From c22dd8eab4c7e4c848446f80ec1dc0e4a8e76079 Mon Sep 17 00:00:00 2001
From: Tarrence van As <tarrencev@users.noreply.github.com>
Date: Thu, 27 Jan 2022 10:33:01 -0800
Subject: [PATCH] feat(types/chain): is_legacy helper (#835)

moving this into ethers-rs from foundry so it can be more easily use elsewhere
---
 ethers-core/src/types/chain.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/ethers-core/src/types/chain.rs b/ethers-core/src/types/chain.rs
index 49fc1f81..4f70e107 100644
--- a/ethers-core/src/types/chain.rs
+++ b/ethers-core/src/types/chain.rs
@@ -116,3 +116,15 @@ impl FromStr for Chain {
         })
     }
 }
+
+impl Chain {
+    /// Helper function for checking if a chainid corresponds to a legacy chainid
+    /// without eip1559
+    pub fn is_legacy(&self) -> bool {
+        // TODO: Add other chains which do not support EIP1559.
+        matches!(
+            self,
+            Chain::Optimism | Chain::OptimismKovan | Chain::Fantom | Chain::FantomTestnet
+        )
+    }
+}