hashmap-entry-ownable
Variation of HashMap::entry()
that accepts borrowed forms of keys.
Compatibility
For std::collections::HashMap
, nightly version of Rust is required, along with the crate feature nightly
.
For details, see hash_raw_entry
).
Support for hashbrown can be enabled through crate feature aptly called hashbrown
.
entry_ownable()
can be used as a drop-in replacement for entry()
, unless:
Entry::key()
is used,- entry is matched as a enum (
Entry::Occupied
/Entry::Vacant
).
Description
Use this crate if you create/update a lot of entries from borrowed forms of keys (e.g. from &str
instead of String
):
use HashMap;
use EntryAPI;
let rhyme = vec!;
let mut words: = new;
for w in rhyme
This code can be emulated with match map.get_mut(k)
/map.insert(k.to_owned(), …)
.
That too would be faster than regular Entry API if keys are reused a lot,
but entry_ownable()
variant:
- is as concise as regular
entry()
one, - only hashes key once, while
get_mut()
/insert()
does it twice if key is not in the map.
Benchmarks
std::collections::HashMap
:
test silly_bench::entry_1 ... bench: 2,162,452 ns/iter (+/- 17,586)
test silly_bench::get_or_insert_1 ... bench: 2,310,910 ns/iter (+/- 7,183)
test silly_bench::entry_ownable_1 ... bench: 1,586,380 ns/iter (+/- 7,156)
test silly_bench::entry_2 ... bench: 3,427,428 ns/iter (+/- 104,755)
test silly_bench::get_or_insert_2 ... bench: 2,926,719 ns/iter (+/- 11,077)
test silly_bench::entry_ownable_2 ... bench: 2,167,021 ns/iter (+/- 8,140)
test silly_bench::entry_4 ... bench: 6,068,954 ns/iter (+/- 56,549)
test silly_bench::get_or_insert_4 ... bench: 4,150,970 ns/iter (+/- 18,292)
test silly_bench::entry_ownable_4 ... bench: 3,321,019 ns/iter (+/- 18,487)
test silly_bench::entry_8 ... bench: 11,278,344 ns/iter (+/- 82,014)
test silly_bench::get_or_insert_8 ... bench: 6,602,424 ns/iter (+/- 33,360)
test silly_bench::entry_ownable_8 ... bench: 5,631,416 ns/iter (+/- 54,613)
hashbrown::HashMap
:
test silly_bench::entry_1 ... bench: 1,469,848 ns/iter (+/- 9,229)
test silly_bench::get_or_insert_1 ... bench: 1,489,309 ns/iter (+/- 10,865)
test silly_bench::entry_ownable_1 ... bench: 1,370,580 ns/iter (+/- 5,152)
test silly_bench::entry_2 ... bench: 2,351,940 ns/iter (+/- 10,374)
test silly_bench::get_or_insert_2 ... bench: 1,801,549 ns/iter (+/- 12,360)
test silly_bench::entry_ownable_2 ... bench: 1,634,317 ns/iter (+/- 7,421)
test silly_bench::entry_4 ... bench: 4,418,648 ns/iter (+/- 18,059)
test silly_bench::get_or_insert_4 ... bench: 2,451,798 ns/iter (+/- 10,702)
test silly_bench::entry_ownable_4 ... bench: 2,292,556 ns/iter (+/- 16,042)
test silly_bench::entry_8 ... bench: 8,350,365 ns/iter (+/- 39,678)
test silly_bench::get_or_insert_8 ... bench: 3,837,979 ns/iter (+/- 20,885)
test silly_bench::entry_ownable_8 ... bench: 3,749,296 ns/iter (+/- 5,678)
License
This crate borrows heavily from Rust's own libstd, hence Apache 2.0 and MIT.