hugo/common/hugio/writers.go

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// Copyright 2018 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package hugio
import (
"io"
"io/ioutil"
)
// As implemented by strings.Builder.
type FlexiWriter interface {
io.Writer
io.ByteWriter
WriteString(s string) (int, error)
WriteRune(r rune) (int, error)
}
type multiWriteCloser struct {
io.Writer
closers []io.WriteCloser
}
func (m multiWriteCloser) Close() error {
var err error
for _, c := range m.closers {
if closeErr := c.Close(); closeErr != nil {
err = closeErr
}
}
return err
}
// NewMultiWriteCloser creates a new io.WriteCloser that duplicates its writes to all the
// provided writers.
func NewMultiWriteCloser(writeClosers ...io.WriteCloser) io.WriteCloser {
writers := make([]io.Writer, len(writeClosers))
for i, w := range writeClosers {
writers[i] = w
}
return multiWriteCloser{Writer: io.MultiWriter(writers...), closers: writeClosers}
}
// ToWriteCloser creates an io.WriteCloser from the given io.Writer.
// If it's not already, one will be created with a Close method that does nothing.
func ToWriteCloser(w io.Writer) io.WriteCloser {
if rw, ok := w.(io.WriteCloser); ok {
return rw
}
return struct {
io.Writer
io.Closer
}{
w,
ioutil.NopCloser(nil),
}
}
// ToReadCloser creates an io.ReadCloser from the given io.Reader.
// If it's not already, one will be created with a Close method that does nothing.
func ToReadCloser(r io.Reader) io.ReadCloser {
if rc, ok := r.(io.ReadCloser); ok {
return rc
}
return struct {
io.Reader
io.Closer
}{
r,
ioutil.NopCloser(nil),
}
}