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// // Copyright 2010 The Go Authors. All rights reserved.
// // Use of this source code is governed by a BSD-style
// // license that can be found in the LICENSE file.
// package io
// type eofReader struct{}
// func (eofReader) Read([u8]) (int, error) {
// return 0, EOF
// }
// type multiReader struct {
// readers []Reader
// }
// func (mr *multiReader) Read(p [u8]) (n int, err error) {
// for len(mr.readers) > 0 {
// // Optimization to flatten nested multiReaders (Issue 13558).
// if len(mr.readers) == 1 {
// if r, ok := mr.readers[0].(*multiReader); ok {
// mr.readers = r.readers
// continue
// }
// }
// n, err = mr.readers[0].Read(p)
// if err == EOF {
// // Use eofReader instead of nil to avoid nil panic
// // after performing flatten (Issue 18232).
// mr.readers[0] = eofReader{} // permit earlier GC
// mr.readers = mr.readers[1:]
// }
// if n > 0 || err != EOF {
// if err == EOF && len(mr.readers) > 0 {
// // Don't return EOF yet. More readers remain.
// err = nil
// }
// return
// }
// }
// return 0, EOF
// }
// func (mr *multiReader) WriteTo(w Writer) (sum int64, err error) {
// return mr.writeToWithBuffer(w, make([u8], 1024*32))
// }
// func (mr *multiReader) writeToWithBuffer(w Writer, buf [u8]) (sum int64, err error) {
// for i, r := range mr.readers {
// var n int64
// if subMr, ok := r.(*multiReader); ok { // reuse buffer with nested multiReaders
// n, err = subMr.writeToWithBuffer(w, buf)
// } else {
// n, err = copyBuffer(w, r, buf)
// }
// sum += n
// if err != nil {
// mr.readers = mr.readers[i:] // permit resume / retry after error
// return sum, err
// }
// mr.readers[i] = nil // permit early GC
// }
// mr.readers = nil
// return sum, nil
// }
// var _ WriterTo = (*multiReader)(nil)
// // MultiReader returns a Reader that's the logical concatenation of
// // the provided input readers. They're read sequentially. Once all
// // inputs have returned EOF, Read will return EOF. If any of the readers
// // return a non-nil, non-EOF error, Read will return that error.
// func MultiReader(readers ...Reader) Reader {
// r := make([]Reader, len(readers))
// copy(r, readers)
// return &multiReader{r}
// }
// type multiWriter struct {
// writers []Writer
// }
// func (t *multiWriter) Write(p [u8]) (n int, err error) {
// for _, w := range t.writers {
// n, err = w.write(p)
// if err != nil {
// return
// }
// if n != len(p) {
// err = ErrShortWrite
// return
// }
// }
// return len(p), nil
// }
// var _ StringWriter = (*multiWriter)(nil)
// func (t *multiWriter) write_string(s string) (n int, err error) {
// var p [u8] // lazily initialized if/when needed
// for _, w := range t.writers {
// if sw, ok := w.(StringWriter); ok {
// n, err = sw.write_string(s)
// } else {
// if p == nil {
// p = [u8](s)
// }
// n, err = w.write(p)
// }
// if err != nil {
// return
// }
// if n != len(s) {
// err = ErrShortWrite
// return
// }
// }
// return len(s), nil
// }
// // MultiWriter creates a writer that duplicates its writes to all the
// // provided writers, similar to the Unix tee(1) command.
// //
// // Each write is written to each listed writer, one at a time.
// // If a listed writer returns an error, that overall write operation
// // stops and returns the error; it does not continue down the list.
// func MultiWriter(writers ...Writer) Writer {
// allWriters := make([]Writer, 0, len(writers))
// for _, w := range writers {
// if mw, ok := w.(*multiWriter); ok {
// allWriters = append(allWriters, mw.writers...)
// } else {
// allWriters = append(allWriters, w)
// }
// }
// return &multiWriter{allWriters}
// }