Add hash() and get_index() to phf_shared.#62
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sfackler merged 1 commit intorust-phf:masterfrom Aug 4, 2015
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In https://github.com/servo/string-cache, we currently use a `phf::OrderedSet` with its `get_index` method to get an identified stored in an `Atom`, and `index` to get a string back from that identifier. However, the extra inderection of `OrderedSet` of `Set` is not necessary. We don’t care about the order, only about getting numeric identifiers. Additionally, when `get_index` returns `None`, we hash the input string again to find it in table of dynamic atoms. With this chang, we can reuse the phf hash instead: servo/string-cache#103 At first I tried adding hash and index access to `phf::Map`, but the API got messy quickly.
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I think this makes sense as-is. I see |
sfackler
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Aug 4, 2015
Add hash() and get_index() to phf_shared.
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So you’re in favor of string-cache using these details from Could you publish this to crates.io? Thanks! |
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Yep, I think that strategy makes sense. Will publish now. |
bors-servo
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Reuse phf hash and remove phf::OrderedSet indirection <s>Do not merge yet.</s> This depends on rust-phf/rust-phf#62 Use the `phf_shared` and `phf_generator` crates directly instead of `phf`. This allows us to re-use the phf hash in the dynamic table and avoid hashing the same string again. Also remove the indirection of `phf::OrderedSet` compared to `phf::Set`: we don’t care about the order, only about getting numeric indices. (The optimization mentioned in a comment of using a bit map of the first 64 atoms in the html5ever tree builder was never implemented. If we want it, the indirection and order preservation can be added back while preserving the hash reuse.) Fixes #38. <!-- Reviewable:start --> [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/string-cache/103) <!-- Reviewable:end -->
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In https://github.com/servo/string-cache, we currently use a
phf::OrderedSetwith itsget_indexmethod to get an identified stored in anAtom, andindexto get a string back from that identifier.However, the extra inderection of
OrderedSetofSetis not necessary. We don’t care about the order, only about getting numeric identifiers.Additionally, when
get_indexreturnsNone, we hash the input string again to find it in table of dynamic atoms. With this chang, we can reuse the phf hash instead: servo/string-cache#103At first I tried adding hash and index access to
phf::Map, but the API got messy quickly. Do you think that is worth pursuing more, rather than having string-cache use phf internals?