Bug 1497389 - Add a fast path for querySelector{,All} when we have classes or tags in the rightmost compound.
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Authored by emilio on Oct 21 2018, 9:54 AM.

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Bugzilla Bug ID

1497389

Summary

Before this patch we were only optimizing the case of a single selector, which
is fine, but not enough to catch ones like .foo .bar or so.

This patch allows us to optimize classes and tags in the rightmost compound,
while keeping the current optimization for #id selectors.

Need to profile this, but code-wise should be ready for review.

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rMOZILLACENTRAL mozilla-central

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phab-bot changed the visibility from "Custom Policy" to "Public (No Login Required)".Oct 21 2018, 9:54 AM

phab-bot changed the edit policy from "Custom Policy" to "Restricted Project (Project)".

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emilio requested review of this revision.Oct 21 2018, 9:54 AM

heycam added a subscriber: heycam.

heycam added inline comments.

servo/components/style/dom_apis.rs
390–398	Since it's a bit more complicated now, can you add to the comment here to describe all the cases that query_selector_fast handles?
502–504	Can you add a comment here saying why we prefer to look at a class rather than a local name, if both are present?
534–535	Nit: maybe s/or such/that we could handle/, since IDs are the only thing that make us return above, but there are still some ID cases where we return Err above.