From 6f07395f37459d7e0c2732888a1f7312fea0c67c Mon Sep 17 00:00:00 2001
From: Hisham Muhammad <hisham@gobolinux.org>
Date: Wed, 28 Feb 2024 20:54:14 -0300
Subject: move luarocks.argparse to luarocks.vendor.argparse

---
 src/luarocks/argparse.lua        | 2103 --------------------------------------
 src/luarocks/cmd.lua             |    2 +-
 src/luarocks/vendor/argparse.lua | 2103 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 2104 insertions(+), 2104 deletions(-)
 delete mode 100644 src/luarocks/argparse.lua
 create mode 100644 src/luarocks/vendor/argparse.lua

(limited to 'src')

diff --git a/src/luarocks/argparse.lua b/src/luarocks/argparse.lua
deleted file mode 100644
index 2c2585dd..00000000
--- a/src/luarocks/argparse.lua
+++ /dev/null
@@ -1,2103 +0,0 @@
--- The MIT License (MIT)
-
--- Copyright (c) 2013 - 2018 Peter Melnichenko
---                      2019 Paul Ouellette
-
--- Permission is hereby granted, free of charge, to any person obtaining a copy of
--- this software and associated documentation files (the "Software"), to deal in
--- the Software without restriction, including without limitation the rights to
--- use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
--- the Software, and to permit persons to whom the Software is furnished to do so,
--- subject to the following conditions:
-
--- The above copyright notice and this permission notice shall be included in all
--- copies or substantial portions of the Software.
-
--- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
--- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
--- FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
--- COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
--- IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
--- CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-local function deep_update(t1, t2)
-   for k, v in pairs(t2) do
-      if type(v) == "table" then
-         v = deep_update({}, v)
-      end
-
-      t1[k] = v
-   end
-
-   return t1
-end
-
--- A property is a tuple {name, callback}.
--- properties.args is number of properties that can be set as arguments
--- when calling an object.
-local function class(prototype, properties, parent)
-   -- Class is the metatable of its instances.
-   local cl = {}
-   cl.__index = cl
-
-   if parent then
-      cl.__prototype = deep_update(deep_update({}, parent.__prototype), prototype)
-   else
-      cl.__prototype = prototype
-   end
-
-   if properties then
-      local names = {}
-
-      -- Create setter methods and fill set of property names.
-      for _, property in ipairs(properties) do
-         local name, callback = property[1], property[2]
-
-         cl[name] = function(self, value)
-            if not callback(self, value) then
-               self["_" .. name] = value
-            end
-
-            return self
-         end
-
-         names[name] = true
-      end
-
-      function cl.__call(self, ...)
-         -- When calling an object, if the first argument is a table,
-         -- interpret keys as property names, else delegate arguments
-         -- to corresponding setters in order.
-         if type((...)) == "table" then
-            for name, value in pairs((...)) do
-               if names[name] then
-                  self[name](self, value)
-               end
-            end
-         else
-            local nargs = select("#", ...)
-
-            for i, property in ipairs(properties) do
-               if i > nargs or i > properties.args then
-                  break
-               end
-
-               local arg = select(i, ...)
-
-               if arg ~= nil then
-                  self[property[1]](self, arg)
-               end
-            end
-         end
-
-         return self
-      end
-   end
-
-   -- If indexing class fails, fallback to its parent.
-   local class_metatable = {}
-   class_metatable.__index = parent
-
-   function class_metatable.__call(self, ...)
-      -- Calling a class returns its instance.
-      -- Arguments are delegated to the instance.
-      local object = deep_update({}, self.__prototype)
-      setmetatable(object, self)
-      return object(...)
-   end
-
-   return setmetatable(cl, class_metatable)
-end
-
-local function typecheck(name, types, value)
-   for _, type_ in ipairs(types) do
-      if type(value) == type_ then
-         return true
-      end
-   end
-
-   error(("bad property '%s' (%s expected, got %s)"):format(name, table.concat(types, " or "), type(value)))
-end
-
-local function typechecked(name, ...)
-   local types = {...}
-   return {name, function(_, value) typecheck(name, types, value) end}
-end
-
-local multiname = {"name", function(self, value)
-   typecheck("name", {"string"}, value)
-
-   for alias in value:gmatch("%S+") do
-      self._name = self._name or alias
-      table.insert(self._aliases, alias)
-      table.insert(self._public_aliases, alias)
-      -- If alias contains '_', accept '-' also.
-      if alias:find("_", 1, true) then
-         table.insert(self._aliases, (alias:gsub("_", "-")))
-      end
-   end
-
-   -- Do not set _name as with other properties.
-   return true
-end}
-
-local multiname_hidden = {"hidden_name", function(self, value)
-   typecheck("hidden_name", {"string"}, value)
-
-   for alias in value:gmatch("%S+") do
-      table.insert(self._aliases, alias)
-      if alias:find("_", 1, true) then
-         table.insert(self._aliases, (alias:gsub("_", "-")))
-      end
-   end
-
-   return true
-end}
-
-local function parse_boundaries(str)
-   if tonumber(str) then
-      return tonumber(str), tonumber(str)
-   end
-
-   if str == "*" then
-      return 0, math.huge
-   end
-
-   if str == "+" then
-      return 1, math.huge
-   end
-
-   if str == "?" then
-      return 0, 1
-   end
-
-   if str:match "^%d+%-%d+$" then
-      local min, max = str:match "^(%d+)%-(%d+)$"
-      return tonumber(min), tonumber(max)
-   end
-
-   if str:match "^%d+%+$" then
-      local min = str:match "^(%d+)%+$"
-      return tonumber(min), math.huge
-   end
-end
-
-local function boundaries(name)
-   return {name, function(self, value)
-      typecheck(name, {"number", "string"}, value)
-
-      local min, max = parse_boundaries(value)
-
-      if not min then
-         error(("bad property '%s'"):format(name))
-      end
-
-      self["_min" .. name], self["_max" .. name] = min, max
-   end}
-end
-
-local actions = {}
-
-local option_action = {"action", function(_, value)
-   typecheck("action", {"function", "string"}, value)
-
-   if type(value) == "string" and not actions[value] then
-      error(("unknown action '%s'"):format(value))
-   end
-end}
-
-local option_init = {"init", function(self)
-   self._has_init = true
-end}
-
-local option_default = {"default", function(self, value)
-   if type(value) ~= "string" then
-      self._init = value
-      self._has_init = true
-      return true
-   end
-end}
-
-local add_help = {"add_help", function(self, value)
-   typecheck("add_help", {"boolean", "string", "table"}, value)
-
-   if self._help_option_idx then
-      table.remove(self._options, self._help_option_idx)
-      self._help_option_idx = nil
-   end
-
-   if value then
-      local help = self:flag()
-         :description "Show this help message and exit."
-         :action(function()
-            print(self:get_help())
-            os.exit(0)
-         end)
-
-      if value ~= true then
-         help = help(value)
-      end
-
-      if not help._name then
-         help "-h" "--help"
-      end
-
-      self._help_option_idx = #self._options
-   end
-end}
-
-local Parser = class({
-   _arguments = {},
-   _options = {},
-   _commands = {},
-   _mutexes = {},
-   _groups = {},
-   _require_command = true,
-   _handle_options = true
-}, {
-   args = 3,
-   typechecked("name", "string"),
-   typechecked("description", "string"),
-   typechecked("epilog", "string"),
-   typechecked("usage", "string"),
-   typechecked("help", "string"),
-   typechecked("require_command", "boolean"),
-   typechecked("handle_options", "boolean"),
-   typechecked("action", "function"),
-   typechecked("command_target", "string"),
-   typechecked("help_vertical_space", "number"),
-   typechecked("usage_margin", "number"),
-   typechecked("usage_max_width", "number"),
-   typechecked("help_usage_margin", "number"),
-   typechecked("help_description_margin", "number"),
-   typechecked("help_max_width", "number"),
-   add_help
-})
-
-local Command = class({
-   _aliases = {},
-   _public_aliases = {}
-}, {
-   args = 3,
-   multiname,
-   typechecked("description", "string"),
-   typechecked("epilog", "string"),
-   multiname_hidden,
-   typechecked("summary", "string"),
-   typechecked("target", "string"),
-   typechecked("usage", "string"),
-   typechecked("help", "string"),
-   typechecked("require_command", "boolean"),
-   typechecked("handle_options", "boolean"),
-   typechecked("action", "function"),
-   typechecked("command_target", "string"),
-   typechecked("help_vertical_space", "number"),
-   typechecked("usage_margin", "number"),
-   typechecked("usage_max_width", "number"),
-   typechecked("help_usage_margin", "number"),
-   typechecked("help_description_margin", "number"),
-   typechecked("help_max_width", "number"),
-   typechecked("hidden", "boolean"),
-   add_help
-}, Parser)
-
-local Argument = class({
-   _minargs = 1,
-   _maxargs = 1,
-   _mincount = 1,
-   _maxcount = 1,
-   _defmode = "unused",
-   _show_default = true
-}, {
-   args = 5,
-   typechecked("name", "string"),
-   typechecked("description", "string"),
-   option_default,
-   typechecked("convert", "function", "table"),
-   boundaries("args"),
-   typechecked("target", "string"),
-   typechecked("defmode", "string"),
-   typechecked("show_default", "boolean"),
-   typechecked("argname", "string", "table"),
-   typechecked("choices", "table"),
-   typechecked("hidden", "boolean"),
-   option_action,
-   option_init
-})
-
-local Option = class({
-   _aliases = {},
-   _public_aliases = {},
-   _mincount = 0,
-   _overwrite = true
-}, {
-   args = 6,
-   multiname,
-   typechecked("description", "string"),
-   option_default,
-   typechecked("convert", "function", "table"),
-   boundaries("args"),
-   boundaries("count"),
-   multiname_hidden,
-   typechecked("target", "string"),
-   typechecked("defmode", "string"),
-   typechecked("show_default", "boolean"),
-   typechecked("overwrite", "boolean"),
-   typechecked("argname", "string", "table"),
-   typechecked("choices", "table"),
-   typechecked("hidden", "boolean"),
-   option_action,
-   option_init
-}, Argument)
-
-function Parser:_inherit_property(name, default)
-   local element = self
-
-   while true do
-      local value = element["_" .. name]
-
-      if value ~= nil then
-         return value
-      end
-
-      if not element._parent then
-         return default
-      end
-
-      element = element._parent
-   end
-end
-
-function Argument:_get_argument_list()
-   local buf = {}
-   local i = 1
-
-   while i <= math.min(self._minargs, 3) do
-      local argname = self:_get_argname(i)
-
-      if self._default and self._defmode:find "a" then
-         argname = "[" .. argname .. "]"
-      end
-
-      table.insert(buf, argname)
-      i = i+1
-   end
-
-   while i <= math.min(self._maxargs, 3) do
-      table.insert(buf, "[" .. self:_get_argname(i) .. "]")
-      i = i+1
-
-      if self._maxargs == math.huge then
-         break
-      end
-   end
-
-   if i < self._maxargs then
-      table.insert(buf, "...")
-   end
-
-   return buf
-end
-
-function Argument:_get_usage()
-   local usage = table.concat(self:_get_argument_list(), " ")
-
-   if self._default and self._defmode:find "u" then
-      if self._maxargs > 1 or (self._minargs == 1 and not self._defmode:find "a") then
-         usage = "[" .. usage .. "]"
-      end
-   end
-
-   return usage
-end
-
-function actions.store_true(result, target)
-   result[target] = true
-end
-
-function actions.store_false(result, target)
-   result[target] = false
-end
-
-function actions.store(result, target, argument)
-   result[target] = argument
-end
-
-function actions.count(result, target, _, overwrite)
-   if not overwrite then
-      result[target] = result[target] + 1
-   end
-end
-
-function actions.append(result, target, argument, overwrite)
-   result[target] = result[target] or {}
-   table.insert(result[target], argument)
-
-   if overwrite then
-      table.remove(result[target], 1)
-   end
-end
-
-function actions.concat(result, target, arguments, overwrite)
-   if overwrite then
-      error("'concat' action can't handle too many invocations")
-   end
-
-   result[target] = result[target] or {}
-
-   for _, argument in ipairs(arguments) do
-      table.insert(result[target], argument)
-   end
-end
-
-function Argument:_get_action()
-   local action, init
-
-   if self._maxcount == 1 then
-      if self._maxargs == 0 then
-         action, init = "store_true", nil
-      else
-         action, init = "store", nil
-      end
-   else
-      if self._maxargs == 0 then
-         action, init = "count", 0
-      else
-         action, init = "append", {}
-      end
-   end
-
-   if self._action then
-      action = self._action
-   end
-
-   if self._has_init then
-      init = self._init
-   end
-
-   if type(action) == "string" then
-      action = actions[action]
-   end
-
-   return action, init
-end
-
--- Returns placeholder for `narg`-th argument.
-function Argument:_get_argname(narg)
-   local argname = self._argname or self:_get_default_argname()
-
-   if type(argname) == "table" then
-      return argname[narg]
-   else
-      return argname
-   end
-end
-
-function Argument:_get_choices_list()
-   return "{" .. table.concat(self._choices, ",") .. "}"
-end
-
-function Argument:_get_default_argname()
-   if self._choices then
-      return self:_get_choices_list()
-   else
-      return "<" .. self._name .. ">"
-   end
-end
-
-function Option:_get_default_argname()
-   if self._choices then
-      return self:_get_choices_list()
-   else
-      return "<" .. self:_get_default_target() .. ">"
-   end
-end
-
--- Returns labels to be shown in the help message.
-function Argument:_get_label_lines()
-   if self._choices then
-      return {self:_get_choices_list()}
-   else
-      return {self._name}
-   end
-end
-
-function Option:_get_label_lines()
-   local argument_list = self:_get_argument_list()
-
-   if #argument_list == 0 then
-      -- Don't put aliases for simple flags like `-h` on different lines.
-      return {table.concat(self._public_aliases, ", ")}
-   end
-
-   local longest_alias_length = -1
-
-   for _, alias in ipairs(self._public_aliases) do
-      longest_alias_length = math.max(longest_alias_length, #alias)
-   end
-
-   local argument_list_repr = table.concat(argument_list, " ")
-   local lines = {}
-
-   for i, alias in ipairs(self._public_aliases) do
-      local line = (" "):rep(longest_alias_length - #alias) .. alias .. " " .. argument_list_repr
-
-      if i ~= #self._public_aliases then
-         line = line .. ","
-      end
-
-      table.insert(lines, line)
-   end
-
-   return lines
-end
-
-function Command:_get_label_lines()
-   return {table.concat(self._public_aliases, ", ")}
-end
-
-function Argument:_get_description()
-   if self._default and self._show_default then
-      if self._description then
-         return ("%s (default: %s)"):format(self._description, self._default)
-      else
-         return ("default: %s"):format(self._default)
-      end
-   else
-      return self._description or ""
-   end
-end
-
-function Command:_get_description()
-   return self._summary or self._description or ""
-end
-
-function Option:_get_usage()
-   local usage = self:_get_argument_list()
-   table.insert(usage, 1, self._name)
-   usage = table.concat(usage, " ")
-
-   if self._mincount == 0 or self._default then
-      usage = "[" .. usage .. "]"
-   end
-
-   return usage
-end
-
-function Argument:_get_default_target()
-   return self._name
-end
-
-function Option:_get_default_target()
-   local res
-
-   for _, alias in ipairs(self._public_aliases) do
-      if alias:sub(1, 1) == alias:sub(2, 2) then
-         res = alias:sub(3)
-         break
-      end
-   end
-
-   res = res or self._name:sub(2)
-   return (res:gsub("-", "_"))
-end
-
-function Option:_is_vararg()
-   return self._maxargs ~= self._minargs
-end
-
-function Parser:_get_fullname(exclude_root)
-   local parent = self._parent
-   if exclude_root and not parent then
-      return ""
-   end
-   local buf = {self._name}
-
-   while parent do
-      if not exclude_root or parent._parent then
-         table.insert(buf, 1, parent._name)
-      end
-      parent = parent._parent
-   end
-
-   return table.concat(buf, " ")
-end
-
-function Parser:_update_charset(charset)
-   charset = charset or {}
-
-   for _, command in ipairs(self._commands) do
-      command:_update_charset(charset)
-   end
-
-   for _, option in ipairs(self._options) do
-      for _, alias in ipairs(option._aliases) do
-         charset[alias:sub(1, 1)] = true
-      end
-   end
-
-   return charset
-end
-
-function Parser:argument(...)
-   local argument = Argument(...)
-   table.insert(self._arguments, argument)
-   return argument
-end
-
-function Parser:option(...)
-   local option = Option(...)
-   table.insert(self._options, option)
-   return option
-end
-
-function Parser:flag(...)
-   return self:option():args(0)(...)
-end
-
-function Parser:command(...)
-   local command = Command():add_help(true)(...)
-   command._parent = self
-   table.insert(self._commands, command)
-   return command
-end
-
-function Parser:mutex(...)
-   local elements = {...}
-
-   for i, element in ipairs(elements) do
-      local mt = getmetatable(element)
-      assert(mt == Option or mt == Argument, ("bad argument #%d to 'mutex' (Option or Argument expected)"):format(i))
-   end
-
-   table.insert(self._mutexes, elements)
-   return self
-end
-
-function Parser:group(name, ...)
-   assert(type(name) == "string", ("bad argument #1 to 'group' (string expected, got %s)"):format(type(name)))
-
-   local group = {name = name, ...}
-
-   for i, element in ipairs(group) do
-      local mt = getmetatable(element)
-      assert(mt == Option or mt == Argument or mt == Command,
-         ("bad argument #%d to 'group' (Option or Argument or Command expected)"):format(i + 1))
-   end
-
-   table.insert(self._groups, group)
-   return self
-end
-
-local usage_welcome = "Usage: "
-
-function Parser:get_usage()
-   if self._usage then
-      return self._usage
-   end
-
-   local usage_margin = self:_inherit_property("usage_margin", #usage_welcome)
-   local max_usage_width = self:_inherit_property("usage_max_width", 70)
-   local lines = {usage_welcome .. self:_get_fullname()}
-
-   local function add(s)
-      if #lines[#lines]+1+#s <= max_usage_width then
-         lines[#lines] = lines[#lines] .. " " .. s
-      else
-         lines[#lines+1] = (" "):rep(usage_margin) .. s
-      end
-   end
-
-   -- Normally options are before positional arguments in usage messages.
-   -- However, vararg options should be after, because they can't be reliable used
-   -- before a positional argument.
-   -- Mutexes come into play, too, and are shown as soon as possible.
-   -- Overall, output usages in the following order:
-   -- 1. Mutexes that don't have positional arguments or vararg options.
-   -- 2. Options that are not in any mutexes and are not vararg.
-   -- 3. Positional arguments - on their own or as a part of a mutex.
-   -- 4. Remaining mutexes.
-   -- 5. Remaining options.
-
-   local elements_in_mutexes = {}
-   local added_elements = {}
-   local added_mutexes = {}
-   local argument_to_mutexes = {}
-
-   local function add_mutex(mutex, main_argument)
-      if added_mutexes[mutex] then
-         return
-      end
-
-      added_mutexes[mutex] = true
-      local buf = {}
-
-      for _, element in ipairs(mutex) do
-         if not element._hidden and not added_elements[element] then
-            if getmetatable(element) == Option or element == main_argument then
-               table.insert(buf, element:_get_usage())
-               added_elements[element] = true
-            end
-         end
-      end
-
-      if #buf == 1 then
-         add(buf[1])
-      elseif #buf > 1 then
-         add("(" .. table.concat(buf, " | ") .. ")")
-      end
-   end
-
-   local function add_element(element)
-      if not element._hidden and not added_elements[element] then
-         add(element:_get_usage())
-         added_elements[element] = true
-      end
-   end
-
-   for _, mutex in ipairs(self._mutexes) do
-      local is_vararg = false
-      local has_argument = false
-
-      for _, element in ipairs(mutex) do
-         if getmetatable(element) == Option then
-            if element:_is_vararg() then
-               is_vararg = true
-            end
-         else
-            has_argument = true
-            argument_to_mutexes[element] = argument_to_mutexes[element] or {}
-            table.insert(argument_to_mutexes[element], mutex)
-         end
-
-         elements_in_mutexes[element] = true
-      end
-
-      if not is_vararg and not has_argument then
-         add_mutex(mutex)
-      end
-   end
-
-   for _, option in ipairs(self._options) do
-      if not elements_in_mutexes[option] and not option:_is_vararg() then
-         add_element(option)
-      end
-   end
-
-   -- Add usages for positional arguments, together with one mutex containing them, if they are in a mutex.
-   for _, argument in ipairs(self._arguments) do
-      -- Pick a mutex as a part of which to show this argument, take the first one that's still available.
-      local mutex
-
-      if elements_in_mutexes[argument] then
-         for _, argument_mutex in ipairs(argument_to_mutexes[argument]) do
-            if not added_mutexes[argument_mutex] then
-               mutex = argument_mutex
-            end
-         end
-      end
-
-      if mutex then
-         add_mutex(mutex, argument)
-      else
-         add_element(argument)
-      end
-   end
-
-   for _, mutex in ipairs(self._mutexes) do
-      add_mutex(mutex)
-   end
-
-   for _, option in ipairs(self._options) do
-      add_element(option)
-   end
-
-   if #self._commands > 0 then
-      if self._require_command then
-         add("<command>")
-      else
-         add("[<command>]")
-      end
-
-      add("...")
-   end
-
-   return table.concat(lines, "\n")
-end
-
-local function split_lines(s)
-   if s == "" then
-      return {}
-   end
-
-   local lines = {}
-
-   if s:sub(-1) ~= "\n" then
-      s = s .. "\n"
-   end
-
-   for line in s:gmatch("([^\n]*)\n") do
-      table.insert(lines, line)
-   end
-
-   return lines
-end
-
-local function autowrap_line(line, max_length)
-   -- Algorithm for splitting lines is simple and greedy.
-   local result_lines = {}
-
-   -- Preserve original indentation of the line, put this at the beginning of each result line.
-   -- If the first word looks like a list marker ('*', '+', or '-'), add spaces so that starts
-   -- of the second and the following lines vertically align with the start of the second word.
-   local indentation = line:match("^ *")
-
-   if line:find("^ *[%*%+%-]") then
-      indentation = indentation .. " " .. line:match("^ *[%*%+%-]( *)")
-   end
-
-   -- Parts of the last line being assembled.
-   local line_parts = {}
-
-   -- Length of the current line.
-   local line_length = 0
-
-   -- Index of the next character to consider.
-   local index = 1
-
-   while true do
-      local word_start, word_finish, word = line:find("([^ ]+)", index)
-
-      if not word_start then
-         -- Ignore trailing spaces, if any.
-         break
-      end
-
-      local preceding_spaces = line:sub(index, word_start - 1)
-      index = word_finish + 1
-
-      if (#line_parts == 0) or (line_length + #preceding_spaces + #word <= max_length) then
-         -- Either this is the very first word or it fits as an addition to the current line, add it.
-         table.insert(line_parts, preceding_spaces) -- For the very first word this adds the indentation.
-         table.insert(line_parts, word)
-         line_length = line_length + #preceding_spaces + #word
-      else
-         -- Does not fit, finish current line and put the word into a new one.
-         table.insert(result_lines, table.concat(line_parts))
-         line_parts = {indentation, word}
-         line_length = #indentation + #word
-      end
-   end
-
-   if #line_parts > 0 then
-      table.insert(result_lines, table.concat(line_parts))
-   end
-
-   if #result_lines == 0 then
-      -- Preserve empty lines.
-      result_lines[1] = ""
-   end
-
-   return result_lines
-end
-
--- Automatically wraps lines within given array,
--- attempting to limit line length to `max_length`.
--- Existing line splits are preserved.
-local function autowrap(lines, max_length)
-   local result_lines = {}
-
-   for _, line in ipairs(lines) do
-      local autowrapped_lines = autowrap_line(line, max_length)
-
-      for _, autowrapped_line in ipairs(autowrapped_lines) do
-         table.insert(result_lines, autowrapped_line)
-      end
-   end
-
-   return result_lines
-end
-
-function Parser:_get_element_help(element)
-   local label_lines = element:_get_label_lines()
-   local description_lines = split_lines(element:_get_description())
-
-   local result_lines = {}
-
-   -- All label lines should have the same length (except the last one, it has no comma).
-   -- If too long, start description after all the label lines.
-   -- Otherwise, combine label and description lines.
-
-   local usage_margin_len = self:_inherit_property("help_usage_margin", 3)
-   local usage_margin = (" "):rep(usage_margin_len)
-   local description_margin_len = self:_inherit_property("help_description_margin", 25)
-   local description_margin = (" "):rep(description_margin_len)
-
-   local help_max_width = self:_inherit_property("help_max_width")
-
-   if help_max_width then
-      local description_max_width = math.max(help_max_width - description_margin_len, 10)
-      description_lines = autowrap(description_lines, description_max_width)
-   end
-
-   if #label_lines[1] >= (description_margin_len - usage_margin_len) then
-      for _, label_line in ipairs(label_lines) do
-         table.insert(result_lines, usage_margin .. label_line)
-      end
-
-      for _, description_line in ipairs(description_lines) do
-         table.insert(result_lines, description_margin .. description_line)
-      end
-   else
-      for i = 1, math.max(#label_lines, #description_lines) do
-         local label_line = label_lines[i]
-         local description_line = description_lines[i]
-
-         local line = ""
-
-         if label_line then
-            line = usage_margin .. label_line
-         end
-
-         if description_line and description_line ~= "" then
-            line = line .. (" "):rep(description_margin_len - #line) .. description_line
-         end
-
-         table.insert(result_lines, line)
-      end
-   end
-
-   return table.concat(result_lines, "\n")
-end
-
-local function get_group_types(group)
-   local types = {}
-
-   for _, element in ipairs(group) do
-      types[getmetatable(element)] = true
-   end
-
-   return types
-end
-
-function Parser:_add_group_help(blocks, added_elements, label, elements)
-   local buf = {label}
-
-   for _, element in ipairs(elements) do
-      if not element._hidden and not added_elements[element] then
-         added_elements[element] = true
-         table.insert(buf, self:_get_element_help(element))
-      end
-   end
-
-   if #buf > 1 then
-      table.insert(blocks, table.concat(buf, ("\n"):rep(self:_inherit_property("help_vertical_space", 0) + 1)))
-   end
-end
-
-function Parser:get_help()
-   if self._help then
-      return self._help
-   end
-
-   local blocks = {self:get_usage()}
-
-   local help_max_width = self:_inherit_property("help_max_width")
-
-   if self._description then
-      local description = self._description
-
-      if help_max_width then
-         description = table.concat(autowrap(split_lines(description), help_max_width), "\n")
-      end
-
-      table.insert(blocks, description)
-   end
-
-   -- 1. Put groups containing arguments first, then other arguments.
-   -- 2. Put remaining groups containing options, then other options.
-   -- 3. Put remaining groups containing commands, then other commands.
-   -- Assume that an element can't be in several groups.
-   local groups_by_type = {
-      [Argument] = {},
-      [Option] = {},
-      [Command] = {}
-   }
-
-   for _, group in ipairs(self._groups) do
-      local group_types = get_group_types(group)
-
-      for _, mt in ipairs({Argument, Option, Command}) do
-         if group_types[mt] then
-            table.insert(groups_by_type[mt], group)
-            break
-         end
-      end
-   end
-
-   local default_groups = {
-      {name = "Arguments", type = Argument, elements = self._arguments},
-      {name = "Options", type = Option, elements = self._options},
-      {name = "Commands", type = Command, elements = self._commands}
-   }
-
-   local added_elements = {}
-
-   for _, default_group in ipairs(default_groups) do
-      local type_groups = groups_by_type[default_group.type]
-
-      for _, group in ipairs(type_groups) do
-         self:_add_group_help(blocks, added_elements, group.name .. ":", group)
-      end
-
-      local default_label = default_group.name .. ":"
-
-      if #type_groups > 0 then
-         default_label = "Other " .. default_label:gsub("^.", string.lower)
-      end
-
-      self:_add_group_help(blocks, added_elements, default_label, default_group.elements)
-   end
-
-   if self._epilog then
-      local epilog = self._epilog
-
-      if help_max_width then
-         epilog = table.concat(autowrap(split_lines(epilog), help_max_width), "\n")
-      end
-
-      table.insert(blocks, epilog)
-   end
-
-   return table.concat(blocks, "\n\n")
-end
-
-function Parser:add_help_command(value)
-   if value then
-      assert(type(value) == "string" or type(value) == "table",
-         ("bad argument #1 to 'add_help_command' (string or table expected, got %s)"):format(type(value)))
-   end
-
-   local help = self:command()
-      :description "Show help for commands."
-   help:argument "command"
-      :description "The command to show help for."
-      :args "?"
-      :action(function(_, _, cmd)
-         if not cmd then
-            print(self:get_help())
-            os.exit(0)
-         else
-            for _, command in ipairs(self._commands) do
-               for _, alias in ipairs(command._aliases) do
-                  if alias == cmd then
-                     print(command:get_help())
-                     os.exit(0)
-                  end
-               end
-            end
-         end
-         help:error(("unknown command '%s'"):format(cmd))
-      end)
-
-   if value then
-      help = help(value)
-   end
-
-   if not help._name then
-      help "help"
-   end
-
-   help._is_help_command = true
-   return self
-end
-
-function Parser:_is_shell_safe()
-   if self._basename then
-      if self._basename:find("[^%w_%-%+%.]") then
-         return false
-      end
-   else
-      for _, alias in ipairs(self._aliases) do
-         if alias:find("[^%w_%-%+%.]") then
-            return false
-         end
-      end
-   end
-   for _, option in ipairs(self._options) do
-      for _, alias in ipairs(option._aliases) do
-         if alias:find("[^%w_%-%+%.]") then
-            return false
-         end
-      end
-      if option._choices then
-         for _, choice in ipairs(option._choices) do
-            if choice:find("[%s'\"]") then
-               return false
-            end
-         end
-      end
-   end
-   for _, argument in ipairs(self._arguments) do
-      if argument._choices then
-         for _, choice in ipairs(argument._choices) do
-            if choice:find("[%s'\"]") then
-               return false
-            end
-         end
-      end
-   end
-   for _, command in ipairs(self._commands) do
-      if not command:_is_shell_safe() then
-         return false
-      end
-   end
-   return true
-end
-
-function Parser:add_complete(value)
-   if value then
-      assert(type(value) == "string" or type(value) == "table",
-         ("bad argument #1 to 'add_complete' (string or table expected, got %s)"):format(type(value)))
-   end
-
-   local complete = self:option()
-      :description "Output a shell completion script for the specified shell."
-      :args(1)
-      :choices {"bash", "zsh", "fish"}
-      :action(function(_, _, shell)
-         io.write(self["get_" .. shell .. "_complete"](self))
-         os.exit(0)
-      end)
-
-   if value then
-      complete = complete(value)
-   end
-
-   if not complete._name then
-      complete "--completion"
-   end
-
-   return self
-end
-
-function Parser:add_complete_command(value)
-   if value then
-      assert(type(value) == "string" or type(value) == "table",
-         ("bad argument #1 to 'add_complete_command' (string or table expected, got %s)"):format(type(value)))
-   end
-
-   local complete = self:command()
-      :description "Output a shell completion script."
-   complete:argument "shell"
-      :description "The shell to output a completion script for."
-      :choices {"bash", "zsh", "fish"}
-      :action(function(_, _, shell)
-         io.write(self["get_" .. shell .. "_complete"](self))
-         os.exit(0)
-      end)
-
-   if value then
-      complete = complete(value)
-   end
-
-   if not complete._name then
-      complete "completion"
-   end
-
-   return self
-end
-
-local function base_name(pathname)
-   return pathname:gsub("[/\\]*$", ""):match(".*[/\\]([^/\\]*)") or pathname
-end
-
-local function get_short_description(element)
-   local short = element:_get_description():match("^(.-)%.%s")
-   return short or element:_get_description():match("^(.-)%.?$")
-end
-
-function Parser:_get_options()
-   local options = {}
-   for _, option in ipairs(self._options) do
-      for _, alias in ipairs(option._aliases) do
-         table.insert(options, alias)
-      end
-   end
-   return table.concat(options, " ")
-end
-
-function Parser:_get_commands()
-   local commands = {}
-   for _, command in ipairs(self._commands) do
-      for _, alias in ipairs(command._aliases) do
-         table.insert(commands, alias)
-      end
-   end
-   return table.concat(commands, " ")
-end
-
-function Parser:_bash_option_args(buf, indent)
-   local opts = {}
-   for _, option in ipairs(self._options) do
-      if option._choices or option._minargs > 0 then
-         local compreply
-         if option._choices then
-            compreply = 'COMPREPLY=($(compgen -W "' .. table.concat(option._choices, " ") .. '" -- "$cur"))'
-         else
-            compreply = 'COMPREPLY=($(compgen -f -- "$cur"))'
-         end
-         table.insert(opts, (" "):rep(indent + 4) .. table.concat(option._aliases, "|") .. ")")
-         table.insert(opts, (" "):rep(indent + 8) .. compreply)
-         table.insert(opts, (" "):rep(indent + 8) .. "return 0")
-         table.insert(opts, (" "):rep(indent + 8) .. ";;")
-      end
-   end
-
-   if #opts > 0 then
-      table.insert(buf, (" "):rep(indent) .. 'case "$prev" in')
-      table.insert(buf, table.concat(opts, "\n"))
-      table.insert(buf, (" "):rep(indent) .. "esac\n")
-   end
-end
-
-function Parser:_bash_get_cmd(buf, indent)
-   if #self._commands == 0 then
-      return
-   end
-
-   table.insert(buf, (" "):rep(indent) .. 'args=("${args[@]:1}")')
-   table.insert(buf, (" "):rep(indent) .. 'for arg in "${args[@]}"; do')
-   table.insert(buf, (" "):rep(indent + 4) .. 'case "$arg" in')
-
-   for _, command in ipairs(self._commands) do
-      table.insert(buf, (" "):rep(indent + 8) .. table.concat(command._aliases, "|") .. ")")
-      if self._parent then
-         table.insert(buf, (" "):rep(indent + 12) .. 'cmd="$cmd ' .. command._name .. '"')
-      else
-         table.insert(buf, (" "):rep(indent + 12) .. 'cmd="' .. command._name .. '"')
-      end
-      table.insert(buf, (" "):rep(indent + 12) .. 'opts="$opts ' .. command:_get_options() .. '"')
-      command:_bash_get_cmd(buf, indent + 12)
-      table.insert(buf, (" "):rep(indent + 12) .. "break")
-      table.insert(buf, (" "):rep(indent + 12) .. ";;")
-   end
-
-   table.insert(buf, (" "):rep(indent + 4) .. "esac")
-   table.insert(buf, (" "):rep(indent) .. "done")
-end
-
-function Parser:_bash_cmd_completions(buf)
-   local cmd_buf = {}
-   if self._parent then
-      self:_bash_option_args(cmd_buf, 12)
-   end
-   if #self._commands > 0 then
-      table.insert(cmd_buf, (" "):rep(12) .. 'COMPREPLY=($(compgen -W "' .. self:_get_commands() .. '" -- "$cur"))')
-   elseif self._is_help_command then
-      table.insert(cmd_buf, (" "):rep(12)
-         .. 'COMPREPLY=($(compgen -W "'
-         .. self._parent:_get_commands()
-         .. '" -- "$cur"))')
-   end
-   if #cmd_buf > 0 then
-      table.insert(buf, (" "):rep(8) .. "'" .. self:_get_fullname(true) .. "')")
-      table.insert(buf, table.concat(cmd_buf, "\n"))
-      table.insert(buf, (" "):rep(12) .. ";;")
-   end
-
-   for _, command in ipairs(self._commands) do
-      command:_bash_cmd_completions(buf)
-   end
-end
-
-function Parser:get_bash_complete()
-   self._basename = base_name(self._name)
-   assert(self:_is_shell_safe())
-   local buf = {([[
-_%s() {
-    local IFS=$' \t\n'
-    local args cur prev cmd opts arg
-    args=("${COMP_WORDS[@]}")
-    cur="${COMP_WORDS[COMP_CWORD]}"
-    prev="${COMP_WORDS[COMP_CWORD-1]}"
-    opts="%s"
-]]):format(self._basename, self:_get_options())}
-
-   self:_bash_option_args(buf, 4)
-   self:_bash_get_cmd(buf, 4)
-   if #self._commands > 0 then
-      table.insert(buf, "")
-      table.insert(buf, (" "):rep(4) .. 'case "$cmd" in')
-      self:_bash_cmd_completions(buf)
-      table.insert(buf, (" "):rep(4) .. "esac\n")
-   end
-
-   table.insert(buf, ([=[
-    if [[ "$cur" = -* ]]; then
-        COMPREPLY=($(compgen -W "$opts" -- "$cur"))
-    fi
-}
-
-complete -F _%s -o bashdefault -o default %s
-]=]):format(self._basename, self._basename))
-
-   return table.concat(buf, "\n")
-end
-
-function Parser:_zsh_arguments(buf, cmd_name, indent)
-   if self._parent then
-      table.insert(buf, (" "):rep(indent) .. "options=(")
-      table.insert(buf, (" "):rep(indent + 2) .. "$options")
-   else
-      table.insert(buf, (" "):rep(indent) .. "local -a options=(")
-   end
-
-   for _, option in ipairs(self._options) do
-      local line = {}
-      if #option._aliases > 1 then
-         if option._maxcount > 1 then
-            table.insert(line, '"*"')
-         end
-         table.insert(line, "{" .. table.concat(option._aliases, ",") .. '}"')
-      else
-         table.insert(line, '"')
-         if option._maxcount > 1 then
-            table.insert(line, "*")
-         end
-         table.insert(line, option._name)
-      end
-      if option._description then
-         local description = get_short_description(option):gsub('["%]:`$]', "\\%0")
-         table.insert(line, "[" .. description .. "]")
-      end
-      if option._maxargs == math.huge then
-         table.insert(line, ":*")
-      end
-      if option._choices then
-         table.insert(line, ": :(" .. table.concat(option._choices, " ") .. ")")
-      elseif option._maxargs > 0 then
-         table.insert(line, ": :_files")
-      end
-      table.insert(line, '"')
-      table.insert(buf, (" "):rep(indent + 2) .. table.concat(line))
-   end
-
-   table.insert(buf, (" "):rep(indent) .. ")")
-   table.insert(buf, (" "):rep(indent) .. "_arguments -s -S \\")
-   table.insert(buf, (" "):rep(indent + 2) .. "$options \\")
-
-   if self._is_help_command then
-      table.insert(buf, (" "):rep(indent + 2) .. '": :(' .. self._parent:_get_commands() .. ')" \\')
-   else
-      for _, argument in ipairs(self._arguments) do
-         local spec
-         if argument._choices then
-            spec = ": :(" .. table.concat(argument._choices, " ") .. ")"
-         else
-            spec = ": :_files"
-         end
-         if argument._maxargs == math.huge then
-            table.insert(buf, (" "):rep(indent + 2) .. '"*' .. spec .. '" \\')
-            break
-         end
-         for _ = 1, argument._maxargs do
-            table.insert(buf, (" "):rep(indent + 2) .. '"' .. spec .. '" \\')
-         end
-      end
-
-      if #self._commands > 0 then
-         table.insert(buf, (" "):rep(indent + 2) .. '": :_' .. cmd_name .. '_cmds" \\')
-         table.insert(buf, (" "):rep(indent + 2) .. '"*:: :->args" \\')
-      end
-   end
-
-   table.insert(buf, (" "):rep(indent + 2) .. "&& return 0")
-end
-
-function Parser:_zsh_cmds(buf, cmd_name)
-   table.insert(buf, "\n_" .. cmd_name .. "_cmds() {")
-   table.insert(buf, "  local -a commands=(")
-
-   for _, command in ipairs(self._commands) do
-      local line = {}
-      if #command._aliases > 1 then
-         table.insert(line, "{" .. table.concat(command._aliases, ",") .. '}"')
-      else
-         table.insert(line, '"' .. command._name)
-      end
-      if command._description then
-         table.insert(line, ":" .. get_short_description(command):gsub('["`$]', "\\%0"))
-      end
-      table.insert(buf, "    " .. table.concat(line) .. '"')
-   end
-
-   table.insert(buf, '  )\n  _describe "command" commands\n}')
-end
-
-function Parser:_zsh_complete_help(buf, cmds_buf, cmd_name, indent)
-   if #self._commands == 0 then
-      return
-   end
-
-   self:_zsh_cmds(cmds_buf, cmd_name)
-   table.insert(buf, "\n" .. (" "):rep(indent) .. "case $words[1] in")
-
-   for _, command in ipairs(self._commands) do
-      local name = cmd_name .. "_" .. command._name
-      table.insert(buf, (" "):rep(indent + 2) .. table.concat(command._aliases, "|") .. ")")
-      command:_zsh_arguments(buf, name, indent + 4)
-      command:_zsh_complete_help(buf, cmds_buf, name, indent + 4)
-      table.insert(buf, (" "):rep(indent + 4) .. ";;\n")
-   end
-
-   table.insert(buf, (" "):rep(indent) .. "esac")
-end
-
-function Parser:get_zsh_complete()
-   self._basename = base_name(self._name)
-   assert(self:_is_shell_safe())
-   local buf = {("#compdef %s\n"):format(self._basename)}
-   local cmds_buf = {}
-   table.insert(buf, "_" .. self._basename .. "() {")
-   if #self._commands > 0 then
-      table.insert(buf, "  local context state state_descr line")
-      table.insert(buf, "  typeset -A opt_args\n")
-   end
-   self:_zsh_arguments(buf, self._basename, 2)
-   self:_zsh_complete_help(buf, cmds_buf, self._basename, 2)
-   table.insert(buf, "\n  return 1")
-   table.insert(buf, "}")
-
-   local result = table.concat(buf, "\n")
-   if #cmds_buf > 0 then
-      result = result .. "\n" .. table.concat(cmds_buf, "\n")
-   end
-   return result .. "\n\n_" .. self._basename .. "\n"
-end
-
-local function fish_escape(string)
-   return string:gsub("[\\']", "\\%0")
-end
-
-function Parser:_fish_get_cmd(buf, indent)
-   if #self._commands == 0 then
-      return
-   end
-
-   table.insert(buf, (" "):rep(indent) .. "set -e cmdline[1]")
-   table.insert(buf, (" "):rep(indent) .. "for arg in $cmdline")
-   table.insert(buf, (" "):rep(indent + 4) .. "switch $arg")
-
-   for _, command in ipairs(self._commands) do
-      table.insert(buf, (" "):rep(indent + 8) .. "case " .. table.concat(command._aliases, " "))
-      table.insert(buf, (" "):rep(indent + 12) .. "set cmd $cmd " .. command._name)
-      command:_fish_get_cmd(buf, indent + 12)
-      table.insert(buf, (" "):rep(indent + 12) .. "break")
-   end
-
-   table.insert(buf, (" "):rep(indent + 4) .. "end")
-   table.insert(buf, (" "):rep(indent) .. "end")
-end
-
-function Parser:_fish_complete_help(buf, basename)
-   local prefix = "complete -c " .. basename
-   table.insert(buf, "")
-
-   for _, command in ipairs(self._commands) do
-      local aliases = table.concat(command._aliases, " ")
-      local line
-      if self._parent then
-         line = ("%s -n '__fish_%s_using_command %s' -xa '%s'")
-            :format(prefix, basename, self:_get_fullname(true), aliases)
-      else
-         line = ("%s -n '__fish_%s_using_command' -xa '%s'"):format(prefix, basename, aliases)
-      end
-      if command._description then
-         line = ("%s -d '%s'"):format(line, fish_escape(get_short_description(command)))
-      end
-      table.insert(buf, line)
-   end
-
-   if self._is_help_command then
-      local line = ("%s -n '__fish_%s_using_command %s' -xa '%s'")
-         :format(prefix, basename, self:_get_fullname(true), self._parent:_get_commands())
-      table.insert(buf, line)
-   end
-
-   for _, option in ipairs(self._options) do
-      local parts = {prefix}
-
-      if self._parent then
-         table.insert(parts, "-n '__fish_" .. basename .. "_seen_command " .. self:_get_fullname(true) .. "'")
-      end
-
-      for _, alias in ipairs(option._aliases) do
-         if alias:match("^%-.$") then
-            table.insert(parts, "-s " .. alias:sub(2))
-         elseif alias:match("^%-%-.+") then
-            table.insert(parts, "-l " .. alias:sub(3))
-         end
-      end
-
-      if option._choices then
-         table.insert(parts, "-xa '" .. table.concat(option._choices, " ") .. "'")
-      elseif option._minargs > 0 then
-         table.insert(parts, "-r")
-      end
-
-      if option._description then
-         table.insert(parts, "-d '" .. fish_escape(get_short_description(option)) .. "'")
-      end
-
-      table.insert(buf, table.concat(parts, " "))
-   end
-
-   for _, command in ipairs(self._commands) do
-      command:_fish_complete_help(buf, basename)
-   end
-end
-
-function Parser:get_fish_complete()
-   self._basename = base_name(self._name)
-   assert(self:_is_shell_safe())
-   local buf = {}
-
-   if #self._commands > 0 then
-      table.insert(buf, ([[
-function __fish_%s_print_command
-    set -l cmdline (commandline -poc)
-    set -l cmd]]):format(self._basename))
-      self:_fish_get_cmd(buf, 4)
-      table.insert(buf, ([[
-    echo "$cmd"
-end
-
-function __fish_%s_using_command
-    test (__fish_%s_print_command) = "$argv"
-    and return 0
-    or return 1
-end
-
-function __fish_%s_seen_command
-    string match -q "$argv*" (__fish_%s_print_command)
-    and return 0
-    or return 1
-end]]):format(self._basename, self._basename, self._basename, self._basename))
-   end
-
-   self:_fish_complete_help(buf, self._basename)
-   return table.concat(buf, "\n") .. "\n"
-end
-
-local function get_tip(context, wrong_name)
-   local context_pool = {}
-   local possible_name
-   local possible_names = {}
-
-   for name in pairs(context) do
-      if type(name) == "string" then
-         for i = 1, #name do
-            possible_name = name:sub(1, i - 1) .. name:sub(i + 1)
-
-            if not context_pool[possible_name] then
-               context_pool[possible_name] = {}
-            end
-
-            table.insert(context_pool[possible_name], name)
-         end
-      end
-   end
-
-   for i = 1, #wrong_name + 1 do
-      possible_name = wrong_name:sub(1, i - 1) .. wrong_name:sub(i + 1)
-
-      if context[possible_name] then
-         possible_names[possible_name] = true
-      elseif context_pool[possible_name] then
-         for _, name in ipairs(context_pool[possible_name]) do
-            possible_names[name] = true
-         end
-      end
-   end
-
-   local first = next(possible_names)
-
-   if first then
-      if next(possible_names, first) then
-         local possible_names_arr = {}
-
-         for name in pairs(possible_names) do
-            table.insert(possible_names_arr, "'" .. name .. "'")
-         end
-
-         table.sort(possible_names_arr)
-         return "\nDid you mean one of these: " .. table.concat(possible_names_arr, " ") .. "?"
-      else
-         return "\nDid you mean '" .. first .. "'?"
-      end
-   else
-      return ""
-   end
-end
-
-local ElementState = class({
-   invocations = 0
-})
-
-function ElementState:__call(state, element)
-   self.state = state
-   self.result = state.result
-   self.element = element
-   self.target = element._target or element:_get_default_target()
-   self.action, self.result[self.target] = element:_get_action()
-   return self
-end
-
-function ElementState:error(fmt, ...)
-   self.state:error(fmt, ...)
-end
-
-function ElementState:convert(argument, index)
-   local converter = self.element._convert
-
-   if converter then
-      local ok, err
-
-      if type(converter) == "function" then
-         ok, err = converter(argument)
-      elseif type(converter[index]) == "function" then
-         ok, err = converter[index](argument)
-      else
-         ok = converter[argument]
-      end
-
-      if ok == nil then
-         self:error(err and "%s" or "malformed argument '%s'", err or argument)
-      end
-
-      argument = ok
-   end
-
-   return argument
-end
-
-function ElementState:default(mode)
-   return self.element._defmode:find(mode) and self.element._default
-end
-
-local function bound(noun, min, max, is_max)
-   local res = ""
-
-   if min ~= max then
-      res = "at " .. (is_max and "most" or "least") .. " "
-   end
-
-   local number = is_max and max or min
-   return res .. tostring(number) .. " " .. noun ..  (number == 1 and "" or "s")
-end
-
-function ElementState:set_name(alias)
-   self.name = ("%s '%s'"):format(alias and "option" or "argument", alias or self.element._name)
-end
-
-function ElementState:invoke()
-   self.open = true
-   self.overwrite = false
-
-   if self.invocations >= self.element._maxcount then
-      if self.element._overwrite then
-         self.overwrite = true
-      else
-         local num_times_repr = bound("time", self.element._mincount, self.element._maxcount, true)
-         self:error("%s must be used %s", self.name, num_times_repr)
-      end
-   else
-      self.invocations = self.invocations + 1
-   end
-
-   self.args = {}
-
-   if self.element._maxargs <= 0 then
-      self:close()
-   end
-
-   return self.open
-end
-
-function ElementState:check_choices(argument)
-   if self.element._choices then
-      for _, choice in ipairs(self.element._choices) do
-         if argument == choice then
-            return
-         end
-      end
-      local choices_list = "'" .. table.concat(self.element._choices, "', '") .. "'"
-      local is_option = getmetatable(self.element) == Option
-      self:error("%s%s must be one of %s", is_option and "argument for " or "", self.name, choices_list)
-   end
-end
-
-function ElementState:pass(argument)
-   self:check_choices(argument)
-   argument = self:convert(argument, #self.args + 1)
-   table.insert(self.args, argument)
-
-   if #self.args >= self.element._maxargs then
-      self:close()
-   end
-
-   return self.open
-end
-
-function ElementState:complete_invocation()
-   while #self.args < self.element._minargs do
-      self:pass(self.element._default)
-   end
-end
-
-function ElementState:close()
-   if self.open then
-      self.open = false
-
-      if #self.args < self.element._minargs then
-         if self:default("a") then
-            self:complete_invocation()
-         else
-            if #self.args == 0 then
-               if getmetatable(self.element) == Argument then
-                  self:error("missing %s", self.name)
-               elseif self.element._maxargs == 1 then
-                  self:error("%s requires an argument", self.name)
-               end
-            end
-
-            self:error("%s requires %s", self.name, bound("argument", self.element._minargs, self.element._maxargs))
-         end
-      end
-
-      local args
-
-      if self.element._maxargs == 0 then
-         args = self.args[1]
-      elseif self.element._maxargs == 1 then
-         if self.element._minargs == 0 and self.element._mincount ~= self.element._maxcount then
-            args = self.args
-         else
-            args = self.args[1]
-         end
-      else
-         args = self.args
-      end
-
-      self.action(self.result, self.target, args, self.overwrite)
-   end
-end
-
-local ParseState = class({
-   result = {},
-   options = {},
-   arguments = {},
-   argument_i = 1,
-   element_to_mutexes = {},
-   mutex_to_element_state = {},
-   command_actions = {}
-})
-
-function ParseState:__call(parser, error_handler)
-   self.parser = parser
-   self.error_handler = error_handler
-   self.charset = parser:_update_charset()
-   self:switch(parser)
-   return self
-end
-
-function ParseState:error(fmt, ...)
-   self.error_handler(self.parser, fmt:format(...))
-end
-
-function ParseState:switch(parser)
-   self.parser = parser
-
-   if parser._action then
-      table.insert(self.command_actions, {action = parser._action, name = parser._name})
-   end
-
-   for _, option in ipairs(parser._options) do
-      option = ElementState(self, option)
-      table.insert(self.options, option)
-
-      for _, alias in ipairs(option.element._aliases) do
-         self.options[alias] = option
-      end
-   end
-
-   for _, mutex in ipairs(parser._mutexes) do
-      for _, element in ipairs(mutex) do
-         if not self.element_to_mutexes[element] then
-            self.element_to_mutexes[element] = {}
-         end
-
-         table.insert(self.element_to_mutexes[element], mutex)
-      end
-   end
-
-   for _, argument in ipairs(parser._arguments) do
-      argument = ElementState(self, argument)
-      table.insert(self.arguments, argument)
-      argument:set_name()
-      argument:invoke()
-   end
-
-   self.handle_options = parser._handle_options
-   self.argument = self.arguments[self.argument_i]
-   self.commands = parser._commands
-
-   for _, command in ipairs(self.commands) do
-      for _, alias in ipairs(command._aliases) do
-         self.commands[alias] = command
-      end
-   end
-end
-
-function ParseState:get_option(name)
-   local option = self.options[name]
-
-   if not option then
-      self:error("unknown option '%s'%s", name, get_tip(self.options, name))
-   else
-      return option
-   end
-end
-
-function ParseState:get_command(name)
-   local command = self.commands[name]
-
-   if not command then
-      if #self.commands > 0 then
-         self:error("unknown command '%s'%s", name, get_tip(self.commands, name))
-      else
-         self:error("too many arguments")
-      end
-   else
-      return command
-   end
-end
-
-function ParseState:check_mutexes(element_state)
-   if self.element_to_mutexes[element_state.element] then
-      for _, mutex in ipairs(self.element_to_mutexes[element_state.element]) do
-         local used_element_state = self.mutex_to_element_state[mutex]
-
-         if used_element_state and used_element_state ~= element_state then
-            self:error("%s can not be used together with %s", element_state.name, used_element_state.name)
-         else
-            self.mutex_to_element_state[mutex] = element_state
-         end
-      end
-   end
-end
-
-function ParseState:invoke(option, name)
-   self:close()
-   option:set_name(name)
-   self:check_mutexes(option, name)
-
-   if option:invoke() then
-      self.option = option
-   end
-end
-
-function ParseState:pass(arg)
-   if self.option then
-      if not self.option:pass(arg) then
-         self.option = nil
-      end
-   elseif self.argument then
-      self:check_mutexes(self.argument)
-
-      if not self.argument:pass(arg) then
-         self.argument_i = self.argument_i + 1
-         self.argument = self.arguments[self.argument_i]
-      end
-   else
-      local command = self:get_command(arg)
-      self.result[command._target or command._name] = true
-
-      if self.parser._command_target then
-         self.result[self.parser._command_target] = command._name
-      end
-
-      self:switch(command)
-   end
-end
-
-function ParseState:close()
-   if self.option then
-      self.option:close()
-      self.option = nil
-   end
-end
-
-function ParseState:finalize()
-   self:close()
-
-   for i = self.argument_i, #self.arguments do
-      local argument = self.arguments[i]
-      if #argument.args == 0 and argument:default("u") then
-         argument:complete_invocation()
-      else
-         argument:close()
-      end
-   end
-
-   if self.parser._require_command and #self.commands > 0 then
-      self:error("a command is required")
-   end
-
-   for _, option in ipairs(self.options) do
-      option.name = option.name or ("option '%s'"):format(option.element._name)
-
-      if option.invocations == 0 then
-         if option:default("u") then
-            option:invoke()
-            option:complete_invocation()
-            option:close()
-         end
-      end
-
-      local mincount = option.element._mincount
-
-      if option.invocations < mincount then
-         if option:default("a") then
-            while option.invocations < mincount do
-               option:invoke()
-               option:close()
-            end
-         elseif option.invocations == 0 then
-            self:error("missing %s", option.name)
-         else
-            self:error("%s must be used %s", option.name, bound("time", mincount, option.element._maxcount))
-         end
-      end
-   end
-
-   for i = #self.command_actions, 1, -1 do
-      self.command_actions[i].action(self.result, self.command_actions[i].name)
-   end
-end
-
-function ParseState:parse(args)
-   for _, arg in ipairs(args) do
-      local plain = true
-
-      if self.handle_options then
-         local first = arg:sub(1, 1)
-
-         if self.charset[first] then
-            if #arg > 1 then
-               plain = false
-
-               if arg:sub(2, 2) == first then
-                  if #arg == 2 then
-                     if self.options[arg] then
-                        local option = self:get_option(arg)
-                        self:invoke(option, arg)
-                     else
-                        self:close()
-                     end
-
-                     self.handle_options = false
-                  else
-                     local equals = arg:find "="
-                     if equals then
-                        local name = arg:sub(1, equals - 1)
-                        local option = self:get_option(name)
-
-                        if option.element._maxargs <= 0 then
-                           self:error("option '%s' does not take arguments", name)
-                        end
-
-                        self:invoke(option, name)
-                        self:pass(arg:sub(equals + 1))
-                     else
-                        local option = self:get_option(arg)
-                        self:invoke(option, arg)
-                     end
-                  end
-               else
-                  for i = 2, #arg do
-                     local name = first .. arg:sub(i, i)
-                     local option = self:get_option(name)
-                     self:invoke(option, name)
-
-                     if i ~= #arg and option.element._maxargs > 0 then
-                        self:pass(arg:sub(i + 1))
-                        break
-                     end
-                  end
-               end
-            end
-         end
-      end
-
-      if plain then
-         self:pass(arg)
-      end
-   end
-
-   self:finalize()
-   return self.result
-end
-
-function Parser:error(msg)
-   io.stderr:write(("%s\n\nError: %s\n"):format(self:get_usage(), msg))
-   os.exit(1)
-end
-
--- Compatibility with strict.lua and other checkers:
-local default_cmdline = rawget(_G, "arg") or {}
-
-function Parser:_parse(args, error_handler)
-   return ParseState(self, error_handler):parse(args or default_cmdline)
-end
-
-function Parser:parse(args)
-   return self:_parse(args, self.error)
-end
-
-local function xpcall_error_handler(err)
-   if not debug then
-      return tostring(err)
-   end
-   return tostring(err) .. "\noriginal " .. debug.traceback("", 2):sub(2)
-end
-
-function Parser:pparse(args)
-   local parse_error
-
-   local ok, result = xpcall(function()
-      return self:_parse(args, function(_, err)
-         parse_error = err
-         error(err, 0)
-      end)
-   end, xpcall_error_handler)
-
-   if ok then
-      return true, result
-   elseif not parse_error then
-      error(result, 0)
-   else
-      return false, parse_error
-   end
-end
-
-local argparse = {}
-
-argparse.version = "0.7.0"
-
-setmetatable(argparse, {__call = function(_, ...)
-   return Parser(default_cmdline[0]):add_help(true)(...)
-end})
-
-return argparse
diff --git a/src/luarocks/cmd.lua b/src/luarocks/cmd.lua
index e8f05575..643023b8 100644
--- a/src/luarocks/cmd.lua
+++ b/src/luarocks/cmd.lua
@@ -9,7 +9,7 @@ local cfg = require("luarocks.core.cfg")
 local dir = require("luarocks.dir")
 local fun = require("luarocks.fun")
 local fs = require("luarocks.fs")
-local argparse = require("luarocks.argparse")
+local argparse = require("luarocks.vendor.argparse")
 
 local unpack = table.unpack or unpack
 local pack = table.pack or function(...) return { n = select("#", ...), ... } end
diff --git a/src/luarocks/vendor/argparse.lua b/src/luarocks/vendor/argparse.lua
new file mode 100644
index 00000000..2c2585dd
--- /dev/null
+++ b/src/luarocks/vendor/argparse.lua
@@ -0,0 +1,2103 @@
+-- The MIT License (MIT)
+
+-- Copyright (c) 2013 - 2018 Peter Melnichenko
+--                      2019 Paul Ouellette
+
+-- Permission is hereby granted, free of charge, to any person obtaining a copy of
+-- this software and associated documentation files (the "Software"), to deal in
+-- the Software without restriction, including without limitation the rights to
+-- use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+-- the Software, and to permit persons to whom the Software is furnished to do so,
+-- subject to the following conditions:
+
+-- The above copyright notice and this permission notice shall be included in all
+-- copies or substantial portions of the Software.
+
+-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+-- FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+-- COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+-- IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+-- CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+local function deep_update(t1, t2)
+   for k, v in pairs(t2) do
+      if type(v) == "table" then
+         v = deep_update({}, v)
+      end
+
+      t1[k] = v
+   end
+
+   return t1
+end
+
+-- A property is a tuple {name, callback}.
+-- properties.args is number of properties that can be set as arguments
+-- when calling an object.
+local function class(prototype, properties, parent)
+   -- Class is the metatable of its instances.
+   local cl = {}
+   cl.__index = cl
+
+   if parent then
+      cl.__prototype = deep_update(deep_update({}, parent.__prototype), prototype)
+   else
+      cl.__prototype = prototype
+   end
+
+   if properties then
+      local names = {}
+
+      -- Create setter methods and fill set of property names.
+      for _, property in ipairs(properties) do
+         local name, callback = property[1], property[2]
+
+         cl[name] = function(self, value)
+            if not callback(self, value) then
+               self["_" .. name] = value
+            end
+
+            return self
+         end
+
+         names[name] = true
+      end
+
+      function cl.__call(self, ...)
+         -- When calling an object, if the first argument is a table,
+         -- interpret keys as property names, else delegate arguments
+         -- to corresponding setters in order.
+         if type((...)) == "table" then
+            for name, value in pairs((...)) do
+               if names[name] then
+                  self[name](self, value)
+               end
+            end
+         else
+            local nargs = select("#", ...)
+
+            for i, property in ipairs(properties) do
+               if i > nargs or i > properties.args then
+                  break
+               end
+
+               local arg = select(i, ...)
+
+               if arg ~= nil then
+                  self[property[1]](self, arg)
+               end
+            end
+         end
+
+         return self
+      end
+   end
+
+   -- If indexing class fails, fallback to its parent.
+   local class_metatable = {}
+   class_metatable.__index = parent
+
+   function class_metatable.__call(self, ...)
+      -- Calling a class returns its instance.
+      -- Arguments are delegated to the instance.
+      local object = deep_update({}, self.__prototype)
+      setmetatable(object, self)
+      return object(...)
+   end
+
+   return setmetatable(cl, class_metatable)
+end
+
+local function typecheck(name, types, value)
+   for _, type_ in ipairs(types) do
+      if type(value) == type_ then
+         return true
+      end
+   end
+
+   error(("bad property '%s' (%s expected, got %s)"):format(name, table.concat(types, " or "), type(value)))
+end
+
+local function typechecked(name, ...)
+   local types = {...}
+   return {name, function(_, value) typecheck(name, types, value) end}
+end
+
+local multiname = {"name", function(self, value)
+   typecheck("name", {"string"}, value)
+
+   for alias in value:gmatch("%S+") do
+      self._name = self._name or alias
+      table.insert(self._aliases, alias)
+      table.insert(self._public_aliases, alias)
+      -- If alias contains '_', accept '-' also.
+      if alias:find("_", 1, true) then
+         table.insert(self._aliases, (alias:gsub("_", "-")))
+      end
+   end
+
+   -- Do not set _name as with other properties.
+   return true
+end}
+
+local multiname_hidden = {"hidden_name", function(self, value)
+   typecheck("hidden_name", {"string"}, value)
+
+   for alias in value:gmatch("%S+") do
+      table.insert(self._aliases, alias)
+      if alias:find("_", 1, true) then
+         table.insert(self._aliases, (alias:gsub("_", "-")))
+      end
+   end
+
+   return true
+end}
+
+local function parse_boundaries(str)
+   if tonumber(str) then
+      return tonumber(str), tonumber(str)
+   end
+
+   if str == "*" then
+      return 0, math.huge
+   end
+
+   if str == "+" then
+      return 1, math.huge
+   end
+
+   if str == "?" then
+      return 0, 1
+   end
+
+   if str:match "^%d+%-%d+$" then
+      local min, max = str:match "^(%d+)%-(%d+)$"
+      return tonumber(min), tonumber(max)
+   end
+
+   if str:match "^%d+%+$" then
+      local min = str:match "^(%d+)%+$"
+      return tonumber(min), math.huge
+   end
+end
+
+local function boundaries(name)
+   return {name, function(self, value)
+      typecheck(name, {"number", "string"}, value)
+
+      local min, max = parse_boundaries(value)
+
+      if not min then
+         error(("bad property '%s'"):format(name))
+      end
+
+      self["_min" .. name], self["_max" .. name] = min, max
+   end}
+end
+
+local actions = {}
+
+local option_action = {"action", function(_, value)
+   typecheck("action", {"function", "string"}, value)
+
+   if type(value) == "string" and not actions[value] then
+      error(("unknown action '%s'"):format(value))
+   end
+end}
+
+local option_init = {"init", function(self)
+   self._has_init = true
+end}
+
+local option_default = {"default", function(self, value)
+   if type(value) ~= "string" then
+      self._init = value
+      self._has_init = true
+      return true
+   end
+end}
+
+local add_help = {"add_help", function(self, value)
+   typecheck("add_help", {"boolean", "string", "table"}, value)
+
+   if self._help_option_idx then
+      table.remove(self._options, self._help_option_idx)
+      self._help_option_idx = nil
+   end
+
+   if value then
+      local help = self:flag()
+         :description "Show this help message and exit."
+         :action(function()
+            print(self:get_help())
+            os.exit(0)
+         end)
+
+      if value ~= true then
+         help = help(value)
+      end
+
+      if not help._name then
+         help "-h" "--help"
+      end
+
+      self._help_option_idx = #self._options
+   end
+end}
+
+local Parser = class({
+   _arguments = {},
+   _options = {},
+   _commands = {},
+   _mutexes = {},
+   _groups = {},
+   _require_command = true,
+   _handle_options = true
+}, {
+   args = 3,
+   typechecked("name", "string"),
+   typechecked("description", "string"),
+   typechecked("epilog", "string"),
+   typechecked("usage", "string"),
+   typechecked("help", "string"),
+   typechecked("require_command", "boolean"),
+   typechecked("handle_options", "boolean"),
+   typechecked("action", "function"),
+   typechecked("command_target", "string"),
+   typechecked("help_vertical_space", "number"),
+   typechecked("usage_margin", "number"),
+   typechecked("usage_max_width", "number"),
+   typechecked("help_usage_margin", "number"),
+   typechecked("help_description_margin", "number"),
+   typechecked("help_max_width", "number"),
+   add_help
+})
+
+local Command = class({
+   _aliases = {},
+   _public_aliases = {}
+}, {
+   args = 3,
+   multiname,
+   typechecked("description", "string"),
+   typechecked("epilog", "string"),
+   multiname_hidden,
+   typechecked("summary", "string"),
+   typechecked("target", "string"),
+   typechecked("usage", "string"),
+   typechecked("help", "string"),
+   typechecked("require_command", "boolean"),
+   typechecked("handle_options", "boolean"),
+   typechecked("action", "function"),
+   typechecked("command_target", "string"),
+   typechecked("help_vertical_space", "number"),
+   typechecked("usage_margin", "number"),
+   typechecked("usage_max_width", "number"),
+   typechecked("help_usage_margin", "number"),
+   typechecked("help_description_margin", "number"),
+   typechecked("help_max_width", "number"),
+   typechecked("hidden", "boolean"),
+   add_help
+}, Parser)
+
+local Argument = class({
+   _minargs = 1,
+   _maxargs = 1,
+   _mincount = 1,
+   _maxcount = 1,
+   _defmode = "unused",
+   _show_default = true
+}, {
+   args = 5,
+   typechecked("name", "string"),
+   typechecked("description", "string"),
+   option_default,
+   typechecked("convert", "function", "table"),
+   boundaries("args"),
+   typechecked("target", "string"),
+   typechecked("defmode", "string"),
+   typechecked("show_default", "boolean"),
+   typechecked("argname", "string", "table"),
+   typechecked("choices", "table"),
+   typechecked("hidden", "boolean"),
+   option_action,
+   option_init
+})
+
+local Option = class({
+   _aliases = {},
+   _public_aliases = {},
+   _mincount = 0,
+   _overwrite = true
+}, {
+   args = 6,
+   multiname,
+   typechecked("description", "string"),
+   option_default,
+   typechecked("convert", "function", "table"),
+   boundaries("args"),
+   boundaries("count"),
+   multiname_hidden,
+   typechecked("target", "string"),
+   typechecked("defmode", "string"),
+   typechecked("show_default", "boolean"),
+   typechecked("overwrite", "boolean"),
+   typechecked("argname", "string", "table"),
+   typechecked("choices", "table"),
+   typechecked("hidden", "boolean"),
+   option_action,
+   option_init
+}, Argument)
+
+function Parser:_inherit_property(name, default)
+   local element = self
+
+   while true do
+      local value = element["_" .. name]
+
+      if value ~= nil then
+         return value
+      end
+
+      if not element._parent then
+         return default
+      end
+
+      element = element._parent
+   end
+end
+
+function Argument:_get_argument_list()
+   local buf = {}
+   local i = 1
+
+   while i <= math.min(self._minargs, 3) do
+      local argname = self:_get_argname(i)
+
+      if self._default and self._defmode:find "a" then
+         argname = "[" .. argname .. "]"
+      end
+
+      table.insert(buf, argname)
+      i = i+1
+   end
+
+   while i <= math.min(self._maxargs, 3) do
+      table.insert(buf, "[" .. self:_get_argname(i) .. "]")
+      i = i+1
+
+      if self._maxargs == math.huge then
+         break
+      end
+   end
+
+   if i < self._maxargs then
+      table.insert(buf, "...")
+   end
+
+   return buf
+end
+
+function Argument:_get_usage()
+   local usage = table.concat(self:_get_argument_list(), " ")
+
+   if self._default and self._defmode:find "u" then
+      if self._maxargs > 1 or (self._minargs == 1 and not self._defmode:find "a") then
+         usage = "[" .. usage .. "]"
+      end
+   end
+
+   return usage
+end
+
+function actions.store_true(result, target)
+   result[target] = true
+end
+
+function actions.store_false(result, target)
+   result[target] = false
+end
+
+function actions.store(result, target, argument)
+   result[target] = argument
+end
+
+function actions.count(result, target, _, overwrite)
+   if not overwrite then
+      result[target] = result[target] + 1
+   end
+end
+
+function actions.append(result, target, argument, overwrite)
+   result[target] = result[target] or {}
+   table.insert(result[target], argument)
+
+   if overwrite then
+      table.remove(result[target], 1)
+   end
+end
+
+function actions.concat(result, target, arguments, overwrite)
+   if overwrite then
+      error("'concat' action can't handle too many invocations")
+   end
+
+   result[target] = result[target] or {}
+
+   for _, argument in ipairs(arguments) do
+      table.insert(result[target], argument)
+   end
+end
+
+function Argument:_get_action()
+   local action, init
+
+   if self._maxcount == 1 then
+      if self._maxargs == 0 then
+         action, init = "store_true", nil
+      else
+         action, init = "store", nil
+      end
+   else
+      if self._maxargs == 0 then
+         action, init = "count", 0
+      else
+         action, init = "append", {}
+      end
+   end
+
+   if self._action then
+      action = self._action
+   end
+
+   if self._has_init then
+      init = self._init
+   end
+
+   if type(action) == "string" then
+      action = actions[action]
+   end
+
+   return action, init
+end
+
+-- Returns placeholder for `narg`-th argument.
+function Argument:_get_argname(narg)
+   local argname = self._argname or self:_get_default_argname()
+
+   if type(argname) == "table" then
+      return argname[narg]
+   else
+      return argname
+   end
+end
+
+function Argument:_get_choices_list()
+   return "{" .. table.concat(self._choices, ",") .. "}"
+end
+
+function Argument:_get_default_argname()
+   if self._choices then
+      return self:_get_choices_list()
+   else
+      return "<" .. self._name .. ">"
+   end
+end
+
+function Option:_get_default_argname()
+   if self._choices then
+      return self:_get_choices_list()
+   else
+      return "<" .. self:_get_default_target() .. ">"
+   end
+end
+
+-- Returns labels to be shown in the help message.
+function Argument:_get_label_lines()
+   if self._choices then
+      return {self:_get_choices_list()}
+   else
+      return {self._name}
+   end
+end
+
+function Option:_get_label_lines()
+   local argument_list = self:_get_argument_list()
+
+   if #argument_list == 0 then
+      -- Don't put aliases for simple flags like `-h` on different lines.
+      return {table.concat(self._public_aliases, ", ")}
+   end
+
+   local longest_alias_length = -1
+
+   for _, alias in ipairs(self._public_aliases) do
+      longest_alias_length = math.max(longest_alias_length, #alias)
+   end
+
+   local argument_list_repr = table.concat(argument_list, " ")
+   local lines = {}
+
+   for i, alias in ipairs(self._public_aliases) do
+      local line = (" "):rep(longest_alias_length - #alias) .. alias .. " " .. argument_list_repr
+
+      if i ~= #self._public_aliases then
+         line = line .. ","
+      end
+
+      table.insert(lines, line)
+   end
+
+   return lines
+end
+
+function Command:_get_label_lines()
+   return {table.concat(self._public_aliases, ", ")}
+end
+
+function Argument:_get_description()
+   if self._default and self._show_default then
+      if self._description then
+         return ("%s (default: %s)"):format(self._description, self._default)
+      else
+         return ("default: %s"):format(self._default)
+      end
+   else
+      return self._description or ""
+   end
+end
+
+function Command:_get_description()
+   return self._summary or self._description or ""
+end
+
+function Option:_get_usage()
+   local usage = self:_get_argument_list()
+   table.insert(usage, 1, self._name)
+   usage = table.concat(usage, " ")
+
+   if self._mincount == 0 or self._default then
+      usage = "[" .. usage .. "]"
+   end
+
+   return usage
+end
+
+function Argument:_get_default_target()
+   return self._name
+end
+
+function Option:_get_default_target()
+   local res
+
+   for _, alias in ipairs(self._public_aliases) do
+      if alias:sub(1, 1) == alias:sub(2, 2) then
+         res = alias:sub(3)
+         break
+      end
+   end
+
+   res = res or self._name:sub(2)
+   return (res:gsub("-", "_"))
+end
+
+function Option:_is_vararg()
+   return self._maxargs ~= self._minargs
+end
+
+function Parser:_get_fullname(exclude_root)
+   local parent = self._parent
+   if exclude_root and not parent then
+      return ""
+   end
+   local buf = {self._name}
+
+   while parent do
+      if not exclude_root or parent._parent then
+         table.insert(buf, 1, parent._name)
+      end
+      parent = parent._parent
+   end
+
+   return table.concat(buf, " ")
+end
+
+function Parser:_update_charset(charset)
+   charset = charset or {}
+
+   for _, command in ipairs(self._commands) do
+      command:_update_charset(charset)
+   end
+
+   for _, option in ipairs(self._options) do
+      for _, alias in ipairs(option._aliases) do
+         charset[alias:sub(1, 1)] = true
+      end
+   end
+
+   return charset
+end
+
+function Parser:argument(...)
+   local argument = Argument(...)
+   table.insert(self._arguments, argument)
+   return argument
+end
+
+function Parser:option(...)
+   local option = Option(...)
+   table.insert(self._options, option)
+   return option
+end
+
+function Parser:flag(...)
+   return self:option():args(0)(...)
+end
+
+function Parser:command(...)
+   local command = Command():add_help(true)(...)
+   command._parent = self
+   table.insert(self._commands, command)
+   return command
+end
+
+function Parser:mutex(...)
+   local elements = {...}
+
+   for i, element in ipairs(elements) do
+      local mt = getmetatable(element)
+      assert(mt == Option or mt == Argument, ("bad argument #%d to 'mutex' (Option or Argument expected)"):format(i))
+   end
+
+   table.insert(self._mutexes, elements)
+   return self
+end
+
+function Parser:group(name, ...)
+   assert(type(name) == "string", ("bad argument #1 to 'group' (string expected, got %s)"):format(type(name)))
+
+   local group = {name = name, ...}
+
+   for i, element in ipairs(group) do
+      local mt = getmetatable(element)
+      assert(mt == Option or mt == Argument or mt == Command,
+         ("bad argument #%d to 'group' (Option or Argument or Command expected)"):format(i + 1))
+   end
+
+   table.insert(self._groups, group)
+   return self
+end
+
+local usage_welcome = "Usage: "
+
+function Parser:get_usage()
+   if self._usage then
+      return self._usage
+   end
+
+   local usage_margin = self:_inherit_property("usage_margin", #usage_welcome)
+   local max_usage_width = self:_inherit_property("usage_max_width", 70)
+   local lines = {usage_welcome .. self:_get_fullname()}
+
+   local function add(s)
+      if #lines[#lines]+1+#s <= max_usage_width then
+         lines[#lines] = lines[#lines] .. " " .. s
+      else
+         lines[#lines+1] = (" "):rep(usage_margin) .. s
+      end
+   end
+
+   -- Normally options are before positional arguments in usage messages.
+   -- However, vararg options should be after, because they can't be reliable used
+   -- before a positional argument.
+   -- Mutexes come into play, too, and are shown as soon as possible.
+   -- Overall, output usages in the following order:
+   -- 1. Mutexes that don't have positional arguments or vararg options.
+   -- 2. Options that are not in any mutexes and are not vararg.
+   -- 3. Positional arguments - on their own or as a part of a mutex.
+   -- 4. Remaining mutexes.
+   -- 5. Remaining options.
+
+   local elements_in_mutexes = {}
+   local added_elements = {}
+   local added_mutexes = {}
+   local argument_to_mutexes = {}
+
+   local function add_mutex(mutex, main_argument)
+      if added_mutexes[mutex] then
+         return
+      end
+
+      added_mutexes[mutex] = true
+      local buf = {}
+
+      for _, element in ipairs(mutex) do
+         if not element._hidden and not added_elements[element] then
+            if getmetatable(element) == Option or element == main_argument then
+               table.insert(buf, element:_get_usage())
+               added_elements[element] = true
+            end
+         end
+      end
+
+      if #buf == 1 then
+         add(buf[1])
+      elseif #buf > 1 then
+         add("(" .. table.concat(buf, " | ") .. ")")
+      end
+   end
+
+   local function add_element(element)
+      if not element._hidden and not added_elements[element] then
+         add(element:_get_usage())
+         added_elements[element] = true
+      end
+   end
+
+   for _, mutex in ipairs(self._mutexes) do
+      local is_vararg = false
+      local has_argument = false
+
+      for _, element in ipairs(mutex) do
+         if getmetatable(element) == Option then
+            if element:_is_vararg() then
+               is_vararg = true
+            end
+         else
+            has_argument = true
+            argument_to_mutexes[element] = argument_to_mutexes[element] or {}
+            table.insert(argument_to_mutexes[element], mutex)
+         end
+
+         elements_in_mutexes[element] = true
+      end
+
+      if not is_vararg and not has_argument then
+         add_mutex(mutex)
+      end
+   end
+
+   for _, option in ipairs(self._options) do
+      if not elements_in_mutexes[option] and not option:_is_vararg() then
+         add_element(option)
+      end
+   end
+
+   -- Add usages for positional arguments, together with one mutex containing them, if they are in a mutex.
+   for _, argument in ipairs(self._arguments) do
+      -- Pick a mutex as a part of which to show this argument, take the first one that's still available.
+      local mutex
+
+      if elements_in_mutexes[argument] then
+         for _, argument_mutex in ipairs(argument_to_mutexes[argument]) do
+            if not added_mutexes[argument_mutex] then
+               mutex = argument_mutex
+            end
+         end
+      end
+
+      if mutex then
+         add_mutex(mutex, argument)
+      else
+         add_element(argument)
+      end
+   end
+
+   for _, mutex in ipairs(self._mutexes) do
+      add_mutex(mutex)
+   end
+
+   for _, option in ipairs(self._options) do
+      add_element(option)
+   end
+
+   if #self._commands > 0 then
+      if self._require_command then
+         add("<command>")
+      else
+         add("[<command>]")
+      end
+
+      add("...")
+   end
+
+   return table.concat(lines, "\n")
+end
+
+local function split_lines(s)
+   if s == "" then
+      return {}
+   end
+
+   local lines = {}
+
+   if s:sub(-1) ~= "\n" then
+      s = s .. "\n"
+   end
+
+   for line in s:gmatch("([^\n]*)\n") do
+      table.insert(lines, line)
+   end
+
+   return lines
+end
+
+local function autowrap_line(line, max_length)
+   -- Algorithm for splitting lines is simple and greedy.
+   local result_lines = {}
+
+   -- Preserve original indentation of the line, put this at the beginning of each result line.
+   -- If the first word looks like a list marker ('*', '+', or '-'), add spaces so that starts
+   -- of the second and the following lines vertically align with the start of the second word.
+   local indentation = line:match("^ *")
+
+   if line:find("^ *[%*%+%-]") then
+      indentation = indentation .. " " .. line:match("^ *[%*%+%-]( *)")
+   end
+
+   -- Parts of the last line being assembled.
+   local line_parts = {}
+
+   -- Length of the current line.
+   local line_length = 0
+
+   -- Index of the next character to consider.
+   local index = 1
+
+   while true do
+      local word_start, word_finish, word = line:find("([^ ]+)", index)
+
+      if not word_start then
+         -- Ignore trailing spaces, if any.
+         break
+      end
+
+      local preceding_spaces = line:sub(index, word_start - 1)
+      index = word_finish + 1
+
+      if (#line_parts == 0) or (line_length + #preceding_spaces + #word <= max_length) then
+         -- Either this is the very first word or it fits as an addition to the current line, add it.
+         table.insert(line_parts, preceding_spaces) -- For the very first word this adds the indentation.
+         table.insert(line_parts, word)
+         line_length = line_length + #preceding_spaces + #word
+      else
+         -- Does not fit, finish current line and put the word into a new one.
+         table.insert(result_lines, table.concat(line_parts))
+         line_parts = {indentation, word}
+         line_length = #indentation + #word
+      end
+   end
+
+   if #line_parts > 0 then
+      table.insert(result_lines, table.concat(line_parts))
+   end
+
+   if #result_lines == 0 then
+      -- Preserve empty lines.
+      result_lines[1] = ""
+   end
+
+   return result_lines
+end
+
+-- Automatically wraps lines within given array,
+-- attempting to limit line length to `max_length`.
+-- Existing line splits are preserved.
+local function autowrap(lines, max_length)
+   local result_lines = {}
+
+   for _, line in ipairs(lines) do
+      local autowrapped_lines = autowrap_line(line, max_length)
+
+      for _, autowrapped_line in ipairs(autowrapped_lines) do
+         table.insert(result_lines, autowrapped_line)
+      end
+   end
+
+   return result_lines
+end
+
+function Parser:_get_element_help(element)
+   local label_lines = element:_get_label_lines()
+   local description_lines = split_lines(element:_get_description())
+
+   local result_lines = {}
+
+   -- All label lines should have the same length (except the last one, it has no comma).
+   -- If too long, start description after all the label lines.
+   -- Otherwise, combine label and description lines.
+
+   local usage_margin_len = self:_inherit_property("help_usage_margin", 3)
+   local usage_margin = (" "):rep(usage_margin_len)
+   local description_margin_len = self:_inherit_property("help_description_margin", 25)
+   local description_margin = (" "):rep(description_margin_len)
+
+   local help_max_width = self:_inherit_property("help_max_width")
+
+   if help_max_width then
+      local description_max_width = math.max(help_max_width - description_margin_len, 10)
+      description_lines = autowrap(description_lines, description_max_width)
+   end
+
+   if #label_lines[1] >= (description_margin_len - usage_margin_len) then
+      for _, label_line in ipairs(label_lines) do
+         table.insert(result_lines, usage_margin .. label_line)
+      end
+
+      for _, description_line in ipairs(description_lines) do
+         table.insert(result_lines, description_margin .. description_line)
+      end
+   else
+      for i = 1, math.max(#label_lines, #description_lines) do
+         local label_line = label_lines[i]
+         local description_line = description_lines[i]
+
+         local line = ""
+
+         if label_line then
+            line = usage_margin .. label_line
+         end
+
+         if description_line and description_line ~= "" then
+            line = line .. (" "):rep(description_margin_len - #line) .. description_line
+         end
+
+         table.insert(result_lines, line)
+      end
+   end
+
+   return table.concat(result_lines, "\n")
+end
+
+local function get_group_types(group)
+   local types = {}
+
+   for _, element in ipairs(group) do
+      types[getmetatable(element)] = true
+   end
+
+   return types
+end
+
+function Parser:_add_group_help(blocks, added_elements, label, elements)
+   local buf = {label}
+
+   for _, element in ipairs(elements) do
+      if not element._hidden and not added_elements[element] then
+         added_elements[element] = true
+         table.insert(buf, self:_get_element_help(element))
+      end
+   end
+
+   if #buf > 1 then
+      table.insert(blocks, table.concat(buf, ("\n"):rep(self:_inherit_property("help_vertical_space", 0) + 1)))
+   end
+end
+
+function Parser:get_help()
+   if self._help then
+      return self._help
+   end
+
+   local blocks = {self:get_usage()}
+
+   local help_max_width = self:_inherit_property("help_max_width")
+
+   if self._description then
+      local description = self._description
+
+      if help_max_width then
+         description = table.concat(autowrap(split_lines(description), help_max_width), "\n")
+      end
+
+      table.insert(blocks, description)
+   end
+
+   -- 1. Put groups containing arguments first, then other arguments.
+   -- 2. Put remaining groups containing options, then other options.
+   -- 3. Put remaining groups containing commands, then other commands.
+   -- Assume that an element can't be in several groups.
+   local groups_by_type = {
+      [Argument] = {},
+      [Option] = {},
+      [Command] = {}
+   }
+
+   for _, group in ipairs(self._groups) do
+      local group_types = get_group_types(group)
+
+      for _, mt in ipairs({Argument, Option, Command}) do
+         if group_types[mt] then
+            table.insert(groups_by_type[mt], group)
+            break
+         end
+      end
+   end
+
+   local default_groups = {
+      {name = "Arguments", type = Argument, elements = self._arguments},
+      {name = "Options", type = Option, elements = self._options},
+      {name = "Commands", type = Command, elements = self._commands}
+   }
+
+   local added_elements = {}
+
+   for _, default_group in ipairs(default_groups) do
+      local type_groups = groups_by_type[default_group.type]
+
+      for _, group in ipairs(type_groups) do
+         self:_add_group_help(blocks, added_elements, group.name .. ":", group)
+      end
+
+      local default_label = default_group.name .. ":"
+
+      if #type_groups > 0 then
+         default_label = "Other " .. default_label:gsub("^.", string.lower)
+      end
+
+      self:_add_group_help(blocks, added_elements, default_label, default_group.elements)
+   end
+
+   if self._epilog then
+      local epilog = self._epilog
+
+      if help_max_width then
+         epilog = table.concat(autowrap(split_lines(epilog), help_max_width), "\n")
+      end
+
+      table.insert(blocks, epilog)
+   end
+
+   return table.concat(blocks, "\n\n")
+end
+
+function Parser:add_help_command(value)
+   if value then
+      assert(type(value) == "string" or type(value) == "table",
+         ("bad argument #1 to 'add_help_command' (string or table expected, got %s)"):format(type(value)))
+   end
+
+   local help = self:command()
+      :description "Show help for commands."
+   help:argument "command"
+      :description "The command to show help for."
+      :args "?"
+      :action(function(_, _, cmd)
+         if not cmd then
+            print(self:get_help())
+            os.exit(0)
+         else
+            for _, command in ipairs(self._commands) do
+               for _, alias in ipairs(command._aliases) do
+                  if alias == cmd then
+                     print(command:get_help())
+                     os.exit(0)
+                  end
+               end
+            end
+         end
+         help:error(("unknown command '%s'"):format(cmd))
+      end)
+
+   if value then
+      help = help(value)
+   end
+
+   if not help._name then
+      help "help"
+   end
+
+   help._is_help_command = true
+   return self
+end
+
+function Parser:_is_shell_safe()
+   if self._basename then
+      if self._basename:find("[^%w_%-%+%.]") then
+         return false
+      end
+   else
+      for _, alias in ipairs(self._aliases) do
+         if alias:find("[^%w_%-%+%.]") then
+            return false
+         end
+      end
+   end
+   for _, option in ipairs(self._options) do
+      for _, alias in ipairs(option._aliases) do
+         if alias:find("[^%w_%-%+%.]") then
+            return false
+         end
+      end
+      if option._choices then
+         for _, choice in ipairs(option._choices) do
+            if choice:find("[%s'\"]") then
+               return false
+            end
+         end
+      end
+   end
+   for _, argument in ipairs(self._arguments) do
+      if argument._choices then
+         for _, choice in ipairs(argument._choices) do
+            if choice:find("[%s'\"]") then
+               return false
+            end
+         end
+      end
+   end
+   for _, command in ipairs(self._commands) do
+      if not command:_is_shell_safe() then
+         return false
+      end
+   end
+   return true
+end
+
+function Parser:add_complete(value)
+   if value then
+      assert(type(value) == "string" or type(value) == "table",
+         ("bad argument #1 to 'add_complete' (string or table expected, got %s)"):format(type(value)))
+   end
+
+   local complete = self:option()
+      :description "Output a shell completion script for the specified shell."
+      :args(1)
+      :choices {"bash", "zsh", "fish"}
+      :action(function(_, _, shell)
+         io.write(self["get_" .. shell .. "_complete"](self))
+         os.exit(0)
+      end)
+
+   if value then
+      complete = complete(value)
+   end
+
+   if not complete._name then
+      complete "--completion"
+   end
+
+   return self
+end
+
+function Parser:add_complete_command(value)
+   if value then
+      assert(type(value) == "string" or type(value) == "table",
+         ("bad argument #1 to 'add_complete_command' (string or table expected, got %s)"):format(type(value)))
+   end
+
+   local complete = self:command()
+      :description "Output a shell completion script."
+   complete:argument "shell"
+      :description "The shell to output a completion script for."
+      :choices {"bash", "zsh", "fish"}
+      :action(function(_, _, shell)
+         io.write(self["get_" .. shell .. "_complete"](self))
+         os.exit(0)
+      end)
+
+   if value then
+      complete = complete(value)
+   end
+
+   if not complete._name then
+      complete "completion"
+   end
+
+   return self
+end
+
+local function base_name(pathname)
+   return pathname:gsub("[/\\]*$", ""):match(".*[/\\]([^/\\]*)") or pathname
+end
+
+local function get_short_description(element)
+   local short = element:_get_description():match("^(.-)%.%s")
+   return short or element:_get_description():match("^(.-)%.?$")
+end
+
+function Parser:_get_options()
+   local options = {}
+   for _, option in ipairs(self._options) do
+      for _, alias in ipairs(option._aliases) do
+         table.insert(options, alias)
+      end
+   end
+   return table.concat(options, " ")
+end
+
+function Parser:_get_commands()
+   local commands = {}
+   for _, command in ipairs(self._commands) do
+      for _, alias in ipairs(command._aliases) do
+         table.insert(commands, alias)
+      end
+   end
+   return table.concat(commands, " ")
+end
+
+function Parser:_bash_option_args(buf, indent)
+   local opts = {}
+   for _, option in ipairs(self._options) do
+      if option._choices or option._minargs > 0 then
+         local compreply
+         if option._choices then
+            compreply = 'COMPREPLY=($(compgen -W "' .. table.concat(option._choices, " ") .. '" -- "$cur"))'
+         else
+            compreply = 'COMPREPLY=($(compgen -f -- "$cur"))'
+         end
+         table.insert(opts, (" "):rep(indent + 4) .. table.concat(option._aliases, "|") .. ")")
+         table.insert(opts, (" "):rep(indent + 8) .. compreply)
+         table.insert(opts, (" "):rep(indent + 8) .. "return 0")
+         table.insert(opts, (" "):rep(indent + 8) .. ";;")
+      end
+   end
+
+   if #opts > 0 then
+      table.insert(buf, (" "):rep(indent) .. 'case "$prev" in')
+      table.insert(buf, table.concat(opts, "\n"))
+      table.insert(buf, (" "):rep(indent) .. "esac\n")
+   end
+end
+
+function Parser:_bash_get_cmd(buf, indent)
+   if #self._commands == 0 then
+      return
+   end
+
+   table.insert(buf, (" "):rep(indent) .. 'args=("${args[@]:1}")')
+   table.insert(buf, (" "):rep(indent) .. 'for arg in "${args[@]}"; do')
+   table.insert(buf, (" "):rep(indent + 4) .. 'case "$arg" in')
+
+   for _, command in ipairs(self._commands) do
+      table.insert(buf, (" "):rep(indent + 8) .. table.concat(command._aliases, "|") .. ")")
+      if self._parent then
+         table.insert(buf, (" "):rep(indent + 12) .. 'cmd="$cmd ' .. command._name .. '"')
+      else
+         table.insert(buf, (" "):rep(indent + 12) .. 'cmd="' .. command._name .. '"')
+      end
+      table.insert(buf, (" "):rep(indent + 12) .. 'opts="$opts ' .. command:_get_options() .. '"')
+      command:_bash_get_cmd(buf, indent + 12)
+      table.insert(buf, (" "):rep(indent + 12) .. "break")
+      table.insert(buf, (" "):rep(indent + 12) .. ";;")
+   end
+
+   table.insert(buf, (" "):rep(indent + 4) .. "esac")
+   table.insert(buf, (" "):rep(indent) .. "done")
+end
+
+function Parser:_bash_cmd_completions(buf)
+   local cmd_buf = {}
+   if self._parent then
+      self:_bash_option_args(cmd_buf, 12)
+   end
+   if #self._commands > 0 then
+      table.insert(cmd_buf, (" "):rep(12) .. 'COMPREPLY=($(compgen -W "' .. self:_get_commands() .. '" -- "$cur"))')
+   elseif self._is_help_command then
+      table.insert(cmd_buf, (" "):rep(12)
+         .. 'COMPREPLY=($(compgen -W "'
+         .. self._parent:_get_commands()
+         .. '" -- "$cur"))')
+   end
+   if #cmd_buf > 0 then
+      table.insert(buf, (" "):rep(8) .. "'" .. self:_get_fullname(true) .. "')")
+      table.insert(buf, table.concat(cmd_buf, "\n"))
+      table.insert(buf, (" "):rep(12) .. ";;")
+   end
+
+   for _, command in ipairs(self._commands) do
+      command:_bash_cmd_completions(buf)
+   end
+end
+
+function Parser:get_bash_complete()
+   self._basename = base_name(self._name)
+   assert(self:_is_shell_safe())
+   local buf = {([[
+_%s() {
+    local IFS=$' \t\n'
+    local args cur prev cmd opts arg
+    args=("${COMP_WORDS[@]}")
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+    opts="%s"
+]]):format(self._basename, self:_get_options())}
+
+   self:_bash_option_args(buf, 4)
+   self:_bash_get_cmd(buf, 4)
+   if #self._commands > 0 then
+      table.insert(buf, "")
+      table.insert(buf, (" "):rep(4) .. 'case "$cmd" in')
+      self:_bash_cmd_completions(buf)
+      table.insert(buf, (" "):rep(4) .. "esac\n")
+   end
+
+   table.insert(buf, ([=[
+    if [[ "$cur" = -* ]]; then
+        COMPREPLY=($(compgen -W "$opts" -- "$cur"))
+    fi
+}
+
+complete -F _%s -o bashdefault -o default %s
+]=]):format(self._basename, self._basename))
+
+   return table.concat(buf, "\n")
+end
+
+function Parser:_zsh_arguments(buf, cmd_name, indent)
+   if self._parent then
+      table.insert(buf, (" "):rep(indent) .. "options=(")
+      table.insert(buf, (" "):rep(indent + 2) .. "$options")
+   else
+      table.insert(buf, (" "):rep(indent) .. "local -a options=(")
+   end
+
+   for _, option in ipairs(self._options) do
+      local line = {}
+      if #option._aliases > 1 then
+         if option._maxcount > 1 then
+            table.insert(line, '"*"')
+         end
+         table.insert(line, "{" .. table.concat(option._aliases, ",") .. '}"')
+      else
+         table.insert(line, '"')
+         if option._maxcount > 1 then
+            table.insert(line, "*")
+         end
+         table.insert(line, option._name)
+      end
+      if option._description then
+         local description = get_short_description(option):gsub('["%]:`$]', "\\%0")
+         table.insert(line, "[" .. description .. "]")
+      end
+      if option._maxargs == math.huge then
+         table.insert(line, ":*")
+      end
+      if option._choices then
+         table.insert(line, ": :(" .. table.concat(option._choices, " ") .. ")")
+      elseif option._maxargs > 0 then
+         table.insert(line, ": :_files")
+      end
+      table.insert(line, '"')
+      table.insert(buf, (" "):rep(indent + 2) .. table.concat(line))
+   end
+
+   table.insert(buf, (" "):rep(indent) .. ")")
+   table.insert(buf, (" "):rep(indent) .. "_arguments -s -S \\")
+   table.insert(buf, (" "):rep(indent + 2) .. "$options \\")
+
+   if self._is_help_command then
+      table.insert(buf, (" "):rep(indent + 2) .. '": :(' .. self._parent:_get_commands() .. ')" \\')
+   else
+      for _, argument in ipairs(self._arguments) do
+         local spec
+         if argument._choices then
+            spec = ": :(" .. table.concat(argument._choices, " ") .. ")"
+         else
+            spec = ": :_files"
+         end
+         if argument._maxargs == math.huge then
+            table.insert(buf, (" "):rep(indent + 2) .. '"*' .. spec .. '" \\')
+            break
+         end
+         for _ = 1, argument._maxargs do
+            table.insert(buf, (" "):rep(indent + 2) .. '"' .. spec .. '" \\')
+         end
+      end
+
+      if #self._commands > 0 then
+         table.insert(buf, (" "):rep(indent + 2) .. '": :_' .. cmd_name .. '_cmds" \\')
+         table.insert(buf, (" "):rep(indent + 2) .. '"*:: :->args" \\')
+      end
+   end
+
+   table.insert(buf, (" "):rep(indent + 2) .. "&& return 0")
+end
+
+function Parser:_zsh_cmds(buf, cmd_name)
+   table.insert(buf, "\n_" .. cmd_name .. "_cmds() {")
+   table.insert(buf, "  local -a commands=(")
+
+   for _, command in ipairs(self._commands) do
+      local line = {}
+      if #command._aliases > 1 then
+         table.insert(line, "{" .. table.concat(command._aliases, ",") .. '}"')
+      else
+         table.insert(line, '"' .. command._name)
+      end
+      if command._description then
+         table.insert(line, ":" .. get_short_description(command):gsub('["`$]', "\\%0"))
+      end
+      table.insert(buf, "    " .. table.concat(line) .. '"')
+   end
+
+   table.insert(buf, '  )\n  _describe "command" commands\n}')
+end
+
+function Parser:_zsh_complete_help(buf, cmds_buf, cmd_name, indent)
+   if #self._commands == 0 then
+      return
+   end
+
+   self:_zsh_cmds(cmds_buf, cmd_name)
+   table.insert(buf, "\n" .. (" "):rep(indent) .. "case $words[1] in")
+
+   for _, command in ipairs(self._commands) do
+      local name = cmd_name .. "_" .. command._name
+      table.insert(buf, (" "):rep(indent + 2) .. table.concat(command._aliases, "|") .. ")")
+      command:_zsh_arguments(buf, name, indent + 4)
+      command:_zsh_complete_help(buf, cmds_buf, name, indent + 4)
+      table.insert(buf, (" "):rep(indent + 4) .. ";;\n")
+   end
+
+   table.insert(buf, (" "):rep(indent) .. "esac")
+end
+
+function Parser:get_zsh_complete()
+   self._basename = base_name(self._name)
+   assert(self:_is_shell_safe())
+   local buf = {("#compdef %s\n"):format(self._basename)}
+   local cmds_buf = {}
+   table.insert(buf, "_" .. self._basename .. "() {")
+   if #self._commands > 0 then
+      table.insert(buf, "  local context state state_descr line")
+      table.insert(buf, "  typeset -A opt_args\n")
+   end
+   self:_zsh_arguments(buf, self._basename, 2)
+   self:_zsh_complete_help(buf, cmds_buf, self._basename, 2)
+   table.insert(buf, "\n  return 1")
+   table.insert(buf, "}")
+
+   local result = table.concat(buf, "\n")
+   if #cmds_buf > 0 then
+      result = result .. "\n" .. table.concat(cmds_buf, "\n")
+   end
+   return result .. "\n\n_" .. self._basename .. "\n"
+end
+
+local function fish_escape(string)
+   return string:gsub("[\\']", "\\%0")
+end
+
+function Parser:_fish_get_cmd(buf, indent)
+   if #self._commands == 0 then
+      return
+   end
+
+   table.insert(buf, (" "):rep(indent) .. "set -e cmdline[1]")
+   table.insert(buf, (" "):rep(indent) .. "for arg in $cmdline")
+   table.insert(buf, (" "):rep(indent + 4) .. "switch $arg")
+
+   for _, command in ipairs(self._commands) do
+      table.insert(buf, (" "):rep(indent + 8) .. "case " .. table.concat(command._aliases, " "))
+      table.insert(buf, (" "):rep(indent + 12) .. "set cmd $cmd " .. command._name)
+      command:_fish_get_cmd(buf, indent + 12)
+      table.insert(buf, (" "):rep(indent + 12) .. "break")
+   end
+
+   table.insert(buf, (" "):rep(indent + 4) .. "end")
+   table.insert(buf, (" "):rep(indent) .. "end")
+end
+
+function Parser:_fish_complete_help(buf, basename)
+   local prefix = "complete -c " .. basename
+   table.insert(buf, "")
+
+   for _, command in ipairs(self._commands) do
+      local aliases = table.concat(command._aliases, " ")
+      local line
+      if self._parent then
+         line = ("%s -n '__fish_%s_using_command %s' -xa '%s'")
+            :format(prefix, basename, self:_get_fullname(true), aliases)
+      else
+         line = ("%s -n '__fish_%s_using_command' -xa '%s'"):format(prefix, basename, aliases)
+      end
+      if command._description then
+         line = ("%s -d '%s'"):format(line, fish_escape(get_short_description(command)))
+      end
+      table.insert(buf, line)
+   end
+
+   if self._is_help_command then
+      local line = ("%s -n '__fish_%s_using_command %s' -xa '%s'")
+         :format(prefix, basename, self:_get_fullname(true), self._parent:_get_commands())
+      table.insert(buf, line)
+   end
+
+   for _, option in ipairs(self._options) do
+      local parts = {prefix}
+
+      if self._parent then
+         table.insert(parts, "-n '__fish_" .. basename .. "_seen_command " .. self:_get_fullname(true) .. "'")
+      end
+
+      for _, alias in ipairs(option._aliases) do
+         if alias:match("^%-.$") then
+            table.insert(parts, "-s " .. alias:sub(2))
+         elseif alias:match("^%-%-.+") then
+            table.insert(parts, "-l " .. alias:sub(3))
+         end
+      end
+
+      if option._choices then
+         table.insert(parts, "-xa '" .. table.concat(option._choices, " ") .. "'")
+      elseif option._minargs > 0 then
+         table.insert(parts, "-r")
+      end
+
+      if option._description then
+         table.insert(parts, "-d '" .. fish_escape(get_short_description(option)) .. "'")
+      end
+
+      table.insert(buf, table.concat(parts, " "))
+   end
+
+   for _, command in ipairs(self._commands) do
+      command:_fish_complete_help(buf, basename)
+   end
+end
+
+function Parser:get_fish_complete()
+   self._basename = base_name(self._name)
+   assert(self:_is_shell_safe())
+   local buf = {}
+
+   if #self._commands > 0 then
+      table.insert(buf, ([[
+function __fish_%s_print_command
+    set -l cmdline (commandline -poc)
+    set -l cmd]]):format(self._basename))
+      self:_fish_get_cmd(buf, 4)
+      table.insert(buf, ([[
+    echo "$cmd"
+end
+
+function __fish_%s_using_command
+    test (__fish_%s_print_command) = "$argv"
+    and return 0
+    or return 1
+end
+
+function __fish_%s_seen_command
+    string match -q "$argv*" (__fish_%s_print_command)
+    and return 0
+    or return 1
+end]]):format(self._basename, self._basename, self._basename, self._basename))
+   end
+
+   self:_fish_complete_help(buf, self._basename)
+   return table.concat(buf, "\n") .. "\n"
+end
+
+local function get_tip(context, wrong_name)
+   local context_pool = {}
+   local possible_name
+   local possible_names = {}
+
+   for name in pairs(context) do
+      if type(name) == "string" then
+         for i = 1, #name do
+            possible_name = name:sub(1, i - 1) .. name:sub(i + 1)
+
+            if not context_pool[possible_name] then
+               context_pool[possible_name] = {}
+            end
+
+            table.insert(context_pool[possible_name], name)
+         end
+      end
+   end
+
+   for i = 1, #wrong_name + 1 do
+      possible_name = wrong_name:sub(1, i - 1) .. wrong_name:sub(i + 1)
+
+      if context[possible_name] then
+         possible_names[possible_name] = true
+      elseif context_pool[possible_name] then
+         for _, name in ipairs(context_pool[possible_name]) do
+            possible_names[name] = true
+         end
+      end
+   end
+
+   local first = next(possible_names)
+
+   if first then
+      if next(possible_names, first) then
+         local possible_names_arr = {}
+
+         for name in pairs(possible_names) do
+            table.insert(possible_names_arr, "'" .. name .. "'")
+         end
+
+         table.sort(possible_names_arr)
+         return "\nDid you mean one of these: " .. table.concat(possible_names_arr, " ") .. "?"
+      else
+         return "\nDid you mean '" .. first .. "'?"
+      end
+   else
+      return ""
+   end
+end
+
+local ElementState = class({
+   invocations = 0
+})
+
+function ElementState:__call(state, element)
+   self.state = state
+   self.result = state.result
+   self.element = element
+   self.target = element._target or element:_get_default_target()
+   self.action, self.result[self.target] = element:_get_action()
+   return self
+end
+
+function ElementState:error(fmt, ...)
+   self.state:error(fmt, ...)
+end
+
+function ElementState:convert(argument, index)
+   local converter = self.element._convert
+
+   if converter then
+      local ok, err
+
+      if type(converter) == "function" then
+         ok, err = converter(argument)
+      elseif type(converter[index]) == "function" then
+         ok, err = converter[index](argument)
+      else
+         ok = converter[argument]
+      end
+
+      if ok == nil then
+         self:error(err and "%s" or "malformed argument '%s'", err or argument)
+      end
+
+      argument = ok
+   end
+
+   return argument
+end
+
+function ElementState:default(mode)
+   return self.element._defmode:find(mode) and self.element._default
+end
+
+local function bound(noun, min, max, is_max)
+   local res = ""
+
+   if min ~= max then
+      res = "at " .. (is_max and "most" or "least") .. " "
+   end
+
+   local number = is_max and max or min
+   return res .. tostring(number) .. " " .. noun ..  (number == 1 and "" or "s")
+end
+
+function ElementState:set_name(alias)
+   self.name = ("%s '%s'"):format(alias and "option" or "argument", alias or self.element._name)
+end
+
+function ElementState:invoke()
+   self.open = true
+   self.overwrite = false
+
+   if self.invocations >= self.element._maxcount then
+      if self.element._overwrite then
+         self.overwrite = true
+      else
+         local num_times_repr = bound("time", self.element._mincount, self.element._maxcount, true)
+         self:error("%s must be used %s", self.name, num_times_repr)
+      end
+   else
+      self.invocations = self.invocations + 1
+   end
+
+   self.args = {}
+
+   if self.element._maxargs <= 0 then
+      self:close()
+   end
+
+   return self.open
+end
+
+function ElementState:check_choices(argument)
+   if self.element._choices then
+      for _, choice in ipairs(self.element._choices) do
+         if argument == choice then
+            return
+         end
+      end
+      local choices_list = "'" .. table.concat(self.element._choices, "', '") .. "'"
+      local is_option = getmetatable(self.element) == Option
+      self:error("%s%s must be one of %s", is_option and "argument for " or "", self.name, choices_list)
+   end
+end
+
+function ElementState:pass(argument)
+   self:check_choices(argument)
+   argument = self:convert(argument, #self.args + 1)
+   table.insert(self.args, argument)
+
+   if #self.args >= self.element._maxargs then
+      self:close()
+   end
+
+   return self.open
+end
+
+function ElementState:complete_invocation()
+   while #self.args < self.element._minargs do
+      self:pass(self.element._default)
+   end
+end
+
+function ElementState:close()
+   if self.open then
+      self.open = false
+
+      if #self.args < self.element._minargs then
+         if self:default("a") then
+            self:complete_invocation()
+         else
+            if #self.args == 0 then
+               if getmetatable(self.element) == Argument then
+                  self:error("missing %s", self.name)
+               elseif self.element._maxargs == 1 then
+                  self:error("%s requires an argument", self.name)
+               end
+            end
+
+            self:error("%s requires %s", self.name, bound("argument", self.element._minargs, self.element._maxargs))
+         end
+      end
+
+      local args
+
+      if self.element._maxargs == 0 then
+         args = self.args[1]
+      elseif self.element._maxargs == 1 then
+         if self.element._minargs == 0 and self.element._mincount ~= self.element._maxcount then
+            args = self.args
+         else
+            args = self.args[1]
+         end
+      else
+         args = self.args
+      end
+
+      self.action(self.result, self.target, args, self.overwrite)
+   end
+end
+
+local ParseState = class({
+   result = {},
+   options = {},
+   arguments = {},
+   argument_i = 1,
+   element_to_mutexes = {},
+   mutex_to_element_state = {},
+   command_actions = {}
+})
+
+function ParseState:__call(parser, error_handler)
+   self.parser = parser
+   self.error_handler = error_handler
+   self.charset = parser:_update_charset()
+   self:switch(parser)
+   return self
+end
+
+function ParseState:error(fmt, ...)
+   self.error_handler(self.parser, fmt:format(...))
+end
+
+function ParseState:switch(parser)
+   self.parser = parser
+
+   if parser._action then
+      table.insert(self.command_actions, {action = parser._action, name = parser._name})
+   end
+
+   for _, option in ipairs(parser._options) do
+      option = ElementState(self, option)
+      table.insert(self.options, option)
+
+      for _, alias in ipairs(option.element._aliases) do
+         self.options[alias] = option
+      end
+   end
+
+   for _, mutex in ipairs(parser._mutexes) do
+      for _, element in ipairs(mutex) do
+         if not self.element_to_mutexes[element] then
+            self.element_to_mutexes[element] = {}
+         end
+
+         table.insert(self.element_to_mutexes[element], mutex)
+      end
+   end
+
+   for _, argument in ipairs(parser._arguments) do
+      argument = ElementState(self, argument)
+      table.insert(self.arguments, argument)
+      argument:set_name()
+      argument:invoke()
+   end
+
+   self.handle_options = parser._handle_options
+   self.argument = self.arguments[self.argument_i]
+   self.commands = parser._commands
+
+   for _, command in ipairs(self.commands) do
+      for _, alias in ipairs(command._aliases) do
+         self.commands[alias] = command
+      end
+   end
+end
+
+function ParseState:get_option(name)
+   local option = self.options[name]
+
+   if not option then
+      self:error("unknown option '%s'%s", name, get_tip(self.options, name))
+   else
+      return option
+   end
+end
+
+function ParseState:get_command(name)
+   local command = self.commands[name]
+
+   if not command then
+      if #self.commands > 0 then
+         self:error("unknown command '%s'%s", name, get_tip(self.commands, name))
+      else
+         self:error("too many arguments")
+      end
+   else
+      return command
+   end
+end
+
+function ParseState:check_mutexes(element_state)
+   if self.element_to_mutexes[element_state.element] then
+      for _, mutex in ipairs(self.element_to_mutexes[element_state.element]) do
+         local used_element_state = self.mutex_to_element_state[mutex]
+
+         if used_element_state and used_element_state ~= element_state then
+            self:error("%s can not be used together with %s", element_state.name, used_element_state.name)
+         else
+            self.mutex_to_element_state[mutex] = element_state
+         end
+      end
+   end
+end
+
+function ParseState:invoke(option, name)
+   self:close()
+   option:set_name(name)
+   self:check_mutexes(option, name)
+
+   if option:invoke() then
+      self.option = option
+   end
+end
+
+function ParseState:pass(arg)
+   if self.option then
+      if not self.option:pass(arg) then
+         self.option = nil
+      end
+   elseif self.argument then
+      self:check_mutexes(self.argument)
+
+      if not self.argument:pass(arg) then
+         self.argument_i = self.argument_i + 1
+         self.argument = self.arguments[self.argument_i]
+      end
+   else
+      local command = self:get_command(arg)
+      self.result[command._target or command._name] = true
+
+      if self.parser._command_target then
+         self.result[self.parser._command_target] = command._name
+      end
+
+      self:switch(command)
+   end
+end
+
+function ParseState:close()
+   if self.option then
+      self.option:close()
+      self.option = nil
+   end
+end
+
+function ParseState:finalize()
+   self:close()
+
+   for i = self.argument_i, #self.arguments do
+      local argument = self.arguments[i]
+      if #argument.args == 0 and argument:default("u") then
+         argument:complete_invocation()
+      else
+         argument:close()
+      end
+   end
+
+   if self.parser._require_command and #self.commands > 0 then
+      self:error("a command is required")
+   end
+
+   for _, option in ipairs(self.options) do
+      option.name = option.name or ("option '%s'"):format(option.element._name)
+
+      if option.invocations == 0 then
+         if option:default("u") then
+            option:invoke()
+            option:complete_invocation()
+            option:close()
+         end
+      end
+
+      local mincount = option.element._mincount
+
+      if option.invocations < mincount then
+         if option:default("a") then
+            while option.invocations < mincount do
+               option:invoke()
+               option:close()
+            end
+         elseif option.invocations == 0 then
+            self:error("missing %s", option.name)
+         else
+            self:error("%s must be used %s", option.name, bound("time", mincount, option.element._maxcount))
+         end
+      end
+   end
+
+   for i = #self.command_actions, 1, -1 do
+      self.command_actions[i].action(self.result, self.command_actions[i].name)
+   end
+end
+
+function ParseState:parse(args)
+   for _, arg in ipairs(args) do
+      local plain = true
+
+      if self.handle_options then
+         local first = arg:sub(1, 1)
+
+         if self.charset[first] then
+            if #arg > 1 then
+               plain = false
+
+               if arg:sub(2, 2) == first then
+                  if #arg == 2 then
+                     if self.options[arg] then
+                        local option = self:get_option(arg)
+                        self:invoke(option, arg)
+                     else
+                        self:close()
+                     end
+
+                     self.handle_options = false
+                  else
+                     local equals = arg:find "="
+                     if equals then
+                        local name = arg:sub(1, equals - 1)
+                        local option = self:get_option(name)
+
+                        if option.element._maxargs <= 0 then
+                           self:error("option '%s' does not take arguments", name)
+                        end
+
+                        self:invoke(option, name)
+                        self:pass(arg:sub(equals + 1))
+                     else
+                        local option = self:get_option(arg)
+                        self:invoke(option, arg)
+                     end
+                  end
+               else
+                  for i = 2, #arg do
+                     local name = first .. arg:sub(i, i)
+                     local option = self:get_option(name)
+                     self:invoke(option, name)
+
+                     if i ~= #arg and option.element._maxargs > 0 then
+                        self:pass(arg:sub(i + 1))
+                        break
+                     end
+                  end
+               end
+            end
+         end
+      end
+
+      if plain then
+         self:pass(arg)
+      end
+   end
+
+   self:finalize()
+   return self.result
+end
+
+function Parser:error(msg)
+   io.stderr:write(("%s\n\nError: %s\n"):format(self:get_usage(), msg))
+   os.exit(1)
+end
+
+-- Compatibility with strict.lua and other checkers:
+local default_cmdline = rawget(_G, "arg") or {}
+
+function Parser:_parse(args, error_handler)
+   return ParseState(self, error_handler):parse(args or default_cmdline)
+end
+
+function Parser:parse(args)
+   return self:_parse(args, self.error)
+end
+
+local function xpcall_error_handler(err)
+   if not debug then
+      return tostring(err)
+   end
+   return tostring(err) .. "\noriginal " .. debug.traceback("", 2):sub(2)
+end
+
+function Parser:pparse(args)
+   local parse_error
+
+   local ok, result = xpcall(function()
+      return self:_parse(args, function(_, err)
+         parse_error = err
+         error(err, 0)
+      end)
+   end, xpcall_error_handler)
+
+   if ok then
+      return true, result
+   elseif not parse_error then
+      error(result, 0)
+   else
+      return false, parse_error
+   end
+end
+
+local argparse = {}
+
+argparse.version = "0.7.0"
+
+setmetatable(argparse, {__call = function(_, ...)
+   return Parser(default_cmdline[0]):add_help(true)(...)
+end})
+
+return argparse
-- 
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