just some examples of Golang io.Reader which trim whitespace

trimreader.go

type TrimReader2 struct{ io.Reader }

var trailingws = regexp.MustCompile(` *\r?\n`)

func (tr TrimReader2) Read(bs []byte) (int, error) {
	// Perform the requested read on the given reader.
	n, err := tr.Reader.Read(bs)
	if err != nil {
		return n, err
	}

	// Remove trailing whitespace from each line.
	lines := string(bs[:n])
	trimmed := []byte(trailingws.ReplaceAllString(lines, ""))
	copy(bs, trimmed)
	return len(trimmed), nil
}





// trimReader is a custom io.Reader that will trim any leading
// whitespace, as this can cause email imports to fail.
type trimReader struct {
	rd io.Reader
}

// Read trims off any unicode whitespace from the originating reader
func (tr trimReader) Read(buf []byte) (int, error) {
	n, err := tr.rd.Read(buf)
	t := bytes.TrimLeftFunc(buf[:n], unicode.IsSpace)
	n = copy(buf, t)
	return n, err
}