Module:Demo

local p = {}

--creates a frame object that cannot access any of the parent's args
--unless a table containing a list keys of not to inherit is provided
function disinherit(frame, onlyTheseKeys)
 local parent = frame:getParent() or frame
 local orphan = parent:newChild{}
 orphan.getParent = parent.getParent --returns nil
 orphan.args = {}
 if onlyTheseKeys then
  local family = {parent, frame}
  for f = 1, 2 do
   for k, v in pairs(family[f] and family[f].args or {}) do
    orphan.args[k] = orphan.args[k] or v
   end
  end
  parent.args = mw.clone(orphan.args)
  setmetatable(orphan.args, nil)
  for _, k in ipairs(onlyTheseKeys) do
   rawset(orphan.args, k, nil)
  end
 end
 return orphan, parent
end

function getSeparator(args, default)
 local br = tonumber(args.br) and ('<br>'):rep(args.br) or args.br
 local sep = args.sep or br or default
 return #sep > 0 and ' ' .. sep .. ' ' or sep
end

function p.get(frame, arg, passArgs)
 local orphan, frame = disinherit(frame, passArgs and {arg or 1})
 local code = frame.args[arg or 1] or ''
 if code:match'UNIQ%-%-nowiki' then
  code = mw.text.unstripNoWiki(code)
   :gsub('&lt;', '<')
   :gsub('&gt;', '>')
   :gsub('&quot;', '"')
   -- Replace `&#125;%-` with `}-` because of some server quirk leading to
   -- =mw.text.unstripNoWiki(mw.getCurrentFrame():preprocess('<nowiki>}-</nowiki>'))
   -- outputting `&#125;-` instead of `}-`, while it's ok with `<nowiki>} -</nowiki>`
   :gsub('&#125;%-', '}-')
   -- The same with `-&#123;`
   :gsub('%-&#123;', '-{')
 end
 local kill_categories = frame.args.demo_kill_categories or frame.args.nocat
 return {
  source = code,
  output = orphan:preprocess(code):gsub(kill_categories and '%[%[Category.-%]%]' or '', ''),
  frame = frame
 }
end

function p.main(frame, demoTable)
 local show = demoTable or p.get(frame)
 local args = show.frame.args
 if show[args.result_arg] then
  return show[args.result_arg]
 end
 local yesno = require('Module:Yesno')
 args.reverse = yesno(args.reverse, false)
 args.sep = getSeparator(args, '')
 local source = frame:extensionTag{
  name = 'syntaxhighlight',
  args = {
   lang = 'wikitext',
   style = args.style
  },
  content = show.source
 }
 return args.reverse and
  show.output .. args.sep .. source or
  source .. args.sep .. show.output
end

-- Alternate function to return an inline result
function p.inline(frame, demoTable)
 local show = demoTable or p.get(frame)
 local args = show.frame.args
 if show[args.result_arg] then
  return show[args.result_arg]
 end
 local yesno = require('Module:Yesno')
 args.reverse = yesno(args.reverse, false)
 args.sep = getSeparator(args, args.reverse and '←' or '→')
 local source =  frame:extensionTag{
  name = 'syntaxhighlight',
  args = {
   lang = 'wikitext',
   inline = true,
   style = args.style
  },
  content = show.source
 }
 return args.reverse and
  show.output .. args.sep .. source or
  source .. args.sep .. show.output
end

--passing of args into other module without preprocessing
function p.module(frame)
 local orphan, frame = disinherit(frame, {
  'demo_template',
  'demo_module',
  'demo_module_func',
  'demo_main',
  'demo_sep',
  'demo_br',
  'demo_result_arg',
  'demo_kill_categories',
  'nocat'
 })
 local template = frame.args.demo_template and 'Template:'..frame.args.demo_template
 local demoFunc = frame.args.demo_module_func or 'main\n'
 local demoModule = require('Module:' .. frame.args.demo_module)[demoFunc:match('^%s*(.-)%s*$')]
 frame.args.br, frame.args.result_arg = frame.args.demo_sep or frame.args.demo_br, frame.args.demo_result_arg
 local kill_categories = frame.args.demo_kill_categories or frame.args.nocat
 if demoModule then
  local named = {insert = function(self, ...) table.insert(self, ...) return self end}
  local source = {insert = named.insert, '{{', frame.args.demo_template or frame.args.demo_module, '\n'}
  if not template then
   source:insert(2, '#invoke:'):insert(4, '|'):insert(5, demoFunc)
  end
  local insertNamed = #source + 1
  for k, v in pairs(orphan.args) do
   local nan, insert = type(k) ~= 'number', {v}
   local target = nan and named or source
   target:insert'|'
   if nan then
    target:insert(k):insert'=':insert'\n'
    table.insert(insert, 1, #target)
   end
   target:insert(unpack(insert))
   local nowiki = v:match('nowiki')
   if nowiki or v:match('{{.-}}') then
    orphan.args[k] = frame:preprocess(nowiki and mw.text.unstripNoWiki(v) or v)
   end
  end
  source:insert'}}'
  table.insert(source, insertNamed, table.concat(named))
  return p.main(orphan, {
   source = table.concat(source), "<>'|=~",
   output = tostring(demoModule(orphan)):gsub(kill_categories and '%[%[Category.-%]%]' or '', ''),
   frame = frame
  })
 else
  return "ERROR: Invalid module function: "..demoFunc
 end
end

return p