[odt] Infer table's caption from the paragraph (#3224)

ODT's reader always put empty captions for the parsed
tables. This commit
1) checks paragraphs that follow the table definition
2) treats specially a paragraph with a style named 'Table'
3) does some postprocessing of the paragraphs that combines
 tables followed immediately by captions

The ODT writer used 'TableCaption' style name for the caption
paragraph. This commit follows the open office approach which
allows for appending captions to table but uses a built-in style
named 'Table' instead of 'TableCaption'. Any users of odt format
(both writer and reader) are therefore required to change the
style's name to 'Table', if necessary.

2 files changed, 22 insertions, 7 deletions

diff --git a/src/Text/Pandoc/Readers/Odt/ContentReader.hs b/src/Text/Pandoc/Readers/Odt/ContentReader.hs
index 3a6a99237..2672b01ef 100644
--- a/src/Text/Pandoc/Readers/Odt/ContentReader.hs
+++ b/src/Text/Pandoc/Readers/Odt/ContentReader.hs
@@ -312,7 +312,7 @@ withNewStyle a = proc x -> do
   where
     isCodeStyle :: StyleName -> Bool
     isCodeStyle "Source_Text" = True
-    isCodeStyle _              = False
+    isCodeStyle _             = False
 
     inlineCode :: Inlines -> Inlines
     inlineCode = code . intercalate "" . map stringify . toList
@@ -415,12 +415,18 @@ constructPara reader = proc blocks -> do
   fStyle <- readStyleByName -< blocks
   case fStyle of
     Left   _    -> reader -< blocks
+    Right (styleName, _) | isTableCaptionStyle styleName -> do
+      blocks' <- reader   -< blocks
+      arr tableCaptionP  -< blocks'
     Right (_, style) -> do
       let modifier = getParaModifier style
-      blocks' <- reader -< blocks
-      arr modifier -<< blocks'
-
-
+      blocks' <- reader   -<  blocks
+      arr modifier        -<< blocks'
+  where
+    isTableCaptionStyle :: StyleName -> Bool
+    isTableCaptionStyle "Table" = True
+    isTableCaptionStyle _       = False
+    tableCaptionP b = divWith ("", ["caption"], []) b
 
 type ListConstructor = [Blocks] -> Blocks
 
@@ -904,6 +910,15 @@ read_text = matchChildContent' [ read_header
                                ]
             >>^ doc
 
+post_process :: Pandoc -> Pandoc
+post_process (Pandoc m blocks) =
+  Pandoc m (post_process' blocks)
+
+post_process' :: [Block] -> [Block]
+post_process' ((Table _ a w h r) : (Div ("", ["caption"], _) [Para inlines] ) : xs) =
+  (Table inlines a w h r) : ( post_process' xs )
+post_process' bs = bs
+
 read_body :: OdtReader _x (Pandoc, MediaBag)
 read_body = executeIn NsOffice "body"
           $ executeIn NsOffice "text"
@@ -911,4 +926,4 @@ read_body = executeIn NsOffice "body"
           $ proc inlines -> do
              txt   <- read_text     -< inlines
              state <- getExtraState -< ()
-             returnA                -< (txt, getMediaBag state)
+             returnA                -< (post_process txt, getMediaBag state)
diff --git a/src/Text/Pandoc/Writers/OpenDocument.hs b/src/Text/Pandoc/Writers/OpenDocument.hs
index 42c151780..8bd0f469e 100644
--- a/src/Text/Pandoc/Writers/OpenDocument.hs
+++ b/src/Text/Pandoc/Writers/OpenDocument.hs
@@ -336,7 +336,7 @@ blockToOpenDocument o bs
         mapM_ addParaStyle . newPara $ paraHStyles ++ paraStyles
         captionDoc <- if null c
                       then return empty
-                      else withParagraphStyle o "TableCaption" [Para c]
+                      else withParagraphStyle o "Table" [Para c]
         th <- if all null h
                  then return empty
                  else colHeadsToOpenDocument o name (map fst paraHStyles) h