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2 files changed, 2852 insertions, 0 deletions

diff --git a/src/luarocks/vendor/argparse.lua b/src/luarocks/vendor/argparse.lua
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+++ 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
diff --git a/src/luarocks/vendor/dkjson.lua b/src/luarocks/vendor/dkjson.lua
new file mode 100644
index 0000000..7a86724
--- /dev/null
+++ b/src/luarocks/vendor/dkjson.lua
@@ -0,0 +1,749 @@
+-- Module options:
+local always_use_lpeg = false
+local register_global_module_table = false
+local global_module_name = 'json'
+
+--[==[
+
+David Kolf's JSON module for Lua 5.1 - 5.4
+
+Version 2.7
+
+
+For the documentation see the corresponding readme.txt or visit
+<http://dkolf.de/src/dkjson-lua.fsl/>.
+
+You can contact the author by sending an e-mail to 'david' at the
+domain 'dkolf.de'.
+
+
+Copyright (C) 2010-2024 David Heiko Kolf
+
+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.
+
+--]==]
+
+-- global dependencies:
+local pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset =
+      pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset
+local error, require, pcall, select = error, require, pcall, select
+local floor, huge = math.floor, math.huge
+local strrep, gsub, strsub, strbyte, strchar, strfind, strlen, strformat =
+      string.rep, string.gsub, string.sub, string.byte, string.char,
+      string.find, string.len, string.format
+local strmatch = string.match
+local concat = table.concat
+
+local json = { version = "dkjson 2.7" }
+
+local jsonlpeg = {}
+
+if register_global_module_table then
+  if always_use_lpeg then
+    _G[global_module_name] = jsonlpeg
+  else
+    _G[global_module_name] = json
+  end
+end
+
+local _ENV = nil -- blocking globals in Lua 5.2 and later
+
+pcall (function()
+  -- Enable access to blocked metatables.
+  -- Don't worry, this module doesn't change anything in them.
+  local debmeta = require "debug".getmetatable
+  if debmeta then getmetatable = debmeta end
+end)
+
+json.null = setmetatable ({}, {
+  __tojson = function () return "null" end
+})
+
+local function isarray (tbl)
+  local max, n, arraylen = 0, 0, 0
+  for k,v in pairs (tbl) do
+    if k == 'n' and type(v) == 'number' then
+      arraylen = v
+      if v > max then
+        max = v
+      end
+    else
+      if type(k) ~= 'number' or k < 1 or floor(k) ~= k then
+        return false
+      end
+      if k > max then
+        max = k
+      end
+      n = n + 1
+    end
+  end
+  if max > 10 and max > arraylen and max > n * 2 then
+    return false -- don't create an array with too many holes
+  end
+  return true, max
+end
+
+local escapecodes = {
+  ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f",
+  ["\n"] = "\\n",  ["\r"] = "\\r",  ["\t"] = "\\t"
+}
+
+local function escapeutf8 (uchar)
+  local value = escapecodes[uchar]
+  if value then
+    return value
+  end
+  local a, b, c, d = strbyte (uchar, 1, 4)
+  a, b, c, d = a or 0, b or 0, c or 0, d or 0
+  if a <= 0x7f then
+    value = a
+  elseif 0xc0 <= a and a <= 0xdf and b >= 0x80 then
+    value = (a - 0xc0) * 0x40 + b - 0x80
+  elseif 0xe0 <= a and a <= 0xef and b >= 0x80 and c >= 0x80 then
+    value = ((a - 0xe0) * 0x40 + b - 0x80) * 0x40 + c - 0x80
+  elseif 0xf0 <= a and a <= 0xf7 and b >= 0x80 and c >= 0x80 and d >= 0x80 then
+    value = (((a - 0xf0) * 0x40 + b - 0x80) * 0x40 + c - 0x80) * 0x40 + d - 0x80
+  else
+    return ""
+  end
+  if value <= 0xffff then
+    return strformat ("\\u%.4x", value)
+  elseif value <= 0x10ffff then
+    -- encode as UTF-16 surrogate pair
+    value = value - 0x10000
+    local highsur, lowsur = 0xD800 + floor (value/0x400), 0xDC00 + (value % 0x400)
+    return strformat ("\\u%.4x\\u%.4x", highsur, lowsur)
+  else
+    return ""
+  end
+end
+
+local function fsub (str, pattern, repl)
+  -- gsub always builds a new string in a buffer, even when no match
+  -- exists. First using find should be more efficient when most strings
+  -- don't contain the pattern.
+  if strfind (str, pattern) then
+    return gsub (str, pattern, repl)
+  else
+    return str
+  end
+end
+
+local function quotestring (value)
+  -- based on the regexp "escapable" in https://github.com/douglascrockford/JSON-js
+  value = fsub (value, "[%z\1-\31\"\\\127]", escapeutf8)
+  if strfind (value, "[\194\216\220\225\226\239]") then
+    value = fsub (value, "\194[\128-\159\173]", escapeutf8)
+    value = fsub (value, "\216[\128-\132]", escapeutf8)
+    value = fsub (value, "\220\143", escapeutf8)
+    value = fsub (value, "\225\158[\180\181]", escapeutf8)
+    value = fsub (value, "\226\128[\140-\143\168-\175]", escapeutf8)
+    value = fsub (value, "\226\129[\160-\175]", escapeutf8)
+    value = fsub (value, "\239\187\191", escapeutf8)
+    value = fsub (value, "\239\191[\176-\191]", escapeutf8)
+  end
+  return "\"" .. value .. "\""
+end
+json.quotestring = quotestring
+
+local function replace(str, o, n)
+  local i, j = strfind (str, o, 1, true)
+  if i then
+    return strsub(str, 1, i-1) .. n .. strsub(str, j+1, -1)
+  else
+    return str
+  end
+end
+
+-- locale independent num2str and str2num functions
+local decpoint, numfilter
+
+local function updatedecpoint ()
+  decpoint = strmatch(tostring(0.5), "([^05+])")
+  -- build a filter that can be used to remove group separators
+  numfilter = "[^0-9%-%+eE" .. gsub(decpoint, "[%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%0") .. "]+"
+end
+
+updatedecpoint()
+
+local function num2str (num)
+  return replace(fsub(tostring(num), numfilter, ""), decpoint, ".")
+end
+
+local function str2num (str)
+  local num = tonumber(replace(str, ".", decpoint))
+  if not num then
+    updatedecpoint()
+    num = tonumber(replace(str, ".", decpoint))
+  end
+  return num
+end
+
+local function addnewline2 (level, buffer, buflen)
+  buffer[buflen+1] = "\n"
+  buffer[buflen+2] = strrep ("  ", level)
+  buflen = buflen + 2
+  return buflen
+end
+
+function json.addnewline (state)
+  if state.indent then
+    state.bufferlen = addnewline2 (state.level or 0,
+                           state.buffer, state.bufferlen or #(state.buffer))
+  end
+end
+
+local encode2 -- forward declaration
+
+local function addpair (key, value, prev, indent, level, buffer, buflen, tables, globalorder, state)
+  local kt = type (key)
+  if kt ~= 'string' and kt ~= 'number' then
+    return nil, "type '" .. kt .. "' is not supported as a key by JSON."
+  end
+  if prev then
+    buflen = buflen + 1
+    buffer[buflen] = ","
+  end
+  if indent then
+    buflen = addnewline2 (level, buffer, buflen)
+  end
+  buffer[buflen+1] = quotestring (key)
+  buffer[buflen+2] = ":"
+  return encode2 (value, indent, level, buffer, buflen + 2, tables, globalorder, state)
+end
+
+local function appendcustom(res, buffer, state)
+  local buflen = state.bufferlen
+  if type (res) == 'string' then
+    buflen = buflen + 1
+    buffer[buflen] = res
+  end
+  return buflen
+end
+
+local function exception(reason, value, state, buffer, buflen, defaultmessage)
+  defaultmessage = defaultmessage or reason
+  local handler = state.exception
+  if not handler then
+    return nil, defaultmessage
+  else
+    state.bufferlen = buflen
+    local ret, msg = handler (reason, value, state, defaultmessage)
+    if not ret then return nil, msg or defaultmessage end
+    return appendcustom(ret, buffer, state)
+  end
+end
+
+function json.encodeexception(reason, value, state, defaultmessage)
+  return quotestring("<" .. defaultmessage .. ">")
+end
+
+encode2 = function (value, indent, level, buffer, buflen, tables, globalorder, state)
+  local valtype = type (value)
+  local valmeta = getmetatable (value)
+  valmeta = type (valmeta) == 'table' and valmeta -- only tables
+  local valtojson = valmeta and valmeta.__tojson
+  if valtojson then
+    if tables[value] then
+      return exception('reference cycle', value, state, buffer, buflen)
+    end
+    tables[value] = true
+    state.bufferlen = buflen
+    local ret, msg = valtojson (value, state)
+    if not ret then return exception('custom encoder failed', value, state, buffer, buflen, msg) end
+    tables[value] = nil
+    buflen = appendcustom(ret, buffer, state)
+  elseif value == nil then
+    buflen = buflen + 1
+    buffer[buflen] = "null"
+  elseif valtype == 'number' then
+    local s
+    if value ~= value or value >= huge or -value >= huge then
+      -- This is the behaviour of the original JSON implementation.
+      s = "null"
+    else
+      s = num2str (value)
+    end
+    buflen = buflen + 1
+    buffer[buflen] = s
+  elseif valtype == 'boolean' then
+    buflen = buflen + 1
+    buffer[buflen] = value and "true" or "false"
+  elseif valtype == 'string' then
+    buflen = buflen + 1
+    buffer[buflen] = quotestring (value)
+  elseif valtype == 'table' then
+    if tables[value] then
+      return exception('reference cycle', value, state, buffer, buflen)
+    end
+    tables[value] = true
+    level = level + 1
+    local isa, n = isarray (value)
+    if n == 0 and valmeta and valmeta.__jsontype == 'object' then
+      isa = false
+    end
+    local msg
+    if isa then -- JSON array
+      buflen = buflen + 1
+      buffer[buflen] = "["
+      for i = 1, n do
+        buflen, msg = encode2 (value[i], indent, level, buffer, buflen, tables, globalorder, state)
+        if not buflen then return nil, msg end
+        if i < n then
+          buflen = buflen + 1
+          buffer[buflen] = ","
+        end
+      end
+      buflen = buflen + 1
+      buffer[buflen] = "]"
+    else -- JSON object
+      local prev = false
+      buflen = buflen + 1
+      buffer[buflen] = "{"
+      local order = valmeta and valmeta.__jsonorder or globalorder
+      if order then
+        local used = {}
+        n = #order
+        for i = 1, n do
+          local k = order[i]
+          local v = value[k]
+          if v ~= nil then
+            used[k] = true
+            buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state)
+            if not buflen then return nil, msg end
+            prev = true -- add a seperator before the next element
+          end
+        end
+        for k,v in pairs (value) do
+          if not used[k] then
+            buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state)
+            if not buflen then return nil, msg end
+            prev = true -- add a seperator before the next element
+          end
+        end
+      else -- unordered
+        for k,v in pairs (value) do
+          buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder, state)
+          if not buflen then return nil, msg end
+          prev = true -- add a seperator before the next element
+        end
+      end
+      if indent then
+        buflen = addnewline2 (level - 1, buffer, buflen)
+      end
+      buflen = buflen + 1
+      buffer[buflen] = "}"
+    end
+    tables[value] = nil
+  else
+    return exception ('unsupported type', value, state, buffer, buflen,
+      "type '" .. valtype .. "' is not supported by JSON.")
+  end
+  return buflen
+end
+
+function json.encode (value, state)
+  state = state or {}
+  local oldbuffer = state.buffer
+  local buffer = oldbuffer or {}
+  state.buffer = buffer
+  updatedecpoint()
+  local ret, msg = encode2 (value, state.indent, state.level or 0,
+                   buffer, state.bufferlen or 0, state.tables or {}, state.keyorder, state)
+  if not ret then
+    error (msg, 2)
+  elseif oldbuffer == buffer then
+    state.bufferlen = ret
+    return true
+  else
+    state.bufferlen = nil
+    state.buffer = nil
+    return concat (buffer)
+  end
+end
+
+local function loc (str, where)
+  local line, pos, linepos = 1, 1, 0
+  while true do
+    pos = strfind (str, "\n", pos, true)
+    if pos and pos < where then
+      line = line + 1
+      linepos = pos
+      pos = pos + 1
+    else
+      break
+    end
+  end
+  return "line " .. line .. ", column " .. (where - linepos)
+end
+
+local function unterminated (str, what, where)
+  return nil, strlen (str) + 1, "unterminated " .. what .. " at " .. loc (str, where)
+end
+
+local function scanwhite (str, pos)
+  while true do
+    pos = strfind (str, "%S", pos)
+    if not pos then return nil end
+    local sub2 = strsub (str, pos, pos + 1)
+    if sub2 == "\239\187" and strsub (str, pos + 2, pos + 2) == "\191" then
+      -- UTF-8 Byte Order Mark
+      pos = pos + 3
+    elseif sub2 == "//" then
+      pos = strfind (str, "[\n\r]", pos + 2)
+      if not pos then return nil end
+    elseif sub2 == "/*" then
+      pos = strfind (str, "*/", pos + 2)
+      if not pos then return nil end
+      pos = pos + 2
+    else
+      return pos
+    end
+  end
+end
+
+local escapechars = {
+  ["\""] = "\"", ["\\"] = "\\", ["/"] = "/", ["b"] = "\b", ["f"] = "\f",
+  ["n"] = "\n", ["r"] = "\r", ["t"] = "\t"
+}
+
+local function unichar (value)
+  if value < 0 then
+    return nil
+  elseif value <= 0x007f then
+    return strchar (value)
+  elseif value <= 0x07ff then
+    return strchar (0xc0 + floor(value/0x40),
+                    0x80 + (floor(value) % 0x40))
+  elseif value <= 0xffff then
+    return strchar (0xe0 + floor(value/0x1000),
+                    0x80 + (floor(value/0x40) % 0x40),
+                    0x80 + (floor(value) % 0x40))
+  elseif value <= 0x10ffff then
+    return strchar (0xf0 + floor(value/0x40000),
+                    0x80 + (floor(value/0x1000) % 0x40),
+                    0x80 + (floor(value/0x40) % 0x40),
+                    0x80 + (floor(value) % 0x40))
+  else
+    return nil
+  end
+end
+
+local function scanstring (str, pos)
+  local lastpos = pos + 1
+  local buffer, n = {}, 0
+  while true do
+    local nextpos = strfind (str, "[\"\\]", lastpos)
+    if not nextpos then
+      return unterminated (str, "string", pos)
+    end
+    if nextpos > lastpos then
+      n = n + 1
+      buffer[n] = strsub (str, lastpos, nextpos - 1)
+    end
+    if strsub (str, nextpos, nextpos) == "\"" then
+      lastpos = nextpos + 1
+      break
+    else
+      local escchar = strsub (str, nextpos + 1, nextpos + 1)
+      local value
+      if escchar == "u" then
+        value = tonumber (strsub (str, nextpos + 2, nextpos + 5), 16)
+        if value then
+          local value2
+          if 0xD800 <= value and value <= 0xDBff then
+            -- we have the high surrogate of UTF-16. Check if there is a
+            -- low surrogate escaped nearby to combine them.
+            if strsub (str, nextpos + 6, nextpos + 7) == "\\u" then
+              value2 = tonumber (strsub (str, nextpos + 8, nextpos + 11), 16)
+              if value2 and 0xDC00 <= value2 and value2 <= 0xDFFF then
+                value = (value - 0xD800)  * 0x400 + (value2 - 0xDC00) + 0x10000
+              else
+                value2 = nil -- in case it was out of range for a low surrogate
+              end
+            end
+          end
+          value = value and unichar (value)
+          if value then
+            if value2 then
+              lastpos = nextpos + 12
+            else
+              lastpos = nextpos + 6
+            end
+          end
+        end
+      end
+      if not value then
+        value = escapechars[escchar] or escchar
+        lastpos = nextpos + 2
+      end
+      n = n + 1
+      buffer[n] = value
+    end
+  end
+  if n == 1 then
+    return buffer[1], lastpos
+  elseif n > 1 then
+    return concat (buffer), lastpos
+  else
+    return "", lastpos
+  end
+end
+
+local scanvalue -- forward declaration
+
+local function scantable (what, closechar, str, startpos, nullval, objectmeta, arraymeta)
+  local len = strlen (str)
+  local tbl, n = {}, 0
+  local pos = startpos + 1
+  if what == 'object' then
+    setmetatable (tbl, objectmeta)
+  else
+    setmetatable (tbl, arraymeta)
+  end
+  while true do
+    pos = scanwhite (str, pos)
+    if not pos then return unterminated (str, what, startpos) end
+    local char = strsub (str, pos, pos)
+    if char == closechar then
+      return tbl, pos + 1
+    end
+    local val1, err
+    val1, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta)
+    if err then return nil, pos, err end
+    pos = scanwhite (str, pos)
+    if not pos then return unterminated (str, what, startpos) end
+    char = strsub (str, pos, pos)
+    if char == ":" then
+      if val1 == nil then
+        return nil, pos, "cannot use nil as table index (at " .. loc (str, pos) .. ")"
+      end
+      pos = scanwhite (str, pos + 1)
+      if not pos then return unterminated (str, what, startpos) end
+      local val2
+      val2, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta)
+      if err then return nil, pos, err end
+      tbl[val1] = val2
+      pos = scanwhite (str, pos)
+      if not pos then return unterminated (str, what, startpos) end
+      char = strsub (str, pos, pos)
+    else
+      n = n + 1
+      tbl[n] = val1
+    end
+    if char == "," then
+      pos = pos + 1
+    end
+  end
+end
+
+scanvalue = function (str, pos, nullval, objectmeta, arraymeta)
+  pos = pos or 1
+  pos = scanwhite (str, pos)
+  if not pos then
+    return nil, strlen (str) + 1, "no valid JSON value (reached the end)"
+  end
+  local char = strsub (str, pos, pos)
+  if char == "{" then
+    return scantable ('object', "}", str, pos, nullval, objectmeta, arraymeta)
+  elseif char == "[" then
+    return scantable ('array', "]", str, pos, nullval, objectmeta, arraymeta)
+  elseif char == "\"" then
+    return scanstring (str, pos)
+  else
+    local pstart, pend = strfind (str, "^%-?[%d%.]+[eE]?[%+%-]?%d*", pos)
+    if pstart then
+      local number = str2num (strsub (str, pstart, pend))
+      if number then
+        return number, pend + 1
+      end
+    end
+    pstart, pend = strfind (str, "^%a%w*", pos)
+    if pstart then
+      local name = strsub (str, pstart, pend)
+      if name == "true" then
+        return true, pend + 1
+      elseif name == "false" then
+        return false, pend + 1
+      elseif name == "null" then
+        return nullval, pend + 1
+      end
+    end
+    return nil, pos, "no valid JSON value at " .. loc (str, pos)
+  end
+end
+
+local function optionalmetatables(...)
+  if select("#", ...) > 0 then
+    return ...
+  else
+    return {__jsontype = 'object'}, {__jsontype = 'array'}
+  end
+end
+
+function json.decode (str, pos, nullval, ...)
+  local objectmeta, arraymeta = optionalmetatables(...)
+  return scanvalue (str, pos, nullval, objectmeta, arraymeta)
+end
+
+function json.use_lpeg ()
+  local g = require ("lpeg")
+
+  if type(g.version) == 'function' and g.version() == "0.11" then
+    error "due to a bug in LPeg 0.11, it cannot be used for JSON matching"
+  end
+
+  local pegmatch = g.match
+  local P, S, R = g.P, g.S, g.R
+
+  local function ErrorCall (str, pos, msg, state)
+    if not state.msg then
+      state.msg = msg .. " at " .. loc (str, pos)
+      state.pos = pos
+    end
+    return false
+  end
+
+  local function Err (msg)
+    return g.Cmt (g.Cc (msg) * g.Carg (2), ErrorCall)
+  end
+
+  local function ErrorUnterminatedCall (str, pos, what, state)
+    return ErrorCall (str, pos - 1, "unterminated " .. what, state)
+  end
+
+  local SingleLineComment = P"//" * (1 - S"\n\r")^0
+  local MultiLineComment = P"/*" * (1 - P"*/")^0 * P"*/"
+  local Space = (S" \n\r\t" + P"\239\187\191" + SingleLineComment + MultiLineComment)^0
+
+  local function ErrUnterminated (what)
+    return g.Cmt (g.Cc (what) * g.Carg (2), ErrorUnterminatedCall)
+  end
+
+  local PlainChar = 1 - S"\"\\\n\r"
+  local EscapeSequence = (P"\\" * g.C (S"\"\\/bfnrt" + Err "unsupported escape sequence")) / escapechars
+  local HexDigit = R("09", "af", "AF")
+  local function UTF16Surrogate (match, pos, high, low)
+    high, low = tonumber (high, 16), tonumber (low, 16)
+    if 0xD800 <= high and high <= 0xDBff and 0xDC00 <= low and low <= 0xDFFF then
+      return true, unichar ((high - 0xD800)  * 0x400 + (low - 0xDC00) + 0x10000)
+    else
+      return false
+    end
+  end
+  local function UTF16BMP (hex)
+    return unichar (tonumber (hex, 16))
+  end
+  local U16Sequence = (P"\\u" * g.C (HexDigit * HexDigit * HexDigit * HexDigit))
+  local UnicodeEscape = g.Cmt (U16Sequence * U16Sequence, UTF16Surrogate) + U16Sequence/UTF16BMP
+  local Char = UnicodeEscape + EscapeSequence + PlainChar
+  local String = P"\"" * (g.Cs (Char ^ 0) * P"\"" + ErrUnterminated "string")
+  local Integer = P"-"^(-1) * (P"0" + (R"19" * R"09"^0))
+  local Fractal = P"." * R"09"^0
+  local Exponent = (S"eE") * (S"+-")^(-1) * R"09"^1
+  local Number = (Integer * Fractal^(-1) * Exponent^(-1))/str2num
+  local Constant = P"true" * g.Cc (true) + P"false" * g.Cc (false) + P"null" * g.Carg (1)
+  local SimpleValue = Number + String + Constant
+  local ArrayContent, ObjectContent
+
+  -- The functions parsearray and parseobject parse only a single value/pair
+  -- at a time and store them directly to avoid hitting the LPeg limits.
+  local function parsearray (str, pos, nullval, state)
+    local obj, cont
+    local start = pos
+    local npos
+    local t, nt = {}, 0
+    repeat
+      obj, cont, npos = pegmatch (ArrayContent, str, pos, nullval, state)
+      if cont == 'end' then
+        return ErrorUnterminatedCall (str, start, "array", state)
+      end
+      pos = npos
+      if cont == 'cont' or cont == 'last' then
+        nt = nt + 1
+        t[nt] = obj
+      end
+    until cont ~= 'cont'
+    return pos, setmetatable (t, state.arraymeta)
+  end
+
+  local function parseobject (str, pos, nullval, state)
+    local obj, key, cont
+    local start = pos
+    local npos
+    local t = {}
+    repeat
+      key, obj, cont, npos = pegmatch (ObjectContent, str, pos, nullval, state)
+      if cont == 'end' then
+        return ErrorUnterminatedCall (str, start, "object", state)
+      end
+      pos = npos
+      if cont == 'cont' or cont == 'last' then
+        t[key] = obj
+      end
+    until cont ~= 'cont'
+    return pos, setmetatable (t, state.objectmeta)
+  end
+
+  local Array = P"[" * g.Cmt (g.Carg(1) * g.Carg(2), parsearray)
+  local Object = P"{" * g.Cmt (g.Carg(1) * g.Carg(2), parseobject)
+  local Value = Space * (Array + Object + SimpleValue)
+  local ExpectedValue = Value + Space * Err "value expected"
+  local ExpectedKey = String + Err "key expected"
+  local End = P(-1) * g.Cc'end'
+  local ErrInvalid = Err "invalid JSON"
+  ArrayContent = (Value * Space * (P"," * g.Cc'cont' + P"]" * g.Cc'last'+ End + ErrInvalid)  + g.Cc(nil) * (P"]" * g.Cc'empty' + End  + ErrInvalid)) * g.Cp()
+  local Pair = g.Cg (Space * ExpectedKey * Space * (P":" + Err "colon expected") * ExpectedValue)
+  ObjectContent = (g.Cc(nil) * g.Cc(nil) * P"}" * g.Cc'empty' + End + (Pair * Space * (P"," * g.Cc'cont' + P"}" * g.Cc'last' + End + ErrInvalid) + ErrInvalid)) * g.Cp()
+  local DecodeValue = ExpectedValue * g.Cp ()
+
+  jsonlpeg.version = json.version
+  jsonlpeg.encode = json.encode
+  jsonlpeg.null = json.null
+  jsonlpeg.quotestring = json.quotestring
+  jsonlpeg.addnewline = json.addnewline
+  jsonlpeg.encodeexception = json.encodeexception
+  jsonlpeg.using_lpeg = true
+
+  function jsonlpeg.decode (str, pos, nullval, ...)
+    local state = {}
+    state.objectmeta, state.arraymeta = optionalmetatables(...)
+    local obj, retpos = pegmatch (DecodeValue, str, pos, nullval, state)
+    if state.msg then
+      return nil, state.pos, state.msg
+    else
+      return obj, retpos
+    end
+  end
+
+  -- cache result of this function:
+  json.use_lpeg = function () return jsonlpeg end
+  jsonlpeg.use_lpeg = json.use_lpeg
+
+  return jsonlpeg
+end
+
+if always_use_lpeg then
+  return json.use_lpeg()
+end
+
+return json
+