Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 89 insertions, 0 deletions

diff --git a/vendor/memchr/src/arch/all/shiftor.rs b/vendor/memchr/src/arch/all/shiftor.rs
new file mode 100644
index 0000000..b690564
--- /dev/null
+++ b/vendor/memchr/src/arch/all/shiftor.rs
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+/*!
+An implementation of the [Shift-Or substring search algorithm][shiftor].
+
+[shiftor]: https://en.wikipedia.org/wiki/Bitap_algorithm
+*/
+
+use alloc::boxed::Box;
+
+/// The type of our mask.
+///
+/// While we don't expose anyway to configure this in the public API, if one
+/// really needs less memory usage or support for longer needles, then it is
+/// suggested to copy the code from this module and modify it to fit your
+/// needs. The code below is written to be correct regardless of whether Mask
+/// is a u8, u16, u32, u64 or u128.
+type Mask = u16;
+
+/// A forward substring searcher using the Shift-Or algorithm.
+#[derive(Debug)]
+pub struct Finder {
+    masks: Box<[Mask; 256]>,
+    needle_len: usize,
+}
+
+impl Finder {
+    const MAX_NEEDLE_LEN: usize = (Mask::BITS - 1) as usize;
+
+    /// Create a new Shift-Or forward searcher for the given `needle`.
+    ///
+    /// The needle may be empty. The empty needle matches at every byte offset.
+    #[inline]
+    pub fn new(needle: &[u8]) -> Option<Finder> {
+        let needle_len = needle.len();
+        if needle_len > Finder::MAX_NEEDLE_LEN {
+            // A match is found when bit 7 is set in 'result' in the search
+            // routine below. So our needle can't be bigger than 7. We could
+            // permit bigger needles by using u16, u32 or u64 for our mask
+            // entries. But this is all we need for this example.
+            return None;
+        }
+        let mut searcher = Finder { masks: Box::from([!0; 256]), needle_len };
+        for (i, &byte) in needle.iter().enumerate() {
+            searcher.masks[usize::from(byte)] &= !(1 << i);
+        }
+        Some(searcher)
+    }
+
+    /// Return the first occurrence of the needle given to `Finder::new` in
+    /// the `haystack` given. If no such occurrence exists, then `None` is
+    /// returned.
+    ///
+    /// Unlike most other substring search implementations in this crate, this
+    /// finder does not require passing the needle at search time. A match can
+    /// be determined without the needle at all since the required information
+    /// is already encoded into this finder at construction time.
+    ///
+    /// The maximum value this can return is `haystack.len()`, which can only
+    /// occur when the needle and haystack both have length zero. Otherwise,
+    /// for non-empty haystacks, the maximum value is `haystack.len() - 1`.
+    #[inline]
+    pub fn find(&self, haystack: &[u8]) -> Option<usize> {
+        if self.needle_len == 0 {
+            return Some(0);
+        }
+        let mut result = !1;
+        for (i, &byte) in haystack.iter().enumerate() {
+            result |= self.masks[usize::from(byte)];
+            result <<= 1;
+            if result & (1 << self.needle_len) == 0 {
+                return Some(i + 1 - self.needle_len);
+            }
+        }
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    define_substring_forward_quickcheck!(|h, n| Some(Finder::new(n)?.find(h)));
+
+    #[test]
+    fn forward() {
+        crate::tests::substring::Runner::new()
+            .fwd(|h, n| Some(Finder::new(n)?.find(h)))
+            .run();
+    }
+}