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Consider using a pointer offset instead of a slice and integer position

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Refactor
Clarity
Mostly clear
Activity status
Stale
Tech stack
rust
Domain
performance

Research direction

Start in src/tokenizer.rs around line 372, where next_byte_unchecked is used by code such as skip_whitespace. Compare the generated assembly for the current slice-and-offset approach with the proposed pointer-offset approach, then verify that tokenizer behavior is unchanged and that the generated code has fewer indirections.

Written by the indexing model from the issue text.

Description

enhancement help wanted

The generated assembly for code using next_byte_unchecked like skip_whitespace has a suprising number of indirections in order to actually get the byte value. This is caused by the need to get the slice, then get the byte at the desired offset from it at https://github.com/servo/rust-cssparser/blob/682087fca5ba5f2f05a09bba72c62dac6b3d778d/src/tokenizer.rs#L372. If we use store a pointer and increase its instead of the offset, it should cause more efficient code to be generated.

Dominant language
Rust
Stars
869
Forks
152
Avg merge
15h 8m
Merged PRs (30d)
12

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