1 files changed, 229 insertions, 0 deletions
diff --git a/src/de.rs b/src/de.rs
new file mode 100644
index 0000000..e4a4732
--- /dev/null
+++ b/src/de.rs
@@ -0,0 +1,229 @@
+use crate::Bytes;
+use core::fmt;
+use core::marker::PhantomData;
+use serde::de::{Error, Visitor};
+use serde::Deserializer;
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+use crate::ByteBuf;
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+use core::cmp;
+
+#[cfg(feature = "alloc")]
+use alloc::borrow::Cow;
+#[cfg(all(feature = "std", not(feature = "alloc")))]
+use std::borrow::Cow;
+
+#[cfg(feature = "alloc")]
+use alloc::boxed::Box;
+#[cfg(feature = "alloc")]
+use alloc::string::String;
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+use serde::de::SeqAccess;
+
+/// Types that can be deserialized via `#[serde(with = "serde_bytes")]`.
+pub trait Deserialize<'de>: Sized {
+    #[allow(missing_docs)]
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>;
+}
+
+impl<'de: 'a, 'a> Deserialize<'de> for &'a [u8] {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        // serde::Deserialize for &[u8] is already optimized, so simply forward to that.
+        serde::Deserialize::deserialize(deserializer)
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de> Deserialize<'de> for Vec<u8> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Deserialize::deserialize(deserializer).map(ByteBuf::into_vec)
+    }
+}
+
+impl<'de: 'a, 'a> Deserialize<'de> for &'a Bytes {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        // serde::Deserialize for &[u8] is already optimized, so simply forward to that.
+        serde::Deserialize::deserialize(deserializer).map(Bytes::new)
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de> Deserialize<'de> for ByteBuf {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        // Via the serde::Deserialize impl for ByteBuf.
+        serde::Deserialize::deserialize(deserializer)
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, [u8]> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct CowVisitor;
+
+        impl<'de> Visitor<'de> for CowVisitor {
+            type Value = Cow<'de, [u8]>;
+
+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter.write_str("a byte array")
+            }
+
+            fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Borrowed(v))
+            }
+
+            fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Borrowed(v.as_bytes()))
+            }
+
+            fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Owned(v.to_vec()))
+            }
+
+            fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Owned(v.as_bytes().to_vec()))
+            }
+
+            fn visit_byte_buf<E>(self, v: Vec<u8>) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Owned(v))
+            }
+
+            fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
+            where
+                E: Error,
+            {
+                Ok(Cow::Owned(v.into_bytes()))
+            }
+
+            fn visit_seq<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
+            where
+                V: SeqAccess<'de>,
+            {
+                let len = cmp::min(visitor.size_hint().unwrap_or(0), 4096);
+                let mut bytes = Vec::with_capacity(len);
+
+                while let Some(b) = visitor.next_element()? {
+                    bytes.push(b);
+                }
+
+                Ok(Cow::Owned(bytes))
+            }
+        }
+
+        deserializer.deserialize_bytes(CowVisitor)
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de: 'a, 'a> Deserialize<'de> for Cow<'a, Bytes> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let cow: Cow<[u8]> = Deserialize::deserialize(deserializer)?;
+        match cow {
+            Cow::Borrowed(bytes) => Ok(Cow::Borrowed(Bytes::new(bytes))),
+            Cow::Owned(bytes) => Ok(Cow::Owned(ByteBuf::from(bytes))),
+        }
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de> Deserialize<'de> for Box<[u8]> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Deserialize::deserialize(deserializer).map(Vec::into_boxed_slice)
+    }
+}
+
+#[cfg(any(feature = "std", feature = "alloc"))]
+impl<'de> Deserialize<'de> for Box<Bytes> {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let bytes: Box<[u8]> = Deserialize::deserialize(deserializer)?;
+        Ok(bytes.into())
+    }
+}
+
+impl<'de, T> Deserialize<'de> for Option<T>
+where
+    T: Deserialize<'de>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        struct BytesVisitor<T> {
+            out: PhantomData<T>,
+        }
+
+        impl<'de, T> Visitor<'de> for BytesVisitor<T>
+        where
+            T: Deserialize<'de>,
+        {
+            type Value = Option<T>;
+
+            fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                f.write_str("optional byte array")
+            }
+
+            fn visit_unit<E: Error>(self) -> Result<Self::Value, E> {
+                Ok(None)
+            }
+
+            fn visit_none<E: Error>(self) -> Result<Self::Value, E> {
+                Ok(None)
+            }
+
+            fn visit_some<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                T::deserialize(deserializer).map(Some)
+            }
+        }
+
+        let visitor = BytesVisitor { out: PhantomData };
+        deserializer.deserialize_option(visitor)
+    }
+}