megaparsec-5.2.0: Monadic parser combinators

Copyright© 2015–2017 Megaparsec contributors
© 2007 Paolo Martini
© 1999–2001 Daan Leijen
LicenseFreeBSD
MaintainerMark Karpov <markkarpov@opmbx.org>
Stabilityexperimental
Portabilitynon-portable
Safe HaskellNone
LanguageHaskell2010

Text.Megaparsec.Char

Contents

Description

Commonly used character parsers.

Synopsis

Simple parsers

newline :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a newline character.

crlf :: (MonadParsec e s m, Token s ~ Char) => m String #

Parses a carriage return character followed by a newline character. Returns sequence of characters parsed.

eol :: (MonadParsec e s m, Token s ~ Char) => m String #

Parses a CRLF (see crlf) or LF (see newline) end of line. Returns the sequence of characters parsed.

eol = (pure <$> newline) <|> crlf

tab :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a tab character.

space :: (MonadParsec e s m, Token s ~ Char) => m () #

Skips zero or more white space characters.

See also: skipMany and spaceChar.

Categories of characters

controlChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses control characters, which are the non-printing characters of the Latin-1 subset of Unicode.

spaceChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a Unicode space character, and the control characters: tab, newline, carriage return, form feed, and vertical tab.

upperChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses an upper-case or title-case alphabetic Unicode character. Title case is used by a small number of letter ligatures like the single-character form of Lj.

lowerChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a lower-case alphabetic Unicode character.

letterChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses alphabetic Unicode characters: lower-case, upper-case and title-case letters, plus letters of case-less scripts and modifiers letters.

alphaNumChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses alphabetic or numeric digit Unicode characters.

Note that numeric digits outside the ASCII range are parsed by this parser but not by digitChar. Such digits may be part of identifiers but are not used by the printer and reader to represent numbers.

printChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses printable Unicode characters: letters, numbers, marks, punctuation, symbols and spaces.

digitChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses an ASCII digit, i.e between “0” and “9”.

octDigitChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses an octal digit, i.e. between “0” and “7”.

hexDigitChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a hexadecimal digit, i.e. between “0” and “9”, or “a” and “f”, or “A” and “F”.

markChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses Unicode mark characters, for example accents and the like, which combine with preceding characters.

numberChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses Unicode numeric characters, including digits from various scripts, Roman numerals, et cetera.

punctuationChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses Unicode punctuation characters, including various kinds of connectors, brackets and quotes.

symbolChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses Unicode symbol characters, including mathematical and currency symbols.

separatorChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses Unicode space and separator characters.

asciiChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a character from the first 128 characters of the Unicode character set, corresponding to the ASCII character set.

latin1Char :: (MonadParsec e s m, Token s ~ Char) => m Char #

Parses a character from the first 256 characters of the Unicode character set, corresponding to the ISO 8859-1 (Latin-1) character set.

charCategory :: (MonadParsec e s m, Token s ~ Char) => GeneralCategory -> m Char #

charCategory cat Parses character in Unicode General Category cat, see GeneralCategory.

categoryName :: GeneralCategory -> String #

Returns human-readable name of Unicode General Category.

More general parsers

char :: (MonadParsec e s m, Token s ~ Char) => Char -> m Char #

char c parses a single character c.

semicolon = char ';'

char' :: (MonadParsec e s m, Token s ~ Char) => Char -> m Char #

The same as char but case-insensitive. This parser returns actually parsed character preserving its case.

>>> parseTest (char' 'e') "E"
'E'
>>> parseTest (char' 'e') "G"
1:1:
unexpected 'G'
expecting 'E' or 'e'

anyChar :: (MonadParsec e s m, Token s ~ Char) => m Char #

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

oneOf :: (Foldable f, MonadParsec e s m, Token s ~ Char) => f Char -> m Char #

oneOf cs succeeds if the current character is in the supplied list of characters cs. Returns the parsed character. Note that this parser doesn't automatically generate “expected” component of error message, so usually you should label it manually with label or (<?>).

See also: satisfy.

digit = oneOf ['0'..'9'] <?> "digit"

oneOf' :: (Foldable f, MonadParsec e s m, Token s ~ Char) => f Char -> m Char #

The same as oneOf, but case-insensitive. Returns the parsed character preserving its case.

vowel = oneOf' "aeiou" <?> "vowel"

noneOf :: (Foldable f, MonadParsec e s m, Token s ~ Char) => f Char -> m Char #

As the dual of oneOf, noneOf cs succeeds if the current character not in the supplied list of characters cs. Returns the parsed character.

noneOf' :: (Foldable f, MonadParsec e s m, Token s ~ Char) => f Char -> m Char #

The same as noneOf, but case-insensitive.

consonant = noneOf' "aeiou" <?> "consonant"

satisfy :: (MonadParsec e s m, Token s ~ Char) => (Char -> Bool) -> m Char #

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

digitChar = satisfy isDigit <?> "digit"
oneOf cs  = satisfy (`elem` cs)

Sequence of characters

string :: (MonadParsec e s m, Token s ~ Char) => String -> m String #

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

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

string' :: (MonadParsec e s m, Token s ~ Char) => String -> m String #

The same as string, but case-insensitive. On success returns string cased as actually parsed input.

>>> parseTest (string' "foobar") "foObAr"
"foObAr"