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122 lines
4.0 KiB
Haskell
122 lines
4.0 KiB
Haskell
module Main where
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import Text.ParserCombinators.ReadP
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import Control.Monad
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import Control.Applicative
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import Text.Printf
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import Debug.Trace
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import Data.List
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type HeaderLevel = Int
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newtype URL = URL {getUrl :: String}
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newtype ImgPath = ImgPath {getPath :: String}
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parseMany :: ReadP a -> ReadP [a]
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parseMany = Text.ParserCombinators.ReadP.many
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data MdToken = Header HeaderLevel MdToken
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| Para [MdToken]
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| Linebreak
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| HorizontalRule
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| Blockquote MdToken
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| UnordList [MdToken]
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| OrdList [MdToken]
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| Code String
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| Codeblock String
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| Link MdToken URL
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| Image MdToken ImgPath
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| Bold MdToken
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| Italic MdToken
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| Strikethrough MdToken
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| Unit String
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-- Deriving Show for MdToken
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instance Show MdToken where
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show (Header level token) = "<h" ++ show level ++ ">" ++ show token ++ "</h" ++ show level ++ ">"
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show (Para tokens) = concat(map show tokens)
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show Linebreak = "\n"
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show HorizontalRule = "---------"
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show (Blockquote token) = "BLOCK" ++ show token
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show (UnordList tokens) = "UNORD" ++ concat(map show tokens)
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show (OrdList tokens) = "ORD" ++ concat(map show tokens)
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show (Code code) = show code
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show (Codeblock code) = show code
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show (Link txt url) = "<a href=" ++ (getUrl url) ++ ">" ++ show txt ++ "</a>"
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show (Image txt path) = "<img src=" ++ (getPath path) ++ ">" ++ show txt ++ "</img>"
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show (Bold token) = "<b>" ++ show token ++ "</b>"
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show (Italic token) = "<i>" ++ show token ++ "</i>"
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show (Strikethrough token) = "<s>" ++ show token ++ "</s>"
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show (Unit unit) = printf "%s" unit
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-- ---------------
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-- Helpers
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mustBeHash :: ReadP Char
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mustBeHash = satisfy (\x -> x == '#')
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leftmostLongest :: (Foldable t) => [(a, t b)] -> (a, t b)
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leftmostLongest xs =
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let lastElem = (last xs)
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filteredLst = (filter (\val -> (length $ snd val) == (length $ snd lastElem)) xs)
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in head filteredLst
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leftmostLongestParse :: ReadP a -> String -> (a, String)
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leftmostLongestParse parser input = leftmostLongest $ readP_to_S parser input
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-- ---------------
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parseHeader :: ReadP MdToken
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parseHeader = do
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headers <- many1 mustBeHash
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when ((length headers) > 6)
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pfail
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_ <- string " "
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text <- munch1 (\x -> x /= '\n') -- Parse until EOL
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-- traceM text
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let parsedText = fst $ leftmostLongestParse parseLine text
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return (Header (length headers) parsedText)
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parseBold :: ReadP MdToken
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parseBold = do
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text <- choice[
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(between (string "__") (string "__") (munch1 (/= '_'))),
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(between (string "**") (string "**") (munch1 (/= '*')))
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]
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-- text <- munch1 (\x -> x /= '_' && x /= '*') -- Parse until first asterisk/underscore
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-- traceM text
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-- _ <- char '_' <|> char '*' -- Throw away the second asterisk/underscore
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let parsedText = fst $ leftmostLongestParse parseLine text
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return (Bold parsedText)
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parseItalic :: ReadP MdToken
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parseItalic = do
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text <- choice[
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(between (string "_") (string "_") (munch1 (/= '_'))),
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(between (string "*") (string "*") (munch1 (/= '*')))
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]
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let parsedText = fst $ leftmostLongestParse parseLine text
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return (Italic parsedText)
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parseString :: ReadP MdToken
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parseString = do
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firstChar <- get -- Must parse at least one character here
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text <- munch (\x -> not (elem x "#*_[\n"))
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return (Unit (firstChar:text))
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--return (Unit text)
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parseToken :: ReadP MdToken
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parseToken = choice [parseHeader, parseBold, parseItalic, parseString]
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parseLine :: ReadP MdToken
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parseLine = do
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parsed <- parseMany parseToken
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-- traceM $ show parsed
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return (Para parsed)
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main :: IO ()
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main = do
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let res = leftmostLongestParse parseLine "## Hello __world_*"
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putStrLn (show res)
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