hledger/doc/site/TableOfContents.hs

83 lines
2.6 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
-- from https://github.com/blaenk/blaenk.github.io
module TableOfContents (
tableOfContents,
ignoreTOC,
collectHeaders,
removeTOCMarker
) where
import Text.Pandoc
import Text.Pandoc.Walk (walk, query)
import Data.List (groupBy)
import Data.Tree (Forest, Tree(Node))
import Data.Monoid ((<>), mconcat)
import Data.Function (on)
import Data.Maybe (fromMaybe)
import Text.Blaze.Html (preEscapedToHtml, (!))
import Text.Blaze.Html.Renderer.String (renderHtml)
import qualified Text.Blaze.Html5 as H
import qualified Text.Blaze.Html5.Attributes as A
headerLevel :: Block -> Int
headerLevel (Header level _ _) = level
headerLevel _ = error "not a header"
ignoreTOC :: Block -> Block
ignoreTOC (Header level (ident, classes, params) inline) =
Header level (ident, "notoc" : classes, params) inline
ignoreTOC x = x
removeTOCMarker :: Block -> Block
removeTOCMarker (BulletList (( (( Plain ((Str "toc"):_)):_)):_)) = Null
removeTOCMarker x = x
collectHeaders :: Block -> [Block]
collectHeaders header@(Header _ (_, classes, _) _) =
if "notoc" `elem` classes
then []
else [header]
collectHeaders _ = []
groupByHierarchy :: [Block] -> Forest Block
groupByHierarchy = map (\(x:xs) -> Node x (groupByHierarchy xs)) . groupBy ((<) `on` headerLevel)
markupHeader :: Tree Block -> H.Html
markupHeader (Node (Header _ (ident, _, keyvals) inline) headers)
| headers == [] = H.li $ link
| otherwise = H.li $ link <> (H.ol $ markupHeaders headers)
where render x = writeHtmlString def (Pandoc nullMeta [(Plain x)])
section = fromMaybe (render inline) (lookup "toc" keyvals)
link = H.a ! A.href (H.toValue $ "#" ++ ident) $ preEscapedToHtml section
markupHeader _ = error "what"
markupHeaders :: Forest Block -> H.Html
markupHeaders = mconcat . map markupHeader
createTable :: Forest Block -> H.Html
createTable headers =
(H.nav ! A.id "toc") $ do
H.p "Contents"
H.ol $ markupHeaders headers
generateTOC :: [Block] -> String -> Block -> Block
generateTOC [] _ x = x
generateTOC headers alignment x@(BulletList (( (( Plain ((Str "toc"):_)):_)):_))
| alignment == "right" = render . (! A.class_ "right-toc") . table $ headers
| alignment == "left" = render . table $ headers
| otherwise = x
where render = (RawBlock "html") . renderHtml
table = createTable . groupByHierarchy
generateTOC _ _ x = x
tableOfContents :: String -> Pandoc -> Pandoc
tableOfContents alignment ast =
if alignment /= "off"
then let headers = query collectHeaders ast
in walk (generateTOC headers alignment) ast
else walk ignoreTOC ast