Splits HEEx source into tokens a code block can colour: {kind, text} pairs whose texts, joined, are the source again. It reads the shapes of a template (tags, components, slots, attributes, strings, {} and <% %> expressions, comments), not the Elixir inside them, so it is cheap and never fails: what it does not know is plain :text.

Kinds: :punct, :html, :component, :slot, :attr, :string, :expr, :comment, :text.