Module Ppx_html_syntax

This library contains the minimal amount of dependencies for the "syntax" of ppx_html

This is used so that we add a minimal amount of dependencies while implementing ppx_html auto-formatting. We do not need to depend on html escaping/ppx_css as ppx_html only depends on these when it is actually "generating" code.

The "ppx html formatting" needs to understand ppx_html syntax for a couple of reasons. We are using prettier(https://prettier.io/) for the "html" formatting; howver ppx_html has some extra syntax of its own:

  [%html
    {|
     <%{Vdom.Node.div}>
      <div attr=%{value} %{attr}>
        %{child}
      </div>
     </>
     |}]

giving this syntax to prettier as-is result in failure, so there is a preprocessing step, that turns the above segment into something like:

  [%html
    {|
     <unique-id-1>
      <div attr=unique-id-2 unique-id-3>
        unique-id-4
      </div>
     </>
     |}]

and then prettier runs, and then the unique identifiers are regex-replaced back into the original interpolated OCaml.