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{-# LANGUAGE NoImplicitPrelude #-}
{- |
Module : Text.Pandoc.Slides
Copyright : Copyright (C) 2012-2019 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 Prelude
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 (_ : xs) = go least xs
go least [] = least
nonHOrHR Header{} = False
nonHOrHR HorizontalRule = False
nonHOrHR _ = True
-- | Prepare a block list to be passed to hierarchicalize.
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 = Header slideLevel nullAttr [Str "\0"] : bs
|
