build(rust): vendor googletest crate

third_party/crates/regex-automata-0.4.18/tests/dfa/api.rs

@@ -0,0 +1,162 @@
+use std::error::Error;
+
+use regex_automata::{
+    dfa::{dense, Automaton, OverlappingState},
+    nfa::thompson,
+    Anchored, HalfMatch, Input, MatchError,
+};
+
+// Tests that quit bytes in the forward direction work correctly.
+#[test]
+fn quit_fwd() -> Result<(), Box<dyn Error>> {
+    let dfa = dense::Builder::new()
+        .configure(dense::Config::new().quit(b'x', true))
+        .build("[[:word:]]+$")?;
+
+    assert_eq!(
+        Err(MatchError::quit(b'x', 3)),
+        dfa.try_search_fwd(&Input::new(b"abcxyz"))
+    );
+    assert_eq!(
+        dfa.try_search_overlapping_fwd(
+            &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 = dense::Builder::new()
+        .configure(dense::Config::new().quit(b'x', true))
+        .thompson(thompson::Config::new().reverse(true))
+        .build("^[[:word:]]+")?;
+
+    assert_eq!(
+        Err(MatchError::quit(b'x', 3)),
+        dfa.try_search_rev(&Input::new(b"abcxyz"))
+    );
+
+    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() {
+    dense::Config::new().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 = dense::Config::new();
+    for b in 0x80..=0xFF {
+        config = config.quit(b, true);
+    }
+    let dfa = dense::Builder::new().configure(config).build(r"\b")?;
+    let expected = HalfMatch::must(0, 1);
+    assert_eq!(Ok(Some(expected)), dfa.try_search_fwd(&Input::new(b" a")));
+    Ok(())
+}
+
+// A variant of [`Automaton::is_special_state`]'s doctest, but with universal
+// start states.
+//
+// See: https://github.com/rust-lang/regex/pull/1195
+#[test]
+fn universal_start_search() -> Result<(), Box<dyn Error>> {
+    fn find<A: Automaton>(
+        dfa: &A,
+        haystack: &[u8],
+    ) -> Result<Option<HalfMatch>, MatchError> {
+        let mut state = dfa
+            .universal_start_state(Anchored::No)
+            .expect("regex should not require lookbehind");
+        let mut last_match = None;
+        // Walk all the bytes in the haystack. We can quit early if we see
+        // a dead or a quit state. The former means the automaton will
+        // never transition to any other state. The latter means that the
+        // automaton entered a condition in which its search failed.
+        for (i, &b) in haystack.iter().enumerate() {
+            state = dfa.next_state(state, b);
+            if dfa.is_special_state(state) {
+                if dfa.is_match_state(state) {
+                    last_match =
+                        Some(HalfMatch::new(dfa.match_pattern(state, 0), i));
+                } else if dfa.is_dead_state(state) {
+                    return Ok(last_match);
+                } else if dfa.is_quit_state(state) {
+                    // It is possible to enter into a quit state after
+                    // observing a match has occurred. In that case, we
+                    // should return the match instead of an error.
+                    if last_match.is_some() {
+                        return Ok(last_match);
+                    }
+                    return Err(MatchError::quit(b, i));
+                }
+                // Implementors may also want to check for start or accel
+                // states and handle them differently for performance
+                // reasons. But it is not necessary for correctness.
+            }
+        }
+        // Matches are always delayed by 1 byte, so we must explicitly walk
+        // the special "EOI" transition at the end of the search.
+        state = dfa.next_eoi_state(state);
+        if dfa.is_match_state(state) {
+            last_match = Some(HalfMatch::new(
+                dfa.match_pattern(state, 0),
+                haystack.len(),
+            ));
+        }
+        Ok(last_match)
+    }
+
+    fn check_impl(
+        dfa: impl Automaton,
+        haystack: &str,
+        pat: usize,
+        offset: usize,
+    ) -> Result<(), Box<dyn Error>> {
+        let haystack = haystack.as_bytes();
+        let mat = find(&dfa, haystack)?.unwrap();
+        assert_eq!(mat.pattern().as_usize(), pat);
+        assert_eq!(mat.offset(), offset);
+        Ok(())
+    }
+
+    fn check(
+        dfa: &dense::DFA<Vec<u32>>,
+        haystack: &str,
+        pat: usize,
+        offset: usize,
+    ) -> Result<(), Box<dyn Error>> {
+        check_impl(dfa, haystack, pat, offset)?;
+        check_impl(dfa.to_sparse()?, haystack, pat, offset)?;
+        Ok(())
+    }
+
+    let dfa = dense::DFA::new(r"[a-z]+")?;
+    let haystack = "123 foobar 4567";
+    check(&dfa, haystack, 0, 10)?;
+
+    let dfa = dense::DFA::new(r"[0-9]{4}")?;
+    let haystack = "123 foobar 4567";
+    check(&dfa, haystack, 0, 15)?;
+
+    let dfa = dense::DFA::new_many(&[r"[a-z]+", r"[0-9]+"])?;
+    let haystack = "123 foobar 4567";
+    check(&dfa, haystack, 1, 3)?;
+    check(&dfa, &haystack[3..], 0, 7)?;
+    check(&dfa, &haystack[10..], 1, 5)?;
+
+    Ok(())
+}

third_party/crates/regex-automata-0.4.18/tests/dfa/mod.rs

@@ -0,0 +1,8 @@
+#[cfg(all(feature = "dfa-build", feature = "dfa-search"))]
+mod api;
+#[cfg(feature = "dfa-onepass")]
+mod onepass;
+#[cfg(all(feature = "dfa-build", feature = "dfa-search"))]
+mod regression;
+#[cfg(all(not(miri), feature = "dfa-build", feature = "dfa-search"))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/dfa/onepass/mod.rs

@@ -0,0 +1,3 @@
+mod regression;
+#[cfg(not(miri))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/dfa/onepass/regression.rs

@@ -0,0 +1,61 @@
+// Regression test for zero-repetition capture groups,
+// which caused a panic when the Vec passed into search_slots
+// contained space for the capture group which would never
+// have any results.
+//
+// See: https://github.com/rust-lang/regex/issues/1327
+#[test]
+fn zero_repetition_capture_group() {
+    use regex_automata::{
+        dfa::onepass::DFA, util::primitives::NonMaxUsize, Anchored, Input,
+    };
+
+    let expr = DFA::new(r"(abc)(ABC){0}").unwrap();
+    let s = "abcABC";
+    let input = Input::new(s).span(0..s.len()).anchored(Anchored::Yes);
+
+    // Test with 4 slots, so the whole match plus the first capture group.
+    let mut cache = expr.create_cache();
+    let mut slots: Vec<Option<NonMaxUsize>> = vec![None; 4];
+    let pid = expr.try_search_slots(&mut cache, &input, &mut slots).unwrap();
+    assert_eq!(pid, Some(regex_automata::PatternID::must(0)));
+    assert_eq!(slots[0], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[1], Some(NonMaxUsize::new(3).unwrap()));
+    assert_eq!(slots[2], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[3], Some(NonMaxUsize::new(3).unwrap()));
+
+    // Test with larger slot array, which would fit the
+    // zero-repetition capture group.
+    slots.resize(6, None);
+    let pid = expr.try_search_slots(&mut cache, &input, &mut slots).unwrap();
+    assert_eq!(pid, Some(regex_automata::PatternID::must(0)));
+    // First capture group should match
+    assert_eq!(slots[2], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[3], Some(NonMaxUsize::new(3).unwrap()));
+    // Second capture group with {0} should be None.
+    assert_eq!(slots[4], None);
+    assert_eq!(slots[5], None);
+}
+
+// Another regression test for the same case as
+// `zero_repetition_capture_group`, but uses a simpler pattern. That
+// is, a zero-repetition capture group is a red herring. The actual bug
+// is simpler: it happens whenever too many slots are provided by the
+// caller.
+#[test]
+fn too_many_slots_normal_pattern() {
+    use regex_automata::{
+        dfa::onepass::DFA, util::primitives::NonMaxUsize, Anchored, Input,
+    };
+
+    let expr = DFA::new(r"abc").unwrap();
+    let s = "abc";
+    let input = Input::new(s).span(0..s.len()).anchored(Anchored::Yes);
+
+    let mut cache = expr.create_cache();
+    let mut slots: Vec<Option<NonMaxUsize>> = vec![None; 4];
+    let pid = expr.try_search_slots(&mut cache, &input, &mut slots).unwrap();
+    assert_eq!(pid, Some(regex_automata::PatternID::must(0)));
+    assert_eq!(slots[0], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[1], Some(NonMaxUsize::new(3).unwrap()));
+}

third_party/crates/regex-automata-0.4.18/tests/dfa/onepass/suite.rs

@@ -0,0 +1,197 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        dfa::onepass::{self, DFA},
+        nfa::thompson,
+        util::{iter, syntax},
+    },
+    regex_test::{
+        CompiledRegex, Match, RegexTest, SearchKind, Span, TestResult,
+        TestRunner,
+    },
+};
+
+use crate::{create_input, suite, testify_captures, untestify_kind};
+
+const EXPANSIONS: &[&str] = &["is_match", "find", "captures"];
+
+/// Tests the default configuration of the hybrid NFA/DFA.
+#[test]
+fn default() -> Result<()> {
+    let builder = DFA::builder();
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when 'starts_for_each_pattern' is enabled for all
+/// tests.
+#[test]
+fn starts_for_each_pattern() -> Result<()> {
+    let mut builder = DFA::builder();
+    builder.configure(DFA::config().starts_for_each_pattern(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when byte classes are disabled.
+///
+/// N.B. Disabling byte classes doesn't avoid any indirection at search time.
+/// All it does is cause every byte value to be its own distinct equivalence
+/// class.
+#[test]
+fn no_byte_classes() -> Result<()> {
+    let mut builder = DFA::builder();
+    builder.configure(DFA::config().byte_classes(false));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+fn compiler(
+    mut builder: onepass::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        // Check if our regex contains things that aren't supported by DFAs.
+        // That is, Unicode word boundaries when searching non-ASCII text.
+        if !configure_onepass_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        let re = match builder.build_many(&regexes) {
+            Ok(re) => re,
+            Err(err) => {
+                let msg = err.to_string();
+                // This is pretty gross, but when a regex fails to compile as
+                // a one-pass regex, then we want to be OK with that and just
+                // skip the test. But we have to be careful to only skip it
+                // when the expected result is that the regex compiles. If
+                // the test is specifically checking that the regex does not
+                // compile, then we should bubble up that error and allow the
+                // test to pass.
+                //
+                // Since our error types are all generally opaque, we just
+                // look for an error string. Not great, but not the end of the
+                // world.
+                if test.compiles() && msg.contains("not one-pass") {
+                    return Ok(CompiledRegex::skip());
+                }
+                return Err(err.into());
+            }
+        };
+        let mut cache = re.create_cache();
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, &mut cache, test)
+        }))
+    }
+}
+
+fn run_test(
+    re: &DFA,
+    cache: &mut onepass::Cache,
+    test: &RegexTest,
+) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => {
+            TestResult::matched(re.is_match(cache, input.earliest(true)))
+        }
+        "find" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                let input =
+                    input.earliest(test.search_kind() == SearchKind::Earliest);
+                let mut caps = re.create_captures();
+                let it = iter::Searcher::new(input)
+                    .into_matches_iter(|input| {
+                        re.try_search(cache, input, &mut caps)?;
+                        Ok(caps.get_match())
+                    })
+                    .infallible()
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    });
+                TestResult::matches(it)
+            }
+            SearchKind::Overlapping => {
+                // The one-pass DFA does not support any kind of overlapping
+                // search. This is not just a matter of not having the API.
+                // It's fundamentally incompatible with the one-pass concept.
+                // If overlapping matches were possible, then the one-pass DFA
+                // would fail to build.
+                TestResult::skip()
+            }
+        },
+        "captures" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                let input =
+                    input.earliest(test.search_kind() == SearchKind::Earliest);
+                let it = iter::Searcher::new(input)
+                    .into_captures_iter(re.create_captures(), |input, caps| {
+                        re.try_search(cache, input, caps)
+                    })
+                    .infallible()
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|caps| testify_captures(&caps));
+                TestResult::captures(it)
+            }
+            SearchKind::Overlapping => {
+                // The one-pass DFA does not support any kind of overlapping
+                // search. This is not just a matter of not having the API.
+                // It's fundamentally incompatible with the one-pass concept.
+                // If overlapping matches were possible, then the one-pass DFA
+                // would fail to build.
+                TestResult::skip()
+            }
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_onepass_builder(
+    test: &RegexTest,
+    builder: &mut onepass::Builder,
+) -> bool {
+    if !test.anchored() {
+        return false;
+    }
+    let match_kind = match untestify_kind(test.match_kind()) {
+        None => return false,
+        Some(k) => k,
+    };
+
+    let config = DFA::config().match_kind(match_kind);
+    builder
+        .configure(config)
+        .syntax(config_syntax(test))
+        .thompson(config_thompson(test));
+    true
+}
+
+/// Configuration of a Thompson NFA compiler from a regex test.
+fn config_thompson(test: &RegexTest) -> thompson::Config {
+    let mut lookm = regex_automata::util::look::LookMatcher::new();
+    lookm.set_line_terminator(test.line_terminator());
+    thompson::Config::new().utf8(test.utf8()).look_matcher(lookm)
+}
+
+/// Configuration of the regex parser from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}

third_party/crates/regex-automata-0.4.18/tests/dfa/regression.rs

@@ -0,0 +1,75 @@
+// A regression test for checking that minimization correctly translates
+// whether a state is a match state or not. Previously, it was possible for
+// minimization to mark a non-matching state as matching.
+#[test]
+#[cfg(not(miri))]
+fn minimize_sets_correct_match_states() {
+    use regex_automata::{
+        dfa::{dense::DFA, Automaton, StartKind},
+        Anchored, Input,
+    };
+
+    let pattern =
+        // This is a subset of the grapheme matching regex. I couldn't seem
+        // to get a repro any smaller than this unfortunately.
+        r"(?x)
+            (?:
+                \p{gcb=Prepend}*
+                (?:
+                    (?:
+                        (?:
+                            \p{gcb=L}*
+                            (?:\p{gcb=V}+|\p{gcb=LV}\p{gcb=V}*|\p{gcb=LVT})
+                            \p{gcb=T}*
+                        )
+                        |
+                        \p{gcb=L}+
+                        |
+                        \p{gcb=T}+
+                    )
+                    |
+                    \p{Extended_Pictographic}
+                    (?:\p{gcb=Extend}*\p{gcb=ZWJ}\p{Extended_Pictographic})*
+                    |
+                    [^\p{gcb=Control}\p{gcb=CR}\p{gcb=LF}]
+                )
+                [\p{gcb=Extend}\p{gcb=ZWJ}\p{gcb=SpacingMark}]*
+            )
+        ";
+
+    let dfa = DFA::builder()
+        .configure(
+            DFA::config().start_kind(StartKind::Anchored).minimize(true),
+        )
+        .build(pattern)
+        .unwrap();
+    let input = Input::new(b"\xE2").anchored(Anchored::Yes);
+    assert_eq!(Ok(None), dfa.try_search_fwd(&input));
+}
+
+// A prefilter must not skip to a new candidate after the DFA has already
+// recorded a match. The DFA is still resolving the priority of that match,
+// and skipping can cause a later match to overwrite it.
+#[test]
+#[cfg(feature = "perf-literal-multisubstring")]
+fn prefilter_does_not_skip_pending_match() {
+    use regex_automata::{
+        dfa::{dense::DFA, Automaton},
+        util::prefilter::Prefilter,
+        HalfMatch, Input, MatchKind,
+    };
+
+    let pre = Prefilter::new(MatchKind::LeftmostFirst, &["ab", "c"])
+        .expect("prefilter");
+    let dfa = DFA::builder()
+        .configure(
+            DFA::config().prefilter(Some(pre)).starts_for_each_pattern(true),
+        )
+        .build(r"(?:ab|c)*c")
+        .unwrap();
+    let expected = Ok(Some(HalfMatch::must(0, 1)));
+    let input = Input::new("cabac");
+
+    assert_eq!(expected, dfa.try_search_fwd(&input));
+    assert_eq!(expected, dfa.to_sparse().unwrap().try_search_fwd(&input));
+}

third_party/crates/regex-automata-0.4.18/tests/dfa/suite.rs

@@ -0,0 +1,443 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        dfa::{
+            self, dense, regex::Regex, sparse, Automaton, OverlappingState,
+            StartKind,
+        },
+        nfa::thompson,
+        util::{prefilter::Prefilter, syntax},
+        Anchored, Input, PatternSet,
+    },
+    regex_test::{
+        CompiledRegex, Match, RegexTest, SearchKind, Span, TestResult,
+        TestRunner,
+    },
+};
+
+use crate::{create_input, suite, untestify_kind};
+
+const EXPANSIONS: &[&str] = &["is_match", "find", "which"];
+
+/// Runs the test suite with the default configuration.
+#[test]
+fn unminimized_default() -> Result<()> {
+    let builder = Regex::builder();
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite with the default configuration and a prefilter enabled,
+/// if one can be built.
+#[test]
+fn unminimized_prefilter() -> Result<()> {
+    let my_compiler = |test: &RegexTest, regexes: &[String]| {
+        // Parse regexes as HIRs so we can get literals to build a prefilter.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+        let kind = match untestify_kind(test.match_kind()) {
+            None => return Ok(CompiledRegex::skip()),
+            Some(kind) => kind,
+        };
+        let pre = Prefilter::from_hirs_prefix(kind, &hirs);
+        let mut builder = Regex::builder();
+        builder.dense(dense::DFA::config().prefilter(pre));
+        compiler(builder, |_, _, re| {
+            Ok(CompiledRegex::compiled(move |test| -> TestResult {
+                run_test(&re, test)
+            }))
+        })(test, regexes)
+    };
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), my_compiler)
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite with start states specialized.
+#[test]
+fn unminimized_specialized_start_states() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dense(dense::Config::new().specialize_start_states(true));
+
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite with byte classes disabled.
+#[test]
+fn unminimized_no_byte_class() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dense(dense::Config::new().byte_classes(false));
+
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite with NFA shrinking enabled.
+#[test]
+fn unminimized_nfa_shrink() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.thompson(thompson::Config::new().shrink(true));
+
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite on a minimized DFA with an otherwise default
+/// configuration.
+#[test]
+fn minimized_default() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dense(dense::Config::new().minimize(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite on a minimized DFA with byte classes disabled.
+#[test]
+fn minimized_no_byte_class() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dense(dense::Config::new().minimize(true).byte_classes(false));
+
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), dense_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite on a sparse unminimized DFA.
+#[test]
+fn sparse_unminimized_default() -> Result<()> {
+    let builder = Regex::builder();
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), sparse_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Runs the test suite on a sparse unminimized DFA with prefilters enabled.
+#[test]
+fn sparse_unminimized_prefilter() -> Result<()> {
+    let my_compiler = |test: &RegexTest, regexes: &[String]| {
+        // Parse regexes as HIRs so we can get literals to build a prefilter.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+        let kind = match untestify_kind(test.match_kind()) {
+            None => return Ok(CompiledRegex::skip()),
+            Some(kind) => kind,
+        };
+        let pre = Prefilter::from_hirs_prefix(kind, &hirs);
+        let mut builder = Regex::builder();
+        builder.dense(dense::DFA::config().prefilter(pre));
+        compiler(builder, |builder, _, re| {
+            let fwd = re.forward().to_sparse()?;
+            let rev = re.reverse().to_sparse()?;
+            let re = builder.build_from_dfas(fwd, rev);
+            Ok(CompiledRegex::compiled(move |test| -> TestResult {
+                run_test(&re, test)
+            }))
+        })(test, regexes)
+    };
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), my_compiler)
+        .assert();
+    Ok(())
+}
+
+/// Another basic sanity test that checks we can serialize and then deserialize
+/// a regex, and that the resulting regex can be used for searching correctly.
+#[test]
+fn serialization_unminimized_default() -> Result<()> {
+    let builder = Regex::builder();
+    let my_compiler = |builder| {
+        compiler(builder, |builder, _, re| {
+            let builder = builder.clone();
+            let (fwd_bytes, _) = re.forward().to_bytes_native_endian();
+            let (rev_bytes, _) = re.reverse().to_bytes_native_endian();
+            Ok(CompiledRegex::compiled(move |test| -> TestResult {
+                let fwd: dense::DFA<&[u32]> =
+                    dense::DFA::from_bytes(&fwd_bytes).unwrap().0;
+                let rev: dense::DFA<&[u32]> =
+                    dense::DFA::from_bytes(&rev_bytes).unwrap().0;
+                let re = builder.build_from_dfas(fwd, rev);
+
+                run_test(&re, test)
+            }))
+        })
+    };
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), my_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// A basic sanity test that checks we can serialize and then deserialize a
+/// regex using sparse DFAs, and that the resulting regex can be used for
+/// searching correctly.
+#[test]
+fn sparse_serialization_unminimized_default() -> Result<()> {
+    let builder = Regex::builder();
+    let my_compiler = |builder| {
+        compiler(builder, |builder, _, re| {
+            let builder = builder.clone();
+            let fwd_bytes = re.forward().to_sparse()?.to_bytes_native_endian();
+            let rev_bytes = re.reverse().to_sparse()?.to_bytes_native_endian();
+            Ok(CompiledRegex::compiled(move |test| -> TestResult {
+                let fwd: sparse::DFA<&[u8]> =
+                    sparse::DFA::from_bytes(&fwd_bytes).unwrap().0;
+                let rev: sparse::DFA<&[u8]> =
+                    sparse::DFA::from_bytes(&rev_bytes).unwrap().0;
+                let re = builder.build_from_dfas(fwd, rev);
+                run_test(&re, test)
+            }))
+        })
+    };
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .blacklist("expensive")
+        .test_iter(suite()?.iter(), my_compiler(builder))
+        .assert();
+    Ok(())
+}
+
+fn dense_compiler(
+    builder: dfa::regex::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    compiler(builder, |_, _, re| {
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, test)
+        }))
+    })
+}
+
+fn sparse_compiler(
+    builder: dfa::regex::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    compiler(builder, |builder, _, re| {
+        let fwd = re.forward().to_sparse()?;
+        let rev = re.reverse().to_sparse()?;
+        let re = builder.build_from_dfas(fwd, rev);
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, test)
+        }))
+    })
+}
+
+fn compiler(
+    mut builder: dfa::regex::Builder,
+    mut create_matcher: impl FnMut(
+        &dfa::regex::Builder,
+        Option<Prefilter>,
+        Regex,
+    ) -> Result<CompiledRegex>,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        // Parse regexes as HIRs for some analysis below.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+
+        // Get a prefilter in case the test wants it.
+        let kind = match untestify_kind(test.match_kind()) {
+            None => return Ok(CompiledRegex::skip()),
+            Some(kind) => kind,
+        };
+        let pre = Prefilter::from_hirs_prefix(kind, &hirs);
+
+        // Check if our regex contains things that aren't supported by DFAs.
+        // That is, Unicode word boundaries when searching non-ASCII text.
+        if !test.haystack().is_ascii() {
+            for hir in hirs.iter() {
+                if hir.properties().look_set().contains_word_unicode() {
+                    return Ok(CompiledRegex::skip());
+                }
+            }
+        }
+        if !configure_regex_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        create_matcher(&builder, pre, builder.build_many(&regexes)?)
+    }
+}
+
+fn run_test<A: Automaton>(re: &Regex<A>, test: &RegexTest) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => TestResult::matched(re.is_match(input.earliest(true))),
+        "find" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                let input =
+                    input.earliest(test.search_kind() == SearchKind::Earliest);
+                TestResult::matches(
+                    re.find_iter(input)
+                        .take(test.match_limit().unwrap_or(std::usize::MAX))
+                        .map(|m| Match {
+                            id: m.pattern().as_usize(),
+                            span: Span { start: m.start(), end: m.end() },
+                        }),
+                )
+            }
+            SearchKind::Overlapping => {
+                try_search_overlapping(re, &input).unwrap()
+            }
+        },
+        "which" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                // There are no "which" APIs for standard searches.
+                TestResult::skip()
+            }
+            SearchKind::Overlapping => {
+                let dfa = re.forward();
+                let mut patset = PatternSet::new(dfa.pattern_len());
+                dfa.try_which_overlapping_matches(&input, &mut patset)
+                    .unwrap();
+                TestResult::which(patset.iter().map(|p| p.as_usize()))
+            }
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_regex_builder(
+    test: &RegexTest,
+    builder: &mut dfa::regex::Builder,
+) -> bool {
+    let match_kind = match untestify_kind(test.match_kind()) {
+        None => return false,
+        Some(k) => k,
+    };
+
+    let starts = if test.anchored() {
+        StartKind::Anchored
+    } else {
+        StartKind::Unanchored
+    };
+    let mut dense_config = dense::Config::new()
+        .start_kind(starts)
+        .match_kind(match_kind)
+        .unicode_word_boundary(true);
+    // When doing an overlapping search, we might try to find the start of each
+    // match with a custom search routine. In that case, we need to tell the
+    // reverse search (for the start offset) which pattern to look for. The
+    // only way that API works is when anchored starting states are compiled
+    // for each pattern. This does technically also enable it for the forward
+    // DFA, but we're okay with that.
+    if test.search_kind() == SearchKind::Overlapping {
+        dense_config = dense_config.starts_for_each_pattern(true);
+    }
+
+    builder
+        .syntax(config_syntax(test))
+        .thompson(config_thompson(test))
+        .dense(dense_config);
+    true
+}
+
+/// Configuration of a Thompson NFA compiler from a regex test.
+fn config_thompson(test: &RegexTest) -> thompson::Config {
+    let mut lookm = regex_automata::util::look::LookMatcher::new();
+    lookm.set_line_terminator(test.line_terminator());
+    thompson::Config::new().utf8(test.utf8()).look_matcher(lookm)
+}
+
+/// Configuration of the regex syntax from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}
+
+/// Execute an overlapping search, and for each match found, also find its
+/// overlapping starting positions.
+///
+/// N.B. This routine used to be part of the crate API, but 1) it wasn't clear
+/// to me how useful it was and 2) it wasn't clear to me what its semantics
+/// should be. In particular, a potentially surprising footgun of this routine
+/// that it is worst case *quadratic* in the size of the haystack. Namely, it's
+/// possible to report a match at every position, and for every such position,
+/// scan all the way to the beginning of the haystack to find the starting
+/// position. Typical leftmost non-overlapping searches don't suffer from this
+/// because, well, matches can't overlap. So subsequent searches after a match
+/// is found don't revisit previously scanned parts of the haystack.
+///
+/// Its semantics can be strange for other reasons too. For example, given
+/// the regex '.*' and the haystack 'zz', the full set of overlapping matches
+/// is: [0, 0], [1, 1], [0, 1], [2, 2], [1, 2], [0, 2]. The ordering of
+/// those matches is quite strange, but makes sense when you think about the
+/// implementation: an end offset is found left-to-right, and then one or more
+/// starting offsets are found right-to-left.
+///
+/// Nevertheless, we provide this routine in our test suite because it's
+/// useful to test the low level DFA overlapping search and our test suite
+/// is written in a way that requires starting offsets.
+fn try_search_overlapping<A: Automaton>(
+    re: &Regex<A>,
+    input: &Input<'_>,
+) -> Result<TestResult> {
+    let mut matches = vec![];
+    let mut fwd_state = OverlappingState::start();
+    let (fwd_dfa, rev_dfa) = (re.forward(), re.reverse());
+    while let Some(end) = {
+        fwd_dfa.try_search_overlapping_fwd(input, &mut fwd_state)?;
+        fwd_state.get_match()
+    } {
+        let revsearch = input
+            .clone()
+            .range(input.start()..end.offset())
+            .anchored(Anchored::Pattern(end.pattern()))
+            .earliest(false);
+        let mut rev_state = OverlappingState::start();
+        while let Some(start) = {
+            rev_dfa.try_search_overlapping_rev(&revsearch, &mut rev_state)?;
+            rev_state.get_match()
+        } {
+            let span = Span { start: start.offset(), end: end.offset() };
+            let mat = Match { id: end.pattern().as_usize(), span };
+            matches.push(mat);
+        }
+    }
+    Ok(TestResult::matches(matches))
+}

third_party/crates/regex-automata-0.4.18/tests/fuzz/dense.rs

@@ -0,0 +1,52 @@
+// This test was found by a fuzzer input that crafted a way to provide
+// an invalid serialization of ByteClasses that passed our verification.
+// Specifically, the verification step in the deserialization of ByteClasses
+// used an iterator that depends on part of the serialized bytes being correct.
+// (Specifically, the encoding of the number of classes.)
+#[test]
+fn invalid_byte_classes() {
+    let data = include_bytes!(
+        "testdata/deserialize_dense_crash-9486fb7c8a93b12c12a62166b43d31640c0208a9",
+    );
+    let _ = fuzz_run(data);
+}
+
+#[test]
+fn invalid_byte_classes_min() {
+    let data = include_bytes!(
+        "testdata/deserialize_dense_minimized-from-9486fb7c8a93b12c12a62166b43d31640c0208a9",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This is the code from the fuzz target. Kind of sucks to duplicate it here,
+// but this is fundamentally how we interpret the date.
+fn fuzz_run(given_data: &[u8]) -> Option<()> {
+    use regex_automata::dfa::Automaton;
+
+    if given_data.len() < 2 {
+        return None;
+    }
+    let haystack_len = usize::from(given_data[0]);
+    let haystack = given_data.get(1..1 + haystack_len)?;
+    let given_dfa_bytes = given_data.get(1 + haystack_len..)?;
+
+    // We help the fuzzer along by adding a preamble to the bytes that should
+    // at least make these first parts valid. The preamble expects a very
+    // specific sequence of bytes, so it makes sense to just force this.
+    let label = "rust-regex-automata-dfa-dense\x00\x00\x00";
+    assert_eq!(0, label.len() % 4);
+    let endianness_check = 0xFEFFu32.to_ne_bytes().to_vec();
+    let version_check = 2u32.to_ne_bytes().to_vec();
+    let mut dfa_bytes: Vec<u8> = vec![];
+    dfa_bytes.extend(label.as_bytes());
+    dfa_bytes.extend(&endianness_check);
+    dfa_bytes.extend(&version_check);
+    dfa_bytes.extend(given_dfa_bytes);
+    // This is the real test: checking that any input we give to
+    // DFA::from_bytes will never result in a panic.
+    let (dfa, _) =
+        regex_automata::dfa::dense::DFA::from_bytes(&dfa_bytes).ok()?;
+    let _ = dfa.try_search_fwd(&regex_automata::Input::new(haystack));
+    Some(())
+}

third_party/crates/regex-automata-0.4.18/tests/fuzz/sparse.rs

@@ -0,0 +1,132 @@
+// This is a regression test for a bug in how special states are handled. The
+// fuzzer found a case where a state returned true for 'is_special_state' but
+// *didn't* return true for 'is_dead_state', 'is_quit_state', 'is_match_state',
+// 'is_start_state' or 'is_accel_state'. This in turn tripped a debug assertion
+// in the core matching loop that requires 'is_special_state' being true to
+// imply that one of the other routines returns true.
+//
+// We fixed this by adding some validation to both dense and sparse DFAs that
+// checks that this property is true for every state ID in the DFA.
+#[test]
+fn invalid_special_state() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-a1b839d899ced76d5d7d0f78f9edb7a421505838",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This is an interesting case where a fuzzer generated a DFA with
+// a transition to a state ID that decoded as a valid state, but
+// where the ID itself did not point to one of the two existing
+// states for this particular DFA. This combined with marking this
+// transition's state ID as special but without actually making one of the
+// 'is_{dead,quit,match,start,accel}_state' predicates return true ended up
+// tripping the 'debug_assert(dfa.is_quit_state(sid))' code in the search
+// routine.
+//
+// We fixed this in alloc mode by checking that every transition points to a
+// valid state ID. Technically this bug still exists in core-only mode, but
+// it's not clear how to fix it. And it's worth pointing out that the search
+// routine won't panic in production. It will just provide invalid results. And
+// that's acceptable within the contract of DFA::from_bytes.
+#[test]
+fn transition_to_invalid_but_valid_state() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-dbb8172d3984e7e7d03f4b5f8bb86ecd1460eff9",
+    );
+    let _ = fuzz_run(data);
+}
+
+// Another one caught by the fuzzer where it generated a DFA that reported a
+// start state as a match state. Since matches are always delayed by one byte,
+// start states specifically cannot be match states. And indeed, the search
+// code relies on this.
+#[test]
+fn start_state_is_not_match_state() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-0da59c0434eaf35e5a6b470fa9244bb79c72b000",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This is variation on 'transition_to_invalid_but_valid_state', but happens
+// to a start state. Namely, the fuzz data here builds a DFA with a start
+// state ID that is incorrect but points to a sequence of bytes that satisfies
+// state decoding validation. This errant state in turn has a non-zero number
+// of transitions, and its those transitions that point to a state that does
+// *not* satisfy state decoding validation. But we never checked those. So the
+// fix here was to add validation of the transitions off of the start state.
+#[test]
+fn start_state_has_valid_transitions() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-61fd8e3003bf9d99f6c1e5a8488727eefd234b98",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This fuzz input generated a DFA with a state whose ID was in the match state
+// ID range, but where the state itself was encoded with zero pattern IDs. We
+// added validation code to check this case.
+#[test]
+fn match_state_inconsistency() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-c383ae07ec5e191422eadc492117439011816570",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This fuzz input generated a DFA with a state whose ID was in the accelerator
+// range, but who didn't have any accelerators. This violated an invariant that
+// assumes that if 'dfa.is_accel_state(sid)' returns true, then the state must
+// have some accelerators.
+#[test]
+fn invalid_accelerators() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-d07703ceb94b10dcd9e4acb809f2051420449e2b",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This fuzz input generated a DFA with a state whose EOI transition led to
+// a quit state, which is generally considered illegal. Why? Because the EOI
+// transition is defined over a special sentinel alphabet element and one
+// cannot configure a DFA to "quit" on that sentinel.
+#[test]
+fn eoi_transition_to_quit_state() {
+    let data = include_bytes!(
+        "testdata/deserialize_sparse_crash-18cfc246f2ddfc3dfc92b0c7893178c7cf65efa9",
+    );
+    let _ = fuzz_run(data);
+}
+
+// This is the code from the fuzz target. Kind of sucks to duplicate it here,
+// but this is fundamentally how we interpret the date.
+fn fuzz_run(given_data: &[u8]) -> Option<()> {
+    use regex_automata::dfa::Automaton;
+
+    if given_data.len() < 2 {
+        return None;
+    }
+    let haystack_len = usize::from(given_data[0]);
+    let haystack = given_data.get(1..1 + haystack_len)?;
+    let given_dfa_bytes = given_data.get(1 + haystack_len..)?;
+
+    // We help the fuzzer along by adding a preamble to the bytes that should
+    // at least make these first parts valid. The preamble expects a very
+    // specific sequence of bytes, so it makes sense to just force this.
+    let label = "rust-regex-automata-dfa-sparse\x00\x00";
+    assert_eq!(0, label.len() % 4);
+    let endianness_check = 0xFEFFu32.to_ne_bytes().to_vec();
+    let version_check = 2u32.to_ne_bytes().to_vec();
+    let mut dfa_bytes: Vec<u8> = vec![];
+    dfa_bytes.extend(label.as_bytes());
+    dfa_bytes.extend(&endianness_check);
+    dfa_bytes.extend(&version_check);
+    dfa_bytes.extend(given_dfa_bytes);
+    // This is the real test: checking that any input we give to
+    // DFA::from_bytes will never result in a panic.
+    let (dfa, _) =
+        regex_automata::dfa::sparse::DFA::from_bytes(&dfa_bytes).ok()?;
+    let _ = dfa.try_search_fwd(&regex_automata::Input::new(haystack));
+    Some(())
+}

third_party/crates/regex-automata-0.4.18/tests/gen/dense/mod.rs

@@ -0,0 +1,22 @@
+use regex_automata::{Input, Match};
+
+mod multi_pattern_v2;
+
+#[test]
+fn multi_pattern_v2() {
+    use multi_pattern_v2::MULTI_PATTERN_V2 as RE;
+
+    assert_eq!(Some(Match::must(0, 0..4)), RE.find("abcd"));
+    assert_eq!(Some(Match::must(0, 2..6)), RE.find("@ abcd @"));
+    assert_eq!(Some(Match::must(1, 0..6)), RE.find("@abcd@"));
+    assert_eq!(Some(Match::must(0, 1..5)), RE.find("\nabcd\n"));
+    assert_eq!(Some(Match::must(0, 1..5)), RE.find("\nabcd wxyz\n"));
+    assert_eq!(Some(Match::must(1, 1..7)), RE.find("\n@abcd@\n"));
+    assert_eq!(Some(Match::must(2, 0..6)), RE.find("@abcd@\r\n"));
+    assert_eq!(Some(Match::must(1, 2..8)), RE.find("\r\n@abcd@"));
+    assert_eq!(Some(Match::must(2, 2..8)), RE.find("\r\n@abcd@\r\n"));
+
+    // Fails because we have heuristic support for Unicode word boundaries
+    // enabled.
+    assert!(RE.try_search(&Input::new(b"\xFF@abcd@\xFF")).is_err());
+}

third_party/crates/regex-automata-0.4.18/tests/gen/dense/multi_pattern_v2.rs

@@ -0,0 +1,43 @@
+// DO NOT EDIT THIS FILE. IT WAS AUTOMATICALLY GENERATED BY:
+//
+//     regex-cli generate serialize dense regex MULTI_PATTERN_V2 tests/gen/dense/ --rustfmt --safe --starts-for-each-pattern --specialize-start-states --start-kind both --unicode-word-boundary --minimize \b[a-zA-Z]+\b (?m)^\S+$ (?Rm)^\S+$
+//
+// regex-cli 0.0.1 is available on crates.io.
+
+use regex_automata::{
+    dfa::{dense::DFA, regex::Regex},
+    util::{lazy::Lazy, wire::AlignAs},
+};
+
+pub static MULTI_PATTERN_V2: Lazy<Regex<DFA<&'static [u32]>>> =
+    Lazy::new(|| {
+        let dfafwd = {
+            static ALIGNED: &AlignAs<[u8], u32> = &AlignAs {
+                _align: [],
+                #[cfg(target_endian = "big")]
+                bytes: *include_bytes!("multi_pattern_v2_fwd.bigendian.dfa"),
+                #[cfg(target_endian = "little")]
+                bytes: *include_bytes!(
+                    "multi_pattern_v2_fwd.littleendian.dfa"
+                ),
+            };
+            DFA::from_bytes(&ALIGNED.bytes)
+                .expect("serialized forward DFA should be valid")
+                .0
+        };
+        let dfarev = {
+            static ALIGNED: &AlignAs<[u8], u32> = &AlignAs {
+                _align: [],
+                #[cfg(target_endian = "big")]
+                bytes: *include_bytes!("multi_pattern_v2_rev.bigendian.dfa"),
+                #[cfg(target_endian = "little")]
+                bytes: *include_bytes!(
+                    "multi_pattern_v2_rev.littleendian.dfa"
+                ),
+            };
+            DFA::from_bytes(&ALIGNED.bytes)
+                .expect("serialized reverse DFA should be valid")
+                .0
+        };
+        Regex::builder().build_from_dfas(dfafwd, dfarev)
+    });

third_party/crates/regex-automata-0.4.18/tests/gen/mod.rs

@@ -0,0 +1,2 @@
+mod dense;
+mod sparse;

third_party/crates/regex-automata-0.4.18/tests/gen/sparse/mod.rs

@@ -0,0 +1,22 @@
+use regex_automata::{Input, Match};
+
+mod multi_pattern_v2;
+
+#[test]
+fn multi_pattern_v2() {
+    use multi_pattern_v2::MULTI_PATTERN_V2 as RE;
+
+    assert_eq!(Some(Match::must(0, 0..4)), RE.find("abcd"));
+    assert_eq!(Some(Match::must(0, 2..6)), RE.find("@ abcd @"));
+    assert_eq!(Some(Match::must(1, 0..6)), RE.find("@abcd@"));
+    assert_eq!(Some(Match::must(0, 1..5)), RE.find("\nabcd\n"));
+    assert_eq!(Some(Match::must(0, 1..5)), RE.find("\nabcd wxyz\n"));
+    assert_eq!(Some(Match::must(1, 1..7)), RE.find("\n@abcd@\n"));
+    assert_eq!(Some(Match::must(2, 0..6)), RE.find("@abcd@\r\n"));
+    assert_eq!(Some(Match::must(1, 2..8)), RE.find("\r\n@abcd@"));
+    assert_eq!(Some(Match::must(2, 2..8)), RE.find("\r\n@abcd@\r\n"));
+
+    // Fails because we have heuristic support for Unicode word boundaries
+    // enabled.
+    assert!(RE.try_search(&Input::new(b"\xFF@abcd@\xFF")).is_err());
+}

third_party/crates/regex-automata-0.4.18/tests/gen/sparse/multi_pattern_v2.rs

@@ -0,0 +1,37 @@
+// DO NOT EDIT THIS FILE. IT WAS AUTOMATICALLY GENERATED BY:
+//
+//     regex-cli generate serialize sparse regex MULTI_PATTERN_V2 regex-automata/tests/gen/sparse/ --rustfmt --safe --starts-for-each-pattern --specialize-start-states --start-kind both --unicode-word-boundary --minimize \b[a-zA-Z]+\b (?m)^\S+$ (?Rm)^\S+$
+//
+// regex-cli 0.0.1 is available on crates.io.
+
+use regex_automata::{
+    dfa::{regex::Regex, sparse::DFA},
+    util::lazy::Lazy,
+};
+
+pub static MULTI_PATTERN_V2: Lazy<Regex<DFA<&'static [u8]>>> =
+    Lazy::new(|| {
+        let dfafwd = {
+            #[cfg(target_endian = "big")]
+            static BYTES: &'static [u8] =
+                include_bytes!("multi_pattern_v2_fwd.bigendian.dfa");
+            #[cfg(target_endian = "little")]
+            static BYTES: &'static [u8] =
+                include_bytes!("multi_pattern_v2_fwd.littleendian.dfa");
+            DFA::from_bytes(BYTES)
+                .expect("serialized forward DFA should be valid")
+                .0
+        };
+        let dfarev = {
+            #[cfg(target_endian = "big")]
+            static BYTES: &'static [u8] =
+                include_bytes!("multi_pattern_v2_rev.bigendian.dfa");
+            #[cfg(target_endian = "little")]
+            static BYTES: &'static [u8] =
+                include_bytes!("multi_pattern_v2_rev.littleendian.dfa");
+            DFA::from_bytes(BYTES)
+                .expect("serialized reverse DFA should be valid")
+                .0
+        };
+        Regex::builder().build_from_dfas(dfafwd, dfarev)
+    });

third_party/crates/regex-automata-0.4.18/tests/hybrid/api.rs

@@ -0,0 +1,201 @@
+use std::error::Error;
+
+use regex_automata::{
+    hybrid::dfa::{OverlappingState, DFA},
+    nfa::thompson,
+    HalfMatch, Input, MatchError,
+};
+
+// A tagged start state can be reached after the DFA has recorded a match. A
+// prefilter must not skip to a new candidate while that match is pending.
+#[test]
+#[cfg(feature = "perf-literal-multisubstring")]
+fn prefilter_does_not_skip_pending_match() -> Result<(), Box<dyn Error>> {
+    use regex_automata::{util::prefilter::Prefilter, Anchored, MatchKind};
+
+    let pre = Prefilter::new(MatchKind::LeftmostFirst, &["ab", "c"])
+        .expect("prefilter");
+    let dfa = DFA::builder()
+        .configure(
+            DFA::config().prefilter(Some(pre)).starts_for_each_pattern(true),
+        )
+        .build(r"(?:ab|c)*c")?;
+    let mut cache = dfa.create_cache();
+    let haystack = "cabac";
+    let expected = Some(HalfMatch::must(0, 1));
+
+    // Cache the anchored start state before the equivalent state is reached
+    // via an ordinary transition. Otherwise, that state is left untagged and
+    // the prefilter bug remains hidden.
+    let input = Input::new(haystack).anchored(Anchored::Yes);
+    assert_eq!(expected, dfa.try_search_fwd(&mut cache, &input)?);
+    assert_eq!(
+        expected,
+        dfa.try_search_fwd(&mut cache, &Input::new(haystack))?,
+    );
+    Ok(())
+}
+
+// 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(24);
+    // 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(26);
+    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(())
+}

third_party/crates/regex-automata-0.4.18/tests/hybrid/mod.rs

@@ -0,0 +1,3 @@
+mod api;
+#[cfg(not(miri))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/hybrid/suite.rs

@@ -0,0 +1,347 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        hybrid::{
+            dfa::{OverlappingState, DFA},
+            regex::{self, Regex},
+        },
+        nfa::thompson,
+        util::{prefilter::Prefilter, syntax},
+        Anchored, Input, PatternSet,
+    },
+    regex_test::{
+        CompiledRegex, Match, RegexTest, SearchKind, Span, TestResult,
+        TestRunner,
+    },
+};
+
+use crate::{create_input, suite, untestify_kind};
+
+const EXPANSIONS: &[&str] = &["is_match", "find", "which"];
+
+/// Tests the default configuration of the hybrid NFA/DFA.
+#[test]
+fn default() -> Result<()> {
+    let builder = Regex::builder();
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA with prefilters enabled.
+#[test]
+fn prefilter() -> Result<()> {
+    let my_compiler = |test: &RegexTest, regexes: &[String]| {
+        // Parse regexes as HIRs so we can get literals to build a prefilter.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+        let kind = match untestify_kind(test.match_kind()) {
+            None => return Ok(CompiledRegex::skip()),
+            Some(kind) => kind,
+        };
+        let pre = Prefilter::from_hirs_prefix(kind, &hirs);
+        let mut builder = Regex::builder();
+        builder.dfa(DFA::config().prefilter(pre));
+        compiler(builder)(test, regexes)
+    };
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), my_compiler)
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA with NFA shrinking enabled.
+///
+/// This is *usually* not the configuration one wants for a lazy DFA. NFA
+/// shrinking is mostly only advantageous when building a full DFA since it
+/// can sharply decrease the amount of time determinization takes. But NFA
+/// shrinking is itself otherwise fairly expensive currently. Since a lazy DFA
+/// has no compilation time (other than for building the NFA of course) before
+/// executing a search, it's usually worth it to forgo NFA shrinking.
+///
+/// Nevertheless, we test to make sure everything is OK with NFA shrinking. As
+/// a bonus, there are some tests we don't need to skip because they now fit in
+/// the default cache capacity.
+#[test]
+fn nfa_shrink() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.thompson(thompson::Config::new().shrink(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when 'starts_for_each_pattern' is enabled for all
+/// tests.
+#[test]
+fn starts_for_each_pattern() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dfa(DFA::config().starts_for_each_pattern(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when 'specialize_start_states' is enabled.
+#[test]
+fn specialize_start_states() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dfa(DFA::config().specialize_start_states(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when byte classes are disabled.
+///
+/// N.B. Disabling byte classes doesn't avoid any indirection at search time.
+/// All it does is cause every byte value to be its own distinct equivalence
+/// class.
+#[test]
+fn no_byte_classes() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dfa(DFA::config().byte_classes(false));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests that hybrid NFA/DFA never clears its cache for any test with the
+/// default capacity.
+///
+/// N.B. If a regex suite test is added that causes the cache to be cleared,
+/// then this should just skip that test. (Which can be done by calling the
+/// 'blacklist' method on 'TestRunner'.)
+#[test]
+fn no_cache_clearing() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.dfa(DFA::config().minimum_cache_clear_count(Some(0)));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        // Without NFA shrinking, this test blows the default cache capacity.
+        .blacklist("expensive/regression-many-repeat-no-stack-overflow")
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the hybrid NFA/DFA when the minimum cache capacity is set.
+#[test]
+fn min_cache_capacity() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder
+        .dfa(DFA::config().cache_capacity(0).skip_cache_capacity_check(true));
+    TestRunner::new()?
+        .expand(EXPANSIONS, |t| t.compiles())
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+fn compiler(
+    mut builder: regex::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        // Parse regexes as HIRs for some analysis below.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+
+        // Check if our regex contains things that aren't supported by DFAs.
+        // That is, Unicode word boundaries when searching non-ASCII text.
+        if !test.haystack().is_ascii() {
+            for hir in hirs.iter() {
+                if hir.properties().look_set().contains_word_unicode() {
+                    return Ok(CompiledRegex::skip());
+                }
+            }
+        }
+        if !configure_regex_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        let re = builder.build_many(&regexes)?;
+        let mut cache = re.create_cache();
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, &mut cache, test)
+        }))
+    }
+}
+
+fn run_test(
+    re: &Regex,
+    cache: &mut regex::Cache,
+    test: &RegexTest,
+) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => {
+            TestResult::matched(re.is_match(cache, input.earliest(true)))
+        }
+        "find" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                let input =
+                    input.earliest(test.search_kind() == SearchKind::Earliest);
+                TestResult::matches(
+                    re.find_iter(cache, input)
+                        .take(test.match_limit().unwrap_or(std::usize::MAX))
+                        .map(|m| Match {
+                            id: m.pattern().as_usize(),
+                            span: Span { start: m.start(), end: m.end() },
+                        }),
+                )
+            }
+            SearchKind::Overlapping => {
+                try_search_overlapping(re, cache, &input).unwrap()
+            }
+        },
+        "which" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Leftmost => {
+                // There are no "which" APIs for standard searches.
+                TestResult::skip()
+            }
+            SearchKind::Overlapping => {
+                let dfa = re.forward();
+                let cache = cache.as_parts_mut().0;
+                let mut patset = PatternSet::new(dfa.pattern_len());
+                dfa.try_which_overlapping_matches(cache, &input, &mut patset)
+                    .unwrap();
+                TestResult::which(patset.iter().map(|p| p.as_usize()))
+            }
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_regex_builder(
+    test: &RegexTest,
+    builder: &mut regex::Builder,
+) -> bool {
+    let match_kind = match untestify_kind(test.match_kind()) {
+        None => return false,
+        Some(k) => k,
+    };
+
+    let mut dfa_config =
+        DFA::config().match_kind(match_kind).unicode_word_boundary(true);
+    // When doing an overlapping search, we might try to find the start of each
+    // match with a custom search routine. In that case, we need to tell the
+    // reverse search (for the start offset) which pattern to look for. The
+    // only way that API works is when anchored starting states are compiled
+    // for each pattern. This does technically also enable it for the forward
+    // DFA, but we're okay with that.
+    if test.search_kind() == SearchKind::Overlapping {
+        dfa_config = dfa_config.starts_for_each_pattern(true);
+    }
+    builder
+        .syntax(config_syntax(test))
+        .thompson(config_thompson(test))
+        .dfa(dfa_config);
+    true
+}
+
+/// Configuration of a Thompson NFA compiler from a regex test.
+fn config_thompson(test: &RegexTest) -> thompson::Config {
+    let mut lookm = regex_automata::util::look::LookMatcher::new();
+    lookm.set_line_terminator(test.line_terminator());
+    thompson::Config::new().utf8(test.utf8()).look_matcher(lookm)
+}
+
+/// Configuration of the regex parser from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}
+
+/// Execute an overlapping search, and for each match found, also find its
+/// overlapping starting positions.
+///
+/// N.B. This routine used to be part of the crate API, but 1) it wasn't clear
+/// to me how useful it was and 2) it wasn't clear to me what its semantics
+/// should be. In particular, a potentially surprising footgun of this routine
+/// that it is worst case *quadratic* in the size of the haystack. Namely, it's
+/// possible to report a match at every position, and for every such position,
+/// scan all the way to the beginning of the haystack to find the starting
+/// position. Typical leftmost non-overlapping searches don't suffer from this
+/// because, well, matches can't overlap. So subsequent searches after a match
+/// is found don't revisit previously scanned parts of the haystack.
+///
+/// Its semantics can be strange for other reasons too. For example, given
+/// the regex '.*' and the haystack 'zz', the full set of overlapping matches
+/// is: [0, 0], [1, 1], [0, 1], [2, 2], [1, 2], [0, 2]. The ordering of
+/// those matches is quite strange, but makes sense when you think about the
+/// implementation: an end offset is found left-to-right, and then one or more
+/// starting offsets are found right-to-left.
+///
+/// Nevertheless, we provide this routine in our test suite because it's
+/// useful to test the low level DFA overlapping search and our test suite
+/// is written in a way that requires starting offsets.
+fn try_search_overlapping(
+    re: &Regex,
+    cache: &mut regex::Cache,
+    input: &Input<'_>,
+) -> Result<TestResult> {
+    let mut matches = vec![];
+    let mut fwd_state = OverlappingState::start();
+    let (fwd_dfa, rev_dfa) = (re.forward(), re.reverse());
+    let (fwd_cache, rev_cache) = cache.as_parts_mut();
+    while let Some(end) = {
+        fwd_dfa.try_search_overlapping_fwd(
+            fwd_cache,
+            input,
+            &mut fwd_state,
+        )?;
+        fwd_state.get_match()
+    } {
+        let revsearch = input
+            .clone()
+            .range(input.start()..end.offset())
+            .anchored(Anchored::Pattern(end.pattern()))
+            .earliest(false);
+        let mut rev_state = OverlappingState::start();
+        while let Some(start) = {
+            rev_dfa.try_search_overlapping_rev(
+                rev_cache,
+                &revsearch,
+                &mut rev_state,
+            )?;
+            rev_state.get_match()
+        } {
+            let span = Span { start: start.offset(), end: end.offset() };
+            let mat = Match { id: end.pattern().as_usize(), span };
+            matches.push(mat);
+        }
+    }
+    Ok(TestResult::matches(matches))
+}

third_party/crates/regex-automata-0.4.18/tests/lib.rs

@@ -0,0 +1,115 @@
+// We have a similar config in the regex-automata crate root. Basically, it is
+// just too annoying to deal with dead code when a subset of features is
+// enabled.
+#![cfg_attr(
+    not(all(
+        feature = "std",
+        feature = "nfa",
+        feature = "dfa",
+        feature = "hybrid",
+        feature = "perf-literal-substring",
+        feature = "perf-literal-multisubstring",
+    )),
+    allow(dead_code, unused_imports, unused_variables)
+)]
+// Similar deal with Miri. Just let dead code warnings be.
+#![cfg_attr(miri, allow(dead_code, unused_imports, unused_variables))]
+
+#[cfg(any(feature = "dfa-search", feature = "dfa-onepass"))]
+mod dfa;
+#[cfg(feature = "dfa-search")]
+mod fuzz;
+#[cfg(feature = "dfa-search")]
+mod gen;
+#[cfg(feature = "hybrid")]
+mod hybrid;
+#[cfg(feature = "meta")]
+mod meta;
+#[cfg(any(feature = "nfa-backtrack", feature = "nfa-pikevm"))]
+mod nfa;
+
+fn suite() -> anyhow::Result<regex_test::RegexTests> {
+    let _ = env_logger::try_init();
+
+    let mut tests = regex_test::RegexTests::new();
+    macro_rules! load {
+        ($name:expr) => {{
+            const DATA: &[u8] =
+                include_bytes!(concat!("../../testdata/", $name, ".toml"));
+            tests.load_slice($name, DATA)?;
+        }};
+    }
+
+    load!("anchored");
+    load!("bytes");
+    load!("crazy");
+    load!("crlf");
+    load!("earliest");
+    load!("empty");
+    load!("expensive");
+    load!("flags");
+    load!("iter");
+    load!("leftmost-all");
+    load!("line-terminator");
+    load!("misc");
+    load!("multiline");
+    load!("no-unicode");
+    load!("overlapping");
+    load!("regression");
+    load!("set");
+    load!("substring");
+    load!("unicode");
+    load!("utf8");
+    load!("word-boundary");
+    load!("word-boundary-special");
+    load!("fowler/basic");
+    load!("fowler/nullsubexpr");
+    load!("fowler/repetition");
+
+    Ok(tests)
+}
+
+/// Configure a regex_automata::Input with the given test configuration.
+fn create_input<'h>(
+    test: &'h regex_test::RegexTest,
+) -> regex_automata::Input<'h> {
+    use regex_automata::Anchored;
+
+    let bounds = test.bounds();
+    let anchored = if test.anchored() { Anchored::Yes } else { Anchored::No };
+    regex_automata::Input::new(test.haystack())
+        .range(bounds.start..bounds.end)
+        .anchored(anchored)
+}
+
+/// Convert capture matches into the test suite's capture values.
+///
+/// The given captures must represent a valid match, where the first capturing
+/// group has a non-None span. Otherwise this panics.
+fn testify_captures(
+    caps: &regex_automata::util::captures::Captures,
+) -> regex_test::Captures {
+    assert!(caps.is_match(), "expected captures to represent a match");
+    let spans = caps.iter().map(|group| {
+        group.map(|m| regex_test::Span { start: m.start, end: m.end })
+    });
+    // These unwraps are OK because we assume our 'caps' represents a match,
+    // and a match always gives a non-zero number of groups with the first
+    // group being non-None.
+    regex_test::Captures::new(caps.pattern().unwrap().as_usize(), spans)
+        .unwrap()
+}
+
+/// Convert a test harness match kind to a regex-automata match kind. If
+/// regex-automata doesn't support the harness kind, then `None` is returned.
+fn untestify_kind(
+    kind: regex_test::MatchKind,
+) -> Option<regex_automata::MatchKind> {
+    match kind {
+        regex_test::MatchKind::All => Some(regex_automata::MatchKind::All),
+        regex_test::MatchKind::LeftmostFirst => {
+            Some(regex_automata::MatchKind::LeftmostFirst)
+        }
+        regex_test::MatchKind::LeftmostLongest => None,
+    }
+}

third_party/crates/regex-automata-0.4.18/tests/meta/mod.rs

@@ -0,0 +1,2 @@
+#[cfg(not(miri))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/meta/suite.rs

@@ -0,0 +1,200 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        meta::{self, Regex},
+        util::syntax,
+        MatchKind, PatternSet,
+    },
+    regex_test::{
+        CompiledRegex, Match, RegexTest, SearchKind, Span, TestResult,
+        TestRunner,
+    },
+};
+
+use crate::{create_input, suite, testify_captures};
+
+const BLACKLIST: &[&str] = &[
+    // These 'earliest' tests are blacklisted because the meta searcher doesn't
+    // give the same offsets that the test expects. This is legal because the
+    // 'earliest' routines don't guarantee a particular match offset other
+    // than "the earliest the regex engine can report a match." Some regex
+    // engines will quit earlier than others. The backtracker, for example,
+    // can't really quit before finding the full leftmost-first match. Many of
+    // the literal searchers also don't have the ability to quit fully or it's
+    // otherwise not worth doing. (A literal searcher not quitting as early as
+    // possible usually means looking at a few more bytes. That's no biggie.)
+    "earliest/",
+];
+
+/// Tests the default configuration of the meta regex engine.
+#[test]
+fn default() -> Result<()> {
+    let builder = Regex::builder();
+    let mut runner = TestRunner::new()?;
+    runner
+        .expand(&["is_match", "find", "captures"], |test| test.compiles())
+        .blacklist_iter(BLACKLIST)
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the default configuration minus the full DFA.
+#[test]
+fn no_dfa() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.configure(Regex::config().dfa(false));
+    let mut runner = TestRunner::new()?;
+    runner
+        .expand(&["is_match", "find", "captures"], |test| test.compiles())
+        .blacklist_iter(BLACKLIST)
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the default configuration minus the full DFA and lazy DFA.
+#[test]
+fn no_dfa_hybrid() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.configure(Regex::config().dfa(false).hybrid(false));
+    let mut runner = TestRunner::new()?;
+    runner
+        .expand(&["is_match", "find", "captures"], |test| test.compiles())
+        .blacklist_iter(BLACKLIST)
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the default configuration minus the full DFA, lazy DFA and one-pass
+/// DFA.
+#[test]
+fn no_dfa_hybrid_onepass() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.configure(Regex::config().dfa(false).hybrid(false).onepass(false));
+    let mut runner = TestRunner::new()?;
+    runner
+        .expand(&["is_match", "find", "captures"], |test| test.compiles())
+        .blacklist_iter(BLACKLIST)
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+/// Tests the default configuration minus the full DFA, lazy DFA, one-pass
+/// DFA and backtracker.
+#[test]
+fn no_dfa_hybrid_onepass_backtrack() -> Result<()> {
+    let mut builder = Regex::builder();
+    builder.configure(
+        Regex::config()
+            .dfa(false)
+            .hybrid(false)
+            .onepass(false)
+            .backtrack(false),
+    );
+    let mut runner = TestRunner::new()?;
+    runner
+        .expand(&["is_match", "find", "captures"], |test| test.compiles())
+        .blacklist_iter(BLACKLIST)
+        .test_iter(suite()?.iter(), compiler(builder))
+        .assert();
+    Ok(())
+}
+
+fn compiler(
+    mut builder: meta::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        if !configure_meta_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        let re = builder.build_many(&regexes)?;
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, test)
+        }))
+    }
+}
+
+fn run_test(re: &Regex, test: &RegexTest) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => TestResult::matched(re.is_match(input)),
+        "find" => match test.search_kind() {
+            SearchKind::Earliest => TestResult::matches(
+                re.find_iter(input.earliest(true))
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    }),
+            ),
+            SearchKind::Leftmost => TestResult::matches(
+                re.find_iter(input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    }),
+            ),
+            SearchKind::Overlapping => {
+                let mut patset = PatternSet::new(re.pattern_len());
+                re.which_overlapping_matches(&input, &mut patset);
+                TestResult::which(patset.iter().map(|p| p.as_usize()))
+            }
+        },
+        "captures" => match test.search_kind() {
+            SearchKind::Earliest => {
+                let it = re
+                    .captures_iter(input.earliest(true))
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|caps| testify_captures(&caps));
+                TestResult::captures(it)
+            }
+            SearchKind::Leftmost => {
+                let it = re
+                    .captures_iter(input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|caps| testify_captures(&caps));
+                TestResult::captures(it)
+            }
+            SearchKind::Overlapping => {
+                // There is no overlapping regex API that supports captures.
+                TestResult::skip()
+            }
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_meta_builder(
+    test: &RegexTest,
+    builder: &mut meta::Builder,
+) -> bool {
+    let match_kind = match test.match_kind() {
+        regex_test::MatchKind::All => MatchKind::All,
+        regex_test::MatchKind::LeftmostFirst => MatchKind::LeftmostFirst,
+        regex_test::MatchKind::LeftmostLongest => return false,
+    };
+    let meta_config = Regex::config()
+        .match_kind(match_kind)
+        .utf8_empty(test.utf8())
+        .line_terminator(test.line_terminator());
+    builder.configure(meta_config).syntax(config_syntax(test));
+    true
+}
+
+/// Configuration of the regex parser from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}

third_party/crates/regex-automata-0.4.18/tests/nfa/mod.rs

@@ -0,0 +1 @@
+mod thompson;

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/backtrack/mod.rs

@@ -0,0 +1,3 @@
+mod regression;
+#[cfg(not(miri))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/backtrack/regression.rs

@@ -0,0 +1,20 @@
+// Tests that we can call the backtracker with more slots
+// than is actually in the compiled regex.
+#[test]
+fn too_many_slots_normal_pattern() {
+    use regex_automata::{
+        nfa::thompson::backtrack::BoundedBacktracker,
+        util::primitives::NonMaxUsize, Anchored, Input,
+    };
+
+    let expr = BoundedBacktracker::new(r"abc").unwrap();
+    let s = "abc";
+    let input = Input::new(s).span(0..s.len()).anchored(Anchored::Yes);
+
+    let mut cache = expr.create_cache();
+    let mut slots: Vec<Option<NonMaxUsize>> = vec![None; 4];
+    let pid = expr.try_search_slots(&mut cache, &input, &mut slots).unwrap();
+    assert_eq!(pid, Some(regex_automata::PatternID::must(0)));
+    assert_eq!(slots[0], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[1], Some(NonMaxUsize::new(3).unwrap()));
+}

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/backtrack/suite.rs

@@ -0,0 +1,213 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        nfa::thompson::{
+            self,
+            backtrack::{self, BoundedBacktracker},
+            NFA,
+        },
+        util::{prefilter::Prefilter, syntax},
+        Input,
+    },
+    regex_test::{
+        CompiledRegex, Match, MatchKind, RegexTest, SearchKind, Span,
+        TestResult, TestRunner,
+    },
+};
+
+use crate::{create_input, suite, testify_captures};
+
+/// Tests the default configuration of the bounded backtracker.
+#[test]
+fn default() -> Result<()> {
+    let builder = BoundedBacktracker::builder();
+    let mut runner = TestRunner::new()?;
+    runner.expand(&["is_match", "find", "captures"], |test| test.compiles());
+    // At the time of writing, every regex search in the test suite fits
+    // into the backtracker's default visited capacity (except for the
+    // blacklisted tests below). If regexes are added that blow that capacity,
+    // then they should be blacklisted here. A tempting alternative is to
+    // automatically skip them by checking the haystack length against
+    // BoundedBacktracker::max_haystack_len, but that could wind up hiding
+    // interesting failure modes. e.g., If the visited capacity is somehow
+    // wrong or smaller than it should be.
+    runner.blacklist("expensive/backtrack-blow-visited-capacity");
+    runner.test_iter(suite()?.iter(), compiler(builder)).assert();
+    Ok(())
+}
+
+/// Tests the backtracker with prefilters enabled.
+#[test]
+fn prefilter() -> Result<()> {
+    let my_compiler = |test: &RegexTest, regexes: &[String]| {
+        // Parse regexes as HIRs so we can get literals to build a prefilter.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+        // We can always select leftmost-first here because the backtracker
+        // only supports leftmost-first matching.
+        let pre = Prefilter::from_hirs_prefix(
+            regex_automata::MatchKind::LeftmostFirst,
+            &hirs,
+        );
+        let mut builder = BoundedBacktracker::builder();
+        builder.configure(BoundedBacktracker::config().prefilter(pre));
+        compiler(builder)(test, regexes)
+    };
+    let mut runner = TestRunner::new()?;
+    runner.expand(&["is_match", "find", "captures"], |test| test.compiles());
+    runner.blacklist("expensive/backtrack-blow-visited-capacity");
+    runner.test_iter(suite()?.iter(), my_compiler).assert();
+    Ok(())
+}
+
+/// Tests the bounded backtracker when its visited capacity is set to its
+/// minimum amount.
+#[test]
+fn min_visited_capacity() -> Result<()> {
+    let mut runner = TestRunner::new()?;
+    runner.expand(&["is_match", "find", "captures"], |test| test.compiles());
+    runner
+        .test_iter(suite()?.iter(), move |test, regexes| {
+            let nfa = NFA::compiler()
+                .configure(config_thompson(test))
+                .syntax(config_syntax(test))
+                .build_many(&regexes)?;
+            let mut builder = BoundedBacktracker::builder();
+            if !configure_backtrack_builder(test, &mut builder) {
+                return Ok(CompiledRegex::skip());
+            }
+            // Setup the bounded backtracker so that its visited capacity is
+            // the absolute minimum required for the test's haystack.
+            builder.configure(BoundedBacktracker::config().visited_capacity(
+                backtrack::min_visited_capacity(
+                    &nfa,
+                    &Input::new(test.haystack()),
+                ),
+            ));
+
+            let re = builder.build_from_nfa(nfa)?;
+            let mut cache = re.create_cache();
+            Ok(CompiledRegex::compiled(move |test| -> TestResult {
+                run_test(&re, &mut cache, test)
+            }))
+        })
+        .assert();
+    Ok(())
+}
+
+fn compiler(
+    mut builder: backtrack::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        if !configure_backtrack_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        let re = builder.build_many(&regexes)?;
+        let mut cache = re.create_cache();
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, &mut cache, test)
+        }))
+    }
+}
+
+fn run_test(
+    re: &BoundedBacktracker,
+    cache: &mut backtrack::Cache,
+    test: &RegexTest,
+) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Overlapping => {
+                TestResult::skip()
+            }
+            SearchKind::Leftmost => {
+                let input = input.earliest(true);
+                TestResult::matched(re.try_is_match(cache, input).unwrap())
+            }
+        },
+        "find" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Overlapping => {
+                TestResult::skip()
+            }
+            SearchKind::Leftmost => TestResult::matches(
+                re.try_find_iter(cache, input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|result| result.unwrap())
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    }),
+            ),
+        },
+        "captures" => match test.search_kind() {
+            SearchKind::Earliest | SearchKind::Overlapping => {
+                TestResult::skip()
+            }
+            SearchKind::Leftmost => TestResult::captures(
+                re.try_captures_iter(cache, input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|result| result.unwrap())
+                    .map(|caps| testify_captures(&caps)),
+            ),
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_backtrack_builder(
+    test: &RegexTest,
+    builder: &mut backtrack::Builder,
+) -> bool {
+    match (test.search_kind(), test.match_kind()) {
+        // For testing the standard search APIs. This is the only supported
+        // configuration for the backtracker.
+        (SearchKind::Leftmost, MatchKind::LeftmostFirst) => {}
+        // Overlapping APIs not supported at all for backtracker.
+        (SearchKind::Overlapping, _) => return false,
+        // Backtracking doesn't really support the notion of 'earliest'.
+        // Namely, backtracking already works by returning as soon as it knows
+        // it has found a match. It just so happens that this corresponds to
+        // the standard 'leftmost' formulation.
+        //
+        // The 'earliest' definition in this crate does indeed permit this
+        // behavior, so this is "fine," but our test suite specifically looks
+        // for the earliest position at which a match is known, which our
+        // finite automata based regex engines have no problem providing. So
+        // for backtracking, we just skip these tests.
+        (SearchKind::Earliest, _) => return false,
+        // For backtracking, 'all' semantics don't really make sense.
+        (_, MatchKind::All) => return false,
+        // Not supported at all in regex-automata.
+        (_, MatchKind::LeftmostLongest) => return false,
+    };
+    let backtrack_config = BoundedBacktracker::config();
+    builder
+        .configure(backtrack_config)
+        .syntax(config_syntax(test))
+        .thompson(config_thompson(test));
+    true
+}
+
+/// Configuration of a Thompson NFA compiler from a regex test.
+fn config_thompson(test: &RegexTest) -> thompson::Config {
+    let mut lookm = regex_automata::util::look::LookMatcher::new();
+    lookm.set_line_terminator(test.line_terminator());
+    thompson::Config::new().utf8(test.utf8()).look_matcher(lookm)
+}
+
+/// Configuration of the regex parser from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/mod.rs

@@ -0,0 +1,4 @@
+#[cfg(feature = "nfa-backtrack")]
+mod backtrack;
+#[cfg(feature = "nfa-pikevm")]
+mod pikevm;

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/pikevm/mod.rs

@@ -0,0 +1,3 @@
+mod regression;
+#[cfg(not(miri))]
+mod suite;

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/pikevm/regression.rs

@@ -0,0 +1,20 @@
+// Tests that we can call the PikeVM with more slots
+// than is actually in the compiled regex.
+#[test]
+fn too_many_slots_normal_pattern() {
+    use regex_automata::{
+        nfa::thompson::pikevm::PikeVM, util::primitives::NonMaxUsize,
+        Anchored, Input,
+    };
+
+    let expr = PikeVM::new(r"abc").unwrap();
+    let s = "abc";
+    let input = Input::new(s).span(0..s.len()).anchored(Anchored::Yes);
+
+    let mut cache = expr.create_cache();
+    let mut slots: Vec<Option<NonMaxUsize>> = vec![None; 4];
+    let pid = expr.search_slots(&mut cache, &input, &mut slots);
+    assert_eq!(pid, Some(regex_automata::PatternID::must(0)));
+    assert_eq!(slots[0], Some(NonMaxUsize::new(0).unwrap()));
+    assert_eq!(slots[1], Some(NonMaxUsize::new(3).unwrap()));
+}

third_party/crates/regex-automata-0.4.18/tests/nfa/thompson/pikevm/suite.rs

@@ -0,0 +1,162 @@
+use {
+    anyhow::Result,
+    regex_automata::{
+        nfa::thompson::{
+            self,
+            pikevm::{self, PikeVM},
+        },
+        util::{prefilter::Prefilter, syntax},
+        PatternSet,
+    },
+    regex_test::{
+        CompiledRegex, Match, RegexTest, SearchKind, Span, TestResult,
+        TestRunner,
+    },
+};
+
+use crate::{create_input, suite, testify_captures, untestify_kind};
+
+/// Tests the default configuration of the hybrid NFA/DFA.
+#[test]
+fn default() -> Result<()> {
+    let builder = PikeVM::builder();
+    let mut runner = TestRunner::new()?;
+    runner.expand(&["is_match", "find", "captures"], |test| test.compiles());
+    runner.test_iter(suite()?.iter(), compiler(builder)).assert();
+    Ok(())
+}
+
+/// Tests the PikeVM with prefilters enabled.
+#[test]
+fn prefilter() -> Result<()> {
+    let my_compiler = |test: &RegexTest, regexes: &[String]| {
+        // Parse regexes as HIRs so we can get literals to build a prefilter.
+        let mut hirs = vec![];
+        for pattern in regexes.iter() {
+            hirs.push(syntax::parse_with(pattern, &config_syntax(test))?);
+        }
+        let kind = match untestify_kind(test.match_kind()) {
+            None => return Ok(CompiledRegex::skip()),
+            Some(kind) => kind,
+        };
+        let pre = Prefilter::from_hirs_prefix(kind, &hirs);
+        let mut builder = PikeVM::builder();
+        builder.configure(PikeVM::config().prefilter(pre));
+        compiler(builder)(test, regexes)
+    };
+    let mut runner = TestRunner::new()?;
+    runner.expand(&["is_match", "find", "captures"], |test| test.compiles());
+    runner.test_iter(suite()?.iter(), my_compiler).assert();
+    Ok(())
+}
+
+fn compiler(
+    mut builder: pikevm::Builder,
+) -> impl FnMut(&RegexTest, &[String]) -> Result<CompiledRegex> {
+    move |test, regexes| {
+        if !configure_pikevm_builder(test, &mut builder) {
+            return Ok(CompiledRegex::skip());
+        }
+        let re = builder.build_many(&regexes)?;
+        let mut cache = re.create_cache();
+        Ok(CompiledRegex::compiled(move |test| -> TestResult {
+            run_test(&re, &mut cache, test)
+        }))
+    }
+}
+
+fn run_test(
+    re: &PikeVM,
+    cache: &mut pikevm::Cache,
+    test: &RegexTest,
+) -> TestResult {
+    let input = create_input(test);
+    match test.additional_name() {
+        "is_match" => TestResult::matched(re.is_match(cache, input)),
+        "find" => match test.search_kind() {
+            SearchKind::Earliest => {
+                let it = re
+                    .find_iter(cache, input.earliest(true))
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    });
+                TestResult::matches(it)
+            }
+            SearchKind::Leftmost => {
+                let it = re
+                    .find_iter(cache, input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|m| Match {
+                        id: m.pattern().as_usize(),
+                        span: Span { start: m.start(), end: m.end() },
+                    });
+                TestResult::matches(it)
+            }
+            SearchKind::Overlapping => {
+                let mut patset = PatternSet::new(re.get_nfa().pattern_len());
+                re.which_overlapping_matches(cache, &input, &mut patset);
+                TestResult::which(patset.iter().map(|p| p.as_usize()))
+            }
+        },
+        "captures" => match test.search_kind() {
+            SearchKind::Earliest => {
+                let it = re
+                    .captures_iter(cache, input.earliest(true))
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|caps| testify_captures(&caps));
+                TestResult::captures(it)
+            }
+            SearchKind::Leftmost => {
+                let it = re
+                    .captures_iter(cache, input)
+                    .take(test.match_limit().unwrap_or(std::usize::MAX))
+                    .map(|caps| testify_captures(&caps));
+                TestResult::captures(it)
+            }
+            SearchKind::Overlapping => {
+                // There is no overlapping PikeVM API that supports captures.
+                TestResult::skip()
+            }
+        },
+        name => TestResult::fail(&format!("unrecognized test name: {name}")),
+    }
+}
+
+/// Configures the given regex builder with all relevant settings on the given
+/// regex test.
+///
+/// If the regex test has a setting that is unsupported, then this returns
+/// false (implying the test should be skipped).
+fn configure_pikevm_builder(
+    test: &RegexTest,
+    builder: &mut pikevm::Builder,
+) -> bool {
+    let match_kind = match untestify_kind(test.match_kind()) {
+        None => return false,
+        Some(k) => k,
+    };
+    let pikevm_config = PikeVM::config().match_kind(match_kind);
+    builder
+        .configure(pikevm_config)
+        .syntax(config_syntax(test))
+        .thompson(config_thompson(test));
+    true
+}
+
+/// Configuration of a Thompson NFA compiler from a regex test.
+fn config_thompson(test: &RegexTest) -> thompson::Config {
+    let mut lookm = regex_automata::util::look::LookMatcher::new();
+    lookm.set_line_terminator(test.line_terminator());
+    thompson::Config::new().utf8(test.utf8()).look_matcher(lookm)
+}
+
+/// Configuration of the regex parser from a regex test.
+fn config_syntax(test: &RegexTest) -> syntax::Config {
+    syntax::Config::new()
+        .case_insensitive(test.case_insensitive())
+        .unicode(test.unicode())
+        .utf8(test.utf8())
+        .line_terminator(test.line_terminator())
+}