impl Cache

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.

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.

# if cfg!(miri) { return Ok(()); } // miri takes too long
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(),
);

# Ok::<(), Box<dyn std::error::Error>>(())

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>().