Docx: single numbering ID for examples - fixes #7895 (#7900)

This change ensures that example list items all belong to a single
number sequence, so that if items are added or deleted in a word
processor, the other items will renumber automatically.

src/Text/Pandoc/Writers/Docx.hs

@@ -27,7 +27,7 @@ import Data.Char (isSpace, isLetter)
 import Data.List (intercalate, isPrefixOf, isSuffixOf)
 import Data.String (fromString)
 import qualified Data.Map as M
-import Data.Maybe (fromMaybe, isNothing, mapMaybe, maybeToList)
+import Data.Maybe (fromMaybe, isNothing, mapMaybe, maybeToList, isJust)
 import qualified Data.Set as Set
 import qualified Data.Text as T
 import Data.Text (Text)
@@ -942,7 +942,10 @@ blockToOpenXML' opts el
     addOpenXMLList marker lst = do
       addList marker
       numid  <- getNumId
-      l <- asList $ concat `fmap` mapM (listItemToOpenXML opts numid) lst
+      exampleid <- case marker of
+                        NumberMarker Example _ _ -> gets stExampleId
+                        _ -> return Nothing
+      l <- asList $ concat `fmap` mapM (listItemToOpenXML opts $ fromMaybe numid exampleid) lst
       setFirstPara
       return l
 blockToOpenXML' opts (DefinitionList items) = do
@@ -963,7 +966,16 @@ definitionListItemToOpenXML opts (term,defs) = do
 addList :: (PandocMonad m) => ListMarker -> WS m ()
 addList marker = do
   lists <- gets stLists
-  modify $ \st -> st{ stLists = lists ++ [marker] }
+  lastExampleId <- gets stExampleId
+  modify $ \st -> st{ stLists = lists ++ case marker of
+                                         -- Use only first occurence of Example for list declaration to avoid overhead
+                                         NumberMarker Example _ _ | isJust lastExampleId -> []
+                                         _ -> [marker]
+                    , stExampleId = case marker of
+                                         -- Reuse the same identifier for all other occurences of Example
+                                         NumberMarker Example _ _ -> lastExampleId <|> Just (baseListId + length lists)
+                                         _ -> lastExampleId
+                  }
 
 listItemToOpenXML :: (PandocMonad m)
                   => WriterOptions

src/Text/Pandoc/Writers/Docx/Types.hs

@@ -107,6 +107,7 @@ data WriterState = WriterState{
        , stExternalLinks  :: M.Map Text Text
        , stImages         :: M.Map FilePath (String, String, Maybe MimeType, B.ByteString)
        , stLists          :: [ListMarker]
+       , stExampleId      :: Maybe Int
        , stInsId          :: Int
        , stDelId          :: Int
        , stStyleMaps      :: StyleMaps
@@ -131,6 +132,7 @@ defaultWriterState = WriterState{
       , stExternalLinks  = M.empty
       , stImages         = M.empty
       , stLists          = [NoMarker]
+      , stExampleId      = Nothing
       , stInsId          = 1
       , stDelId          = 1
       , stStyleMaps      = StyleMaps M.empty M.empty