multicursor.nvim match textobjects

sample.lua

local mc = require "multicursor-nvim.core"
local TERM_CODES = require "multicursor-nvim.term-codes"

--- @param a Cursor
--- @param b Cursor
--- @return boolean past If the beginning of b is after the end of a
local function visual_past(a, b)
  local _, a_end = a:getVisual()
  local b_start, _ = b:getVisual()
  return b_start[1] > a_end[1] or b_start[1] == a_end[1] and b_start[2] > a_end[2]
end

--- @param a Cursor
--- @param b Cursor
--- @return boolean same If a and b select the same text
local function visual_same(a, b)
  local a_start, a_end = a:getVisual()
  local b_start, b_end = b:getVisual()
  return a_start[1] == b_start[1]
    and a_start[2] == b_start[2]
    and a_end[1] == b_end[1]
    and a_end[2] == b_end[2]
end

--- @param cursor Cursor
--- @return boolean success If the cursor was moved
local function move_cursor_next(cursor)
  local start_line = cursor:line()
  local start_col = cursor:col()
  local function moved() return cursor:col() ~= start_col or cursor:line() ~= start_line end

  cursor:feedkeys "l"
  if moved() then return true end

  cursor:feedkeys "j0"
  return moved()
end

local function matchVisualObjects(textobject)
  mc.action(function(ctx)
    local orig_cursor = ctx:mainCursor()

    -- Search from the start of the original selection.
    local search_cursor = orig_cursor:clone()
    search_cursor:feedkeys(TERM_CODES.ESC)
    search_cursor:feedkeys "`<"

    -- Search to the end of the original selection.
    local end_cursor = orig_cursor:clone()
    end_cursor:feedkeys(TERM_CODES.ESC)
    end_cursor:feedkeys "`>"

    local prev_match = nil
    while true do
      -- Record this search position.
      local search_line = search_cursor:line()
      local search_col = search_cursor:col()

      -- Use the remap option to take advantage of user-defined textobjects.
      search_cursor:feedkeys("v" .. textobject, { remap = true })

      if search_cursor:mode() == "n" then
        -- If we tried to do visual selection and ended up in normal mode,
        -- there was nothing to select.
        break
      elseif visual_past(end_cursor, search_cursor) then
        -- If the next matching object is beyond the original selection,
        -- we've found all the objects _in_ the selection.
        break
      elseif prev_match and visual_same(prev_match, search_cursor) then
        -- We found the same object again.
      else
        prev_match = search_cursor:clone()
      end

      -- Move to the end of the matched object.
      search_cursor:feedkeys(TERM_CODES.ESC)
      search_cursor:feedkeys "`>"

      -- Is the cursor closer to the end than the location of the last search?
      local function after_previous()
        return search_cursor:line() > search_line
          or search_cursor:line() == search_line and search_cursor:col() > search_col
      end

      -- Some i textobjects move the cursor to before the search position. To
      -- prepare for the next search, move the cursor beyond the end of the
      -- current match, or past where we started this iteration of search,
      -- whichever is closer to the end.
      if after_previous() then
        search_line = search_cursor:line()
        search_col = search_cursor:col()
      end

      local at_end = false
      while not at_end and not after_previous() do
        at_end = not move_cursor_next(search_cursor)
      end

      -- If we couldn't move the search, then we're at the end of file.
      if not after_previous() then break end
    end

    search_cursor:delete()
    end_cursor:delete()
    orig_cursor:delete()
  end)
end

vim.keymap.set({ "n", "x" }, "<leader>j", function()
  local object = vim.fn.input "textobject:"
  matchVisualObjects(object)
end)