => (t -> String) | Token pretty-printing function. | 
| -> (SourcePos -> t -> s -> SourcePos) | Next position calculating function. | 
| -> (t -> Maybe a) | Matching function for the token to parse. | 
| -> ParsecT s u m a | 
The parser tokenPrim showTok nextPos testTok accepts a token t
 with result x when the function testTok t returns Just xshowTok t. The position of the next
 token should be returned when nextPos is called with the current
 source position pos, the current token t and the rest of the
 tokens toks, nextPos pos t toks.
This is the most primitive combinator for accepting tokens. For
 example, the char parser could be implemented as:
 char c
   = tokenPrim showChar nextPos testChar
   where
     showChar x        = "'" ++ x ++ "'"
     testChar x        = if x == c then Just x else Nothing
     nextPos pos x xs  = updatePosChar pos xtokenPrimEx :: Stream s m t => (t -> String) -> (SourcePos -> t -> s -> SourcePos) -> Maybe (SourcePos -> t -> s -> u -> u) -> (t -> Maybe a) -> ParsecT s u m a #
many :: ParsecT s u m a -> ParsecT s u m [a] #
many p applies the parser p zero or more times. Returns a
    list of the returned values of p.
 identifier  = do{ c  <- letter
                 ; cs <- many (alphaNum <|> char '_')
                 ; return (c:cs)
                 }skipMany :: ParsecT s u m a -> ParsecT s u m () #
skipMany p applies the parser p zero or more times, skipping
 its result.
spaces = skipMany space
runPT :: Stream s m t => ParsecT s u m a -> u -> SourceName -> s -> m (Either ParseError a) #
runP :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a #
runParserT :: Stream s m t => ParsecT s u m a -> u -> SourceName -> s -> m (Either ParseError a) #
The most general way to run a parser. runParserT 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 a computation in the underlying monad m that return either a ParseError (Left) or a
 value of type a (Right).
runParser :: Stream s Identity t => Parsec s u a -> u -> SourceName -> s -> Either ParseError a #
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)
       }parse :: Stream s Identity t => Parsec s () a -> SourceName -> s -> Either ParseError a #
parse p filePath input runs a parser p over Identity without user
 state. 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).
 main    = case (parse numbers "" "11, 2, 43") of
            Left err  -> print err
            Right xs  -> print (sum xs)
 numbers = commaSep integerparseTest :: (Stream s Identity t, Show a) => Parsec s () a -> s -> IO () #
The expression parseTest p input applies a parser p against
 input input and prints the result to stdout. Used for testing
 parsers.
getPosition :: Monad m => ParsecT s u m SourcePos #
Returns the current source position. See also SourcePos.
setPosition :: Monad m => SourcePos -> ParsecT s u m () #
setPosition pos sets the current source position to pos.
setInput :: Monad m => s -> ParsecT s u m () #
setInput input continues parsing with input. The getInput and
 setInput functions can for example be used to deal with #include
 files.
getParserState :: Monad m => ParsecT s u m (State s u) #
Returns the full parser state as a State record.
setParserState :: Monad m => State s u -> ParsecT s u m (State s u) #
setParserState st set the full parser state to st.
updateParserState :: (State s u -> State s u) -> ParsecT s u m (State s u) #
updateParserState f applies function f to the parser state.
modifyState :: Monad m => (u -> u) -> ParsecT s u m () #
modifyState f applies function f to the user state. Suppose
 that we want to count identifiers in a source, we could use the user
 state as:
 expr  = do{ x <- identifier
           ; modifyState (+1)
           ; return (Id x)
           }updateState :: Monad m => (u -> u) -> ParsecT s u m () #
An alias for modifyState for backwards compatibility.