LaTeX reader: improve references.

- Resolve references to theorem environments.
- Remove Span caused by "label" in figure, table, and theorem
  environments; this had an id that duplicated the environments' id.

See #813.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -1101,7 +1101,8 @@ addImageCaption = walkM go
           case sCaption st of
             Nothing -> return p
             Just figureCaption -> do
-              let attr' = case sLastLabel st of
+              let mblabel = sLastLabel st
+              let attr' = case mblabel of
                             Just lab -> (lab, cls, kvs)
                             Nothing  -> attr
               case attr' of
@@ -1113,7 +1114,9 @@ addImageCaption = walkM go
                           , sLabels = M.insert ident
                                      [Str (renderDottedNum num)] (sLabels st) }
 
-              return $ SimpleFigure attr' (B.toList figureCaption) (src, tit)
+              return $ SimpleFigure attr'
+                       (maybe id removeLabel mblabel (B.toList figureCaption))
+                       (src, tit)
         go x = return x
 
 coloredBlock :: PandocMonad m => Text -> LP m Blocks

src/Text/Pandoc/Readers/LaTeX/Math.hs

@@ -142,14 +142,15 @@ newtheorem inline = do
 theoremEnvironment :: PandocMonad m
                    => LP m Blocks -> LP m Inlines -> Text -> LP m Blocks
 theoremEnvironment blocks opt name = do
+  resetCaption
   tmap <- sTheoremMap <$> getState
   case M.lookup name tmap of
     Nothing -> mzero
     Just tspec -> do
        optTitle <- option mempty $ (\x -> space <> "(" <> x <> ")") <$> opt
-       mblabel <- option Nothing $ Just . untokenize <$>
-                   try (spaces >> controlSeq "label" >> spaces >> braced)
        bs <- env name blocks
+       mblabel <- sLastLabel <$> getState
+
        number <-
          if theoremNumber tspec
             then do
@@ -182,6 +183,7 @@ theoremEnvironment blocks opt name = do
        let title = titleEmph (theoremName tspec <> number)
                       <> optTitle <> "." <> space
        return $ divWith (fromMaybe "" mblabel, [name], []) $ addTitle title
+              $ maybe id removeLabel mblabel
               $ case theoremStyle tspec of
                   PlainStyle -> walk italicize bs
                   _          -> bs

src/Text/Pandoc/Readers/LaTeX/Parsing.hs

@@ -90,6 +90,7 @@ module Text.Pandoc.Readers.LaTeX.Parsing
   , resetCaption
   , env
   , addMeta
+  , removeLabel
   ) where
 
 import Control.Applicative (many, (<|>))
@@ -119,6 +120,7 @@ import Text.Pandoc.Readers.LaTeX.Types (ExpansionPoint (..), Macro (..),
                                         ArgSpec (..), Tok (..), TokType (..))
 import Text.Pandoc.Shared
 import Text.Parsec.Pos
+import Text.Pandoc.Walk
 
 newtype DottedNum = DottedNum [Int]
   deriving (Show, Eq)
@@ -1067,3 +1069,16 @@ tokWith inlineParser = try $ spaces >>
 addMeta :: PandocMonad m => ToMetaValue a => Text -> a -> LP m ()
 addMeta field val = updateState $ \st ->
    st{ sMeta = addMetaField field val $ sMeta st }
+
+-- remove label spans to avoid duplicated identifier
+removeLabel :: Walkable [Inline] a => Text -> a -> a
+removeLabel lbl = walk go
+ where
+  go (Span (_,_,kvs) _ : rest)
+    | Just lbl' <- lookup "label" kvs
+    , lbl' == lbl = go (dropWhile isSpaceOrSoftBreak rest)
+  go (x:xs) = x : go xs
+  go [] = []
+  isSpaceOrSoftBreak Space = True
+  isSpaceOrSoftBreak SoftBreak = True
+  isSpaceOrSoftBreak _ = False

src/Text/Pandoc/Readers/LaTeX/Table.hs

@@ -368,7 +368,9 @@ addTableCaption = walkM go
                         ((_,classes,kvs), Just ident) ->
                            (ident,classes,kvs)
                         _ -> attr
-          return $ addAttrDiv attr' $ Table nullAttr capt spec th tb tf
+          return $ addAttrDiv attr'
+                 $ maybe id removeLabel mblabel
+                 $ Table nullAttr capt spec th tb tf
         go x = return x
 
 -- TODO: For now we add a Div to contain table attributes, since