pub struct Cache { /* private fields */ }
Expand description
A cache represents mutable state that a PikeVM
requires during a
search.
For a given PikeVM
, its corresponding cache may be created either via
PikeVM::create_cache
, or via Cache::new
. They are equivalent in
every way, except the former does not require explicitly importing Cache
.
A particular Cache
is coupled with the PikeVM
from which it
was created. It may only be used with that PikeVM
. A cache and its
allocations may be re-purposed via Cache::reset
, in which case, it can
only be used with the new PikeVM
(and not the old one).
Implementations§
source§impl Cache
impl Cache
sourcepub fn new(re: &PikeVM) -> Cache
pub fn new(re: &PikeVM) -> Cache
Create a new PikeVM
cache.
A potentially more convenient routine to create a cache is
PikeVM::create_cache
, as it does not require also importing the
Cache
type.
If you want to reuse the returned Cache
with some other PikeVM
,
then you must call Cache::reset
with the desired PikeVM
.
sourcepub fn reset(&mut self, re: &PikeVM)
pub fn reset(&mut self, re: &PikeVM)
Reset this cache such that it can be used for searching with a
different PikeVM
.
A cache reset permits reusing memory already allocated in this cache
with a different PikeVM
.
Example
This shows how to re-purpose a cache for use with a different PikeVM
.
use regex_automata::{nfa::thompson::pikevm::PikeVM, Match};
let re1 = PikeVM::new(r"\w")?;
let re2 = PikeVM::new(r"\W")?;
let mut cache = re1.create_cache();
assert_eq!(
Some(Match::must(0, 0..2)),
re1.find_iter(&mut cache, "Δ").next(),
);
// Using 'cache' with re2 is not allowed. It may result in panics or
// incorrect results. In order to re-purpose the cache, we must reset
// it with the PikeVM we'd like to use it with.
//
// Similarly, after this reset, using the cache with 're1' is also not
// allowed.
cache.reset(&re2);
assert_eq!(
Some(Match::must(0, 0..3)),
re2.find_iter(&mut cache, "☃").next(),
);
sourcepub fn memory_usage(&self) -> usize
pub fn memory_usage(&self) -> usize
Returns the heap memory usage, in bytes, of this cache.
This does not include the stack size used up by this cache. To
compute that, use std::mem::size_of::<Cache>()
.