subgraph code base from OB sg repo

subgraph/src/erc20.ts

@@ -0,0 +1,26 @@
+import { Address } from "@graphprotocol/graph-ts";
+import { ReserveToken, Transfer } from "../generated/OrderBook/ReserveToken";
+import { ERC20 } from "../generated/schema";
+import { toDisplayWithDecimals } from "./utils";
+
+export function handleTransfer(event: Transfer): void {
+  let token = ERC20.load(event.address.toHex());
+
+  if (
+    token &&
+    (event.params.from == Address.zero() || event.params.to == Address.zero())
+  ) {
+    let reserveToken = ReserveToken.bind(Address.fromBytes(event.address));
+
+    let totalSupply = reserveToken.try_totalSupply();
+
+    if (!totalSupply.reverted) {
+      let value = totalSupply.value;
+
+      token.totalSupply = value;
+      token.totalSupplyDisplay = toDisplayWithDecimals(value, token.decimals);
+
+      token.save();
+    }
+  }
+}