Extend fzf-lua with tags with custom command

fzf-lua-tags.lua

local function getPath(str)
  return str:match("(.*[/\\])")
end

local function cutTagBasePath(tags, str)
  for _, v in pairs(tags) do
    print(v)
    str = str:gsub(getPath(v), "")
  end
  return str
end

local function GetTableLng(tbl)
  local getN = 0
  for _ in pairs(tbl) do
    getN = getN + 1
  end
  return getN
end

local function fn_transform_tbl(tbl)
  -- format all entires as “fzf-lua compatible”
  return vim.tbl_map(function(x)
    -- 1 tag
    -- 2 filename
    -- 5 line number
    -- 8 decorated tag line -- additional job
    print("fn_transform_tbl")
    local el = Split(x, "\t")
    local tag = el[1]
    local filename = el[2]
    local path = getPath(el[GetTableLng(el)])
    local no = Split(el[5], ":")[2]
    local target = string.format("%s%s:%s:%s", path, filename, no, tag)
    -- print(target)
    return target
  end, tbl)
end

function Split(s, delimiter)
  local result = {};
  for match in (s .. delimiter):gmatch("(.-)" .. delimiter) do
    table.insert(result, match);
  end
  return result;
end

_G.fif_grep = function(opts)
  local fzf_lua = require 'fzf-lua'
  local tags = vim.opt.tags:get()

  opts = opts or {}
  if opts.buffer ~= "" and opts.buffer ~= nil and opts.search ~= "" and opts.search ~= nil then
    local buf = cutTagBasePath(tags, opts.buffer)
    opts.prompt = "fif  :'" .. buf .. "'  :'" .. opts.search .. "'❯ "
    opts.fzf_cli_args = '-q ' .. vim.fn.shellescape(buf) .. ' ' .. vim.fn.shellescape(opts.search)
  elseif opts.buffer ~= "" and opts.buffer ~= nil then
    local buf = cutTagBasePath(tags, opts.buffer)
    opts.prompt = "fif  :'" .. buf .. "'❯ "
    opts.fzf_cli_args = '-q ' .. vim.fn.shellescape(buf)
  elseif opts.search ~= "" and opts.search ~= nil then
    opts.prompt = "fif  :'" .. opts.search .. "'❯ "
    opts.fzf_cli_args = '-q ' .. vim.fn.shellescape(opts.search)
  else
    opts.prompt = "fif❯ "
  end
  print(opts.fzf_cli_args)

  opts.git_icons = true
  opts.file_icons = true
  opts.color_icons = true
  -- setup default actions for edit, quickfix, etc
  opts.actions = fzf_lua.defaults.actions.files
  -- see preview overview for more info on previewers
  opts.previewer = "builtin"

  opts.actions = {
    -- ["<bind1>"] = { fn = function(selected) end, reload = true }
    -- ["<o>"] = { fn = require'fzf-lua'.actions.file_edit, reload = true }
    ["default"] = function(selected, o)
      require 'fzf-lua'.actions.file_edit_or_qf(fn_transform_tbl(selected), o)
    end,
  }

  local cmdt = { "tag-dec" }
  for _, value in pairs(tags) do
    table.insert(cmdt, value)
  end
  for _, value in pairs({ "|", "rg", "-v", "'^!'" }) do
    table.insert(cmdt, value)
  end
  local cmd = table.concat(cmdt, " ")
  print(cmd)

  return fzf_lua.fzf_exec(cmd, opts)
end

vim.keymap.set("n", ";t", function() _G.fif_grep({ search = "" }) end)
vim.keymap.set("n", "<leader>t", function() _G.fif_grep({ search = "" }) end)
vim.keymap.set("n", ";T", function() _G.fif_grep({ search = vim.fn.expand('<cword>') }) end)
vim.keymap.set("n", "<leader>T", function() _G.fif_grep({ search = vim.fn.expand('<cword>') }) end)
vim.keymap.set("n", ";o", function() _G.fif_grep({ search = "", buffer = vim.fn.expand('%') }) end)
vim.keymap.set("n", "<leader>o", function() _G.fif_grep({ search = "", buffer = vim.fn.expand('%') }) end)
vim.keymap.set("n", ";O", function() _G.fif_grep({ search = vim.fn.expand('<cword>'), buffer = vim.fn.expand('%') }) end)
vim.keymap.set("n", "<leader>O",
  function() _G.fif_grep({ search = vim.fn.expand('<cword>'), buffer = vim.fn.expand('%') }) end)

Tags require to have absolute paths.
tag-dec could be replaced with perl script from junegunn https://github.com/junegunn/fzf.vim/blob/master/bin/tags.pl