Mercurial > xmpp-mass-pep-downloader / file comparison
comparison: util/promise.lua
util/promise.lua
- changeset 0
- 550f506de75a
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| -1:000000000000 | 0:550f506de75a |
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| 1 local promise_methods = {}; | |
| 2 local promise_mt = { __name = "promise", __index = promise_methods }; | |
| 3 | |
| 4 local xpcall = require "util.xpcall".xpcall; | |
| 5 | |
| 6 function promise_mt:__tostring() | |
| 7 return "promise (" .. (self._state or "invalid") .. ")"; | |
| 8 end | |
| 9 | |
| 10 local function is_promise(o) | |
| 11 local mt = getmetatable(o); | |
| 12 return mt == promise_mt; | |
| 13 end | |
| 14 | |
| 15 local function wrap_handler(f, resolve, reject, default) | |
| 16 if not f then | |
| 17 return default; | |
| 18 end | |
| 19 return function (param) | |
| 20 local ok, ret = xpcall(f, debug.traceback, param); | |
| 21 if ok then | |
| 22 resolve(ret); | |
| 23 else | |
| 24 reject(ret); | |
| 25 end | |
| 26 return true; | |
| 27 end; | |
| 28 end | |
| 29 | |
| 30 local function next_pending(self, on_fulfilled, on_rejected, resolve, reject) | |
| 31 table.insert(self._pending_on_fulfilled, wrap_handler(on_fulfilled, resolve, reject, resolve)); | |
| 32 table.insert(self._pending_on_rejected, wrap_handler(on_rejected, resolve, reject, reject)); | |
| 33 end | |
| 34 | |
| 35 local function next_fulfilled(promise, on_fulfilled, on_rejected, resolve, reject) -- luacheck: ignore 212/on_rejected | |
| 36 wrap_handler(on_fulfilled, resolve, reject, resolve)(promise.value); | |
| 37 end | |
| 38 | |
| 39 local function next_rejected(promise, on_fulfilled, on_rejected, resolve, reject) -- luacheck: ignore 212/on_fulfilled | |
| 40 wrap_handler(on_rejected, resolve, reject, reject)(promise.reason); | |
| 41 end | |
| 42 | |
| 43 local function promise_settle(promise, new_state, new_next, cbs, value) | |
| 44 if promise._state ~= "pending" then | |
| 45 return; | |
| 46 end | |
| 47 promise._state = new_state; | |
| 48 promise._next = new_next; | |
| 49 for _, cb in ipairs(cbs) do | |
| 50 cb(value); | |
| 51 end | |
| 52 -- No need to keep references to callbacks | |
| 53 promise._pending_on_fulfilled = nil; | |
| 54 promise._pending_on_rejected = nil; | |
| 55 return true; | |
| 56 end | |
| 57 | |
| 58 local function new_resolve_functions(p) | |
| 59 local resolved = false; | |
| 60 local function _resolve(v) | |
| 61 if resolved then return; end | |
| 62 resolved = true; | |
| 63 if is_promise(v) then | |
| 64 v:next(new_resolve_functions(p)); | |
| 65 elseif promise_settle(p, "fulfilled", next_fulfilled, p._pending_on_fulfilled, v) then | |
| 66 p.value = v; | |
| 67 end | |
| 68 | |
| 69 end | |
| 70 local function _reject(e) | |
| 71 if resolved then return; end | |
| 72 resolved = true; | |
| 73 if promise_settle(p, "rejected", next_rejected, p._pending_on_rejected, e) then | |
| 74 p.reason = e; | |
| 75 end | |
| 76 end | |
| 77 return _resolve, _reject; | |
| 78 end | |
| 79 | |
| 80 local function new(f) | |
| 81 local p = setmetatable({ _state = "pending", _next = next_pending, _pending_on_fulfilled = {}, _pending_on_rejected = {} }, promise_mt); | |
| 82 if f then | |
| 83 local resolve, reject = new_resolve_functions(p); | |
| 84 local ok, ret = xpcall(f, debug.traceback, resolve, reject); | |
| 85 if not ok and p._state == "pending" then | |
| 86 reject(ret); | |
| 87 end | |
| 88 end | |
| 89 return p; | |
| 90 end | |
| 91 | |
| 92 local function all(promises) | |
| 93 return new(function (resolve, reject) | |
| 94 local count, total, results = 0, #promises, {}; | |
| 95 for i = 1, total do | |
| 96 promises[i]:next(function (v) | |
| 97 results[i] = v; | |
| 98 count = count + 1; | |
| 99 if count == total then | |
| 100 resolve(results); | |
| 101 end | |
| 102 end, reject); | |
| 103 end | |
| 104 end); | |
| 105 end | |
| 106 | |
| 107 local function all_settled(promises) | |
| 108 return new(function (resolve) | |
| 109 local count, total, results = 0, #promises, {}; | |
| 110 for i = 1, total do | |
| 111 promises[i]:next(function (v) | |
| 112 results[i] = { status = "fulfilled", value = v }; | |
| 113 count = count + 1; | |
| 114 if count == total then | |
| 115 resolve(results); | |
| 116 end | |
| 117 end, function (e) | |
| 118 results[i] = { status = "rejected", reason = e }; | |
| 119 count = count + 1; | |
| 120 if count == total then | |
| 121 resolve(results); | |
| 122 end | |
| 123 end); | |
| 124 end | |
| 125 end); | |
| 126 end | |
| 127 | |
| 128 local function race(promises) | |
| 129 return new(function (resolve, reject) | |
| 130 for i = 1, #promises do | |
| 131 promises[i]:next(resolve, reject); | |
| 132 end | |
| 133 end); | |
| 134 end | |
| 135 | |
| 136 local function resolve(v) | |
| 137 return new(function (_resolve) | |
| 138 _resolve(v); | |
| 139 end); | |
| 140 end | |
| 141 | |
| 142 local function reject(v) | |
| 143 return new(function (_, _reject) | |
| 144 _reject(v); | |
| 145 end); | |
| 146 end | |
| 147 | |
| 148 local function try(f) | |
| 149 return resolve():next(function () return f(); end); | |
| 150 end | |
| 151 | |
| 152 function promise_methods:next(on_fulfilled, on_rejected) | |
| 153 return new(function (resolve, reject) --luacheck: ignore 431/resolve 431/reject | |
| 154 self:_next(on_fulfilled, on_rejected, resolve, reject); | |
| 155 end); | |
| 156 end | |
| 157 | |
| 158 function promise_methods:catch(on_rejected) | |
| 159 return self:next(nil, on_rejected); | |
| 160 end | |
| 161 | |
| 162 function promise_methods:finally(on_finally) | |
| 163 local function _on_finally(value) on_finally(); return value; end | |
| 164 local function _on_catch_finally(err) on_finally(); return reject(err); end | |
| 165 return self:next(_on_finally, _on_catch_finally); | |
| 166 end | |
| 167 | |
| 168 return { | |
| 169 new = new; | |
| 170 resolve = resolve; | |
| 171 reject = reject; | |
| 172 all = all; | |
| 173 all_settled = all_settled; | |
| 174 race = race; | |
| 175 try = try; | |
| 176 is_promise = is_promise; | |
| 177 } |
