Module:Sandbox/trappist the monk/strcmp

Documentation for this module may be created at Module:Sandbox/trappist the monk/strcmp/doc

--local function strcmp (str_a, str_b)
local function strcmp (frame)
	local str_a = frame.args[1];
	local str_b = frame.args[2];

	str_a = str_a:gsub ('(%-%-templatestyles%-)%x+(%-)', '%100000000%2')
	str_b = str_b:gsub ('(%-%-templatestyles%-)%x+(%-)', '%100000000%2')

	local result = {};
	
	local len_a = str_a:len();
	local len_b = str_b:len();
	
	local t_str_a = {}
	local t_str_b = {}
	
	local limit = len_a;														-- assume that both strings are same length

	if len_a == len_b then
		if str_a == str_b then
			return 'equal';
		end
	else
		table.insert (result, 'length mismatch: a: ' .. len_a .. '; b: ' .. len_b);
		if len_a < len_b then
			limit = len_a;
		else
			limit = len_b;
		end
	end

	for c in string.gmatch (str_a, '.') do
		table.insert (t_str_a, c);
	end
	for c in str_b:gmatch ('.') do
		table.insert (t_str_b, c);
	end
	
	local i = 1;
	while i < limit do
		if t_str_a[i] == t_str_b[i] then
			i = i + 1;															-- position of last equal character
		else
			break;
		end
	end

	if len_a ~= len_b then														-- if length mismatch 
		if not t_str_a[i] and t_str_b[i] or 									-- if one but not both are nil
			t_str_a[i] and not t_str_b[i] then
				i = i + 1;														-- point to last matching character
		end
	end

	if limit == i then															-- if we tested <limit> number of characters
		table.insert (result, 'strings eq to position: ' .. i);
	else
		table.insert (result, 'strings eq to position: ' .. i .. ': ' .. string.byte (t_str_a[i]) .. '(' .. t_str_a[i] .. ') ≠ ' .. string.byte (t_str_b[i]) .. '(' .. t_str_b[i] .. ')')
	end
	
	return table.concat (result, '<br />');
end

return {strcmp = strcmp}