github.com/graemephi/kahugo@v0.62.3-0.20211121071557-d78c0423784d/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  type multiWriteCloser struct {
    22  	io.Writer
    23  	closers []io.WriteCloser
    24  }
    25  
    26  func (m multiWriteCloser) Close() error {
    27  	var err error
    28  	for _, c := range m.closers {
    29  		if closeErr := c.Close(); err != nil {
    30  			err = closeErr
    31  		}
    32  	}
    33  	return err
    34  }
    35  
    36  // NewMultiWriteCloser creates a new io.WriteCloser that duplicates its writes to all the
    37  // provided writers.
    38  func NewMultiWriteCloser(writeClosers ...io.WriteCloser) io.WriteCloser {
    39  	writers := make([]io.Writer, len(writeClosers))
    40  	for i, w := range writeClosers {
    41  		writers[i] = w
    42  	}
    43  	return multiWriteCloser{Writer: io.MultiWriter(writers...), closers: writeClosers}
    44  }
    45  
    46  // ToWriteCloser creates an io.WriteCloser from the given io.Writer.
    47  // If it's not already, one will be created with a Close method that does nothing.
    48  func ToWriteCloser(w io.Writer) io.WriteCloser {
    49  	if rw, ok := w.(io.WriteCloser); ok {
    50  		return rw
    51  	}
    52  
    53  	return struct {
    54  		io.Writer
    55  		io.Closer
    56  	}{
    57  		w,
    58  		ioutil.NopCloser(nil),
    59  	}
    60  }
    61  
    62  // ToReadCloser creates an io.ReadCloser from the given io.Reader.
    63  // If it's not already, one will be created with a Close method that does nothing.
    64  func ToReadCloser(r io.Reader) io.ReadCloser {
    65  	if rc, ok := r.(io.ReadCloser); ok {
    66  		return rc
    67  	}
    68  
    69  	return struct {
    70  		io.Reader
    71  		io.Closer
    72  	}{
    73  		r,
    74  		ioutil.NopCloser(nil),
    75  	}
    76  }