{-# LANGUAGE OverloadedStrings #-} {- | Module : Text.Pandoc.Slides Copyright : Copyright (C) 2012-2021 John MacFarlane License : GNU GPL, version 2 or above Maintainer : John MacFarlane <jgm@berkeley.edu> Stability : alpha Portability : portable Utility functions for splitting documents into slides for slide show formats (dzslides, revealjs, s5, slidy, slideous, beamer). -} module Text.Pandoc.Slides ( getSlideLevel, prepSlides ) where import Text.Pandoc.Definition -- | Find level of header that starts slides (defined as the least header -- level that occurs before a non-header/non-hrule in the blocks). getSlideLevel :: [Block] -> Int getSlideLevel = go 6 where go least (Header n _ _ : x : xs) | n < least && nonHOrHR x = go n xs | otherwise = go least (x:xs) go least (Div _ bs : xs) = min (go least bs) (go least xs) go least (_ : xs) = go least xs go least [] = least nonHOrHR Header{} = False nonHOrHR HorizontalRule = False nonHOrHR _ = True -- | Prepare a block list to be passed to makeSections. prepSlides :: Int -> [Block] -> [Block] prepSlides slideLevel = ensureStartWithH . splitHrule . extractRefsHeader where splitHrule (HorizontalRule : Header n attr xs : ys) | n == slideLevel = Header slideLevel attr xs : splitHrule ys splitHrule (HorizontalRule : xs) = Header slideLevel nullAttr [Str "\0"] : splitHrule xs splitHrule (x : xs) = x : splitHrule xs splitHrule [] = [] extractRefsHeader bs = case reverse bs of (Div ("refs",classes,kvs) (Header n attrs xs : ys) : zs) -> reverse zs ++ [Header n attrs xs, Div ("refs",classes,kvs) ys] _ -> bs ensureStartWithH bs@(Header n _ _:_) | n <= slideLevel = bs ensureStartWithH bs@(Div _ (Header n _ _:_) : _) | n <= slideLevel = bs ensureStartWithH bs = Header slideLevel nullAttr [Str "\0"] : bs