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136 lines
4.5 KiB
Haskell
136 lines
4.5 KiB
Haskell
-----------------------------------------------------------------------------
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-- |
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-- Module : Text.Parsec.Char
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-- Copyright : (c) Daan Leijen 1999-2001, (c) Paolo Martini 2007
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-- License : BSD-style (see the LICENSE file)
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--
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-- Maintainer : derek.a.elkins@gmail.com
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-- Stability : provisional
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-- Portability : portable
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--
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-- Commonly used character parsers.
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--
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-----------------------------------------------------------------------------
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{-# LANGUAGE FlexibleContexts #-}
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module Text.Parsec.Char where
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import Data.Char
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import Text.Parsec.Pos
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import Text.Parsec.Prim
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-- | @oneOf cs@ succeeds if the current character is in the supplied
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-- list of characters @cs@. Returns the parsed character. See also
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-- 'satisfy'.
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--
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-- > vowel = oneOf "aeiou"
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oneOf :: (Stream s m Char) => [Char] -> ParsecT s u m Char
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oneOf cs = satisfy (\c -> elem c cs)
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-- | As the dual of 'oneOf', @noneOf cs@ succeeds if the current
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-- character /not/ in the supplied list of characters @cs@. Returns the
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-- parsed character.
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--
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-- > consonant = noneOf "aeiou"
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noneOf :: (Stream s m Char) => [Char] -> ParsecT s u m Char
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noneOf cs = satisfy (\c -> not (elem c cs))
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-- | Skips /zero/ or more white space characters. See also 'skipMany'.
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spaces :: (Stream s m Char) => ParsecT s u m ()
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spaces = skipMany space <?> "white space"
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-- | Parses a white space character (any character which satisfies 'isSpace')
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-- Returns the parsed character.
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space :: (Stream s m Char) => ParsecT s u m Char
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space = satisfy isSpace <?> "space"
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-- | Parses a newline character (\'\\n\'). Returns a newline character.
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newline :: (Stream s m Char) => ParsecT s u m Char
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newline = char '\n' <?> "new-line"
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-- | Parses a tab character (\'\\t\'). Returns a tab character.
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tab :: (Stream s m Char) => ParsecT s u m Char
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tab = char '\t' <?> "tab"
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-- | Parses an upper case letter (a character between \'A\' and \'Z\').
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-- Returns the parsed character.
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upper :: (Stream s m Char) => ParsecT s u m Char
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upper = satisfy isUpper <?> "uppercase letter"
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-- | Parses a lower case character (a character between \'a\' and \'z\').
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-- Returns the parsed character.
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lower :: (Stream s m Char) => ParsecT s u m Char
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lower = satisfy isLower <?> "lowercase letter"
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-- | Parses a letter or digit (a character between \'0\' and \'9\').
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-- Returns the parsed character.
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alphaNum :: (Stream s m Char => ParsecT s u m Char)
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alphaNum = satisfy isAlphaNum <?> "letter or digit"
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-- | Parses a letter (an upper case or lower case character). Returns the
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-- parsed character.
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letter :: (Stream s m Char) => ParsecT s u m Char
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letter = satisfy isAlpha <?> "letter"
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-- | Parses a digit. Returns the parsed character.
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digit :: (Stream s m Char) => ParsecT s u m Char
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digit = satisfy isDigit <?> "digit"
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-- | Parses a hexadecimal digit (a digit or a letter between \'a\' and
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-- \'f\' or \'A\' and \'F\'). Returns the parsed character.
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hexDigit :: (Stream s m Char) => ParsecT s u m Char
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hexDigit = satisfy isHexDigit <?> "hexadecimal digit"
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-- | Parses an octal digit (a character between \'0\' and \'7\'). Returns
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-- the parsed character.
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octDigit :: (Stream s m Char) => ParsecT s u m Char
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octDigit = satisfy isOctDigit <?> "octal digit"
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-- | @char c@ parses a single character @c@. Returns the parsed
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-- character (i.e. @c@).
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--
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-- > semiColon = char ';'
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char :: (Stream s m Char) => Char -> ParsecT s u m Char
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char c = satisfy (==c) <?> show [c]
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-- | This parser succeeds for any character. Returns the parsed character.
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anyChar :: (Stream s m Char) => ParsecT s u m Char
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anyChar = satisfy (const True)
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-- | The parser @satisfy f@ succeeds for any character for which the
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-- supplied function @f@ returns 'True'. Returns the character that is
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-- actually parsed.
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-- > digit = satisfy isDigit
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-- > oneOf cs = satisfy (\c -> c `elem` cs)
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satisfy :: (Stream s m Char) => (Char -> Bool) -> ParsecT s u m Char
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satisfy f = tokenPrim (\c -> show [c])
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(\pos c _cs -> updatePosChar pos c)
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(\c -> if f c then Just c else Nothing)
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-- | @string s@ parses a sequence of characters given by @s@. Returns
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-- the parsed string (i.e. @s@).
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--
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-- > divOrMod = string "div"
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-- > <|> string "mod"
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string :: (Stream s m Char) => String -> ParsecT s u m String
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string s = tokens show updatePosString s
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