From d05638adaceaf4847a1c2dfa541124bec83ec6bb Mon Sep 17 00:00:00 2001
From: legendtkl <taokelu@gmail.com>
Date: Tue, 6 Sep 2016 15:45:18 +0800
Subject: [PATCH] concurrency/generator: implement generator pattern
---
README.md | 2 +-
concurrency/generator.md | 6 ++++++
concurrency/generators.go | 43 +++++++++++++++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 1 deletion(-)
create mode 100644 concurrency/generator.md
create mode 100644 concurrency/generators.go
diff --git a/README.md b/README.md
index 9460ea3..94d98c1 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@ A curated collection of idiomatic design & application patterns for Go language.
| [Bounded Parallelism](/concurrency/bounded_parallelism.md) | Completes large number of independent tasks with resource limits | ✔ |
| [Broadcast](/concurrency/broadcast.md) | Transfers a message to all recipients simultaneously | ✘ |
| [Coroutines](/concurrency/coroutine.md) | Subroutines that allow suspending and resuming execution at certain locations | ✘ |
-| [Generators](/concurrency/generator.md) | Yields a sequence of values one at a time | ✘ |
+| [Generators](/concurrency/generator.md) | Yields a sequence of values one at a time | ✔ |
| [Reactor](/concurrency/reactor.md) | Demultiplexes service requests delivered concurrently to a service handler and dispatches them syncronously to the associated request handlers | ✘ |
| [Parallelism](/concurrency/parallelism.md) | Completes large number of independent tasks | ✔ |
| [Producer Consumer](/concurrency/producer_consumer.md) | Separates tasks from task executions | ✘ |
diff --git a/concurrency/generator.md b/concurrency/generator.md
new file mode 100644
index 0000000..2161248
--- /dev/null
+++ b/concurrency/generator.md
@@ -0,0 +1,6 @@
+# Generator Pattern
+
+[Generator](https://en.wikipedia.org/wiki/Generator_(computer_programming)) is a special routine that can be used to control the iteration behavior of a loop.
+
+# Implementation and Example
+With Go language, we can implement generator in two ways: channel and closure. Fibonacci number generation example can be found in [generators.go](generators.go).
\ No newline at end of file
diff --git a/concurrency/generators.go b/concurrency/generators.go
new file mode 100644
index 0000000..5b2b8b2
--- /dev/null
+++ b/concurrency/generators.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+ "fmt"
+)
+
+//FibonacciClosure implements fibonacci number generation using closure
+func FibonacciClosure() func() int {
+ a, b := 0, 1
+ return func() int {
+ a, b = b, a+b
+ return a
+ }
+}
+
+//FibonacciChan implements fibonacci number generation using channel
+func FibonacciChan(n int) chan int {
+ c := make(chan int)
+
+ go func() {
+ a, b := 0, 1
+ for i := 0; i < n; i++ {
+ c <- b
+ a, b = b, a+b
+ }
+ close(c)
+ }()
+
+ return c
+}
+
+func main() {
+ //closure
+ nextFib := FibonacciClosure()
+ for i := 0; i < 20; i++ {
+ fmt.Println(nextFib())
+ }
+
+ //channel
+ for i := range FibonacciChan(20) {
+ fmt.Println(i)
+ }
+}