loader/nop_closer.go

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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 loader

import "io"

// from golang io.NopCloser for compacity
// NopCloser returns a ReadCloser with a no-op Close method wrapping
// the provided Reader r.
// If r implements WriterTo, the returned ReadCloser will implement WriterTo
// by forwarding calls to r.
func NopCloser(r io.Reader) io.ReadCloser {
	if _, ok := r.(io.WriterTo); ok {
		return nopCloserWriterTo{r}
	}
	return nopCloser{r}
}

type nopCloser struct {
	io.Reader
}

func (nopCloser) Close() error { return nil }

type nopCloserWriterTo struct {
	io.Reader
}

func (nopCloserWriterTo) Close() error { return nil }

func (c nopCloserWriterTo) WriteTo(w io.Writer) (n int64, err error) {
	return c.Reader.(io.WriterTo).WriteTo(w)
}