Módulo:Buffer

--[[=============================
Este módulo foi criado de https://en.wikipedia.org/wiki/Module:Buffer e
https://en.wikipedia.org/wiki/User:Codehydro

=============================--]]
local function Valid(v)--type validation
	if v and v~=true then--reject nil/boolean; faster than 2 type() comparisons
		local str = tostring(v)--functions not filtered since unlikely passed by accident (Scribunto does not have userdata/thread types)
		if str~=v and str=='table' then return rawget(v, 1) and table.concat(v) end--tostring(string-type) returns same ref; same refs compare faster than type()
		if str~='' then return str end--numbers are coerced to string per table.concat op; appending in string form saves ops on repeat concat
	end
end
local noOp, MBpairs = function()end do local iMap, vMap, oMap, pIter, pOther, pFast, Next--Map
	local function init()--init = noOp after first run
		function Next(t) return next, t end--slightly faster to do this than to use select()
		function pIter(t, k) k = (iMap[t] or MBpairs(t, true) and iMap[t])[not k and 1 or vMap[t][k]] return k, t[k] end--don't use rawget; accepting unmapped tables does not measurably affect performance.
		function pOther(t, k) k = (oMap[t] or MBpairs(t, true) and oMap[t])[nil==k and 1 or vMap[t][k]] return k, t[k] end--comparison to nil because false is a valid key
		function pFast(t, k) k = not k and 1 or k < (vMap[t] or #t) and k + 1 or nil return k, t[k] end--mapless iterator; almost as fast as native ipairs; slight performance penalty when length not cached
							   --k and k < (vMap[t] or #t) and k + 1 or not k and 1 or nil return k, t[k] end--mapless iterator; almost as fast as native ipairs; slight performance penalty when length not cached
		local mk = {__mode = 'k'}--use mode 'k'; found that mode 'kv' sometimes garbage collects maps mid-loop (may not error because iterators auto re-map, but that's expensive)
		init, iMap, vMap, oMap = noOp, setmetatable({}, mk), setmetatable({}, mk), setmetatable({}, mk)--iMap is numeric keys, oMap is non-numeric keys, and vMap points to next key
	end
	function MBpairs(t, ...)--pairs always iterates in order
		local iter, ex = ...
		iter = iter==init()--nil
		if iter and not oMap[t] and ex==nil and rawget(t, 1)~=nil and next(t, #t)==nil then--while possible to miss keys, more thorough check would negate the benefit of pFast
			vMap[t] = #t return pFast, t, nil
		elseif ... or not vMap[t] or select('#', ...)~=1 then
			local ti, tn, to, n = {}, {}, {}, #t--reduces table lookups
			iMap[t], vMap[t], oMap[t] = ti, tn, to
			for k = 1, n do ti[k], tn[k] = k, k + 1 end--stage one avoids number type checking op in stage two for most numeric keys
			for k in (ex or Next)(t) do
				if not tn[k] then table.insert(tonumber(k)~=k and to or ti, k) end
			end
			if #ti~=n then
				table.sort(ti)
				for k = 1, #ti do tn[ti[k]] = k + 1 end--somewhat wasteful, but trying to avoid overwriting can be even more expensive
			end
			for k = 1, #to do tn[to[k]] = k + 1 end
		end
		return iter and pIter or oMap[t] and pOther or noOp, t--noOp for mapless
	end
end
local parent, rawkey, spec do--new scope for variables not reused outside (reduces number of var names that need to checked outside of scope)
	local mkv = {__mode='kv', __call=function(t,k,v)t[k]=v return k end}--shared meta for Buffer parent property, raw mode, and specialized functions
	parent, rawkey, spec = setmetatable({}, mkv), setmetatable({}, mkv), setmetatable({}, mkv)--shared meta less memory
end

local MB, MBi, MBmix, buffHTML, gfuncs, noCache, Element do--minimize number of locals per scope to reduce time spent sifting through irrelevant variable names
	local _stream do local stream--keep stream near top of scope
		local function init(f)--init = noOp after first run
			local function each(self, ...)
				for k = 1, select('#', ...) do
					k = Valid(select(k, ...))--slightly faster than table.insert(self, (Valid(select(k, ...))))
					if k then table.insert(self, k) end
				end
				return self
			end
			init, stream, _stream = noOp, {
				__call = function(t, v) v = v and Valid(v) return v and table.insert(t, v) or t end,--last_concat cleared before entering stream mode
				__index = function(t, i) return i=='each' and each or MB.__index(t, i) and setmetatable(t, MB)[i] end,--no table look up minimizes resources to retrieve the only stream function
				__tostring = function(t) return setmetatable(t, MB)() end
			} for k, v in next, MB do stream[k] = stream[k] or v end
			setmetatable(stream, getmetatable(MB))
		end
		function _stream(self, ...) self.last_concat = init() return setmetatable(self, stream):each(...) end
	end
	local function isMBfunc(Buffer, s, ...)--helper for :getParent()-like methods (including getBuffer which does not return a parent)
		return s and (select('#', ...)==0 and--eventually should figure out to make this work for :getHTML which is very similar
				(not rawkey[s] and tostring(s):match'^_.*' and MB.__index(Buffer, s) and MB.__index(Buffer, s)(Buffer) or MBmix(Buffer, s))--unprefixed function names append as a string
				or assert(MB.__index(Buffer, s), ('" %s " does not match any available Module:Buffer function'):format(s))(Buffer, ...)--getParent is a one-way trip so one-time assert not expensive
			) or Buffer
	end
	local function MBselect(n, ...)--helper for :_out and :_str
		local n, seps = n - 1, {select(2, ...)}
		if type(seps[n])=='table' then
			if buffHTML and rawget(seps[n], buffHTML) then return ... end
			setmetatable(seps, {__index = setmetatable(seps[n], {__index = function(t) return rawget(t, 1) end})})[n] = nil
		end
		return ..., seps
	end
	local _inHTML do local lastBuffer, lastHTML
		local function init(...)--init replaced and new version called on return
			local create, mwFunc = mw.html.create do
				local mwHTMLmeta = getmetatable(create())
				buffHTML, mwFunc, _inHTML = setmetatable(mw.clone(mwHTMLmeta), getmetatable(MB)), mwHTMLmeta.__index--buffHTML declared near top of module; remove _inHTML from outer scope
				function init(nodes, ...)
					local name, args, tag = select(... and type(...)=='table' and 1 or 2, nil, ...)
					tag = create(Valid(name), args)
					if nodes then table.insert(nodes, tag.parent and tag or rawset(tag, 'parent', parent[nodes])) end
					if args then
						local a, b = args.selfClosing, args.parent
						args.selfClosing, args.parent = nil
						if next(args) then Element._add(parent(tag.nodes, tag), args) end
						args.selfClosing, args.parent = a, b--in case args is reused
					end
					return tag
				end
				for k, v in next, {[mw] = mwHTMLmeta,
					__call = function(h, v) return MBmix(spec[h.nodes] and h.nodes or spec(setmetatable(parent(h.nodes, h), MB), Element), v) end,
					__concat = false,--false means take from MB
					__eq = false
				} do buffHTML[k] = v or MB[k] end
			end
			local nonSelf, BHi = {tag=true,done=true,allDone=true}, buffHTML.__index do local g
				g = {__index = function(t, i)
					if gfuncs and gfuncs[i] then g.__index, gfuncs = gfuncs return g.__index[i] end
				end}
				setmetatable(nonSelf, g)
				setmetatable(BHi, g)
			end
			for k in next, nonSelf do--any HTML objects returned by these funcs will be granted Module:Buffer enhancements
				local func = mwFunc[k]
				BHi[k] = function(t, ...) local HTML = func(t, ...) return parent[HTML] and HTML or setmetatable(parent(HTML, t), buffHTML) end
			end
			do local function joinNode(HTML, sep)
					local nodes, join = HTML.nodes
					if noCache and rawkey[sep] or Valid(sep) then join, HTML.nodes = tostring(rawset(HTML, 'nodes', {MB.__call(nodes, sep)})), nodes end
					return join or tostring(HTML)
				end
				for k, v in next, {
					getParent = function(HTML, ...) lastHTML = HTML return MBi.getParent(HTML:allDone(), ...) end,--return to Buffer that created the HTML tree
					getBuffer = function(HTML, ...) lastHTML = HTML return isMBfunc(lastBuffer, ...) end,--return to last used
					killParent = function(HTML, ...) MBi.killParent(HTML:allDone(), ...) return HTML end,
					_out = function(HTML, ...)
						if ...==0 then MBi._out(HTML.nodes, ...) return HTML end
						lastHTML, HTML = HTML, HTML:allDone()
						local n, ops, seps = select('#', ...)
						if n > 1 then
							local ops, seps = MBselect(n, ...)
							return parent[HTML]:_in(joinNode(HTML, rawget(seps, 0))):_out(ops, rawset(seps, buffHTML, true))
						end
						return parent[HTML]:_(joinNode(HTML, ...))
					end,
					_str = function(HTML, ...)--does not set lastHTML
						if ...==0 then return joinNode(HTML, select(2, ...)) end--passing 0 strings without calling allDone()
						local HTML, n = HTML:allDone(), select('#', ...)
						if n > 1 then
							local ops, seps = MBselect(n, ...)
							return parent[HTML]:_in(joinNode(HTML, rawget(seps, 1))):_str(ops, rawset(seps, buffHTML, true))
						end
						return joinNode(HTML, ...)
					end,
					_parent = function(HTML, ...) table.insert(HTML.nodes, parent[HTML:allDone()]:_str(...)) return HTML end
				} do BHi[k] = v end
			end
			do local htmlArg, skip, outFuncs = {parent=true,selfClosing=true,tagName=true}, {}
				do local out local function func(nodes, ...) return out(parent[nodes], ...) end
					outFuncs = setmetatable({
						tag = function(nodes, ...) return parent(setmetatable(init(nodes, ...), buffHTML), parent[nodes]) end,
						done = function(b, ops)
							b = parent[b]
							while b.parent and ops~=0 do b, ops = b.parent, ops and ops - 1 or 0 end
							return b
						end
					}, {__index = function(nodes, i)
						if rawget(BHi, i) then out = BHi[i] return func end--rawget to exclude globals
					end})
				end
				Element = {
					_add = function(nodes, t)
						for k, v in MBpairs(t), t, skip[t] do (v~=true and MBmix or noOp)(nodes, v) end
						local HTML = parent[nodes] for k, v in MBpairs(t, false) do
							if htmlArg[k] then HTML[k] = v
							elseif v and v~=true then
								if nonSelf[k] then
									if k=='tag' then
										if type(v)=='table' then
											skip[v], k = 1, rawset(create(Valid(v[1])), 'parent', HTML)
											Element._add(spec(parent(k.nodes, k, table.insert(nodes, k)), Element), v)
											if k.selfClosing then k.nodes = nil else spec[k.nodes], parent[k.nodes] = nil end--free memory/reduce clutter; parent ref will auto-unset when k.nodes is nil
											if not k.tagName then k.styles, k.attributes = nil end
										else table.insert(nodes, create(v)) end
									elseif mwFunc[k] then
										if k=='done' and tonumber(v)~=v and v[1] and tonumber(v[1])==v[1] then skip[v] = 1 end
										MBmix(outFuncs[k](nodes, skip[v] and v[1]).nodes, v)
									elseif v[1] or v[2] then
										k = MBi[k](nodes, unpack(v, 1, rawset(skip, v, k=='_B' and 1 or 2)[v]))
										Element._add(getmetatable(k) and rawget(k, 'nodes') or k, v)--if k is not a table, then v should not contain any extra keys or this may error.
									else MBi[k](nodes, v) end--k probably == '_G' or '_R'
								elseif mwFunc[k] then
									if type(v)~='table' or rawget(v, 'nodes') then mwFunc[k](HTML, v)
									else
										local css = k=='css'
										for x, y in MBpairs(v, true) do (y and y~=true and mwFunc[k] or noOp)(HTML, css and x:gsub('_', '-') or x, y) end--iterate non-numbers first
										for _, y in MBpairs(v, nil) do (y and y~=true and mwFunc[k] or noOp)(HTML, y) end--don't bother with gsub since text must be quoted anyhow
									end
								elseif rawget(Element, k) or rawget(MBi, k) then
									if tonumber(v)==v or v[1]==nil or getmetatable(v) then (Element[k] or MBi[k])(nodes, v)--v is probably string-able object, or a table to be handled by :_all
									else (Element[k] or MBi[k])(nodes, unpack(v, 1, table.maxn(v))) end--v is definately a table
								else mwFunc.css(HTML, k:gsub('_', '-', 1), tostring(v)) end--oddly enough, :_add clocked its fastest runtime after adding auto-gsub as a feature
								skip[v] = nil
							end
						end
						return nodes
					end
				}
				local tempMeta = {mode='v', copy={styles=true,attributes=true}}
				function tempMeta.__index(t, i) return tempMeta.copy[i] and rawset(t, i, MBi._cc(false, 0, t.orig[i]))[i] or t.orig[i] end
				rawkey[setmetatable(Element, {__index = outFuncs, __concat=function(Element, v) return setmetatable({nodes=spec({}, Element),orig=parent[v]}, tempMeta) end})] = math.huge
			end
			function MBi:getHTML(...)
				lastBuffer = self
				if ... then
					if select('#', ...)==1 then return not rawkey[s] and tostring(...):match'^_' and BHi[...] and BHi[...](lastHTML) or lastHTML(...)
					else return assert(BHi[...], ('" %s " does not match any mw.html or Buffer-mw.html function'):format(tostring(...)))(lastHTML, select(2, ...)) end
				end
				return lastHTML
			end
			function MBi:_html(...) return MBi._(self, lastHTML, select(spec[self]==Element and select('#', ...)==0 and 1 or 2, true, ...)) end
			return init(...)
		end
		function _inHTML(self, ...)
			local HTML = init(nil, ...)
			if HTML.selfClosing and spec[self]==Element then self.last_concat = table.insert(self, HTML) return self end
			lastBuffer, lastHTML = self, setmetatable(parent(HTML, self), buffHTML)--set after 'args' table processed by :_add
			return HTML
		end
	end
	local _var, unbuild do local prev, rebuild
		local function init(...)--init replaced before return
			local function pick(b, v) return b and table.insert(b, v) or v end
			local function c(a, num) return rawset(a.a or a, 0, a[0] and a[0] + a.c or num and a[1] or a[1]:byte())[0] end
			local same, build, alt = {__tostring = function(a, b) return a.a[0] and pick(b, a.a.string and string.char(a.a[0]) or a.a.table and a.a[1][a.a[0]] or a.a[0]) end}, {
				__index = {c = 1},
				__tostring = function(t) return t:_build() end,
				table = function(a, b) local i = next(a[1], a[0]) or a[0]==#a[1] and next(a[1]) return pick(b, rawset(a.a or a, 0, i)[1][i]) end,--change rate (a.c) ignored since users control the table's contents
				number = function(a, b) return pick(b, c(a, true)) end,
				string = function(a, b) return pick(b, string.char(c(a))) end
			}, {__index = function(a, i) return a.a[i] end, __tostring = function(a, b) return (rawget(a, 0) and a[0]==tostring(a[0]) and rawset(a, 0, a[0]:byte()) or a).a._build(a, b) end}
			local function shift(t, c)
				t[0] = t[0] and t[0] + c or t:_build() and t[0] - t.c + c
				if t.table then t[0] = (t[0] - 1) % #t[1] + 1 end
			end
			function rebuild(...)
				local v, c = ...
				if v or select('#', ...)==0 then
					if v and not c then return prev end
					local meta, c = select(v and 1 or 3, alt, c, same, 0)
					return setmetatable({a = prev, _build = meta.__tostring, c = c}, meta)
				elseif v==nil then--no-op
				elseif c then shift(prev, c)--v == false
				else prev:_build() end
			end
			init, noCache = function(v, c) prev = setmetatable({v, c = c, _build = build[type(v)] or v, [type(v)] = true, alt = {}}, build) return prev end, true
			return init(...)
		end
		function unbuild(sep)
			for k, v in MBpairs(sep, nil) do
				k = getmetatable(v) if k and (k==build or k==alt) then shift(v.a or v, -v.c) end
			end
		end
		function _var(self, ...)
			local obj if ... and ...~=true then obj = init(...)
			elseif prev then
				if ...~=false then obj = rebuild(...)
				else rebuild(...) end
			end
			return obj and MBi._(self, obj, nil, true) or self
		end
	end
	local lib; MBi = setmetatable({stream = _stream,
		_inHTML = _inHTML,
		_var = _var,
		_ = function(self, v, ...)
			local at, raw = select(select('#', ...)==1 and ...==true and 1 or 2, nil, ...)
			if raw then rawkey[self] = math.huge else v = Valid(v) end
			if v or raw then
				if at or rawkey[self] then raw = #self end--if length increases by more than one after table.insert, then set rawkey[self] = math.huge; rawkey[self] may be equal to a previous 'at'
				at, self.last_concat = at and (tonumber(at)~=at and raw + at or at)
				table.insert(self, select(at and 1 or 2, at, v))
				if at and at < 0 or raw and #self - raw > 1 then rawkey[self] = math.huge elseif at and #self==raw then rawkey[self] = rawkey[self] and math.max(rawkey[self], at) or at end
			end--above line looks bizarre because one table.insert op may make length jump from 0 to 8: local wtf={[2]=2,[4]=4,[8]=8}mw.log(#wtf,table.insert(wtf,1),#wtf)
			return self
		end,
		_nil = function(self, at, ...)
			if ...~=true and ...~=false then--faster than type(...) ~= 'boolean'
				if not at or at=='0' then
					self[#self] = ... if ... then rawkey[self] = math.huge end
				else
					local n, v = tonumber(at), ...
					if n~=at then
						if n then n = #self + at
						elseif at~=true and select('#', ...)==0 then v, n = at, #self end
					end
					if n then
						if v==nil and n > 0 then table.remove(self, n)
						else self[math.floor(n)], rawkey[self] = v, math.huge end--floor position for consistency with Table library
					end
				end
				self.last_concat = nil
			end
			return self
		end,
		_all = function(self, t, valKey)
			for k, v in MBpairs(t) do MBmix(self, v, valKey) end
			for k, v in valKey and MBpairs(t, false) or noOp, t do
				if tonumber(v) then MBi._(self, k, v)--self not always a buffer
				elseif rawget(MBi, k) and v and v~=true then
					if v[1]==nil or getmetatable(v) then MBi[k](self, v)
					else MBi[k](self, unpack(v, 1, table.maxn(v))) end
				end
			end
			return self
		end,
		_str = function(t, ...)
			local n = select('#', ...)
			if n > 1 then
				local k, ops, seps, r = 2, MBselect(n, ...)
				r = MB(t(seps[1]))
				while parent[t] and ops > 1 and r:_(parent[t](seps[k]), 1) do t, k, ops = parent[t], k + 1, ops - 1 end
				return table.concat(r, seps[k] or nil)
			end
			return MB.__call(t, ...)
		end,
		_in = function (self, ...) return parent(MB(...), self) end,
		_out = function(t, ...)
			if ...==0 then return parent(t, parent[t], MBi._cc(t, t, MB.__call(t, (select(2, ...))), getmetatable(t))) end--love how :_cc needed nothing new to implement this *self pat on back*
			local n = select('#', ...)
			if n > 1 then
				local k, ops, seps = 1, MBselect(n, ...)
				while parent[t] and ops > 0 do t, k, ops = parent[t]:_(t(seps[k])), k + 1, ops - 1 end
			elseif parent[t] then return parent[t]:_(t(...)) end
			return t
		end,
		_cc = function(self, clear, copy, meta)
			if clear then
				if rawequal(clear, copy) then return self, spec[MBi._cc] and setmetatable(spec[MBi._cc], MB)--rawequal to avoid re-string via __eq in case both are different Buffer objects
				elseif copy==true then copy = self end
				if clear~=0 then
					assert(type(clear)=='table', debug.traceback('Buffer:_cc can only "clear" tables. Did you forget to call with a colon?', 2))--errors can be hard to trace without this
					for k in self and next or noOp, clear do rawset(clear, k, nil) end
				else return MBi._cc(false, {unpack(copy)}, copy) end--copy length w/o empty strings; recursion to avoid self = false causing garbage collection (non-weak child may exist)
				if self==false or copy and type(copy)=='table' then--self==false means copy is a table (saves a type op for recursive calls)
					meta = meta or getmetatable(copy)
					if self and #copy > 1 then--preserves length with empty strings; developed from studying http://www.lua.org/source/5.1/ltable.c.html		
						local n, null, i, e = #copy, {}, math.ldexp(2, select(2, math.frexp(#copy)) - 2)
						e, spec[MBi._cc], parent[null] = i - 1, null, clear
						for k = 1, e do table.insert(clear, false) end
						while i<=n do table.insert(clear, i, '') i, null[i] = i + math.ldexp(2, select(2, math.frexp(n - i)) - 2), '' end
						for k = 1, e do rawset(clear, k, nil) end
					end
					for k, v in next, copy do rawset(clear, k, type(v)=='table' and MBi._cc(false, 0, v) or v) end
				elseif copy then rawset(clear, 1, (Valid(copy))) end
				rawkey[setmetatable(clear, meta)], parent[clear] = rawkey[copy], parent[copy]
			end
			return self and rawset(self, 'last_concat', nil) or clear
		end,
		_parent = function(self, ...) return parent[self] and MBi._(self, parent[self]:_str(...)) or self end,
		getParent = function(self, ...) return isMBfunc(parent[self] or parent[parent(self, setmetatable({}, MB))], ...) end,
		killParent = function(self, ...) return parent[self] and isMBfunc(parent[self], ...) and parent(self) or self end,
		_build = function(self, t) table.insert(t, self()) end,--for compatibility with mw.html:node()
		last_concat = false--prevent library check
	}, {__index = function(t, i)--import string, mw.text, and mw.ustring libraries on an as-needed basis
		local func = string[i] or mw.text[i] or mw.ustring[i] or type(i)=='string' and mw.ustring[i:match'^u(.+)'] if func then
			lib	= lib or function (s, f, ...)
				if parent[s] and next(s)==nil then return s:_((f(tostring(parent[Element and (spec[s]==Element and s:allDone() or spec[parent[s]]==Element and parent[s]) or s]), ...))) end
				return f(tostring(s), ...)--not using ternary/logical operators here to allow multiple return values
			end
			return rawset(t, i, i:match'^u?gsub' and function(self, p, r, ...)return lib(self, func, p, r or '', ...)end--Why are ugsub/gsub special? because empty strings are against my religion!
				or function(self, ...)return lib(self, func, ...)end)[i]
		end
	end})
end

function MBmix(t, v, ...) return v and ((type(v)~='table' or getmetatable(v)) and MBi._(t, v) or (select('#', ...)==0 and spec[t] and spec[t]._add or MBi._all)(t, v, ...)) or t end--:_all always passes two args

local _G, new_G = _G--localize _G for console testing (console _G ~= module _G)
return setmetatable({__index = function(t, i) return spec[t] and spec[t][i] or MBi[i] end,
	__call = function(t, ...)
		local rawsep, sep, i, j, raw = noCache and rawkey[...] and ..., ...
		if i or j or rawsep or Valid(sep) then
			raw, sep, i, j = rawkey[spec[t]] or rawkey[t], rawsep or Valid(sep), i and (i~=tonumber(i) and i + #t or i), j and (j~=tonumber(j) and j + #t or j)
			if rawsep or raw and (raw>=(j or #t) or i < 1) then
				raw, i, j = {}, i and math.floor(i), j and math.floor(j)--floor for consistency with table.concat(t, sep, i, j), which ignores decimals
				raw.lc, t.last_concat = t.last_concat--temporarily unset last_concat to prevent disqualification from mapless iteration
				for k, v in MBpairs(t) do
					if raw[1] or not i or k>=i then if j and k > j then break end
						if raw.s then raw.s = table.insert(raw, tostring(sep)) end--if sep contains v and v is a Buffer-variable, sep must be strung before v
						k = Valid(v) if k then
							raw.s = rawsep or sep and raw[1] and table.insert(raw, sep)
							table.insert(raw, k)
						end
					end
				end
				if rawsep and not raw.s then raw[#raw] = unbuild(sep) end--unbuild rawsep if final index in t was invalid
				t.last_concat = raw.lc return table.concat(raw)
			end
			return table.concat(t, sep, i and math.max(i, 1), j and math.min(j, #t))
		end
		return MB.__tostring(t)
	end,
	__tostring = function(t)
		if t.last_concat then return t.last_concat end
		local r = rawkey[spec[t]] or rawkey[t]
		r = table.concat(r and r>=#t and MBi._all({}, t) or t)
		return (noCache or rawset(t, 'last_concat', r)) and r
	end,
	__concat = function(a, b)
		if buffHTML then
			for k = 1, 2 do local v = select(k, a, b)--faster than for k, v in pairs{a, b} do
				if v and spec[v] and spec[v]==Element then
					if parent[v].selfClosing then
						if rawequal(a, b) then return (not noCache or parent[v].tagName) and v:_str(0):rep(2) or v:_str(0)..v:_str(0) end--rawequal avoids premature tostring of Buffer:_var objects;
						b, a = select(k, b, parent[v], a)
					else local temp = Element .. v --helper method; returns a mirror of parent[v]
						MBmix(MBmix(parent(temp.nodes, temp), a), k==1 and spec[b]==Element and parent[b] or b)
						return buffHTML.__tostring(setmetatable(temp, {__index=parent[v], __mode='v'}))--switch from tempMeta to avoid MBi._cc op of styles/attributes
					end
				end
			end
		end
		return table.concat(MBmix(MBmix({}, a), b))
	end,
	__pairs = MBpairs,
	__ipairs = MBpairs,
	__eq = function(a, b) return tostring(a)==tostring(b) end--avoid a==b in this module; use rawequal(a,b) when they may be different Buffers (premature tostring waste ops and is bad for Buffer:_var)
}, {__tostring = function()return''end,
	__call = function(self, ...) MB = MB or self
		if new_G then if ... and _G and ...==_G then new_G = ... end
		elseif ... and (...==_G or type(...)=='table' and (...)._G==...) then
			local Nil, mG = {}, (...):getmetatable() or (...):setmetatable{}:getmetatable()
			new_G, _G, gfuncs = ..., ..., {--gfuncs stored for Buffer:_inHTML; new_G is a is a Module:Buffer local declared just before the final return statement.
				_G = function(self, i, ...)
					local X, save = rawget(new_G, i), select('#', ...)==0 and self or ...
					if i and i~=true and not (X and save and rawequal(X, save)) and rawset(new_G, i, save) and (X~=nil or save==nil and new_G[i]~=nil) then--rawequal in case X is another buffer
						local mG = getmetatable(new_G) or {__call=mG.__call}
						if mG.__index then pcall(rawset, mG.__index, i, X)
						else mG.__index = setmetatable(new_G, mG) and {[i] = X} end
					end
					return self, ...--avoiding __eq with rawequal(self,save) is overkill since buffers can self-save without being passed as save
				end,
				_R = function(self, i, v, m)
					if i~='new_G' then if i and i~=true then rawset(new_G, i , v) end
					elseif not v or v==true or v._G~=_G then new_G = setmetatable(v~=true and v or {}, {__call = mG.__call, __index = v~=true and m~=true and (m or new_G) or nil})
					else new_G, (not m and (m~=nil or v==new_G) and Nil or getmetatable(v)).__index = v, m~=true and (m or new_G) or nil end--setting Nil.__index is noOp
					return self
				end,
				_2 = function(self, ...)
					if new_G[...]~=nil then return new_G[...] end--higher priority so Buffer:_G('new_G', ...) can prevent an overwrite
					if ...=='new_G' then return rawset((select('#', ...)~=1 and MBi._R(new_G, ...) or new_G), '_G', _G) end
					return select(select('#', ...)==1 and 1 or 2, self:_G(...))--return only one value; 'return select(2, self:_G(...)) or self' doesn't work for returning nil
				end,
				_B = function(self, v) return v or v==nil and Nil end
			} for k, v in next, gfuncs do MBi[k] = v end
			setmetatable(Nil,{__concat=MB.__concat,__newindex=noOp,__call=noOp,__tostring=noOp,__metatable=MB,__index=setmetatable({_B=MBi._B,_=function()return Nil end,last_concat=''},
				{__index=function(t,i)return (MBi[i] or i and not tonumber(i)) and t._ or nil end})})
			function mG.__call(G, k, ...) return (k._G or G.type(k)=='table') and (G.select('#', ...)~=1 and G.rawset(k, ...) or G:rawset(..., k) and k) or G:rawset(k, (...)) and ... end
		end
		local new = setmetatable({}, self)
		if ... and (...)==new_G then return select(2, ...) and MBmix(new:_G((select(2, ...))), select(3, ...)) or new end
		return ... and MBi._(new, ...) or new
	end,
	__index = function(t, i)
		MB = MB or t return MBi[i] and function(...) return MBi[i](setmetatable({}, t), select(...==t and 2 or 1,...)) end
	end
})