- Smaller, more consistent streams API (Advance, Back, pos, Seek)
- Remove implementations from the header, in favor of creation functions.
Observe:
- Performance:
- All Utf16CharacterStream methods have an inlinable V8_LIKELY w/ a
body of only a few instructions. I expect most calls to end up there.
- There used to be performance problems w/ bookmarking, particularly
with copying too much data on SetBookmark w/ UTF-8 streaming streams.
All those copies are gone.
- The old streaming streams implementation used to copy data even for
2-byte input. It no longer does.
- The only remaining 'slow' method is the Seek(.) slow case for utf-8
streaming streams. I don't expect this to be called a lot; and even if,
I expect it to be offset by the gains in the (vastly more frequent)
calls to the other methods or the 'fast path'.
- If it still bothers us, there are several ways to speed it up.
- API & code cleanliness:
- I want to remove the 'old' API in a follow-up CL, which should mostly
delete code, or replace it 1:1.
- In a 2nd follow-up I want to delete much of the UTF-8 handling in Blink
for streaming streams.
- The "bookmark" is now always implemented (and mostly very fast), so we
should be able to use it for more things.
- Testing & correctness:
- The unit tests now cover all stream implementations,
and are pretty good and triggering all the edge cases.
- Vastly more DCHECKs of the invariants.
BUG=v8:4947
Review-Url: https://codereview.chromium.org/2314663002
Cr-Commit-Position: refs/heads/master@{#39464}
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