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use std::error::Error;
use regex_automata::{
hybrid::dfa::{OverlappingState, DFA},
nfa::thompson,
HalfMatch, Input, MatchError,
};
// Tests that too many cache resets cause the lazy DFA to quit.
//
// We only test this on 64-bit because the test is gingerly crafted based on
// implementation details of cache sizes. It's not a great test because of
// that, but it does check some interesting properties around how positions are
// reported when a search "gives up."
//
// NOTE: If you change something in lazy DFA implementation that causes this
// test to fail by reporting different "gave up" positions, then it's generally
// okay to update the positions in the test below as long as you're sure your
// changes are correct. Namely, it is expected that if there are changes in the
// cache size (or changes in how big things are inside the cache), then its
// utilization may change slightly and thus impact where a search gives up.
// Precisely where a search gives up is not an API guarantee, so changing the
// offsets here is OK.
#[test]
#[cfg(target_pointer_width = "64")]
#[cfg(not(miri))]
fn too_many_cache_resets_cause_quit() -> Result<(), Box<dyn Error>> {
// This is a carefully chosen regex. The idea is to pick one that requires
// some decent number of states (hence the bounded repetition). But we
// specifically choose to create a class with an ASCII letter and a
// non-ASCII letter so that we can check that no new states are created
// once the cache is full. Namely, if we fill up the cache on a haystack
// of 'a's, then in order to match one 'β', a new state will need to be
// created since a 'β' is encoded with multiple bytes.
//
// So we proceed by "filling" up the cache by searching a haystack of just
// 'a's. The cache won't have enough room to add enough states to find the
// match (because of the bounded repetition), which should result in it
// giving up before it finds a match.
//
// Since there's now no more room to create states, we search a haystack
// of 'β' and confirm that it gives up immediately.
let pattern = r"[aβ]{99}";
let dfa = DFA::builder()
.configure(
// Configure it so that we have the minimum cache capacity
// possible. And that if any resets occur, the search quits.
DFA::config()
.skip_cache_capacity_check(true)
.cache_capacity(0)
.minimum_cache_clear_count(Some(0)),
)
.thompson(thompson::NFA::config())
.build(pattern)?;
let mut cache = dfa.create_cache();
let haystack = "a".repeat(101).into_bytes();
let err = MatchError::gave_up(25);
// Notice that we make the same amount of progress in each search! That's
// because the cache is reused and already has states to handle the first
// N bytes.
assert_eq!(
Err(err.clone()),
dfa.try_search_fwd(&mut cache, &Input::new(&haystack))
);
assert_eq!(
Err(err.clone()),
dfa.try_search_overlapping_fwd(
&mut cache,
&Input::new(&haystack),
&mut OverlappingState::start()
),
);
let haystack = "β".repeat(101).into_bytes();
let err = MatchError::gave_up(2);
assert_eq!(
Err(err),
dfa.try_search_fwd(&mut cache, &Input::new(&haystack))
);
// no need to test that other find routines quit, since we did that above
// OK, if we reset the cache, then we should be able to create more states
// and make more progress with searching for betas.
cache.reset(&dfa);
let err = MatchError::gave_up(27);
assert_eq!(
Err(err),
dfa.try_search_fwd(&mut cache, &Input::new(&haystack))
);
// ... switching back to ASCII still makes progress since it just needs to
// set transitions on existing states!
let haystack = "a".repeat(101).into_bytes();
let err = MatchError::gave_up(13);
assert_eq!(
Err(err),
dfa.try_search_fwd(&mut cache, &Input::new(&haystack))
);
Ok(())
}
// Tests that quit bytes in the forward direction work correctly.
#[test]
fn quit_fwd() -> Result<(), Box<dyn Error>> {
let dfa = DFA::builder()
.configure(DFA::config().quit(b'x', true))
.build("[[:word:]]+$")?;
let mut cache = dfa.create_cache();
assert_eq!(
dfa.try_search_fwd(&mut cache, &Input::new("abcxyz")),
Err(MatchError::quit(b'x', 3)),
);
assert_eq!(
dfa.try_search_overlapping_fwd(
&mut cache,
&Input::new(b"abcxyz"),
&mut OverlappingState::start()
),
Err(MatchError::quit(b'x', 3)),
);
Ok(())
}
// Tests that quit bytes in the reverse direction work correctly.
#[test]
fn quit_rev() -> Result<(), Box<dyn Error>> {
let dfa = DFA::builder()
.configure(DFA::config().quit(b'x', true))
.thompson(thompson::Config::new().reverse(true))
.build("^[[:word:]]+")?;
let mut cache = dfa.create_cache();
assert_eq!(
dfa.try_search_rev(&mut cache, &Input::new("abcxyz")),
Err(MatchError::quit(b'x', 3)),
);
Ok(())
}
// Tests that if we heuristically enable Unicode word boundaries but then
// instruct that a non-ASCII byte should NOT be a quit byte, then the builder
// will panic.
#[test]
#[should_panic]
fn quit_panics() {
DFA::config().unicode_word_boundary(true).quit(b'\xFF', false);
}
// This tests an intesting case where even if the Unicode word boundary option
// is disabled, setting all non-ASCII bytes to be quit bytes will cause Unicode
// word boundaries to be enabled.
#[test]
fn unicode_word_implicitly_works() -> Result<(), Box<dyn Error>> {
let mut config = DFA::config();
for b in 0x80..=0xFF {
config = config.quit(b, true);
}
let dfa = DFA::builder().configure(config).build(r"\b")?;
let mut cache = dfa.create_cache();
let expected = HalfMatch::must(0, 1);
assert_eq!(
Ok(Some(expected)),
dfa.try_search_fwd(&mut cache, &Input::new(" a")),
);
Ok(())
}