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Allow callback to return multiple values. #8

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91 changes: 49 additions & 42 deletions src/promise.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,9 @@ local PENDING = 'PENDING'
local FULFILLED = 'FULFILLED'
local REJECTED = 'REJECTED'

-- Compatibility trick
local unpack = unpack or table.unpack

local function noop() end

local function isCallable(x)
Expand All @@ -51,6 +54,8 @@ local resolve
local promiseOnFulfilled
local promiseOnRejected

local function parsePCall(success, ...) return success, {...} end

local function isPromise(x)
if type(x) ~= 'table' then return false end
local mtSeen = {}
Expand All @@ -65,57 +70,56 @@ local function isPromise(x)
return false
end

local function execFulfilled(thenInfo, value)
local function execFulfilled(thenInfo, ...)
local n = thenInfo
if not isCallable(n.onFulfilled) then
promiseOnFulfilled(n.promise, value)
promiseOnFulfilled(n.promise, ...)
else
local success, ret = pcall(n.onFulfilled, value)
local success, ret = parsePCall(pcall(n.onFulfilled, ...))
if success then
resolve(n.promise, ret)
resolve(n.promise, unpack(ret))
else
promiseOnRejected(n.promise, ret)
promiseOnRejected(n.promise, unpack(ret))
end
end
end

local function execRejected(thenInfo, reason)
local function execRejected(thenInfo, ...)
local n = thenInfo
if not isCallable(n.onRejected) then
promiseOnRejected(n.promise, reason)
promiseOnRejected(n.promise, ...)
else
local success, ret = pcall(n.onRejected, reason)
local success, ret = parsePCall(pcall(n.onRejected, ...))
if success then
resolve(n.promise, ret)
resolve(n.promise, unpack(ret))
else
promiseOnRejected(n.promise, ret)
promiseOnRejected(n.promise, unpack(ret))
end
end
end

promiseOnFulfilled = function (p, value)
promiseOnFulfilled = function(p, ...)
if p._state == PENDING then
p._value = value
p._value = {...}
p._reason = nil
p._state = FULFILLED
end
for _,n in ipairs(p.thenInfoList) do
execFulfilled(n, value)
for _, n in ipairs(p.thenInfoList) do
execFulfilled(n, ...)
end
end

promiseOnRejected = function (p, reason)
promiseOnRejected = function(p, ...)
if p._state == PENDING then
p._value = nil
p._reason = reason
p._reason = {...}
p._state = REJECTED
end
for _,n in ipairs(p.thenInfoList) do
execRejected(n, reason)
for _, n in ipairs(p.thenInfoList) do
execRejected(n, ...)
end
end


local function resolveThenable(p, x)
local thenCall = x.thenCall
if isCallable(thenCall) then
Expand Down Expand Up @@ -144,7 +148,7 @@ end
--[[
define promise resolution procedure
--]]
resolve = function (p, x)
resolve = function(p, x)
if p == x then
promiseOnRejected(p, 'TypeError: Promise resolution procedure got two identical parameters.')
return
Expand Down Expand Up @@ -190,9 +194,9 @@ function promise:thenCall(onFulfilled, onRejected)


if self._state == FULFILLED then
execFulfilled(thenInfo, self._value)
execFulfilled(thenInfo, unpack(self._value))
elseif self._state == REJECTED then
execRejected(thenInfo, self._reason)
execRejected(thenInfo, unpack(self._reason))
end

table.insert(self.thenInfoList, thenInfo)
Expand All @@ -204,19 +208,19 @@ function promise:catch(onRejected)
return self:thenCall(nil, onRejected)
end

newPromise = function (func)
newPromise = function(func)
local obj = promise:new()
local isCalled = false
local function onFulfilled(value)
local function onFulfilled(...)
if isCalled then return end
isCalled = true
promiseOnFulfilled(obj, value)
promiseOnFulfilled(obj, ...)
end

local function onRejected(reason)
local function onRejected(...)
if isCalled then return end
isCalled = true
promiseOnRejected(obj, reason)
promiseOnRejected(obj, ...)
end

if isCallable(func) then
Expand All @@ -234,17 +238,18 @@ setmetatable(Promise, {

Promise.new = newPromise

local function newPromiseFromValue(value)
local function newPromiseFromValue(...)
local p = newPromise(noop)
p._state = FULFILLED
p._value = value
p._value = {...}
p._reason = nil
return p
end

function Promise.resolve(value)
if isPromise(value) then return value end
if isThenable(value) then
function Promise.resolve(...)
if isPromise(...) then return ... end
if isThenable(...) then
local value = arg[1]
local thenCall = value.thenCall
if isCallable(thenCall) then
return newPromise(function(onFulfilled, onRejected)
Expand All @@ -256,26 +261,28 @@ function Promise.resolve(value)
end)
end
end
return newPromiseFromValue(value)
return newPromiseFromValue(...)
end


function Promise.reject(value)
function Promise.reject(...)
local args = {...}
return newPromise(function(_, onRejected)
onRejected(value)
onRejected(unpack(args))
end)
end

function promise:finally(func)
return self:thenCall(
function(value)
function(...)
local value = {...}
return Promise.resolve(func()):thenCall(function()
return Promise.resolve(value)
return Promise.resolve(unpack(value))
end)
end,
function(reason)
function(...)
local reason = {...}
return Promise.resolve(func()):thenCall(function()
return Promise.reject(reason)
return Promise.reject(unpack(reason))
end)
end
)
Expand Down Expand Up @@ -304,10 +311,10 @@ function Promise.all(array)
local function res(i, val)
if isPromise(val) then
if val._state == FULFILLED then
return res(i, val._value)
return res(i, unpack(val._value))
end
if val._state == REJECTED then
onRejected(val._reason)
onRejected(unpack(val._reason))
end
val:thenCall(function (v)
res(i, v)
Expand Down