84 lines
2.9 KiB
Haskell
84 lines
2.9 KiB
Haskell
-- from https://github.com/blaenk/blaenk.github.io
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE CPP #-}
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import Text.Pandoc
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import Text.Pandoc.Walk (walk, query)
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import Text.Pandoc.Class (runPure)
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import Text.Pandoc.Builder (text, toList)
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import Text.Pandoc.Options (def)
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import Text.Pandoc.JSON (toJSONFilter)
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import Data.Either (fromRight)
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import Data.List (groupBy)
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import Data.Tree (Forest, Tree(Node))
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import Data.Function (on)
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import Data.Maybe (fromMaybe)
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import Data.Text (unpack)
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data TOCAlignment = TOCOff | TOCLeft | TOCRight
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headerLevel :: Block -> Int
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headerLevel (Header level _ _) = level
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headerLevel _ = error "not a header"
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ignoreTOC :: Block -> Block
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ignoreTOC (Header level (ident, classes, params) inlines) =
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Header level (ident, "notoc" : classes, params) inlines
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ignoreTOC x = x
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collectHeaders :: Block -> [Block]
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collectHeaders header@(Header _ (_, classes, _) _) =
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if "notoc" `elem` classes
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then []
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else [header]
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collectHeaders _ = []
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groupByHierarchy :: [Block] -> Forest Block
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groupByHierarchy = map (\(x:xs) -> Node x (groupByHierarchy xs)) . groupBy ((<) `on` headerLevel)
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markupLink :: Attr -> [Inline] -> Inline
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markupLink (headerId, _, headerProperties) headerText
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= let linkText = fromMaybe headerText (fmap (toList . text) $ lookup "toc" headerProperties)
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in Link nullAttr linkText (("#" ++ headerId), headerId)
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markupHeader :: Tree Block -> [Block]
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markupHeader n@(Node (Header _ hAttr hText) headers)
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| headers == [] = [link]
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| otherwise = [link, markupHeaders headers]
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where link = Plain [markupLink hAttr hText]
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markupHeader n = error $ "'markupHeader' should only be passed a 'Node $ Header'\n"
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++ " saw: " ++ show n
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markupHeaders :: Forest Block -> Block
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markupHeaders = OrderedList (1, Decimal, Period) . map markupHeader
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createTable :: TOCAlignment -> Forest Block -> Block
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createTable _ [] = Null
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createTable alignment headers
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= let alignAttr = case alignment of
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TOCRight -> " class=\"right-toc\""
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_ -> ""
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navBegin = "<nav id=\"toc\"" ++ alignAttr ++ ">"
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navEnd = "</nav>"
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tocDoc = Pandoc nullMeta [Para [Str "Contents"], markupHeaders headers]
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tocString = unpack . fromRight mempty . runPure . writeHtml5String def $ tocDoc
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in RawBlock "html" (navBegin ++ "\n" ++ tocString ++ "\n" ++ navEnd)
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generateTOC :: [Block] -> TOCAlignment -> Block -> Block
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generateTOC headers alignment x@(BulletList (( (( Plain ((Str "toc"):_)):_)):_))
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= createTable alignment . groupByHierarchy $ headers
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generateTOC _ _ x = x
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tableOfContents :: TOCAlignment -> Pandoc -> Pandoc
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tableOfContents alignment ast
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= let headers = query collectHeaders ast
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tocGen = case alignment of
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TOCOff -> walk ignoreTOC
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_ -> walk (generateTOC headers alignment)
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in tocGen $ ast
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main :: IO ()
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main = toJSONFilter (tableOfContents TOCRight)
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