add memmem implementation, upgrade to Rust 2018, bump MSRV to Rust 1.41.1 #82
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This was long overdue, but I had been busy with other things. This also bumps the MSRV to Rust 1.41, which is what is currently in Debian stable.
This basically bumps down all of the memchr tests/benchmarks into a sub-module in order to make room for tests/benchmarks for other APIs like memmem.
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This was long overdue, and we were motivated by memchr's move to Rust 2018 in BurntSushi/memchr#82. Rust 1.41.1 was selected because it's the current version of Rust in Debian Stable. It also feels old enough to assure wide support.
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This is in line with similar changes to the regex and memchr crates: BurntSushi/memchr#82 and rust-lang/regex#767
This commit primarily adds vectorized substring search routines in a new memmem sub-module. They were originally taken from bstr, but heavily modified to incorporate a variant of the "generic SIMD" algorithm[1]. The main highlights: * We guarantee `O(m + n)` time complexity and constant space complexity. * Two-Way is the primary implementation that can handle all cases. * Vectorized variants handle a number of common cases. * Vectorized code uses a heuristic informed by a frequency background distribution of bytes, originally devised inside the regex crate. This makes it more likely that searching will spend more time in the fast vector loops. While adding memmem to this crate is perhaps a bit of a scope increase, I think it fits well. It also puts a core primitive, substring search, very low in the dependency DAG and therefore making it widely available. For example, it is intended to use these new routines in the regex, aho-corasick and bstr crates. This commit does a number of other things, mainly as a result of convenience. It drastically improves test coverage for substring search (as compared to what bstr had), completely overhauls the benchmark suite to make it more comprehensive and adds `cargo fuzz` support for all API items in the crate. Closes #58, Closes #72 [1] - http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd
This makes it easy to link to benchmarks when someone asks, but also serves as a good way to archive benchmark data at defined points for comparison later. We also make a (feeble) attempt at putting a "pretty" version of a subset of benchmarks in the README of each run directory.
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This is in line with similar changes to the regex and memchr crates: BurntSushi/memchr#82 and rust-lang/regex#767
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This was long overdue, and we were motivated by memchr's move to Rust 2018 in BurntSushi/memchr#82. Rust 1.41.1 was selected because it's the current version of Rust in Debian Stable. It also feels old enough to assure wide support.
BurntSushi
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Apr 30, 2021
This was long overdue, and we were motivated by memchr's move to Rust 2018 in BurntSushi/memchr#82. Rust 1.41.1 was selected because it's the current version of Rust in Debian Stable. It also feels old enough to assure wide support.
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This was long overdue, and we were motivated by memchr's move to Rust 2018 in BurntSushi/memchr#82. Rust 1.41.1 was selected because it's the current version of Rust in Debian Stable. It also feels old enough to assure wide support.
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Excellent, thanks for this! |
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This commit primarily adds vectorized substring search routines in
a new memmem sub-module. They were originally taken from bstr, but
heavily modified to incorporate a variant of the "generic SIMD"
algorithm[1]. The main highlights:
O(m + n)time complexity and constant spacecomplexity.
distribution of bytes, originally devised inside the regex crate.
This makes it more likely that searching will spend more time in the
fast vector loops.
While adding memmem to this crate is perhaps a bit of a scope increase,
I think it fits well. It also puts a core primitive, substring
search, very low in the dependency DAG and therefore making it widely
available. For example, it is intended to use these new routines in the
regex, aho-corasick and bstr crates.
This commit does a number of other things, mainly as a result of
convenience. It drastically improves test coverage for substring search
(as compared to what bstr had), completely overhauls the benchmark suite
to make it more comprehensive and adds
cargo fuzzsupport for all APIitems in the crate.
[1] - http://0x80.pl/articles/simd-strfind.html#algorithm-1-generic-simd