Need help trying to define a custom surround (deletion)

[smjonas]

I am trying to create my own custom surrounds but I can't get this one to work. @kylechui Any idea why the following doesn't do anything when I run ds* (e.g. when the line is **word** and the cursor is on w)?

require("nvim-surround").buffer_setup {
  surrounds = {
    ["*"] = {
      find = function()
        return require("nvim-surround.config").get_selection { textobject = "*" }
      end,
      delete = "^(%*%*?)().-(%*%*?)()$",
    },
  },
}

Also, is the find key even required? I couldn't find anything in the docs and haven't looked at the code yet. If that is currently the case, wouldn't it be possible to infer the selections from the deletion pattern? Otherwise a warning might be good to let users know that their surround won't work :)

[kylechui]

Here you're going to want to use find = "%*%*?.-%*%*?". This is because the text-object a* does not exist (unless it is defined by another plugin, e.g. targets.vim). The idea is that the textobject key should only really be used for built-in text-objects or for characters for which there exists a defined text-object, e.g. T key uses t for finding the parent selection. I'll look into improving the docs; the find key can be omitted but it defaults to invalid_key_behavior's find key, which just looks for a surrounding pair of the character you inputted.

In general, the process is:

• The find key finds a "parent" selection that includes the surrounding pair
  • If omitted, nvim-surround will fallback on what's defined by invalid_key_behavior
  • The textobject key finds the "nearest" Vim text-object and uses that as the selection
  • The pattern key uses a Lua pattern to match the parent selection
• The delete/change.target keys will then narrow the parent selection down to the pair of selections you would like to delete/change

General rule of thumb: If you can't do va[char] and highlight a selection, then the text-object a[char] doesn't exist

Also I assume you mean ds* in your question :)

[kylechui]

Does va* select around a pair of asterisks like I think it should? If that's the case, then theoretically what you originally had should work as well 🤔 I'll re-install targets.vim later today and give it a go

[kylechui]

Reading through the documentation, it seems like targets treats those "separator" characters much like ", where a* doesn't actually select both of the characters. In this case, it seems like A* would make it work, but I didn't take into account that people might want to use other (non a[char]) text-objects :/ Try using my suggestion above, but I would need a minor breaking change in order to give a "proper" compatibility fix with targets.

[smjonas]

For some reason va* won't include the last asterisk in the selection, maybe that's why it couldn't find the pair of *. That's seems to be strange behavior from targets.vim.

Edit: beat me to it in your edit 😄

[kylechui]

Also another thing I noticed is that vA* doesn't actually select multiple pairs?, e.g. for **hello** it would only select the inner pair, so you couldn't delete double asterisks with it. However, if you're okay with that and don't mind a bit of jank, here's what you can do to utilize it:

require("nvim-surround").setup({
    surrounds = {
        ["*"] = {
            find = function()
                local esc = vim.api.nvim_replace_termcodes("<esc>", true, false, true)
                return require("nvim-surround.config").get_selection({ textobject = esc .. "g@A*" })
            end,
            delete = "^(%*%*?)().-(%*%*?)()$",
        },
    },
})

The text-object key actually just runs a normal command with "normal g@a" .. char behind the scenes, so you can just "cancel" it and run the desired one.

[kylechui]

Alternatively you can use the following:

require("nvim-surround").setup({
    surrounds = {
        ["*"] = {
            find = "(%*+).-(%*+)",
            delete = "^(%*+)().-(%*+)()$",
        },
    },
})

which will delete all sets of asterisk pairs. The only caveat is that imbalanced pairs will not be deleted. However, if that's desired I'm sure there's a way to do it using the given config.get_selection and config.get_selections functions, where you validate matched pairs before returning.