writers.go (2102B)
1 // Copyright 2018 The Hugo Authors. All rights reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 // http://www.apache.org/licenses/LICENSE-2.0
7 //
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13
14 package hugio
15
16 import (
17 "io"
18 "io/ioutil"
19 )
20
21 // As implemented by strings.Builder.
22 type FlexiWriter interface {
23 io.Writer
24 io.ByteWriter
25 WriteString(s string) (int, error)
26 WriteRune(r rune) (int, error)
27 }
28
29 type multiWriteCloser struct {
30 io.Writer
31 closers []io.WriteCloser
32 }
33
34 func (m multiWriteCloser) Close() error {
35 var err error
36 for _, c := range m.closers {
37 if closeErr := c.Close(); err != nil {
38 err = closeErr
39 }
40 }
41 return err
42 }
43
44 // NewMultiWriteCloser creates a new io.WriteCloser that duplicates its writes to all the
45 // provided writers.
46 func NewMultiWriteCloser(writeClosers ...io.WriteCloser) io.WriteCloser {
47 writers := make([]io.Writer, len(writeClosers))
48 for i, w := range writeClosers {
49 writers[i] = w
50 }
51 return multiWriteCloser{Writer: io.MultiWriter(writers...), closers: writeClosers}
52 }
53
54 // ToWriteCloser creates an io.WriteCloser from the given io.Writer.
55 // If it's not already, one will be created with a Close method that does nothing.
56 func ToWriteCloser(w io.Writer) io.WriteCloser {
57 if rw, ok := w.(io.WriteCloser); ok {
58 return rw
59 }
60
61 return struct {
62 io.Writer
63 io.Closer
64 }{
65 w,
66 ioutil.NopCloser(nil),
67 }
68 }
69
70 // ToReadCloser creates an io.ReadCloser from the given io.Reader.
71 // If it's not already, one will be created with a Close method that does nothing.
72 func ToReadCloser(r io.Reader) io.ReadCloser {
73 if rc, ok := r.(io.ReadCloser); ok {
74 return rc
75 }
76
77 return struct {
78 io.Reader
79 io.Closer
80 }{
81 r,
82 ioutil.NopCloser(nil),
83 }
84 }