feat: add promise All, Race, Any methods

async/promise.go

@@ -1,7 +1,7 @@
 // Copyright 2023 dudaodong@gmail.com. All rights reserved.
 // Use of this source code is governed by MIT license
 
-// Package async contain some features to support async programming. eg, promise, asycn/await, eventbus.
+// Package async contain some featurese to support async programming. eg, promise, asycn/await, eventbus.
 package async
 
 import (
@@ -11,6 +11,7 @@ import (
 )
 
 // Promise represents the eventual completion (or failure) of an asynchronous operation and its resulting value.
+// ref : chebyrash/promise (https://github.com/chebyrash/promise)
 // see js promise: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
 type Promise[T any] struct {
 	runnable func(resolve func(T), reject func(error))
@@ -35,12 +36,6 @@ func New[T any](runnable func(resolve func(T), reject func(error))) *Promise[T]
 		wg:      &sync.WaitGroup{},
 	}
 
-	// p.wg.Add(1)
-	// go func() {
-	// 	defer p.handlePanic()
-	// 	runnable(p.resolve, p.reject)
-	// }()
-
 	defer p.run()
 
 	return p
@@ -113,7 +108,7 @@ func (p *Promise[T]) reject(err error) {
 }
 
 // Then allows chain calls to other promise methods.
-func Then[T1, T2 any](promise Promise[T1], resolve1 func(value T1) T2) *Promise[T2] {
+func Then[T1, T2 any](promise *Promise[T1], resolve1 func(value T1) T2) *Promise[T2] {
 	return New(func(resolve2 func(T2), reject func(error)) {
 		result, err := promise.Await()
 		if err != nil {
@@ -165,3 +160,116 @@ func (p *Promise[T]) Await() (T, error) {
 	p.wg.Wait()
 	return p.result, p.err
 }
+
+type tuple[T1, T2 any] struct {
+	_1 T1
+	_2 T2
+}
+
+// All resolves when all of the promises have resolved, reject immediately upon any of the input promises rejecting.
+func All[T any](promises []*Promise[T]) *Promise[[]T] {
+	if len(promises) == 0 {
+		return nil
+	}
+
+	return New(func(resolve func([]T), reject func(error)) {
+		valsChan := make(chan tuple[T, int], len(promises))
+		errsChan := make(chan error, 1)
+
+		for idx, p := range promises {
+			idx := idx
+			_ = Then(p, func(data T) T {
+				valsChan <- tuple[T, int]{_1: data, _2: idx}
+				return data
+			})
+			_ = Catch(p, func(err error) error {
+				errsChan <- err
+				return err
+			})
+		}
+
+		resolutions := make([]T, len(promises))
+		for idx := 0; idx < len(promises); idx++ {
+			select {
+			case val := <-valsChan:
+				resolutions[val._2] = val._1
+			case err := <-errsChan:
+				reject(err)
+				return
+			}
+		}
+		resolve(resolutions)
+	})
+}
+
+// Race will settle the first fullfiled promise among muti promises.
+func Race[T any](promises []*Promise[T]) *Promise[T] {
+	if len(promises) == 0 {
+		return nil
+	}
+
+	return New(func(resolve func(T), reject func(error)) {
+		valsChan := make(chan T, 1)
+		errsChan := make(chan error, 1)
+
+		for _, p := range promises {
+			_ = Then(p, func(data T) T {
+				valsChan <- data
+				return data
+			})
+			_ = Catch(p, func(err error) error {
+				errsChan <- err
+				return err
+			})
+		}
+
+		select {
+		case val := <-valsChan:
+			resolve(val)
+		case err := <-errsChan:
+			reject(err)
+		}
+	})
+}
+
+// Any resolves as soon as any of the input's Promises resolve, with the value of the resolved Promise.
+// Any rejects if all of the given Promises are rejected with a combination of all errors.
+func Any[T any](promises ...*Promise[T]) *Promise[T] {
+	if len(promises) == 0 {
+		return nil
+	}
+
+	return New(func(resolve func(T), reject func(error)) {
+		valsChan := make(chan T, 1)
+		errsChan := make(chan tuple[error, int], len(promises))
+
+		for idx, p := range promises {
+			idx := idx
+			_ = Then(p, func(data T) T {
+				valsChan <- data
+				return data
+			})
+			_ = Catch(p, func(err error) error {
+				errsChan <- tuple[error, int]{_1: err, _2: idx}
+				return err
+			})
+		}
+
+		errs := make([]error, len(promises))
+		for idx := 0; idx < len(promises); idx++ {
+			select {
+			case val := <-valsChan:
+				resolve(val)
+				return
+			case err := <-errsChan:
+				errs[err._2] = err._1
+			}
+		}
+
+		errCombo := errs[0]
+		// for _, err := range errs[1:] {
+		// 	errCombo = errors.
+		// }
+		reject(errCombo)
+	})
+}