Org reader: fix behavior for successive calls of `#+EXCLUDE_TAGS`. (#4951)

Calling `#+EXCLUDE_TAGS` multiple times should preserve the status of
the previously declared tags.

2 files changed, 13 insertions, 8 deletions

diff --git a/src/Text/Pandoc/Readers/Org/Meta.hs b/src/Text/Pandoc/Readers/Org/Meta.hs
index 921cd27e0..cad1d7123 100644
--- a/src/Text/Pandoc/Readers/Org/Meta.hs
+++ b/src/Text/Pandoc/Readers/Org/Meta.hs
@@ -159,7 +159,7 @@ optionLine = try $ do
     "seq_todo" -> todoSequence >>= updateState . registerTodoSequence
     "typ_todo" -> todoSequence >>= updateState . registerTodoSequence
     "macro"    -> macroDefinition >>= updateState . registerMacro
-    "exclude_tags" -> excludedTagSet >>= updateState . setExcludedTags
+    "exclude_tags" -> excludedTagList >>= updateState . setExcludedTags
     "pandoc-emphasis-pre" -> emphChars >>= updateState . setEmphasisPreChar
     "pandoc-emphasis-post" -> emphChars >>= updateState . setEmphasisPostChar
     _          -> mzero
@@ -192,14 +192,17 @@ parseFormat = try $ replacePlain <|> replaceUrl <|> justAppend
    rest            = manyTill anyChar         (eof <|> () <$ oneOf "\n\r")
    tillSpecifier c = manyTill (noneOf "\n\r") (try $ string ('%':c:""))
 
-excludedTagSet :: Monad m => OrgParser m (Set.Set Tag)
-excludedTagSet = do
+excludedTagList :: Monad m => OrgParser m [Tag]
+excludedTagList = do
   skipSpaces
-  Set.fromList . map Tag <$>
-                      many (orgTagWord <* skipSpaces) <* newline
-
-setExcludedTags :: Set.Set Tag -> OrgParserState -> OrgParserState
-setExcludedTags tagSet st = st { orgStateExcludedTags = tagSet }
+  map Tag <$> many (orgTagWord <* skipSpaces) <* newline
+
+setExcludedTags :: [Tag] -> OrgParserState -> OrgParserState
+setExcludedTags tagList st =
+  let finalSet = if orgStateExcludedTagsChanged st
+                   then foldr Set.insert (orgStateExcludedTags st) tagList
+                   else Set.fromList tagList
+  in st { orgStateExcludedTags = finalSet, orgStateExcludedTagsChanged = True}
 
 setEmphasisPreChar :: Maybe [Char] -> OrgParserState -> OrgParserState
 setEmphasisPreChar csMb st =
diff --git a/src/Text/Pandoc/Readers/Org/ParserState.hs b/src/Text/Pandoc/Readers/Org/ParserState.hs
index 381d4c5ee..59478256f 100644
--- a/src/Text/Pandoc/Readers/Org/ParserState.hs
+++ b/src/Text/Pandoc/Readers/Org/ParserState.hs
@@ -118,6 +118,7 @@ data OrgParserState = OrgParserState
   , orgStateEmphasisPostChars    :: [Char] -- ^ Chars allowed at after emphasis
   , orgStateEmphasisNewlines     :: Maybe Int
   , orgStateExcludedTags         :: Set.Set Tag
+  , orgStateExcludedTagsChanged  :: Bool
   , orgStateExportSettings       :: ExportSettings
   , orgStateHeaderMap            :: M.Map Inlines String
   , orgStateIdentifiers          :: Set.Set String
@@ -189,6 +190,7 @@ defaultOrgParserState = OrgParserState
   , orgStateEmphasisNewlines = Nothing
   , orgStateExportSettings = def
   , orgStateExcludedTags = Set.singleton $ Tag "noexport"
+  , orgStateExcludedTagsChanged = False
   , orgStateHeaderMap = M.empty
   , orgStateIdentifiers = Set.empty
   , orgStateIncludeFiles = []