1 files changed, 22 insertions, 0 deletions
diff --git a/evc/src/format/ser.rs b/evc/src/format/ser.rs
index 817cafe..995ca75 100644
--- a/evc/src/format/ser.rs
+++ b/evc/src/format/ser.rs
@@ -103,6 +103,28 @@ impl<T: Ser> Ser for Vec<T> {
     }
 }
 
+pub trait ConstSizeSerExt: Sized {
+    fn write_const_size(&self, sink: &mut impl Write, size: usize) -> anyhow::Result<()>;
+    fn read_const_size(source: &mut impl Read, size: usize) -> anyhow::Result<Self>;
+}
+impl<T: Ser> ConstSizeSerExt for Vec<T> {
+    fn write_const_size(&self, sink: &mut impl Write, size: usize) -> anyhow::Result<()> {
+        assert_eq!(self.len(), size);
+        for e in self {
+            e.write(sink).context("some const-size vec")?;
+        }
+        Ok(())
+    }
+
+    fn read_const_size(source: &mut impl Read, size: usize) -> anyhow::Result<Self> {
+        let mut v = vec![];
+        for _ in 0..size {
+            v.push(T::read(source)?)
+        }
+        Ok(v)
+    }
+}
+
 impl Ser for u8 {
     fn write(&self, sink: &mut impl Write) -> anyhow::Result<()> {
         Ok(sink.write_all(&[*self]).context("write u8")?)