gosaxml is a streaming XML decoder and encoder, similar in interface to the encoding/xml, but with a focus on performance, low memory footprint and on fixing many of the issues present in encoding/xml mainly related to handling of namespaces (see golang/go#13400).

In addition to handling namespaces, gosaxml can also canonicalize and minify XML namespaces bindings in a document (with and without prefixes) and does not repeat the prefix-less namespace declaration on all encoded XML elements, like encoding/xml does.

Due to the way it is implemented right now, the byte slices it reads from a provided io.Reader can only be ASCII or UTF-8 encoded. UTF-16 and UTF-32 character encodings or other encodings not identical with the ASCII character set or not using multi-byte encodings where the high bit is always set, are not supported.

Get it

go get -u github.com/HBTGmbH/gosaxml

Features

• zero-allocation stream decoding of XML inputs (from io.Reader)
• zero-allocation stream encoding of XML elements (to io.Writer)
• tidying of XML namespace declarations of the encoder input
• SIMD-accelerated scanning on amd64 (SSE2/AVX2) and arm64 (NEON), with a portable fallback on every other architecture

Limitations

• CDATA sections are not yet implemented (decoding returns an error)
• <!DOCTYPE> declarations are not supported (decoding returns an error)
• entity references (like &) are not decoded/encoded but passed through verbatim (round-trip-safe)
• element nesting depth is limited to 255

Simple examples

Decode and re-encode

The following example (in the form of a Go test) decodes from a given io.Reader and encodes the same tokens into a provided io.Writer:

func TestDecodeAndEncode(t *testing.T) {
	// given
	var r io.Reader = strings.NewReader(
		`<a xmlns="http://mynamespace.org">
		<b>Hi!</b>
		<c></c>
		</a>`)
	var w bytes.Buffer
	dec := gosaxml.NewDecoder(r)
	enc := gosaxml.NewEncoder(&w)

	// when
	var tk gosaxml.Token
	for {
		err := dec.NextToken(&tk)
		if err == io.EOF {
			break
		}
		assert.Nil(t, err)

		err = enc.EncodeToken(&tk)
		assert.Nil(t, err)
	}
	assert.Nil(t, enc.Flush())

	// then
	assert.Equal(t,
	`<a xmlns="http://mynamespace.org"><b>Hi!</b><c/></a>`,
	w.String())
}