From 092bd96a39abc2965cec9756967db6310b8fba88 Mon Sep 17 00:00:00 2001
From: Tarrence van As <tarrencev@users.noreply.github.com>
Date: Tue, 11 Jan 2022 01:31:09 -0800
Subject: [PATCH] feat(chain): enum values + TryFrom<u64> (#782)

* feat(chain): map Chain enum to values

* feat(chain): support TryFrom<u64>

* chore: use parsechain error for the try_from impl

Co-authored-by: Georgios Konstantopoulos <me@gakonst.com>
---
 ethers-core/src/types/chain.rs | 79 +++++++++++++++++++---------------
 1 file changed, 45 insertions(+), 34 deletions(-)

diff --git a/ethers-core/src/types/chain.rs b/ethers-core/src/types/chain.rs
index 217e2d3b..c522b1e5 100644
--- a/ethers-core/src/types/chain.rs
+++ b/ethers-core/src/types/chain.rs
@@ -1,6 +1,7 @@
 use serde::Deserialize;
 use thiserror::Error;
 
+use core::convert::TryFrom;
 use std::{fmt, str::FromStr};
 
 use crate::types::U256;
@@ -9,25 +10,26 @@ use crate::types::U256;
 #[error("Failed to parse chain: {0}")]
 pub struct ParseChainError(String);
 
+#[repr(u64)]
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum Chain {
-    Mainnet,
-    Ropsten,
-    Rinkeby,
-    Goerli,
-    Kovan,
-    XDai,
-    Polygon,
-    PolygonMumbai,
-    Avalanche,
-    AvalancheFuji,
-    Sepolia,
-    Moonbeam,
-    MoonbeamDev,
-    Moonriver,
-    Optimism,
-    OptimismKovan,
+    Mainnet = 1,
+    Ropsten = 3,
+    Rinkeby = 4,
+    Goerli = 5,
+    Kovan = 42,
+    XDai = 100,
+    Polygon = 137,
+    PolygonMumbai = 80001,
+    Avalanche = 43114,
+    AvalancheFuji = 43113,
+    Sepolia = 11155111,
+    Moonbeam = 1287,
+    MoonbeamDev = 1281,
+    Moonriver = 1285,
+    Optimism = 10,
+    OptimismKovan = 69,
 }
 
 impl fmt::Display for Chain {
@@ -38,24 +40,7 @@ impl fmt::Display for Chain {
 
 impl From<Chain> for u32 {
     fn from(chain: Chain) -> Self {
-        match chain {
-            Chain::Mainnet => 1,
-            Chain::Ropsten => 3,
-            Chain::Rinkeby => 4,
-            Chain::Goerli => 5,
-            Chain::Kovan => 42,
-            Chain::XDai => 100,
-            Chain::Polygon => 137,
-            Chain::PolygonMumbai => 80001,
-            Chain::Avalanche => 43114,
-            Chain::AvalancheFuji => 43113,
-            Chain::Sepolia => 11155111,
-            Chain::Moonbeam => 1287,
-            Chain::MoonbeamDev => 1281,
-            Chain::Moonriver => 1285,
-            Chain::Optimism => 10,
-            Chain::OptimismKovan => 69,
-        }
+        chain as u32
     }
 }
 
@@ -71,6 +56,32 @@ impl From<Chain> for u64 {
     }
 }
 
+impl TryFrom<u64> for Chain {
+    type Error = ParseChainError;
+
+    fn try_from(chain: u64) -> Result<Chain, Self::Error> {
+        match chain {
+            1 => Ok(Chain::Mainnet),
+            3 => Ok(Chain::Ropsten),
+            4 => Ok(Chain::Rinkeby),
+            5 => Ok(Chain::Goerli),
+            42 => Ok(Chain::Kovan),
+            100 => Ok(Chain::XDai),
+            137 => Ok(Chain::Polygon),
+            80001 => Ok(Chain::PolygonMumbai),
+            43114 => Ok(Chain::Avalanche),
+            43113 => Ok(Chain::AvalancheFuji),
+            11155111 => Ok(Chain::Sepolia),
+            1287 => Ok(Chain::Moonbeam),
+            1281 => Ok(Chain::MoonbeamDev),
+            1285 => Ok(Chain::Moonriver),
+            10 => Ok(Chain::Optimism),
+            69 => Ok(Chain::OptimismKovan),
+            _ => return Err(ParseChainError(chain.to_string())),
+        }
+    }
+}
+
 impl FromStr for Chain {
     type Err = ParseChainError;
     fn from_str(chain: &str) -> Result<Self, Self::Err> {