Calling `font-lock-flush` or `font-lock-ensure` from font-lock-keywords
is quite odd. I'd call something like `font-lock-fontify-region` instead.
Using `font-lock-fontify-region` instead causes Emacs to become mostly unresponsive. Sending a USR2 reveals:
Debugger entered--entering a function:
* #f(compiled-function () #<bytecode 0x1fed77d1f329>)()
font-lock-default-fontify-region(188 189 nil)
font-lock-fontify-region(188 189)
#f(compiled-function (fun) #<bytecode 0x1fed77d1f2f9>)(font-lock-fontify-region)
run-hook-wrapped(#f(compiled-function (fun) #<bytecode 0x1fed77d1f2f9>) font-lock-fontify-region)
jit-lock--run-functions(188 189)
jit-lock-fontify-now(188 688)
jit-lock-function(188)
redisplay_internal\ \(C\ function\)()
There's one thing with which you might want to be careful, tho, which is
the `syntax-ppss` state. You might want to `narrow-to-region` around
the call to `font-lock-fontify-region` (maybe narrow to pmark...(point-max)?).
This is because in a shell buffer, some of the past interactions may
have been truncated (e.g. by `comint-truncate-buffer`), so you may end
up with (point-min) being in the middle of a string or something.
[ Similar problems can occur if the prompt itself contains funny characters
like unmatched quotes. or if past interactions include output which
is not lexically valid Python code. ]
Well hmm, this is a bummer. l tested for this issue by inserting an entirely unmatched quote:
and this does affect the syntax (everything is a string). But unfortunately narrowing as follows doesn’t seem to fix this:
(save-restriction
(narrow-to-region pmark (point-max))
(with-syntax-table python-mode-syntax-table
(font-lock-flush start limit)
(font-lock-ensure start limit)))))))
I’m not sure it’s the same thing, but I found a related issue with `indent-for-tab-command'. In attempting to ignore the prompt for computing indentation, I narrowed to a region which excluded it, but indent.el calls `indent--funcall-widened’, which undoes my narrowing!
Is there any way to specify "narrow to this region and don’t let anybody widen it(!)"?