nvim-treesitter/lua/nvim-treesitter/textobjects/swap.lua

local ts_utils = require'nvim-treesitter.ts_utils'
local shared = require'nvim-treesitter.textobjects.shared'
local attach = require'nvim-treesitter.textobjects.attach'

local M = {}

local function swap_textobject(query_string, direction)
  local bufnr, textobject_range, node = shared.textobject_at_point(query_string)
  if not node then return end

  local step = direction > 0 and 1 or -1
  local overlapping_range_ok = false
  local same_parent = true
  for _ = 1, math.abs(direction), step do
    local forward = direction > 0
    local adjacent = shared.get_adjacent(forward, node, query_string, same_parent, overlapping_range_ok, bufnr)
    ts_utils.swap_nodes(textobject_range, adjacent, bufnr, "yes, set cursor!")
  end
end

function M.swap_next(query_string)
  swap_textobject(query_string, 1)
end

function M.swap_previous(query_string)
  swap_textobject(query_string, -1)
end

local normal_mode_functions = {"swap_next",
                               "swap_previous"}

M.attach = attach.make_attach(normal_mode_functions, "swap")
M.deattach = attach.make_detach(normal_mode_functions, "swap")

return M