Support custom-style attribute for docx table

[Sebbones]

This is a suggested fix to support the custom-style attribute for docx tables. I'm referring to the issues #9603, #7549, #6496, #4697. I needed this feature to support multiple table styles in one document and saw a lot of issues addressing this feature. With absolutely no prior experience in Haskell, I just gave it a shot :)

The conversion from html to docx with and without it, worked fine. With the table[custom-style="CustomStyle"] attribute, it used the CustomStyle for the table and if omitted, the fallback/default style is "Table".

I hope the code is okayish, but happy to change it if needed.

[jgm]

Perfect! Thanks.

[tdewin]

FINALLY, thank you soo soo soo much for those 4 golden lines of code

Since I'm editing in markdown and you can't seem to add the style on a table (as far as I can tell?), I wrote a small luafilter

https://github.com/tdewin/pandoc-lua-timo-filters/blob/main/defaulttabstyle.lua

You can pass a default value for the tables with

-M tablestyle:"table"

You can override a value in text with a code block

```tablemeta{custom-style=tablestylecustom}
```

  ----------------------------------------------------------------- 
  test   test2   test\
                 dezdezdez dezd ze dez d ez d ez dez dez de z dez
  ------ ------- --------------------------------------------------
  test   test2   test3

  -----------------------------------------------------------------


  ----------------------------------------------------------------- 
  test   test2   test\
                 dezdezdez dezd ze dez d ez d ez dez dez de z dez
  ------ ------- --------------------------------------------------
  test   test2   test3

  -----------------------------------------------------------------

[R3myG]

Would it be possible to have an example of how to use this new parameter?
I'm using Quarto 1.6.32 which uses Pandoc 3.4 and the following didn't work:

::: {custom-style="TableCustom"}
| Header 1 | Header 2 |
|----------|----------|
| Val1         |    Val2      |
:::

| Header 1 | Header 2 |
|----------|----------|
| Val1         |    Val2      |
: {custom-style="TableCustom"}

[tarleb]

Pandoc Markdown doesn't yet have built-in syntax for table attributes. With --from=commonmark_x one would write

{custom-style="TableCustom"}
| Header 1 | Header 2 |
|----------|----------|
| Val1     |    Val2      |

For pandoc Markdown it's best to use the Div-based syntax, but that requires an additional Lua filter like the one below (untested)

function Div (div)
  -- do nothing if the div doesn't have a custom-style attribute
  -- or if the div doesn't have exactly one element
  if not div.attributes['custom-style'] or #div.content == 1 then
    return div
  end
  local tbl = div.content[1]
  if tbl.t == 'Table' then
    tbl.attributes['custom-style'] = div.attributes['custom-style']
    return tbl
  end
end

[R3myG]

@tarleb Thank you for the suggestion, I've tested it in quarto and couldn't make it work unfortunately.

I had to use the following notation because of quarto:

::: {custom-style="TableCustom"}
| Header 1 | Header 2 |
|----------|----------|
| Val1     |    Val2      |
:::

I also had to adapt the lua code to:

function Div (div)
    -- First, check if we have the custom-style attribute
    if not div.attributes['custom-style'] then
        return div
    end

    -- Check if div has content
    if not div.content or #div.content == 0 then
        return div
    end

    -- Get the first element
    local first_elem = div.content[1]
    
    -- Check if it's a table
    if first_elem and first_elem.t == 'Table' then
        -- Copy the custom-style attribute to the table
        if not first_elem.attributes then
            first_elem.attributes = {}
        end
        first_elem.attributes['custom-style'] = div.attributes['custom-style']
        return first_elem
    end

    -- If we get here, return the original div
    return div
end

Unfortunately, afterwards the tables were still using the Table style.

If you have any suggestions on how to make it work, don't hesitate.