Lua filters: allow filtering of element lists (#6040)

Lists of Inline and Block elements can now be filtered via `Inlines` and
`Blocks` functions, respectively. This is helpful if a filter conversion
depends on the order of elements rather than a single element.

For example, the following filter can be used to remove all spaces
before a citation:

    function isSpaceBeforeCite (spc, cite)
      return spc and spc.t == 'Space'
       and cite and cite.t == 'Cite'
    end

    function Inlines (inlines)
      for i = #inlines-1,1,-1 do
        if isSpaceBeforeCite(inlines[i], inlines[i+1]) then
          inlines:remove(i)
        end
      end
      return inlines
    end

Closes: #6038

1 files changed, 1 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Lua/Init.hs b/src/Text/Pandoc/Lua/Init.hs
index cf6c71231..5ade83e4d 100644
--- a/src/Text/Pandoc/Lua/Init.hs
+++ b/src/Text/Pandoc/Lua/Init.hs
@@ -119,6 +119,7 @@ putConstructorsInRegistry = do
   constrsToReg $ Pandoc.Citation mempty mempty mempty Pandoc.AuthorInText 0 0
   putInReg "Attr"  -- used for Attr type alias
   putInReg "ListAttributes"  -- used for ListAttributes type alias
+  putInReg "List"  -- pandoc.List
  where
   constrsToReg :: Data a => a -> Lua ()
   constrsToReg = mapM_ (putInReg . showConstr) . dataTypeConstrs . dataTypeOf