From 5c1458ba46832911a32fb2df1e6fbcbb79298a6f Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Fri, 8 Mar 2019 13:19:37 +1100
Subject: [PATCH] Add bls serde_vistors file

---
 eth2/utils/bls/src/serde_vistors.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 eth2/utils/bls/src/serde_vistors.rs

diff --git a/eth2/utils/bls/src/serde_vistors.rs b/eth2/utils/bls/src/serde_vistors.rs
new file mode 100644
index 000000000..55eadb883
--- /dev/null
+++ b/eth2/utils/bls/src/serde_vistors.rs
@@ -0,0 +1,20 @@
+use hex;
+use serde::de::{self, Visitor};
+use std::fmt;
+
+pub struct HexVisitor;
+
+impl<'de> Visitor<'de> for HexVisitor {
+    type Value = Vec<u8>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a hex string (without 0x prefix)")
+    }
+
+    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
+    where
+        E: de::Error,
+    {
+        Ok(hex::decode(value).map_err(|e| de::Error::custom(format!("invalid hex ({:?})", e)))?)
+    }
+}