text: --!A cross-platform build utility based on Lua
  --
  -- Licensed under the Apache License, Version 2.0 (the "License");
  -- you may not use this file except in compliance with the License.
  -- You may obtain a copy of the License at
  --
  --     http://www.apache.org/licenses/LICENSE-2.0
  --
  -- Unless required by applicable law or agreed to in writing, software
  -- distributed under the License is distributed on an "AS IS" BASIS,
  -- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  -- See the License for the specific language governing permissions and
  -- limitations under the License.
  --
  -- Copyright (C) 2015-2020, TBOOX Open Source Group.
  --
  -- @author      ruki
  -- @file        xmake.lua
  --
  
  -- define task
  task("update")
  
      -- set category
      set_category("action")
  
      -- on run
      on_run("main")
  
      -- set menu
      set_menu {
                  -- usage
                  usage = "xmake update [options] [xmakever]"
  
                  -- description
              ,   description = "Update and uninstall the xmake program."
  
                  -- options
              ,   options =
                  {
                      {nil, "uninstall",   "k",   nil,    "Uninstall the current xmake program."                     }
                  ,   {                                                                                              }
                  ,   {'s', "scriptonly",  "k",   nil,    "Update script only"                                       }
                  ,   {'f', "force",       "k",   nil,    "Force to update and reinstall the given version."         }
                  ,   {nil, "xmakever",    "v",   nil,    "The given xmake version, or a git source (and branch). ",
                                                          "e.g.",
                                                          "    from official source: ",
                                                          "        latest, ~2.2.3, dev, master",
                                                          "    from custom source:",
                                                          "        https://github.com/xmake-io/xmake",
                                                          "        github:xmake-io/xmake#~2.2.3",
                                                          "        git://github.com/xmake-io/xmake.git#master",
                                                          values = function (complete)
                                                              if not complete then
                                                                  return
                                                              end
                                                              return try{ function ()
                                                                  import("private.action.update.fetch_version")
  
                                                                  local seg = complete:split('#', { plain = true, limit = 2, strict = true })
                                                                  if #seg == 1 then
                                                                      if seg[1]:find(':', 1, true) then
                                                                          -- incomplete custom source
                                                                          return
                                                                      else
                                                                          seg[1] = ""
                                                                      end
                                                                  end
  
                                                                  local versions = fetch_version(seg[1])
                                                                  for i,v in ipairs(versions.tags) do
                                                                      if v:startswith("v") and #v > 5 then
                                                                          versions.tags[i] = v:sub(2)
                                                                      end
                                                                  end
                                                                  local candidates = table.join("latest", versions.branches, table.reverse(versions.tags))
                                                                  if versions.is_official then
                                                                      return candidates
                                                                  else
                                                                      for i, v in ipairs(candidates) do
                                                                          candidates[i] = seg[1] .. "#" .. v
                                                                      end
                                                                      return candidates
                                                                  end
                                                              end }
                                                          end}
                  }
              }
  
  
  
  