Allow to overwrite top-level division type heuristics (#3258)

Pandoc uses heuristics to determine the most resonable top-level
division type when emitting LaTeX or Docbook markup.  It is now possible
to overwrite this implicitly set top-level division via the
`top-level-division` command line parameter.

API change (`Text.Pandoc.Options`): the type of the
`writerTopLevelDivision` field in of the `WriterOptions` data type is
altered from `Division` to `Maybe Division`. The field's default value
is changed from `Section` to `Nothing`.

Closes: #3197

4 files changed, 17 insertions, 11 deletions

diff --git a/src/Text/Pandoc/Writers/ConTeXt.hs b/src/Text/Pandoc/Writers/ConTeXt.hs
index 6d66ce48c..8e6faefe2 100644
--- a/src/Text/Pandoc/Writers/ConTeXt.hs
+++ b/src/Text/Pandoc/Writers/ConTeXt.hs
@@ -37,7 +37,7 @@ import Text.Pandoc.Walk (query)
 import Text.Printf ( printf )
 import Data.List ( intercalate, intersperse )
 import Data.Char ( ord )
-import Data.Maybe ( catMaybes )
+import Data.Maybe ( catMaybes, fromMaybe )
 import Control.Monad.State
 import Text.Pandoc.Pretty
 import Text.Pandoc.ImageSize
@@ -84,9 +84,10 @@ pandocToConTeXt options (Pandoc meta blocks) = do
   let context =   defField "toc" (writerTableOfContents options)
                 $ defField "placelist" (intercalate ("," :: String) $
                      take (writerTOCDepth options +
-                           if writerTopLevelDivision options < Section
-                           then 0
-                           else 1)
+                           case writerTopLevelDivision options of
+                             Just Part    -> 0
+                             Just Chapter -> 0
+                             _            -> 1)
                        ["chapter","section","subsection","subsubsection",
                         "subsubsubsection","subsubsubsubsection"])
                 $ defField "body" main
@@ -422,7 +423,7 @@ sectionHeader (ident,classes,_) hdrLevel lst = do
   contents <- inlineListToConTeXt lst
   st <- get
   let opts = stOptions st
-  let level' = case writerTopLevelDivision opts of
+  let level' = case fromMaybe Section (writerTopLevelDivision opts) of
                  Part    -> hdrLevel - 2
                  Chapter -> hdrLevel - 1
                  Section -> hdrLevel
diff --git a/src/Text/Pandoc/Writers/Docbook.hs b/src/Text/Pandoc/Writers/Docbook.hs
index c28056153..6dc2c3a4b 100644
--- a/src/Text/Pandoc/Writers/Docbook.hs
+++ b/src/Text/Pandoc/Writers/Docbook.hs
@@ -39,6 +39,7 @@ import Text.Pandoc.Templates (renderTemplate')
 import Text.Pandoc.Readers.TeXMath
 import Data.List ( stripPrefix, isPrefixOf, intercalate, isSuffixOf )
 import Data.Char ( toLower )
+import Data.Maybe ( fromMaybe, isNothing )
 import Data.Monoid ( Any(..) )
 import Text.Pandoc.Highlighting ( languages, languagesByExtension )
 import Text.Pandoc.Pretty
@@ -81,11 +82,11 @@ writeDocbook opts (Pandoc meta blocks) =
                     else Nothing
       render'  = render colwidth
       opts'    = if ("/book>" `isSuffixOf` (trimr $ writerTemplate opts) &&
-                     writerTopLevelDivision opts >= Section)
-                    then opts{ writerTopLevelDivision = Chapter }
+                     isNothing (writerTopLevelDivision opts))
+                    then opts{ writerTopLevelDivision = Just Chapter }
                     else opts
       -- The numbering here follows LaTeX's internal numbering
-      startLvl = case writerTopLevelDivision opts' of
+      startLvl = case fromMaybe Section (writerTopLevelDivision opts') of
                    Part    -> -1
                    Chapter -> 0
                    Section -> 1
diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index 52740ebe7..b75f56cef 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -88,7 +88,10 @@ writeLaTeX options document =
                 stTable = False, stStrikeout = False,
                 stUrl = False, stGraphics = False,
                 stLHS = False,
-                stBook = writerTopLevelDivision options < Section,
+                stBook = (case writerTopLevelDivision options of
+                           Just Part    -> True
+                           Just Chapter -> True
+                           _            -> False),
                 stCsquotes = False, stHighlighting = False,
                 stIncremental = writerIncremental options,
                 stInternalLinks = [], stUsesEuro = False }
@@ -758,7 +761,7 @@ sectionHeader unnumbered ident level lst = do
                          <> braces (text plain))
   book <- gets stBook
   opts <- gets stOptions
-  let topLevelDivision = min (if book then Chapter else Section)
+  let topLevelDivision = fromMaybe (if book then Chapter else Section)
                              (writerTopLevelDivision opts)
   let level' = if writerBeamer opts && topLevelDivision < Section
                -- beamer has parts but no chapters
diff --git a/src/Text/Pandoc/Writers/TEI.hs b/src/Text/Pandoc/Writers/TEI.hs
index 6120330ca..4b3a205a1 100644
--- a/src/Text/Pandoc/Writers/TEI.hs
+++ b/src/Text/Pandoc/Writers/TEI.hs
@@ -36,6 +36,7 @@ import Text.Pandoc.Writers.Shared
 import Text.Pandoc.Options
 import Text.Pandoc.Templates (renderTemplate')
 import Data.List ( stripPrefix, isPrefixOf )
+import Data.Maybe ( fromMaybe )
 import Data.Char ( toLower )
 import Text.Pandoc.Highlighting ( languages, languagesByExtension )
 import Text.Pandoc.Pretty
@@ -60,7 +61,7 @@ writeTEI opts (Pandoc meta blocks) =
                     then Just $ writerColumns opts
                     else Nothing
       render' = render colwidth
-      startLvl = case writerTopLevelDivision opts of
+      startLvl = case fromMaybe Section (writerTopLevelDivision opts) of
                    Part    -> -1
                    Chapter -> 0
                    Section -> 1