3 files changed, 248 insertions, 0 deletions

diff --git a/bbcode/src/BBCode.hs b/bbcode/src/BBCode.hs
new file mode 100644
index 0000000..750fb0f
--- /dev/null
+++ b/bbcode/src/BBCode.hs
@@ -0,0 +1,96 @@
+{-# LANGUAGE OverloadedStrings, OverloadedLists, RankNTypes, ImpredicativeTypes #-}
+
+module BBCode
+       ( parse
+       ) where
+
+import Thermoprint
+
+import BBCode.Tokenizer
+import BBCode.Syntax
+
+import Data.Maybe
+import Data.Monoid
+import Data.Either
+import Data.Bifunctor
+import Data.List
+import Data.Ord
+import Data.Foldable
+
+import Data.Function (on)
+
+import           Data.CaseInsensitive  ( CI )
+import qualified Data.CaseInsensitive as CI
+
+import           Data.Map  ( Map )
+import qualified Data.Map as Map
+
+import Prelude hiding (takeWhile)
+
+import Debug.Trace
+
+knownTags :: Map (CI String) (Either (Block String -> Block String) (Inline String -> Inline String))
+knownTags = [ ("center", Left Center)
+            , ("u", Right Underline)
+            ]
+
+isBlock, isInline :: String -> Bool
+isBlock = testTag isLeft
+isInline = testTag isRight
+testTag f k = fromMaybe False (f <$> Map.lookup (CI.mk k) knownTags)
+
+data Decorated c = Decorated c [String]
+                 deriving (Show, Eq)
+
+parse :: String -> Either String (Block String)
+parse input = (remerge . blockify <$> (tokenize input >>= treeify)) >>= semantics
+
+blockify :: ContentForest -> [Decorated String]
+blockify = map sortDeco . concat . map (blockify' [])
+  where
+    blockify' _ Empty = []
+    blockify' initial (Content str) = [str `Decorated` initial]
+    blockify' initial (Tagged cs tag) = concat $ map (blockify' $ tag : initial) cs
+    sortDeco :: Decorated c -> Decorated c
+    sortDeco (Decorated c tags) = Decorated c $ (nubBy ((==) `on` CI.mk) . sortBy blockiness) tags
+    blockiness :: String -> String -> Ordering
+    blockiness a b = comparing isBlock a b <> comparing CI.mk a b -- sort also alphabetically for the benefit of remerge
+
+remerge :: [Decorated String] -> ContentForest
+remerge [] = []
+remerge [(Decorated c deco)] = [appEndo applyDeco $ Content c]
+  where
+    applyDeco = foldMap (\t -> Endo (\c -> Tagged [c] t)) $ reverse deco
+remerge xs = concat $ map toTree $ groupLasts xs
+  where
+    groupLasts = groupBy ((==) `on` (listToMaybe . reverse . (\(Decorated _ ds) -> ds)))
+    -- toTree :: [Decorated String] -> [ContentTree]
+    toTree [] = []
+    toTree (x@(Decorated _ []):xs) = map (Content . (\(Decorated c []) -> c)) (x:xs)
+    toTree (x@(Decorated _ ds):xs) = [Tagged content tag]
+      where
+        tag = last ds
+        content = toTree $ map stripLast (x:xs)
+        stripLast (Decorated c ds) = Decorated c (init ds)
+
+unknownTag :: forall a. String -> Either String a
+unknownTag tag = Left $ "Unknown tag: " ++ tag
+
+semantics :: ContentForest -> Either String (Block String)
+semantics forest = Over <$> mapM semantics' forest
+
+semantics' :: ContentTree -> Either String (Block String)
+semantics' Empty = Right $ Over []
+semantics' (Content str) = Right $ Paragraph (Cooked str)
+semantics' (Tagged cs tag) = case Map.lookup (CI.mk tag) knownTags of
+  Nothing -> unknownTag tag
+  Just (Left f) -> Over . map f <$> mapM semantics' cs
+  Just (Right f) -> Paragraph . Beside . map f<$> mapM iSemantics cs
+
+iSemantics :: ContentTree -> Either String (Inline String)
+iSemantics Empty = Right $ Beside []
+iSemantics (Content str) = Right $ Cooked str
+iSemantics (Tagged cs tag) = case Map.lookup (CI.mk tag) knownTags of
+  Nothing -> unknownTag tag
+  Just (Left f) -> error "Known inline tag sorted within block"
+  Just (Right f) -> Beside . map f <$> mapM iSemantics cs
diff --git a/bbcode/src/BBCode/Syntax.hs b/bbcode/src/BBCode/Syntax.hs
new file mode 100644
index 0000000..a196e05
--- /dev/null
+++ b/bbcode/src/BBCode/Syntax.hs
@@ -0,0 +1,108 @@
+{-# LANGUAGE RecordWildCards #-}
+
+module BBCode.Syntax
+       ( treeify
+       , ContentForest
+       , ContentTree(..)
+       ) where
+
+import BBCode.Tokenizer (Token(..))
+
+import Data.Foldable
+import Data.Bifunctor
+import Data.Monoid
+
+import Control.Monad.State
+import Control.Monad.Trans
+import Control.Monad
+  
+import           Data.CaseInsensitive  ( CI )
+import qualified Data.CaseInsensitive as CI
+
+import Data.Function (on)
+
+type ContentForest = [ContentTree]
+data ContentTree = Content String
+                 | Tagged [ContentTree] String
+                 | Empty
+                 deriving (Show, Eq)
+
+data Step = Down [ContentTree] [ContentTree] String
+          deriving (Show)
+
+data Zipper = Zipper
+              { hole :: String
+              , prevs :: [ContentTree]
+              , steps :: [Step]
+              }
+              deriving (Show)
+
+type Parser = StateT Zipper (Either String)
+abort :: String -> Parser a
+abort = lift . Left
+
+
+treeify :: [Token] -> Either String ContentForest
+treeify tokenStream = second (postProcess . unZip) $ execStateT (mapM_ incorporate tokenStream) (Zipper "" [] [])
+
+postProcess :: ContentForest -> ContentForest
+postProcess forest = do
+  tree <- forest
+  let
+    tree' = postProcess' tree
+  guard $ tree' /= Empty
+  return tree'
+  where
+    postProcess' :: ContentTree -> ContentTree
+    postProcess' (Content "") = Empty
+    postProcess' (Tagged [] _) = Empty
+    postProcess' (Tagged cs t) = Tagged [c' | c <- cs, let c' = postProcess' c, c' /= Empty ] t
+    postProcess' x = x
+
+unZip :: Zipper -> ContentForest
+unZip Zipper{..} = reverse (apply hole steps : prevs)
+
+apply :: String -> [Step] -> ContentTree
+apply hole steps = hole `apply'` (reverse steps)
+apply' "" [] = Empty
+apply' hole [] = Content hole
+apply' hole (Down pres posts tag:steps) = Tagged (reverse pres ++ [hole `apply` steps] ++ posts) tag
+
+incorporate :: Token -> Parser ()
+incorporate (Text str) = append str
+incorporate (Whitespace str)
+  | delimitsPar str = do
+      currSteps <- gets steps
+      if null currSteps then
+        modify (\Zipper{..} -> Zipper { hole = "", steps = [], prevs = (hole `apply` steps : prevs) })
+        else
+        append str
+  | otherwise = append str
+  where
+    delimitsPar str = (sum . map (const (1 :: Integer)) . filter (== '\n') $ str) >= 1
+incorporate (TagOpen tagName) = modify $ (\z@(Zipper{..}) -> z { steps = (Down [] [] tagName : steps) })
+incorporate (TagClose tagName) = do
+  currSteps <- gets steps
+  case currSteps of
+    [] -> abort $ "Closing unopenend tag: " ++ tagName
+    (Down pres posts tagName':s) -> if ((==) `on` CI.mk) tagName tagName' then
+                                      goUp
+                                    else
+                                       abort $ "Mismatched tags: [" ++ tagName' ++ "]...[/" ++ tagName ++ "]"
+
+append :: String -> Parser ()
+append str = modify (\z@(Zipper{..}) -> z { hole = hole ++ str })
+
+goUp :: Parser ()
+goUp = do
+  (Down pres posts tagName:s) <- gets steps
+  hole <- gets hole
+  let
+    steppedHole = Tagged (reverse pres ++ [Content hole] ++ posts) tagName
+  case s of
+    [] -> modify $ (\z@(Zipper{..}) -> Zipper { hole = "", prevs = steppedHole : prevs, steps = [] })
+    (t:ts) -> do
+      let
+        (Down pres posts tagName) = t
+        t' = Down (steppedHole : pres) posts tagName
+      modify $ (\z -> z { hole = "", steps = (t':ts) })
diff --git a/bbcode/src/BBCode/Tokenizer.hs b/bbcode/src/BBCode/Tokenizer.hs
new file mode 100644
index 0000000..c860c7c
--- /dev/null
+++ b/bbcode/src/BBCode/Tokenizer.hs
@@ -0,0 +1,44 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module BBCode.Tokenizer
+       ( Token(..)
+       , tokenize
+       ) where
+
+import qualified Data.Text.Lazy as TL
+import qualified Data.Text as T
+
+import Control.Applicative
+import Data.Attoparsec.Text.Lazy
+
+import Data.Char (isSpace)
+import Data.Monoid (mconcat)
+
+data Token = Text String
+           | Whitespace String
+           | TagOpen String
+           | TagClose String
+           deriving (Show, Read, Eq)
+
+tokenize :: String -> Either String [Token]
+tokenize = eitherResult . parse (tokenize' <* endOfInput) . TL.pack
+
+tokenize' :: Parser [Token]
+tokenize' = many $ choice [ whitespace
+                          , Text . T.unpack <$> ("\\" *> "[")
+                          , tagClose
+                          , tagOpen
+                          , text
+                          ]
+
+whitespace :: Parser Token
+whitespace = Whitespace <$> many1 space
+
+tagOpen :: Parser Token
+tagOpen = TagOpen . T.unpack <$> ("[" *> takeWhile1 (/= ']') <* "]")
+
+tagClose :: Parser Token
+tagClose = TagClose . T.unpack <$> ("[/" *> takeWhile1 (/= ']') <* "]")
+
+text :: Parser Token
+text = Text . T.unpack <$> takeWhile1 (\c -> not (isSpace c) && notInClass "[" c)