374907 - make rule nodes know their level in the cascade

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: work in progress (nowhere close to compiling)

I'd like to make rule nodes know their level in the cascade.  This would be useful for bug 240117, and perhaps other things.  (I don't think the rules should know, since a style sheet could technically occur at multiple levels.  I'm not sure how real a possibility that is, but I don't want to rule it out.  But this does mean we need to make the level part of the equality test for rule nodes when building the lexicographic tree.)

I have a very preliminary partial patch.  I stopped partway through and filed bug 374906; depending on whether that's fixed affects how I should continue.

Comment 1

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: patch

Compiles and runs; not tested beyond that.

Comment 2

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: patch

Oops, forgot the hashKey callback!

Comment 3

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: patch

This one is updated to the trunk, and actually works.

Note that an alternative approach would be making rules know their level and importance.  I considered that, but I think we'd break it if we ever did presentational hint stuff correctly (which would involve having an html-preshint.css that went in at the *appropriate* pres-hint level, plus making some of the the mapped attribute rules UA-level).

Comment 4

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 264971 [details] [diff] [review]
patch

>+++ b/layout/style/nsRuleNode.h
>+  // It's probably better to allocate the table itself using malloc and
>+  // free rather than the pres shell's arena because the table doesn't

This seems to be missing the end of the sentence...

>+++ b/layout/style/nsRuleWalker.h
>@@ -49,23 +49,27 @@ public:

>+    if (mCurrent) {

That's to handle OOM on previous calls, right?  Maybe document that?

r+sr=bzbarsky with the nits.

Comment 5

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Attachment: patch

The comment in nsRuleNode.h was accidental copy-paste; I added a comment in nsRuleWalker.

Comment 6

[David Baron :dbaron: (⌚️UTC-5, no longer working on Mozilla)]

Checked in to trunk.