Sort class items inside HTML.

class.lua

local T = vim.treesitter
local query = T.query

-- caps indicate config values
local SORTERS = {}
SORTERS.ASCII = function(a, b) return string.byte(a:sub(1, 1)) > string.byte(b:sub(1, 1)) end
-- add more

local SELECTED_SORTERS = { SORTERS.ASCII } -- add more
local FILETYPE = vim.o.filetype
local ALLOW = { "class" }
local QUERY = [[
;; query
(attribute
  ((attribute_name) @name
  (quoted_attribute_value
    (attribute_value) @contents)))
]]

local language_tree = T.get_parser(0, FILETYPE)
local parsed_tree = language_tree:parse()
local parsed_query = query.parse(FILETYPE, QUERY)

local box = {}
for _, node, _ in parsed_query:iter_captures(parsed_tree[1]:root(), QUERY, 0, -1) do
  local record = {
    type = node:type(),
    range = node:range(),
    text = T.get_node_text(node, 0),
    full_range = T.get_range(node, 0),
  }
  box[record.range] = vim.F.if_nil(box[record.range], {})
  box[record.range][record.type] = record.text
  if record.type == "attribute_value" then
    box[record.range].attribute_value = vim.split(record.text, " ", { plain = true })
    box[record.range].full_range = {
      starting = { row = record.full_range[1], column = record.full_range[2] },
      ending = { row = record.full_range[4], column = record.full_range[5] },
    }
  end
end

box = vim.tbl_filter(function(item)
  return vim.tbl_contains(ALLOW, item.attribute_name)
end, box)

for index, attribute in ipairs(box) do
  for _, sorter in ipairs(SELECTED_SORTERS) do
    -- apply sorters
    table.sort(box[index].attribute_value, sorter)
  end
  local params = {
    0,
    attribute.full_range.starting.row,
    attribute.full_range.starting.column,
    attribute.full_range.ending.row,
    attribute.full_range.ending.column,
    { table.concat(box[index].attribute_value, " ") },
  }
  vim.api.nvim_buf_set_text(unpack(params))
end