attoparsec-0.8.2.0: Fast combinator parsing for bytestringsSource codeContentsIndex
Data.Attoparsec.Char8
Portabilityunknown
Stabilityexperimental
Maintainerbos@serpentine.com
Contents
Character encodings
Parser types
Running parsers
Combinators
Parsing individual characters
Special character parsers
Fast predicates
Character classes
Efficient string handling
Text parsing
Numeric parsers
State observation and manipulation functions
Description
Simple, efficient, character-oriented combinator parsing for ByteString strings, loosely based on the Parsec library.
Synopsis
data Parser a
data Result r
= Fail !ByteString [String] String
| Partial (ByteString -> Result r)
| Done !ByteString r
parse :: Parser a -> ByteString -> Result a
parseTest :: Show a => Parser a -> ByteString -> IO ()
parseWith :: Monad m => m ByteString -> Parser a -> ByteString -> m (Result a)
feed :: Result r -> ByteString -> Result r
(<?>) :: Parser a -> String -> Parser a
try :: Parser a -> Parser a
module Data.Attoparsec.Combinator
satisfy :: (Char -> Bool) -> Parser Char
char :: Char -> Parser Char
anyChar :: Parser Char
char8 :: Char -> Parser Word8
notChar :: Char -> Parser Char
digit :: Parser Char
letter_iso8859_15 :: Parser Char
letter_ascii :: Parser Char
space :: Parser Char
isDigit :: Char -> Bool
isDigit_w8 :: Word8 -> Bool
isAlpha_iso8859_15 :: Char -> Bool
isAlpha_ascii :: Char -> Bool
isSpace :: Char -> Bool
isSpace_w8 :: Word8 -> Bool
inClass :: String -> Char -> Bool
notInClass :: String -> Char -> Bool
string :: ByteString -> Parser ByteString
stringCI :: ByteString -> Parser ByteString
skipSpace :: Parser ()
skipWhile :: (Char -> Bool) -> Parser ()
take :: Int -> Parser ByteString
takeTill :: (Char -> Bool) -> Parser ByteString
takeWhile :: (Char -> Bool) -> Parser ByteString
takeWhile1 :: (Char -> Bool) -> Parser ByteString
endOfLine :: Parser ()
isEndOfLine :: Word8 -> Bool
isHorizontalSpace :: Word8 -> Bool
decimal :: Integral a => Parser a
hexadecimal :: Integral a => Parser a
signed :: Num a => Parser a -> Parser a
endOfInput :: Parser ()
ensure :: Int -> Parser ()
Character encodings

This module is intended for parsing text that is represented using an 8-bit character set, e.g. ASCII or ISO-8859-15. It does not make any attempt to deal with character encodings, multibyte characters, or wide characters. In particular, all attempts to use characters above code point U+00FF will give wrong answers.

Code points below U+0100 are simply translated to and from their numeric values, so e.g. the code point U+00A4 becomes the byte 0xA4 (which is the Euro symbol in ISO-8859-15, but the generic currency sign in ISO-8859-1). Haskell Char values above U+00FF are truncated, so e.g. U+1D6B7 is truncated to the byte 0xB7.

Parser types
data Parser a Source
The Parser type is a monad.
show/hide Instances
data Result r Source
The result of a parse.
Constructors
Fail !ByteString [String] StringThe parse failed. The ByteString is the input that had not yet been consumed when the failure occurred. The [String] is a list of contexts in which the error occurred. The String is the message describing the error, if any.
Partial (ByteString -> Result r)Supply this continuation with more input so that the parser can resume. To indicate that no more input is available, use an empty string.
Done !ByteString rThe parse succeeded. The ByteString is the input that had not yet been consumed (if any) when the parse succeeded.
show/hide Instances
Running parsers
parse :: Parser a -> ByteString -> Result aSource
Run a parser and return its result.
parseTest :: Show a => Parser a -> ByteString -> IO ()Source
Run a parser and print its result to standard output.
parseWithSource
:: Monad m
=> m ByteString
-> Parser aInitial input for the parser.
-> ByteString
-> m (Result a)
Run a parser with an initial input string, and a monadic action that can supply more input if needed.
feed :: Result r -> ByteString -> Result rSource
If a parser has returned a Partial result, supply it with more input.
Combinators
(<?>)Source
::
=> Parser athe name to use if parsing fails
-> String
-> Parser a
try :: Parser a -> Parser aSource

Attempt a parse, and if it fails, rewind the input so that no input appears to have been consumed.

This combinator is useful in cases where a parser might consume some input before failing, i.e. the parser needs arbitrary lookahead. The downside to using this combinator is that it can retain input for longer than is desirable.

module Data.Attoparsec.Combinator
Parsing individual characters
satisfy :: (Char -> Bool) -> Parser CharSource

The parser satisfy p succeeds for any byte for which the predicate p returns True. Returns the byte that is actually parsed. 

digit = satisfy isDigit
    where isDigit c = c >= '0' && c <= '9'
char :: Char -> Parser CharSource
Match a specific character.
anyChar :: Parser CharSource
Match any character.
char8 :: Char -> Parser Word8Source
Match a specific character, but return its Word8 value.
notChar :: Char -> Parser CharSource
Match any character except the given one.
Special character parsers
digit :: Parser CharSource
Parse a single digit.
letter_iso8859_15 :: Parser CharSource
Match a letter, in the ISO-8859-15 encoding.
letter_ascii :: Parser CharSource
Match a letter, in the ASCII encoding.
space :: Parser CharSource

Parse a space character.

Note: This parser only gives correct answers for the ASCII encoding. For instance, it does not recognise U+00A0 (non-breaking space) as a space character, even though it is a valid ISO-8859-15 byte.

Fast predicates
isDigit :: Char -> BoolSource
A fast digit predicate.
isDigit_w8 :: Word8 -> BoolSource
A fast digit predicate.
isAlpha_iso8859_15 :: Char -> BoolSource

A fast alphabetic predicate for the ISO-8859-15 encoding

Note: For all character encodings other than ISO-8859-15, and almost all Unicode code points above U+00A3, this predicate gives wrong answers.

isAlpha_ascii :: Char -> BoolSource

A fast alphabetic predicate for the ASCII encoding

Note: For all character encodings other than ASCII, and almost all Unicode code points above U+007F, this predicate gives wrong answers.

isSpace :: Char -> BoolSource

Fast predicate for matching ASCII space characters.

Note: This predicate only gives correct answers for the ASCII encoding. For instance, it does not recognise U+00A0 (non-breaking space) as a space character, even though it is a valid ISO-8859-15 byte. For a Unicode-aware and only slightly slower predicate, use Data.Char.isSpace

isSpace_w8 :: Word8 -> BoolSource
Fast Word8 predicate for matching ASCII space characters.
Character classes
inClass :: String -> Char -> BoolSource

Match any character in a set. 

vowel = inClass "aeiou"

Range notation is supported. 

halfAlphabet = inClass "a-nA-N"

To add a literal '-' to a set, place it at the beginning or end of the string.

notInClass :: String -> Char -> BoolSource
Match any character not in a set.
Efficient string handling
string :: ByteString -> Parser ByteStringSource

string s parses a sequence of bytes that identically match s. Returns the parsed string (i.e. s). This parser consumes no input if it fails (even if a partial match).

Note: The behaviour of this parser is different to that of the similarly-named parser in Parsec, as this one is all-or-nothing. To illustrate the difference, the following parser will fail under Parsec given an input of for: 

string "foo" <|> string "for"

The reason for its failure is that that the first branch is a partial match, and will consume the letters 'f' and 'o' before failing. In Attoparsec, the above parser will succeed on that input, because the failed first branch will consume nothing.

stringCI :: ByteString -> Parser ByteStringSource
Satisfy a literal string, ignoring case.
skipSpace :: Parser ()Source
Skip over white space.
skipWhile :: (Char -> Bool) -> Parser ()Source
Skip past input for as long as the predicate returns True.
take :: Int -> Parser ByteStringSource
Consume exactly n bytes of input.
takeTill :: (Char -> Bool) -> Parser ByteStringSource

Consume input as long as the predicate returns False (i.e. until it returns True), and return the consumed input.

This parser does not fail. It will return an empty string if the predicate returns True on the first byte of input.

Note: Because this parser does not fail, do not use it with combinators such as many, because such parsers loop until a failure occurs. Careless use will thus result in an infinite loop.

takeWhile :: (Char -> Bool) -> Parser ByteStringSource

Consume input as long as the predicate returns True, and return the consumed input.

This parser does not fail. It will return an empty string if the predicate returns False on the first byte of input.

Note: Because this parser does not fail, do not use it with combinators such as many, because such parsers loop until a failure occurs. Careless use will thus result in an infinite loop.

takeWhile1 :: (Char -> Bool) -> Parser ByteStringSource

Consume input as long as the predicate returns True, and return the consumed input.

This parser requires the predicate to succeed on at least one byte of input: it will fail if the predicate never returns True or if there is no input left.

Text parsing
endOfLine :: Parser ()Source
Match either a single newline character '\n', or a carriage return followed by a newline character "\r\n".
isEndOfLine :: Word8 -> BoolSource
A predicate that matches either a carriage return '\r' or newline '\n' character.
isHorizontalSpace :: Word8 -> BoolSource
A predicate that matches either a space ' ' or horizontal tab '\t' character.
Numeric parsers
decimal :: Integral a => Parser aSource
Parse and decode an unsigned decimal number.
hexadecimal :: Integral a => Parser aSource

Parse and decode an unsigned hexadecimal number. The hex digits 'a' through 'f' may be upper or lower case.

This parser does not accept a leading "0x" string.

signed :: Num a => Parser a -> Parser aSource
Parse a number with an optional leading '+' or '-' sign character.
State observation and manipulation functions
endOfInput :: Parser ()Source
Match only if all input has been consumed.
ensure :: Int -> Parser ()Source
Succeed only if at least n bytes of input are available.
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