Add @parameter.outer for Python/C/C++

[theHamsta]

Addresses: #22

Requires: nvim-treesitter/nvim-treesitter#657

It only works if your cursor is between the parameter or and the end character of the ",". I try to add @stsewd select next textobject soon to make it also work on spaces before the parameter

[theHamsta]

@andreypopp could you test this? and maybe even add the queries for you favorite language?

[andreypopp]

Wow!

Testing it with python. It works well with argument lists which have the trailing comma but with the following one:

def some(aa, bbb, ccc):
    pass

It cannot extract a range from (no trailing coma after ccc). The result is a traceback:

E5108: Error executing lua .../plugged/nvim-treesitter/lua/nvim-tr
eesitter/tsrange.lua:30: attempt to index local 'end_node' (a nil
value)

I've tried to match on ["," ")"] @_end but it obviously eats the ) in that case...

[theHamsta]

But did you apply the patch in the description for nvim-treesitter? This should handle the nil case.

[andreypopp]

Oops, I apologize, I missed that requirement. It works that way!

I actually tried to patch nvim-treesitter the same way but thought that it's a bit non intuitive behaviour. What if the range's intent is to cover more than two siblings?

a @start b c? @_end

In case c is absent it will result in only [a, a] range.

[theHamsta]

Is that bad? If b is not captured the query can not know about it. What you would like to have in that situation would be the ternary (make-range! @a @b @c). If you make @c with ? it is clear that it is optional.

We have a lot of stuff that can be optionally carry a something before or after it.

[andreypopp]

Is that bad? If b is not captured the query can not know about it.

idk, probably not bad...

Another idea — I think it could be a useful in API to specify an open range.. something like

argument . ["," @_end ")" @_open_end]

To result in:
a. [argument, ","] when comma matches
b. [argument, ")") otherwise, an @_open_end location will be produced by going one char left from the ")".

[andreypopp]

By the way "open ranges" could with another thing — I've wanted to try to redefine @block.inner not to include braces { and }. As it seems reasonable to me exclude them on cib and so on.

[theHamsta]

Yes, with the new TSRange object you can do many things. We could easily implement the open-range thing. However, it's also possible to use the current approach and just capture the node before the open range. Or to just capture the last node. The last node thing, is however a bit unreliable and it for some reason does not work when you also specify a first node in a query.

You should be able to implement open-range in nvim-treesitter with get_next_node and get_previous_node.

[theHamsta]

With this last? predicate:

query.add_predicate('last?', function (match, pattern, bufnr, pred)
  if #pred ~= 2 then error("last? must have exactly one argument!") end
  local node = match[pred[2]]
  if node and node:parent() then
    return node:parent():named_child(node:parent():named_child_count() - 1) == node
  end

  return false
end)

((compound_statement .
  (_) @_start 
  (_) @_end 
 )
 (make-range! "block.inner" @_start @_end)
 (last? @_end)) 

Last is actually only necessary since the . operator does not work at the moment (in tree-sitter).

[theHamsta]

I created a bug report regarding the last (tree-sitter/tree-sitter#806). Would be nice if we could specify @block.inner as

(compound_statement .
  (_) @_start 
  (_) @_end .)

[stsewd]

I try to add @stsewd select next textobject soon to make it also work on spaces before the parameter

Thanks, I said I'd do it, but been busy lately :(

[andreypopp]

@theHamsta don know if you’ve seen but I made a PR to your fork with this text object for JavaScript

[AckslD]

@theHamsta This is really nice! 🎉 What would it take to be able to also make it work on spaces before the argument? I could try to look into it but just started with treesitter so would be happy to hear any advice :) Similarly it would be great to make it so that when one does e.g. d{@parameter.outer} that whitespace before (or after) gets deleted, as with e.g. daw.

[liujoey]

@theHamsta This is really nice! 🎉 What would it take to be able to also make it work on spaces before the argument? I could try to look into it but just started with treesitter so would be happy to hear any advice :) Similarly it would be great to make it so that when one does e.g. d{@parameter.outer} that whitespace before (or after) gets deleted, as with e.g. daw.

If we can add this support then I can completely remove targets.vim from my plugin list. As far as I know Tree Sitter doesn't mark whitespaces as nodes, so one possible approach would be looking for next sibling in the parameter_list and select all the way to that sibling, which effectively deletes the whitespaces.

Edit: typo

[theHamsta]

@liujoey PRs are welcome 🙂