1 files changed, 63 insertions, 0 deletions
diff --git a/third_party/rust/digest/src/core_api/xof_reader.rs b/third_party/rust/digest/src/core_api/xof_reader.rs
new file mode 100644
index 0000000000..e18ac133a6
--- /dev/null
+++ b/third_party/rust/digest/src/core_api/xof_reader.rs
@@ -0,0 +1,63 @@
+use super::{AlgorithmName, XofReaderCore};
+use crate::XofReader;
+use block_buffer::EagerBuffer;
+use core::fmt;
+use crypto_common::typenum::{IsLess, Le, NonZero, U256};
+
+/// Wrapper around [`XofReaderCore`] implementations.
+///
+/// It handles data buffering and implements the mid-level traits.
+#[derive(Clone, Default)]
+pub struct XofReaderCoreWrapper<T>
+where
+    T: XofReaderCore,
+    T::BlockSize: IsLess<U256>,
+    Le<T::BlockSize, U256>: NonZero,
+{
+    pub(super) core: T,
+    pub(super) buffer: EagerBuffer<T::BlockSize>,
+}
+
+impl<T> fmt::Debug for XofReaderCoreWrapper<T>
+where
+    T: XofReaderCore + AlgorithmName,
+    T::BlockSize: IsLess<U256>,
+    Le<T::BlockSize, U256>: NonZero,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        T::write_alg_name(f)?;
+        f.write_str(" { .. }")
+    }
+}
+
+impl<T> XofReader for XofReaderCoreWrapper<T>
+where
+    T: XofReaderCore,
+    T::BlockSize: IsLess<U256>,
+    Le<T::BlockSize, U256>: NonZero,
+{
+    #[inline]
+    fn read(&mut self, buffer: &mut [u8]) {
+        let Self { core, buffer: buf } = self;
+        buf.set_data(buffer, |blocks| {
+            for block in blocks {
+                *block = core.read_block();
+            }
+        });
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl<T> std::io::Read for XofReaderCoreWrapper<T>
+where
+    T: XofReaderCore,
+    T::BlockSize: IsLess<U256>,
+    Le<T::BlockSize, U256>: NonZero,
+{
+    #[inline]
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        XofReader::read(self, buf);
+        Ok(buf.len())
+    }
+}