Method readProcInst

xmlparser/decoder.go:408–451

readProcInst reads a processing instruction (until `?>`). If the processing instruction specifies an encoding, it recreates the reader with the specified encoding.

()

// If the processing instruction specifies an encoding, it recreates
// the reader with the specified encoding.
func (d *Decoder) readProcInst() ([]byte, []byte, bool) {
	// Discard '<?'
	if !d.discard(len(procInstStart)) {
		return nil, nil, false
	}

	// Target name should follow immediately after `<?`.
	if !d.readName() {
		// If we couldn't read a name but there was no error, it means
		// there was no valid target name after <?.
		// Set an error in this case.
		if d.err == nil {
			d.setSyntaxErrorf("expected target name after <?")
		}
		return nil, nil, false
	}

	target := d.buf.Bytes()

	// Read until '?>'
	// We don't reset the buffer here, as we don't want target name to be overwritten.
	for {
		if !d.mustReadUntil('>') {
			return nil, nil, false
		}

		if d.buf.HasSuffix(procInstEnd) {
			break
		}
	}

	// Trim the trailing '?>'
	d.buf.Remove(len(procInstEnd))

	// Separate the target and data
	data := d.buf.Bytes()[len(target):]

	if bytes.Equal(target, targetXML) {
		// Get the encoding from the processing instruction data
		data = d.handleProcInstEncoding(data)
	}

	return target, data, true
}

// handleProcInstEncoding replaces the encoding declaration in the processing instruction data
// with "UTF-8" and returns the updated data.