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util.promise: Add join() convenience method Usage: promise.join(p1, p2, function (result1, result2) [...] end)

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equal deleted inserted replaced

-:24ce9d380475
+:a0120e935442
 local promise_methods = {};
 local promise_mt = { __name = "promise", __index = promise_methods };
 local xpcall = require "util.xpcall".xpcall;
+local unpack = table.unpack or unpack; --luacheck: ignore 113
 function promise_mt:__tostring()
 	return  "promise (" .. (self._state or "invalid") .. ")";
 end
 			resolve(results);
 		end
 	end);
 end
+local function join(...)
+	local promises, n = { ... }, select("#", ...);
+	local handler = promises[n];
+	promises[n] = nil;
+	return all(promises):next(function (results)
+		return handler(unpack(results, 1, n - 1));
+	end);
+end
 local function race(promises)
 	return new(function (resolve, reject)
 		for i = 1, #promises do
 			promises[i]:next(resolve, reject);
 		end
 end
 return {
 	new = new;
 	resolve = resolve;
+	join = join;
 	reject = reject;
 	all = all;
 	all_settled = all_settled;
 	race = race;
 	try = try;