How to define text-object of "between markdown code fence with syntax"?

Question

I want to create a binding for using vim-slime to run code between a code fence in markdown.

This worked with a simple fence, using i` as a text-object:

nmap <leader>s7 <Plug>SlimeMotionSendi`

but when adding the language to the code fence, e.g.:

```python
print("hello")
```

it obviously broke. So now I'm looking to define a text-object the would mean all the lines between the two triple backticks. How do I go about this?

Answer 1

I would define the iq text object:

vnoremap iq ?```.*$?1<CR>o/```/-1<CR>$
omap iq :normal Viq<CR>

Where the v mapping does:

• Search backward the triple quotes and move to the next line: ?```.*$<CR>?1
• Select the other side of the selection: o
• Search forward the triple quotes and move to the previous line: /```/-1<CR>
• Go to the end of the line: $

And the do the following mapping:

nmap <leader>s7 <Plug>SlimeMotionSendiq

Here is another version that leave the / register unchanged:

function! VisualCodeBlock()
  call search('```', 'b')
  normal! j0v
  call search('```')
  normal! k$
endfunction

vnoremap iq :<C-u>call VisualCodeBlock()<CR>
omap iq :normal Viq<CR>

Remarks:

In a standard omap the start of the text object is the cursor position and end of the text object is the position of the cursor after the mapping has been executed.

If you need a text object that doesn't start with the cursor position you need to switch in visual mode and make the selection covering the range you want.

Usually in such case two mappings are defined such that the text object can also be used in visual mode.

Remark <C-u>:

The <C-u> trick is usually used when a mapping use the Command mode to kill the existing character in the command. If the user select some line before triggering the mapping a range will present when the mapping triggers :