local getArgs = require('Module:Arguments').getArgs local p = {} -- module's table  -- Elements with wiki links local am = { 	H = "হাইড্রোজেন", 	He = "হিলিয়াম", 	Li = "লিথিয়াম", 	Be = "বেরিলিয়াম", 	B = "বোরন", 	C = "কার্বন", 	N = "নাইট্রোজেন", 	O = "অক্সিজেন", 	F = "ফ্লোরিন", 	Ne = "নিয়ন", 	Na = "  সোডিয়াম ", 	Mg = "ম্যাগনেসিয়াম", 	Al = "অ্যালুমিনিয়াম", 	Si = "সিলিকন", 	P = "ফসফরাস", 	S = "সালফার", 	Cl = "ক্লোরিন", 	Ar = "আর্গন", 	K = "পটাসিয়াম", 	Ca = "ক্যালসিয়াম", 	Sc = "স্ক্যান্ডিয়াম", 	Ti = "টাইটানিয়াম", 	V = "ভ্যানডিয়াম", 	Cr = "ক্রোমিয়াম", 	Mn = "ম্যাঙ্গানিজ", 	Fe = "লোহা", 	Co = "কোবল্ট", 	Ni = "নিকেল", 	Cu = "তামা", 	Zn = "জিঙ্ক", 	Ga = "গ্যালিয়াম", 	Ge = "জার্মানিয়াম", 	As = "আর্সেনিক", 	Se = "সেলেনিয়াম", 	Br = "ব্রোমিন", 	Kr = "ক্রিপ্টন", 	Rb = "রুবিডিয়াম", 	Sr = "স্ট্রনটিয়াম", 	Y = "Yttrium", 	Zr = "জিরকোনিয়াম", 	Nb = "নিওবিয়াম", 	Mo = "মলিবডেনাম", 	Tc = "টেকনেটিয়াম", 	Ru = "রুথেনিয়াম", 	Rh = "রোডিয়াম", 	Pd = "প্যালাডিয়াম", 	Ag = "সিলভার", 	Cd = "ক্যাডমিয়াম", 	In = "ইন্ডিয়াম", 	Sn = "টিন", 	Sb = "অ্যান্টিমনি", 	Te = "টেলুরিয়াম", 	I = "আয়োডিন", 	Xe = "জেনন", 	Cs = "সিসিয়াম", 	Ba = "বেরিয়াম", 	La = "ল্যান্থানাম", 	Ce = "সেরিয়াম", 	Pr = "প্রাসোডিয়ামিয়াম", 	Nd = "নিওডিয়ামিয়াম", 	Pm = "প্রোমিথিয়াম", 	Sm = "সামেরিয়াম", 	Eu = "ইউরোপিয়াম", 	Gd = "গ্যাডোলিনিয়াম", 	Tb = "টার্বিয়াম", 	Dy = "Dysprosium", 	Ho = "হোলমিয়াম", 	Er = "Erbium", 	Tm = "থুলিয়াম", 	Yb = "Ytterbium", 	Lu = "লুটেটিয়াম", 	Hf = "হাফনিয়াম", 	Ta = "ট্যান্টালাম", 	W = "টাংস্টেন", 	Re = "রেনিয়াম", 	Os = "ওসমিয়াম", 	Ir = "ইরিডিয়াম", 	Pt = "প্ল্যাটিনাম", 	Au = "সোনা", 	Hg = "বুধ (উপাদান)", 	Tl = "থ্যালিয়াম", 	Pb = "লিড", 	Bi = "বিসমাথ", 	Po = "পোলোনিয়াম", 	At = "অ্যাস্টাটাইন", 	Rn = "Radon", 	Fr = "ফ্রান্সিয়াম", 	Ra = "রেডিয়াম", 	Ac = "অ্যাক্টিনিয়াম", 	Th = "থোরিয়াম", 	Pa = "প্রোট্যাক্টিনিয়াম", 	U = "ইউরেনিয়াম", 	Np = "নেপচুনিয়াম", 	Pu = "প্লুটোনিয়াম", 	Am = "Americium", 	Cm = "কিউরিয়াম", 	Bk = "বার্কেলিয়াম", 	Cf = "ক্যালিফোর্নিয়াম", 	Es = "আইনস্টাইনিয়াম", 	Fm = "ফার্মিয়াম", 	Md = "মেন্ডেলভিয়াম", 	No = "নোবেলিয়াম", 	Lr = "লরেন্সিয়াম", 	Rf = "রাদারফোর্ডিয়াম", 	Db = "ডবনিয়াম", 	Sg = "সিবোরজিয়াম", 	Bh = "বোহরিয়াম", 	Hs = "হাসিয়াম", 	Mt = "মেইটনেরিয়াম", 	Ds = "ডার্মস্টাডটিয়াম", 	Rg = "রেন্টজেনিয়াম", 	Cp = "কোপার্নিশিয়াম", 	Nh = "নিহোনিয়াম", 	Fl = "ফ্লেরভিয়াম", 	Mc = "মস্কোভিয়াম", 	Lv = "লিভারমোরিয়াম", 	Ts = "টেনেসাইন", 	Og = "ওগেনেসন", 	 	-- গ্রুপ ইত্যাদি উপাদানের মত নাম 	Bn = 'বেনজিল গ্রুপ', 	Bz = 'বেনজয়েল গ্রুপ', 	D = 'ডিউটেরিয়াম', 	Et = 'ইথাইল গ্রুপ', 	Ln = 'ল্যান্থানাইড', 	Nu = 'নিউক্লিওফাইল', 	Ph = 'ফিনাইল গ্রুপ', 	R = 'প্রতিস্থাপক', 	T = 'ট্রিটিয়াম', 	Tf = 'ট্রাইফ্লুরোমিথাইলসালফোনাইল গ্রুপ', 	X = 'হ্যালোজেন', }  -- Groups which are redirected from their normal target if wikilinked; never -- autolinked. local groups = { 	CH3 = 'মিথাইল গ্রুপ', 	CO3 = 'কার্বনেট', 	COOH = 'কারবক্সিল গ্রুপ', 	ClO = 'হাইপোক্লোরাইট', 	ClO2 = 'ক্লোরাইট', 	ClO3 = 'ক্লোরেট', 	ClO4 = 'পারক্লোরেট', 	H2O = 'ক্রিস্টালাইজেশনের জল', 	H3O = 'হাইড্রোনিয়াম', 	NH2 = 'আমিন গ্রুপ', 	NH4 = 'অ্যামোনিয়াম', 	NO3 = 'নাইট্রেট', 	PO3 = 'ফসফাইট', 	PO4 = 'ফসফেট', 	SH = 'থিওল গ্রুপ', 	SO3 = 'সালফাইট', 	SO4 = 'সালফেট', 	SeH = 'সেলেনল গ্রুপ' }  local T_ELEM = 0         -- token types local T_NUM = 1          -- number local T_OPEN = 2         -- open '(' local T_CLOSE = 3        -- close ')' local T_PM_CHARGE = 4    -- + or − local T_WATER = 6        -- .xH2O x number local T_CRYSTAL = 9      -- .x local T_CHARGE = 8       -- charge (x+), (x-) local T_SUF_CHARGE = 10  -- suffix and charge e.g. 2+ from H2+ local T_SUF_CHARGE2 = 12 -- suffix and (charge) e.g. 2(2+) from He2(2+) local T_SPECIAL = 14     -- starting with \ e.g. \d for double bond (=) local T_SPECIAL2 = 16    -- starting with \y{x} e.g. \i{12} for isotope with mass number 12 local T_ARROW_R = 17     -- match: -> local T_ARROW_EQ = 18    -- match: <-> local T_UNDERSCORE = 19  -- _{ ... } local T_CARET = 20       -- ^{ ... } local T_LINKOPEN = 21    -- Opening of link, always like "" even if the source wasn't local T_NOCHANGE = 30    -- Anything else like ☃  function su(up, down) 	if up == "" then 		return ('%s'):format(down) 	end 	if down == "" then 		return ('%s'):format(up) 	end     return ('%s%s'):format(up, down) end  function DotIt()     return '·' end  function item(f) -- (iterator) returns one token (type, value) at a time from the formula 'f'     local i = 1      return function ()         local t, x = nil, nil          if (i == 1) and f:match('^[0-9]', i) then              x = f:match('^[%d.]+', i); t = T_NOCHANGE; i = i + x:len();   -- matching coefficient (need a space first)          elseif i <= f:len() then             x = f:match('^%s+[%d.]+', i); t = T_NOCHANGE;  -- matching coefficient (need a space first)             if not x then x = f:match('^%s[+]', i); t = T_NOCHANGE; end       -- matching + (H2O + H2O)             if not x then x = f:match('^%&%#[%w%d]+%;', i); t = T_NOCHANGE; end       -- &#...;             if not x then x = f:match('^%<%-%>', i); t = T_ARROW_EQ; end       -- matching <->             if not x then x = f:match('^%-%>', i); t = T_ARROW_R; end       -- matching ->             if not x then x = f:match('^%u%l*', i); t = T_ELEM; end        -- matching symbols like Aaaaa             if not x then x = f:match('^%d+[+-]', i); t = T_SUF_CHARGE; end        -- matching x+, x-             if not x then x = f:match('^%d+%(%d*[+-]%)', i); t = T_SUF_CHARGE2; end        -- matching x(y+/-), x(+/-)             if not x then x = f:match('^%(%d*[+-]%)', i); t = T_CHARGE; end        -- matching (x+) (xx+), (x-) (xx-)             if not x then x = f:match('^[%d.]+', i); t = T_NUM; end        -- matching number             if not x and (f:match('^%[%[%[[^[]', i) or f:match('^%[[^[]', i)) then             	i = i + 1; return T_OPEN, '[' end -- escape [[[X or [X (relevant to auto-linking)             if not x and f:sub(i, i + 1) == '[[' then             	x = f:match('^%[%[([^]|]*)', i) -- link target             	local len = x:len() + 3             	x = '[[' .. (groups[x] or am[x] or x) .. '|'  -- override link target for common groups              	if f:sub(len + i, len + i) == ']' then             		-- We're going to read the link twice, once as target and once as             		-- chemical markup, e.g. CH3 => "", "CH3"             		i = i + 2             	else             		i = i + len             	end             	return T_LINKOPEN, x             end             if not x then x = f:match('^[(|{|%[]', i); t = T_OPEN; end     -- matching ({[             if not x then x = f:match('^[)|}|%', i); t = T_CLOSE; end    -- matching )}]             if not x then x = f:match('^[+-]', i); t = T_PM_CHARGE; end    -- matching + or -             if not x then x = f:match('^%*[%d.]*H2O', i); t = T_WATER; end -- Crystal water             if not x then x = f:match('^%*[%d.]*', i); t = T_CRYSTAL; end  -- Crystal             if not x then x = f:match('^[\\].{%d+}', i); t = T_SPECIAL2; end -- \y{x}             if not x then x = f:match('^[\\].', i); t = T_SPECIAL; end -- \x             if not x then x = f:match('^_{[^}]*}', i); t = T_UNDERSCORE; end -- _{...}             if not x then x = f:match('^\^{[^}]*}', i); t = T_CARET; end   -- ^{...}             if not x then x = f:match('^.', i); t = T_NOCHANGE; end  --the rest - one by one             if x then i = i + x:len(); else i = i + 999; error("Invalid character in formula! : "..f) end         end         return t, x     end end  function p._chem(args)     local f = args[1] or     f = string.gsub(f, "–", "-")  -- replace – with - (hyphen not ndash)     f = string.gsub(f, "−", "-")  -- replace – with - (hyphen not minus sign)      local formula =      local t, x      local link = args['link'] or ""     local auto = args['auto'] or ""     local seen = {}     local _debug = false      if not (link == '') then formula = formula .. ""; end   -- wikilink start       for t, x in item(f) do      	if _debug then     		formula = ("%s\n* %d %s"):format(formula, t, x)         elseif t == T_ELEM then             if (auto == ) or (not am[x]) or seen[x] then formula = formula .. x             else formula = ("%s%s"):format(formula, am[x], x); seen[x] = true             end         elseif t == T_COEFFICIENT then formula = formula .. x         elseif t == T_NUM   then formula = formula .. su("", x);         elseif t == T_LINKOPEN  then formula = formula .. x;      --         elseif t == T_OPEN  then formula = formula .. x;          -- ([{         elseif t == T_CLOSE then formula = formula .. x;          -- )]}         elseif t == T_PM_CHARGE    then formula = formula .. su(x:gsub("-", "−"), "");         elseif t == T_SUF_CHARGE then              formula = formula .. su(x:match("[+-]"):gsub("-", "−"), x:match("%d+"), "");         elseif t == T_SUF_CHARGE2 then              formula = formula .. su(x:match("%(%d*[+-]"):gsub("-", "−"):sub(2, -1), x:match("%d+"))         elseif t == T_CHARGE then         	formula = formula .. ""         	if x:match("%d+") then formula = formula .. x:match("%d+"); end         	formula = formula .. x:match("[%+-]"):gsub("-", "−") .. "";         	-- Cannot concatenat a nil value from x:match("%d+");         elseif t == T_CRYSTAL then formula = formula .. DotIt() .. string.gsub( x, "*", , 1 );         elseif t == T_SPECIAL then             parameter = x:sub(2, 2) -- x fra \x               if     parameter == "s" then formula = formula .. "−"   -- single bond             elseif parameter == "d" then formula = formula .. "="   -- double bond             elseif parameter == "t" then formula = formula .. "≡"   -- tripple bond             elseif parameter == "q" then formula = formula .. "≣"   -- Quadruple bond             elseif parameter == "h" then formula = formula .. "η"   -- η, hapticity             elseif parameter == "*" then formula = formula .. "*"   -- *, normal *             elseif parameter == "-" then formula = formula .. "-"   -- -             elseif parameter == "\\" then formula = formula .. "\\"   -- \             elseif parameter == "\'" then formula = formula .. "'"   -- html-code for '             end         elseif t == T_SPECIAL2 then  -- \y{x}             parameter = x:sub(2, 2) -- y fra \y{x}              if parameter  == "h" then --Hapticity                 if (auto == ) then formula = formula .. "η" .. x:match('%d+') .. "-"                 else                     formula = formula .. "η" .. x:match('%d+') .. "-"                 end             elseif parameter == "m" then formula = formula .. "μ" .. x:match('%d+') .. "-" -- mu (bridging ligand)             end         elseif t == T_WATER then              if x:match("^%*[%d.]") then                  formula = formula .. DotIt() .. x:match("%f[%.%d]%d*%.?%d*%f[^%.%d%") .. "H2O";             else                 formula = formula .. DotIt() .. "H2O";             end           elseif t == T_UNDERSCORE  then formula = formula .. su("", x:sub(3,-2)) -- x contains _{string}         elseif t == T_CARET then formula = formula .. su(x:sub(3,-2), "") -- x contains ^{string}         elseif t == T_ARROW_R then formula = formula .. " → "         elseif t == T_ARROW_EQ then formula = formula .. " ⇌ "         elseif t == T_NOCHANGE  then formula = formula .. x;  -- The rest - everything which isn't captured by the regular expresions.               else error('unreachable - ???') end -- in fact, unreachable     end      if not (link == nil or link == ) then formula = formula .. ""; end   -- wikilink closing      formula = mw.getCurrentFrame():preprocess('') ..         '' .. formula .. ''     if args[2] or args[3] or args[4] then         formula = formula .. require('Module:If preview')._warning{ '{{chem2}} was called with multiple positional arguments. It should have just one, e.g. {{chem2|H2O}}.'         }     end     return formula end  function p.chem(frame)     local args = getArgs(frame)     return p._chem(args) end  -- PRIVATE function to generate documentation. function p._autodoc(frame) 	local TableTools = require('Module:TableTools') -- we don't want to load this on articles for no reason 	local result = { 		'===Elements and element-style symbols===\nThese may be automatically linked or used as if they were redirects.\n', 		'{| class="wikitable"\n! Symbol !! Link target\n' 	} 	for symbol, target in TableTools.sortedPairs(am) do 		result[#result + 1] = ('|-\n| %s || %s\n'):format(symbol, target) 	end 	result[#result + 1] = '|}\n===Groups===\nThese must be linked manually; they work as if they were redirects.\n' 	result[#result + 1] = '{| class="wikitable"\n! Symbol !! Link target\n' 	for symbol, target in TableTools.sortedPairs(groups) do 		result[#result + 1] = ('|-\n| %s || %s\n'):format(symbol, target) 	end 	result[#result + 1] = '|}' 	return table.concat(result) end  return p