Add serialize method that takes a supplied vec

Author: djkoloski

src/ser/mod.rs

@@ -283,3 +283,14 @@ where
     value.serialize(&mut serializer)?;
     Ok(serializer.into_vec())
 }
+
+/// Serialize the given `T` as a BSON byte vector into the provided writer.
+#[inline]
+pub fn into_vec<T>(value: &T, vec: Vec<u8>) -> Result<Vec<u8>>
+where
+    T: Serialize,
+{
+    let mut serializer = raw::Serializer::with_vec(vec);
+    value.serialize(&mut serializer)?;
+    Ok(serializer.into_vec())
+}

src/ser/raw/mod.rs

@@ -56,8 +56,13 @@ impl SerializerHint {
 
 impl Serializer {
     pub(crate) fn new() -> Self {
+        Self::with_vec(Vec::new())
+    }
+
+    pub(crate) fn with_vec(mut bytes: Vec<u8>) -> Self {
+        bytes.clear();
         Self {
-            bytes: Vec::new(),
+            bytes,
             type_index: 0,
             hint: SerializerHint::None,
         }