Re: Lua Filter: Get to parent of current element?

[Albert Krewinkel <albert+pandoc-9EawChwDxG8hFhg+JK9F0w@public.gmane.org>]

ThomasH <therch-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:

> is there a way to get to the parent in the Pandoc AST from the
> current element in a Lua filter?
> I would like to distinguish treatment of elements depending on their
> context in the syntax tree, e.g. handle a 'span' element differently
> if it is a child of a 'cell' element in a table.

This is currently not supported in Lua; panflute (Python) filters do
enable that though.

What Lua does support though is to change the order in which elements
are traversed, as well as the option to stop processing of a subtree.
See https://pandoc.org/lua-filters.html#traversal-order

E.g., to handle all Spans in a table differently you'd use

    traverse = 'topdown'

    function Table (tbl)
      return tbl:walk(my_filter_for_table_spans), false
    end

    function Span (span)
      -- default span processing
      return span
    end

It's a bit of a brain-twister (and can be slower than normal filters)
but it enables most of the actions that one would otherwise use the
parent element for.


-- 
Albert Krewinkel
GPG: 8eed e3e2 e8c5 6f18 81fe  e836 388d c0b2 1f63 1124