graphID  = regexp.MustCompile(`<g id="graph\d"`)
	svgClose = regexp.MustCompile(`</svg>`)
)

// massageSVG enhances the SVG output from DOT to provide better
// panning inside a web browser. It uses the svgpan library, which is
// embedded into the svgpan.JSSource variable.
func massageSVG(svg string) string {
	// Work around for dot bug which misses quoting some ampersands,
	// resulting on unparsable SVG.

	return func(input io.Reader, output io.Writer, ui plugin.UI) error {
		baseSVG := new(bytes.Buffer)
		if err := generateSVG(input, baseSVG, ui); err != nil {
			return err
		}
		_, err := output.Write([]byte(massageSVG(baseSVG.String())))
		return err
	}
}

func invokeVisualizer(suffix string, visualizers []string) PostProcessor {
	return func(input io.Reader, output io.Writer, ui plugin.UI) error {