Minimal fzy integration for Neovim in ~100 lines (oldfiles, cmd history, buffers, jumplist, etc.)

fzy.lua

-- https://github.com/jhawthorn/fzy/pull/116#issuecomment-538708329
local function fzy(a)
  local saved_spk = vim.o.splitkeep
  local src_winid = vim.fn.win_getid()
  -- lines >= 3 is a hardcoded limit in fzy
  local fzy_lines = (vim.v.count > 2 and vim.v.count) or 10
  local tempfile = vim.fn.tempname()
  local term_cmd = a.input .. ' | fzy -l' .. fzy_lines .. ' > ' .. tempfile

  -- FIXME: terminal buffer shows in `:ls!` after exiting.
  local on_exit = function ()
    vim.cmd.bwipeout()
    vim.o.splitkeep = saved_spk
    vim.fn.win_gotoid(src_winid)
    if vim.fn.filereadable(tempfile) then
      local lines = vim.fn.readfile(tempfile)
      if #lines > 0 then (a.action or vim.cmd.edit)(lines[1]) end
    end
    vim.fn.delete(tempfile)
  end

  vim.o.splitkeep = 'screen'
  vim.cmd('botright' .. (fzy_lines + 1) .. 'new')
  -- NOTE: `cwd` can also be specified for the job
  local id = vim.fn.termopen(term_cmd, { on_exit = on_exit, env = a.env, })
  vim.keymap.set('n', '<esc>', function () vim.fn.jobstop(id) end, {buffer=true})
  vim.cmd('keepalt file fzy')
  vim.cmd.startinsert()
end

local function fd ()
  local inp = vim.fn.input('fd -H '); if #inp < 1 then return end
  fzy { input = 'fdfind -H ' .. inp }
end

local function rg ()
  local inp = vim.fn.input('rg --vimgrep '); if #inp < 1 then return end
  fzy {
    input = 'rg --vimgrep ' .. inp,
    action = function (line)
      local file, lnum, col = unpack(vim.split(line, ':'))
      vim.cmd.edit(file)
      vim.fn.cursor(lnum, col)
      vim.cmd('normal! zz')
    end,
  }
end

-- Mind the double quotes around env vars (do substitute, but without
-- wildcard expansions and word splitting).
local function buffers ()
  fzy {
    env = { NVIM_BUFFERS = vim.fn.execute('ls') },
    input = 'echo "$NVIM_BUFFERS"',
    action = function (line) vim.cmd('b' .. string.match(line, '%d+')) end,
  }
end

-- TODO: echoed stuff disappears (should use g<)
local function history ()
  local history = vim.fn.execute('history cmd')
  history = vim.split(history, '\n')
  for i = 1, #history do
    history[i] = history[i]:gsub('>?%s*%S+%s*', ':', 1)
  end
  history = table.concat(vim.fn.reverse(history), '\n')
  fzy {
    env = { NVIM_HISTORY = history },
    input = 'echo "$NVIM_HISTORY"', -- | tac | sed "s/>\\?\\s*\\S\\+\\s*/:/" ',
    action = function (line) vim.cmd(line:gsub(':', '', 1)) end,
  }
end

local function oldfiles ()
  fzy { 
    env = { NVIM_OLDFILES = table.concat(vim.v.oldfiles, '\n') },
    input = 'echo "$NVIM_OLDFILES"',
  }
end

-- NOTE: getjumplist()
local function jumplist ()

  local prepare_jumplist = function ()
    jumps = vim.split(vim.fn.execute('jumps'), '\n', {trimempty=true})
    -- Find '>'.
    local current_pos = nil
    for n, line in ipairs(jumps) do
      if line:match('^%s*>') then current_pos = n end
    end
    -- Add +/- (newer/older) prefixes to lines (to be able to decide
    -- which key to use - <c-o>/<c-i> - on the selected item).
    for n, line in ipairs(jumps) do
      if n > 1 then
        local prefix = ' '
        if n < current_pos then prefix = '-' end
        if n > current_pos then prefix = '+' end
        jumps[n] = line:gsub('%s', prefix, 1)
      end
    end
    -- Get rid of unneeded content (header, >), and reverse the list.
    local res = {}
    for i= #jumps,1,-1 do
      if not jumps[i]:match('^%s*>') and jumps[i]:match('%d') then
        table.insert(res, jumps[i])
      end
    end
    return table.concat(res, '\n')
  end

  fzy {
    env = { NVIM_JUMPS = prepare_jumplist() },
    input = 'echo "$NVIM_JUMPS"',
    action = function (line)
      local n = line:match('%d+')
      local key = vim.api.nvim_replace_termcodes(
          line:match('^%s*%+') and '<c-i>' or '<c-o>', true, true, true)
      vim.fn.execute('normal! ' .. n .. key)
    end,
  }
end

return {
  fzy = fzy,
  fd = fd,
  rg = rg, 
  buffers = buffers,
  history = history,
  oldfiles = oldfiles, 
  jumplist = jumplist,
}

-- Usage:
-- vim.keymap.set('n', '<leader>ff', function () require'fzy'.fd() end)
-- vim.keymap.set('n', '<leader>fg', function () require'fzy'.rg() end)
-- vim.keymap.set('n', '<leader>fb', function () require'fzy'.buffers() end)
-- vim.keymap.set('n', '<leader>fh', function () require'fzy'.history() end)
-- vim.keymap.set('n', '<leader>fo', function () require'fzy'.oldfiles() end)
-- vim.keymap.set('n', '<leader>fj', function () require'fzy'.jumplist() end)