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{-# LANGUAGE FlexibleContexts #-}
module CSV(
Settings(..),
specialChars,
defaultSettings,
unParseRecord,
parseRecord
) where
-- This source is licensed under Creative Commons CC0 v1.0.
-- To read the full text, see license.txt in the main directory of this repository
-- or go to https://creativecommons.org/publicdomain/zero/1.0/legalcode.txt
-- For a human readable summary, go to https://creativecommons.org/publicdomain/zero/1.0/
import Text.ParserCombinators.Parsec ( (<|>), (<?>) )
import qualified Text.ParserCombinators.Parsec as Parsec
import qualified Data.Char as Char
import qualified Data.List as List
data Settings = Settings
{ separator :: Char
, quote :: Char
, escape :: Char }
defaultSettings = Settings
{ separator = ','
, quote = '\"'
, escape = '\\' }
specialChars :: Settings -> String
specialChars s = (separator s):(quote s):(escape s):[]
unParseRecord :: Settings -> [String] -> String
unParseRecord settings record =
let escFunc c = if (c == escape settings || c == quote settings) then (escape settings):c:[] else c:[]
escapeField s = ((quote settings) : (concatMap escFunc s)) ++ ((quote settings):[])
in List.intercalate [separator settings] (map escapeField record)
parseRecord :: Settings -> String -> Either Parsec.ParseError [String]
parseRecord settings input =
Parsec.parse (record settings) "error" input
record s = do
f <- (field s) `Parsec.sepBy` (Parsec.char (separator s))
Parsec.optional eol
Parsec.eof
return f
field s =
Parsec.many (Parsec.try (quoted s) <|> Parsec.many1 (fieldChar s)) >>=
return . foldl1 (++)
quoted s =
Parsec.between
(Parsec.char (quote s))
(Parsec.char (quote s))
(Parsec.many (quotedChar s))
fieldChar s = allExcept s (specialChars s)
quotedChar s = allExcept s [quote s]
allExcept s c =
Parsec.try (escapeChar s) <|>
Parsec.satisfy (\x -> (not (Char.isControl x)) && (x `notElem` c))
escapeChar s = do
Parsec.char (escape s)
Parsec.oneOf (specialChars s)
eol = Parsec.try (Parsec.string "\r\n")
<|> Parsec.try (Parsec.string "\r")
<|> Parsec.try (Parsec.string "\n")
<?> "end of line"
|
