compress/gzip: add examples

Updates #16360.

Adds examples uing:
+ Writer, Reader
+ Reader.Multistream to concatenate and then
individually retrieve multiple gzipped files
+ Reset

Change-Id: I9ad9b92729a5cd58f7368eaf2db05f1cdf21063d
Reviewed-on: https://go-review.googlesource.com/29218
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/compress/gzip/example_test.go b/src/compress/gzip/example_test.go
new file mode 100644 (file)
index 0000000..e32346b
--- /dev/null
+++ b/src/compress/gzip/example_test.go
@@ -0,0 +1,128 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gzip_test
+
+import (
+       "bytes"
+       "compress/gzip"
+       "fmt"
+       "io"
+       "log"
+       "os"
+       "time"
+)
+
+func Example_writerReader() {
+       var buf bytes.Buffer
+       zw := gzip.NewWriter(&buf)
+
+       // Setting the Header fields is optional.
+       zw.Name = "a-new-hope.txt"
+       zw.Comment = "an epic space opera by George Lucas"
+       zw.ModTime = time.Date(1977, time.May, 25, 0, 0, 0, 0, time.UTC)
+
+       _, err := zw.Write([]byte("A long time ago in a galaxy far, far away..."))
+       if err != nil {
+               log.Fatal(err)
+       }
+
+       if err := zw.Close(); err != nil {
+               log.Fatal(err)
+       }
+
+       zr, err := gzip.NewReader(&buf)
+       if err != nil {
+               log.Fatal(err)
+       }
+
+       fmt.Printf("Name: %s\nComment: %s\nModTime: %s\n\n", zr.Name, zr.Comment, zr.ModTime.UTC())
+
+       if _, err := io.Copy(os.Stdout, zr); err != nil {
+               log.Fatal(err)
+       }
+
+       if err := zr.Close(); err != nil {
+               log.Fatal(err)
+       }
+
+       // Output:
+       // Name: a-new-hope.txt
+       // Comment: an epic space opera by George Lucas
+       // ModTime: 1977-05-25 00:00:00 +0000 UTC
+       //
+       // A long time ago in a galaxy far, far away...
+}
+
+func ExampleReader_Multistream() {
+       var buf bytes.Buffer
+       zw := gzip.NewWriter(&buf)
+
+       var files = []struct {
+               name    string
+               comment string
+               modTime time.Time
+               data    string
+       }{
+               {"file-1.txt", "file-header-1", time.Date(2006, time.February, 1, 3, 4, 5, 0, time.UTC), "Hello Gophers - 1"},
+               {"file-2.txt", "file-header-2", time.Date(2007, time.March, 2, 4, 5, 6, 1, time.UTC), "Hello Gophers - 2"},
+       }
+
+       for _, file := range files {
+               zw.Name = file.name
+               zw.Comment = file.comment
+               zw.ModTime = file.modTime
+
+               if _, err := zw.Write([]byte(file.data)); err != nil {
+                       log.Fatal(err)
+               }
+
+               if err := zw.Close(); err != nil {
+                       log.Fatal(err)
+               }
+
+               zw.Reset(&buf)
+       }
+
+       zr, err := gzip.NewReader(&buf)
+       if err != nil {
+               log.Fatal(err)
+       }
+
+       for {
+               zr.Multistream(false)
+               fmt.Printf("Name: %s\nComment: %s\nModTime: %s\n\n", zr.Name, zr.Comment, zr.ModTime.UTC())
+
+               if _, err := io.Copy(os.Stdout, zr); err != nil {
+                       log.Fatal(err)
+               }
+
+               fmt.Println("\n")
+
+               err = zr.Reset(&buf)
+               if err == io.EOF {
+                       break
+               }
+               if err != nil {
+                       log.Fatal(err)
+               }
+       }
+
+       if err := zr.Close(); err != nil {
+               log.Fatal(err)
+       }
+
+       // Output:
+       // Name: file-1.txt
+       // Comment: file-header-1
+       // ModTime: 2006-02-01 03:04:05 +0000 UTC
+       //
+       // Hello Gophers - 1
+       //
+       // Name: file-2.txt
+       // Comment: file-header-2
+       // ModTime: 2007-03-02 04:05:06 +0000 UTC
+       //
+       // Hello Gophers - 2
+}