Docx writer: Print subtitle from metadata if present.

Use Subtitle style.

See #1451.

README

@@ -541,9 +541,9 @@ Options affecting specific writers
     for a file `reference.docx` in the user data directory (see
     `--data-dir`). If this is not found either, sensible defaults will be
     used. The following styles are used by pandoc: [paragraph]
-    Normal, Compact, Title, Authors, Date, Abstract, Heading 1, Heading 2,
-    Heading 3, Heading 4, Heading 5, Block Quote, Definition Term, Definition,
-    Body Text, Table Caption, Image Caption; [character] Default
+    Normal, Compact, Title, Subtitle, Authors, Date, Abstract, Heading 1,
+    Heading 2, Heading 3, Heading 4, Heading 5, Block Quote, Definition Term,
+    Definition, Body Text, Table Caption, Image Caption; [character] Default
     Paragraph Font, Body Text Char, Verbatim Char, Footnote Ref,
     Link.
 

src/Text/Pandoc/Writers/Docx.hs

@@ -485,9 +485,15 @@ writeOpenXML opts (Pandoc meta blocks) = do
                        Just (MetaBlocks bs) -> bs
                        Just (MetaInlines ils) -> [Plain ils]
                        _ -> []
+  let subtitle' = case lookupMeta "subtitle" meta of
+                       Just (MetaBlocks [Plain xs]) -> xs
+                       Just (MetaBlocks [Para  xs]) -> xs
+                       Just (MetaInlines xs)        -> xs
+                       _ -> []
   title <- withParaProp (pStyle "Title") $ blocksToOpenXML opts [Para tit | not (null tit)]
-  authors <- withParaProp (pStyle "Authors") $ blocksToOpenXML opts
-                 [Para (intercalate [LineBreak] auths) | not (null auths)]
+  subtitle <- withParaProp (pStyle "Subtitle") $ blocksToOpenXML opts [Para subtitle' | not (null subtitle')]
+  authors <- withParaProp (pStyle "Author") $ blocksToOpenXML opts $
+       map Para auths
   date <- withParaProp (pStyle "Date") $ blocksToOpenXML opts [Para dat | not (null dat)]
   abstract <- if null abstract'
                  then return []
@@ -498,7 +504,7 @@ writeOpenXML opts (Pandoc meta blocks) = do
   let blocks' = bottomUp convertSpace $ blocks
   doc' <- blocksToOpenXML opts blocks'
   notes' <- reverse `fmap` gets stFootnotes
-  let meta' = title ++ authors ++ date ++ abstract
+  let meta' = title ++ subtitle ++ authors ++ date ++ abstract
   return (meta' ++ doc', notes')
 
 -- | Convert a list of Pandoc blocks to OpenXML.