Org reader: fix handling of empty table cells, rows

This fixes Org mode parsing of some corner cases regarding empty cells
and rows.  Empty cells weren't parsed correctly, e.g. `|||` should be
two empty cells, but would be parsed as a single cell containing a pipe
character.  Empty rows where parsed as alignment rows and dropped from
the output.

This fixes #2616.

src/Text/Pandoc/Readers/Org.hs

@@ -35,6 +35,7 @@ import           Text.Pandoc.Builder ( Inlines, Blocks, HasMeta(..),
                                        trimInlines )
 import           Text.Pandoc.Definition
 import           Text.Pandoc.Compat.Monoid ((<>))
+import           Text.Pandoc.Error
 import           Text.Pandoc.Options
 import qualified Text.Pandoc.Parsing as P
 import           Text.Pandoc.Parsing hiding ( F, unF, askF, asksF, runF
@@ -57,8 +58,6 @@ import qualified Data.Set as Set
 import           Data.Maybe (fromMaybe, isJust)
 import           Network.HTTP (urlEncode)
 
-import           Text.Pandoc.Error
-
 -- | Parse org-mode string and return a Pandoc document.
 readOrg :: ReaderOptions -- ^ Reader options
         -> String        -- ^ String to parse (assuming @'\n'@ line endings)
@@ -807,18 +806,19 @@ tableRows = try $ many (tableAlignRow <|> tableHline <|> tableContentRow)
 
 tableContentRow :: OrgParser OrgTableRow
 tableContentRow = try $
-  OrgContentRow . sequence <$> (tableStart *> manyTill tableContentCell newline)
+  OrgContentRow . sequence <$> (tableStart *> many1Till tableContentCell newline)
 
 tableContentCell :: OrgParser (F Blocks)
 tableContentCell = try $
-  fmap B.plain . trimInlinesF . mconcat <$> many1Till inline endOfCell
-
-endOfCell :: OrgParser Char
-endOfCell = try $ char '|' <|> lookAhead newline
+  fmap B.plain . trimInlinesF . mconcat <$> manyTill inline endOfCell
 
 tableAlignRow :: OrgParser OrgTableRow
-tableAlignRow = try $
-  OrgAlignRow <$> (tableStart *> manyTill tableAlignCell newline)
+tableAlignRow = try $ do
+  tableStart
+  cells <- many1Till tableAlignCell newline
+  -- Empty rows are regular (i.e. content) rows, not alignment rows.
+  guard $ any (/= AlignDefault) cells
+  return $ OrgAlignRow cells
 
 tableAlignCell :: OrgParser Alignment
 tableAlignCell =
@@ -833,15 +833,19 @@ tableAlignCell =
     where emptyCell = try $ skipSpaces *> endOfCell
 
 tableAlignFromChar :: OrgParser Alignment
-tableAlignFromChar = try $ choice [ char 'l' *> return AlignLeft
-                                  , char 'c' *> return AlignCenter
-                                  , char 'r' *> return AlignRight
-                                  ]
+tableAlignFromChar = try $
+  choice [ char 'l' *> return AlignLeft
+         , char 'c' *> return AlignCenter
+         , char 'r' *> return AlignRight
+         ]
 
 tableHline :: OrgParser OrgTableRow
 tableHline = try $
   OrgHlineRow <$ (tableStart *> char '-' *> anyLine)
 
+endOfCell :: OrgParser Char
+endOfCell = try $ char '|' <|> lookAhead newline
+
 rowsToTable :: [OrgTableRow]
             -> F OrgTable
 rowsToTable = foldM rowToContent emptyTable

tests/Tests/Readers/Org.hs

@@ -941,7 +941,7 @@ tests =
 
       , "Empty table" =:
           "||" =?>
-          simpleTable' 1 mempty mempty
+          simpleTable' 1 mempty [[mempty]]
 
       , "Glider Table" =:
           unlines [ "| 1 | 0 | 0 |"
@@ -996,6 +996,17 @@ tests =
                 , [ plain "dynamic", plain "Lisp" ]
                 ]
 
+      , "Table with empty cells" =:
+          "|||c|" =?>
+          simpleTable' 3 mempty [[mempty, mempty, plain "c"]]
+
+      , "Table with empty rows" =:
+          unlines [ "| first  |"
+                  , "|        |"
+                  , "| third  |"
+                  ] =?>
+          simpleTable' 1 mempty [[plain "first"], [mempty], [plain "third"]]
+
       , "Table with alignment row" =:
           unlines [ "| Numbers | Text | More |"
                   , "| <c>     | <r>  |      |"