1 files changed, 88 insertions, 0 deletions
diff --git a/third_party/rust/regex-automata/src/util/prefilter/memmem.rs b/third_party/rust/regex-automata/src/util/prefilter/memmem.rs
new file mode 100644
index 0000000000..deea17bd9d
--- /dev/null
+++ b/third_party/rust/regex-automata/src/util/prefilter/memmem.rs
@@ -0,0 +1,88 @@
+use crate::util::{
+    prefilter::PrefilterI,
+    search::{MatchKind, Span},
+};
+
+#[derive(Clone, Debug)]
+pub(crate) struct Memmem {
+    #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+    _unused: (),
+    #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+    finder: memchr::memmem::Finder<'static>,
+}
+
+impl Memmem {
+    pub(crate) fn new<B: AsRef<[u8]>>(
+        _kind: MatchKind,
+        needles: &[B],
+    ) -> Option<Memmem> {
+        #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+        {
+            None
+        }
+        #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+        {
+            if needles.len() != 1 {
+                return None;
+            }
+            let needle = needles[0].as_ref();
+            let finder = memchr::memmem::Finder::new(needle).into_owned();
+            Some(Memmem { finder })
+        }
+    }
+}
+
+impl PrefilterI for Memmem {
+    fn find(&self, haystack: &[u8], span: Span) -> Option<Span> {
+        #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+        {
+            unreachable!()
+        }
+        #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+        {
+            self.finder.find(&haystack[span]).map(|i| {
+                let start = span.start + i;
+                let end = start + self.finder.needle().len();
+                Span { start, end }
+            })
+        }
+    }
+
+    fn prefix(&self, haystack: &[u8], span: Span) -> Option<Span> {
+        #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+        {
+            unreachable!()
+        }
+        #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+        {
+            let needle = self.finder.needle();
+            if haystack[span].starts_with(needle) {
+                Some(Span { end: span.start + needle.len(), ..span })
+            } else {
+                None
+            }
+        }
+    }
+
+    fn memory_usage(&self) -> usize {
+        #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+        {
+            unreachable!()
+        }
+        #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+        {
+            self.finder.needle().len()
+        }
+    }
+
+    fn is_fast(&self) -> bool {
+        #[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
+        {
+            unreachable!()
+        }
+        #[cfg(all(feature = "std", feature = "perf-literal-substring"))]
+        {
+            true
+        }
+    }
+}