125 lines
4.0 KiB
Haskell
Executable File
125 lines
4.0 KiB
Haskell
Executable File
#!/usr/bin/env stack
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{- stack runghc --verbosity info
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--package pandoc
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-}
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-- Replace a table of contents marker
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-- (a bullet list item containing "toc[-N[-M]]")
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-- with a table of contents based on headings.
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-- toc means full contents, toc-N means contents to depth N
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-- and toc-N-M means contents from depth N to depth M.
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-- Based on code 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 Data.Char (isDigit)
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import Data.List (groupBy)
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import Data.List.Split
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import Data.Tree (Forest, Tree(Node))
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#if !(MIN_VERSION_base(4,11,0))
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import Data.Monoid ((<>), mconcat)
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#endif
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import Data.Function (on)
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import Data.Maybe (fromMaybe)
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import Safe
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import Text.Blaze.Html (preEscapedToHtml, (!))
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import Text.Blaze.Html.Renderer.String (renderHtml)
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import qualified Text.Blaze.Html5 as H
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import qualified Text.Blaze.Html5.Attributes as A
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import Text.Pandoc
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import Text.Pandoc.JSON
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import Text.Pandoc.Walk (walk, query)
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main :: IO ()
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main = toJSONFilter tableOfContents
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tableOfContents :: Pandoc -> Pandoc
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tableOfContents doc =
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let headers = query collectHeaders doc
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in walk (generateTOC headers) doc
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collectHeaders :: Block -> [Block]
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collectHeaders header@(Header _ (_, classes, _) _)
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| "notoc" `elem` classes = []
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| otherwise = [header]
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collectHeaders _ = []
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generateTOC :: [Block] -> Block -> Block
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generateTOC [] x = x
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generateTOC headers x@(BulletList (( (( Plain ((Str txt):_)):_)):_)) =
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case tocParams txt of
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Just (mstartlevel, mendlevel) ->
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render .
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forestDrop mstartlevel .
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forestPrune mendlevel .
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groupByHierarchy $
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headers -- (! A.class_ "right-toc") .
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where
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render = (RawBlock "html") . renderHtml . createTable
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Nothing -> x
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generateTOC _ x = x
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tocParams :: String -> Maybe (Maybe Int, Maybe Int)
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tocParams s =
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case splitOn "-" s of
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["toc"] -> Just (Nothing, Nothing)
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["toc",a] | all isDigit a -> Just (Nothing, readMay a)
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["toc",a,b] | all isDigit a, all isDigit b -> Just (readMay a, readMay b)
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_ -> Nothing
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forestDrop :: Maybe Int -> Forest a -> Forest a
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forestDrop Nothing f = f
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forestDrop (Just n) ts = concatMap (treeDrop n) ts
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treeDrop :: Int -> Tree a -> Forest a
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treeDrop n t | n < 1 = [t]
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treeDrop n (Node _ ts) = concatMap (treeDrop (n-1)) ts
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forestPrune :: Maybe Int -> Forest a -> Forest a
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forestPrune Nothing f = f
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forestPrune (Just n) ts = map (treePrune n) ts
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treePrune :: Int -> Tree a -> Tree a
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treePrune n t | n < 1 = t
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treePrune n (Node v ts) = Node v $ map (treePrune (n-1)) ts
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-- | remove all nodes past a certain depth
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-- treeprune :: Int -> Tree a -> Tree a
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-- treeprune 0 t = Node (root t) []
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-- treeprune d t = Node (root t) (map (treeprune $ d-1) $ branches t)
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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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headerLevel :: Block -> Int
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headerLevel (Header level _ _) = level
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headerLevel _ = error "not a header"
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createTable :: Forest Block -> H.Html
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createTable headers =
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(H.nav ! A.id "toc") $ do
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H.p "Contents"
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H.ol $ markupHeaders headers
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markupHeader :: Tree Block -> H.Html
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markupHeader (Node (Header _ (ident, _, keyvals) inline) headers)
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| headers == [] = H.li $ link
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| otherwise = H.li $ link <> (H.ol $ markupHeaders headers)
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where render x = writeHtmlString def (Pandoc nullMeta [(Plain x)])
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section = fromMaybe (render inline) (lookup "toc" keyvals)
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link = H.a ! A.href (H.toValue $ "#" ++ ident) $ preEscapedToHtml section
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markupHeader _ = error "what"
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markupHeaders :: Forest Block -> H.Html
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markupHeaders = mconcat . map markupHeader
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-- ignoreTOC :: Block -> Block
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-- ignoreTOC (Header level (ident, classes, params) inline) =
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-- Header level (ident, "notoc" : classes, params) inline
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-- ignoreTOC x = x
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-- removeTOCMarker :: Block -> Block
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-- removeTOCMarker (BulletList (( (( Plain ((Str "toc"):_)):_)):_)) = Null
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-- removeTOCMarker x = x
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