Rename "desirability" to "preference" (much less awkward), with the

[match/match.git] / program / TSV.hs

module TSV (
	parseTSV, formatTSV
) where
import Data.List

-- Simple implementation of tab-separated values with a trailing newline and no
-- quoting support.

splitList :: Eq a => a -> Bool -> [a] -> [[a]]
splitList delim terminated =
	let sl [] | terminated = []
	    sl l = case break (== delim) l of
	           (hh, []) -> [hh]
	           (hh, {-delim-} _ : t) -> hh : sl t
	in sl

-- We use the Eq only to check the validity...
joinList :: Eq a => a -> Bool -> [[a]] -> [a]
joinList delim terminated l =
	if any (any (== delim)) l then error "joinList: item contains delimiter"
	else if terminated
	then concatMap (++ [delim]) l
	else intercalate [delim] l

type TSV = [[String]]

formatTSV :: TSV -> String
formatTSV = joinList '\n' True . map (joinList '\t' False)

parseTSV :: String -> TSV
parseTSV = map (splitList '\t' False) . splitList '\n' True