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

[H <agents-FcZObrvlYduBUy7/sJONFg@public.gmane.org>]

On 06/20/2023 06:37 AM, mf wrote:
> 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.
>
Thank you! I will play around with the code.

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