1 files changed, 58 insertions, 0 deletions
diff --git a/third_party/rust/regex-automata/src/util/prefilter/byteset.rs b/third_party/rust/regex-automata/src/util/prefilter/byteset.rs
new file mode 100644
index 0000000000..a669d6c9d7
--- /dev/null
+++ b/third_party/rust/regex-automata/src/util/prefilter/byteset.rs
@@ -0,0 +1,58 @@
+use crate::util::{
+    prefilter::PrefilterI,
+    search::{MatchKind, Span},
+};
+
+#[derive(Clone, Debug)]
+pub(crate) struct ByteSet([bool; 256]);
+
+impl ByteSet {
+    pub(crate) fn new<B: AsRef<[u8]>>(
+        _kind: MatchKind,
+        needles: &[B],
+    ) -> Option<ByteSet> {
+        #[cfg(not(feature = "perf-literal-multisubstring"))]
+        {
+            None
+        }
+        #[cfg(feature = "perf-literal-multisubstring")]
+        {
+            let mut set = [false; 256];
+            for needle in needles.iter() {
+                let needle = needle.as_ref();
+                if needle.len() != 1 {
+                    return None;
+                }
+                set[usize::from(needle[0])] = true;
+            }
+            Some(ByteSet(set))
+        }
+    }
+}
+
+impl PrefilterI for ByteSet {
+    fn find(&self, haystack: &[u8], span: Span) -> Option<Span> {
+        haystack[span].iter().position(|&b| self.0[usize::from(b)]).map(|i| {
+            let start = span.start + i;
+            let end = start + 1;
+            Span { start, end }
+        })
+    }
+
+    fn prefix(&self, haystack: &[u8], span: Span) -> Option<Span> {
+        let b = *haystack.get(span.start)?;
+        if self.0[usize::from(b)] {
+            Some(Span { start: span.start, end: span.start + 1 })
+        } else {
+            None
+        }
+    }
+
+    fn memory_usage(&self) -> usize {
+        0
+    }
+
+    fn is_fast(&self) -> bool {
+        false
+    }
+}