github.com/kovansky/hugo@v0.92.3-0.20220224232819-63076e4ff19f/common/hugio/writers.go (about)

     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  }