bufio: ReadSlice with size argument #35738
Description
ReadSlice works wonderful with character termination. How to get the same performance and simplicity with size prefixes, i.e. how to read a string with 'n' bytes?
Unless there's a good solution, I'm happy to contribute an implementation of the following.
// ReadSliceSize reads n bytes of input, returning a slice pointing at the bytes
// in the buffer. The bytes stop being valid at the next read. An n value larger
// than the buffer causes an ErrBufferFull, without any I/O.
// When ReadSliceSize encounters an io.EOF after reading some data, but not all,
// then it returns all the data in the buffer with an io.ErrUnexpectedEOF.
// Because the data returned from ReadSliceSize will be overwritten by the next
// I/O operation, most clients should use Read or WriteTo instead. ReadSliceSize
// returns err != nil if, and only if, an error occurs before buffering n bytes.
func (r *Reader) ReadSliceSize(n int) ([]byte, error) // ReadString demos ReadSliceSize.
func ReadString(r *bufio.Reader) (string, error) {
sizePrefix, err := r.ReadByte()
if err != nil {
return "", err
}
slice, err := r.ReadSliceSize(int(sizePrefix))
if err != nil {
return "", err
}
return string(slice), nil
}