Creation of a poly-mode for a T4-like language

[mcraveiro]

Hi poly-mode developers,

Thanks for an extremely useful mode. I have setup a simple derived mode that almost does all I need. My objective is to define a mode for a file format very similar to Microsoft's T4, text-templating language [1]. The main exception is where they use C# as the host language, I use C++. I have defined the mode as follows:

(require 'polymode)

(define-hostmode poly-stitch-hostmode :mode 'c++-mode)

(define-innermode poly-stitch-directive-innermode
  :mode 'conf-unix-mode
  :head-matcher "<#@"
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-innermode poly-stitch-expansion-block-innermode
  :mode 'conf-unix-mode
  :head-matcher "<#\$"
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-innermode poly-stitch-expression-control-block-innermode
  :mode 'c++-mode
  :head-matcher "<#="
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-polymode poly-stitch-mode
  :hostmode 'poly-stitch-hostmode
  :innermodes '(poly-stitch-directive-innermode
                poly-stitch-expansion-block-innermode
                poly-stitch-expression-control-block-innermode))

;; (add-to-list 'auto-mode-alist '("\\.stitch" . stitch-mode))

The main problem I have at present is that when I open a file with this mode, I don't see either the host or the inner mode highlighted with a different background as I see on your examples (please see screenshot below of what I see). They all have the same background, making it hard to distinguish. Ideally, I'd like them to be visually quite distinct, as the examples are.

A second, but slightly less important problem, is that I am not matching correctly lines starting with:

<#$

This is probably some basic regex error, so I'm playing around with regexes. At any rate, any pointers as to what I am doing wrong would be greatly appreciated.

Many thanks for your time.

[1] https://docs.microsoft.com/en-us/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2019

[mcraveiro]

I checked the values of the following variables:

poly-lock-allow-fontification
poly-lock-allow-background-adjustment

And they are both t. I suspect I am not marking the entries as a "span", somehow... Or perhaps the theme doom-dark+ does not play well with this logic...

[mcraveiro]

Actually, I tried a light theme (doom-solarized-light) and it partially answered my question; it does seem its having some kind of effect. However, not all "blocks" are marked as dark as I'd expect.

[mcraveiro]

OK I'm not entirely sure but after changing themes a few times I managed to get what I was looking for :-) The final mode is as follows:

(require 'polymode)

(define-hostmode poly-stitch-hostmode :mode 'fundamental-mode)

(define-innermode poly-stitch-directive-innermode
  :mode 'fundamental-mode
  :head-matcher "<#@"
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-innermode poly-stitch-expansion-block-innermode
  :mode 'fundamental-mode
  :head-matcher "<#\\$"
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-innermode poly-stitch-big-block-innermode
  :mode 'c++-mode
  :head-matcher "<#\\+"
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-innermode poly-stitch-expression-control-block-innermode
  :mode 'c++-mode
  :head-matcher "<#="
  :tail-matcher "#>"
  :head-mode 'host
  :tail-mode 'host)

(define-polymode poly-stitch-mode
  :hostmode 'poly-stitch-hostmode
  :innermodes '(poly-stitch-directive-innermode
                poly-stitch-expansion-block-innermode
                poly-stitch-big-block-innermode
                poly-stitch-expression-control-block-innermode))

And it looks like so:

Ideally I'd like them to be even more visually distinctive, but this is good enough for now. Thanks!