Re: Wrapping sections of existing document in <div></div>

[mf <massifrg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Il 20/06/23 02:14, H ha scritto:
> On June 19, 2023 6:11:35 PM EDT, H <agents-FcZObrvlYduBUy7/sJONFg@public.gmane.org> wrote:
>> What is the "best" way of wrapping parts of an existing document in
>> <div></div> in a filter?
>>
>> Using insert.table(existingtable, pandoc.Div(existingtextblocks)) does
>> not work since the existing text blocks get duplicated in the output.
>>
>> I see two options but there might be others:
>>
>> - Surround existing text blocks with pandoc.RawInline(1, 'html,
>> '<div>') and pandoc.RawInLine('html', '</div>').
>>
>> - Create a new table and use insert.table(newtable,
>> pandoc.Div(existingtextblock)) and also insert the rest of the
>> document.
>>

This would apply only to HTML output.

>> Are there other options?
> 
> Replying to my own question, it seems the most "elegant" way of accomplishing this requires this to be done be in two stages:
> 
> - First, delete the blocks in question from the block list table, eg doc.blocks.
> - Second, insert them into the same table using pandoc.Div().
> 
> Unfortunately it seems table.delete() does not accept a list of blocks, only one block at a time, pandoc.Div, on the other hand, accepts a table. Here is a code example when I was trying it out:
> 
> local temp = {}
> for i = 3, 1, -1 do
>    table.insert(temp, table.remove(doc.blocks, 5))
> end
> 
> table.insert(doc.blocks, 2, pandoc.Div(temp))
> 
> The above code removes blocks 5 through 7 from doc.blocks, then inserts them, in the same order but surrounded by <div></div>, in position 2.
> 
> If there is a better way of accomplishing this, I would appreciate hearing it.
> 

Consider using the Blocks function in the filter (see 
https://pandoc.org/lua-filters.html#filters-on-element-sequences).

The Blocks function is called on every sequence of blocks.
Here's an example:

local my_filter = {
   {
     Blocks = function(blocks)
       local first_in_div, last_in_div = detect_seq_for_div(blocks)
       -- check if last is after first and the Div will not be empty
       if first_in_div and last_in_div and last_in_div - first_in_div > 
1 then
         local newblocks = pandoc.List()
         local divblocks = pandoc.List()
         for i = 1, #blocks do
           if i < first_in_div or i > last_in_div then
             newblocks:insert(blocks[i])
           else
             divblocks:insert(blocks[i])
             if i == last_in_div then
               local div = pandoc.Div(divblocks)
               newblocks:insert(div)
             end
           end
         end
         return newblocks
       end
       -- if no meaningful sequence is detected,
       -- no return statement to keep the current blocks
     end,
   }
}

You should write the detect_seq_for_div function that scans a list of 
blocks and returns two positive integers only if it contains a 
meaningful sequence of blocks that you want to wrap in a Div. Otherwise 
it should return nil.

Those two integers are the indexes of the first and the last block you 
want to put in the Div.