Avoid rebuilding/parsing ABI the same contract objects every time

src/api/address-resolver/ERCTokenResolver.ts

@@ -1,18 +1,18 @@
 import { BaseProvider } from "@ethersproject/providers";
 import { Contract } from "@ethersproject/contracts";
-import { Interface } from "@ethersproject/abi";
+import { AddressZero } from "@ethersproject/constants";
 import { IAddressResolver } from "./address-resolver";
 import erc20 from "../../erc20.json";
 import { TokenMeta } from "../../types";
 
-const erc20Interface = new Interface(erc20);
+const ERC20_PROTOTYPE = new Contract(AddressZero, erc20);
 
 export class ERCTokenResolver implements IAddressResolver<TokenMeta> {
   async resolveAddress(
     provider: BaseProvider,
     address: string
   ): Promise<TokenMeta | undefined> {
-    const erc20Contract = new Contract(address, erc20Interface, provider);
+    const erc20Contract = ERC20_PROTOTYPE.connect(provider).attach(address);
     try {
       const name = (await erc20Contract.name()) as string;
       if (!name.trim()) {

src/api/address-resolver/UniswapV1Resolver.ts

@@ -12,6 +12,11 @@ const UNISWAP_V1_FACTORY_ABI = [
 
 const NULL_ADDRESS = "0x0000000000000000000000000000000000000000";
 
+const UNISWAP_V1_FACTORY_PROTOTYPE = new Contract(
+  UNISWAP_V1_FACTORY,
+  UNISWAP_V1_FACTORY_ABI
+);
+
 export type UniswapV1TokenMeta = {
   address: ChecksummedAddress;
 } & TokenMeta;
@@ -28,11 +33,7 @@ export class UniswapV1Resolver implements IAddressResolver<UniswapV1PairMeta> {
     provider: BaseProvider,
     address: string
   ): Promise<UniswapV1PairMeta | undefined> {
-    const factoryContract = new Contract(
-      UNISWAP_V1_FACTORY,
-      UNISWAP_V1_FACTORY_ABI,
-      provider
-    );
+    const factoryContract = UNISWAP_V1_FACTORY_PROTOTYPE.connect(provider);
 
     try {
       // First, probe the getToken() function; if it responds with an UniswapV1 exchange

src/api/address-resolver/UniswapV2Resolver.ts

@@ -1,5 +1,6 @@
 import { BaseProvider } from "@ethersproject/providers";
 import { Contract } from "@ethersproject/contracts";
+import { AddressZero } from "@ethersproject/constants";
 import { IAddressResolver } from "./address-resolver";
 import { ChecksummedAddress, TokenMeta } from "../../types";
 import { ERCTokenResolver } from "./ERCTokenResolver";
@@ -16,6 +17,16 @@ const UNISWAP_V2_PAIR_ABI = [
   "function token1() external view returns (address)",
 ];
 
+const UNISWAP_V2_FACTORY_PROTOTYPE = new Contract(
+  UNISWAP_V2_FACTORY,
+  UNISWAP_V2_FACTORY_ABI
+);
+
+const UNISWAP_V2_PAIR_PROTOTYPE = new Contract(
+  AddressZero,
+  UNISWAP_V2_PAIR_ABI
+);
+
 export type UniswapV2TokenMeta = {
   address: ChecksummedAddress;
 } & TokenMeta;
@@ -33,12 +44,9 @@ export class UniswapV2Resolver implements IAddressResolver<UniswapV2PairMeta> {
     provider: BaseProvider,
     address: string
   ): Promise<UniswapV2PairMeta | undefined> {
-    const pairContract = new Contract(address, UNISWAP_V2_PAIR_ABI, provider);
-    const factoryContract = new Contract(
-      UNISWAP_V2_FACTORY,
-      UNISWAP_V2_FACTORY_ABI,
-      provider
-    );
+    const pairContract =
+      UNISWAP_V2_PAIR_PROTOTYPE.connect(provider).attach(address);
+    const factoryContract = UNISWAP_V2_FACTORY_PROTOTYPE.connect(provider);
 
     try {
       // First, probe the factory() function; if it responds with UniswapV2 factory

src/api/address-resolver/UniswapV3Resolver.ts

@@ -1,5 +1,6 @@
 import { BaseProvider } from "@ethersproject/providers";
 import { Contract } from "@ethersproject/contracts";
+import { AddressZero } from "@ethersproject/constants";
 import { IAddressResolver } from "./address-resolver";
 import { ChecksummedAddress, TokenMeta } from "../../types";
 import { ERCTokenResolver } from "./ERCTokenResolver";
@@ -17,6 +18,16 @@ const UNISWAP_V3_PAIR_ABI = [
   "function fee() external view returns (uint24)",
 ];
 
+const UNISWAP_V3_FACTORY_PROTOTYPE = new Contract(
+  UNISWAP_V3_FACTORY,
+  UNISWAP_V3_FACTORY_ABI
+);
+
+const UNISWAP_V3_PAIR_PROTOTYPE = new Contract(
+  AddressZero,
+  UNISWAP_V3_PAIR_ABI
+);
+
 export type UniswapV3TokenMeta = {
   address: ChecksummedAddress;
 } & TokenMeta;
@@ -35,12 +46,9 @@ export class UniswapV3Resolver implements IAddressResolver<UniswapV3PairMeta> {
     provider: BaseProvider,
     address: string
   ): Promise<UniswapV3PairMeta | undefined> {
-    const poolContract = new Contract(address, UNISWAP_V3_PAIR_ABI, provider);
-    const factoryContract = new Contract(
-      UNISWAP_V3_FACTORY,
-      UNISWAP_V3_FACTORY_ABI,
-      provider
-    );
+    const poolContract =
+      UNISWAP_V3_PAIR_PROTOTYPE.connect(provider).attach(address);
+    const factoryContract = UNISWAP_V3_FACTORY_PROTOTYPE.connect(provider);
 
     try {
       // First, probe the factory() function; if it responds with UniswapV2 factory

src/useErigonHooks.ts

@@ -10,6 +10,7 @@ import { Contract } from "@ethersproject/contracts";
 import { defaultAbiCoder } from "@ethersproject/abi";
 import { BigNumber } from "@ethersproject/bignumber";
 import { arrayify, hexDataSlice, isHexString } from "@ethersproject/bytes";
+import { AddressZero } from "@ethersproject/constants";
 import useSWR from "swr";
 import useSWRImmutable from "swr/immutable";
 import {
@@ -638,13 +639,19 @@ export const useHasCode = (
   return data as boolean | undefined;
 };
 
+const ERC20_PROTOTYPE = new Contract(AddressZero, erc20);
+
 const tokenMetadataFetcher =
   (provider: JsonRpcProvider | undefined) =>
   async (
     _: "tokenmeta",
     address: ChecksummedAddress
   ): Promise<TokenMeta | null> => {
-    const erc20Contract = new Contract(address, erc20, provider);
+    if (provider === undefined) {
+      return null;
+    }
+
+    const erc20Contract = ERC20_PROTOTYPE.connect(provider).attach(address);
     try {
       const name = (await erc20Contract.name()) as string;
       if (!name.trim()) {

src/usePriceOracle.ts

@@ -1,6 +1,7 @@
 import { JsonRpcProvider, BlockTag } from "@ethersproject/providers";
 import { Contract } from "@ethersproject/contracts";
 import { BigNumber } from "@ethersproject/bignumber";
+import { AddressZero } from "@ethersproject/constants";
 import AggregatorV3Interface from "@chainlink/contracts/abi/v0.8/AggregatorV3Interface.json";
 import FeedRegistryInterface from "@chainlink/contracts/abi/v0.8/FeedRegistryInterface.json";
 import { Fetcher } from "swr";
@@ -26,11 +27,20 @@ const feedRegistryFetcherKey = (
   return [tokenAddress, blockTag];
 };
 
+const FEED_REGISTRY_MAINNET_PROTOTYPE = new Contract(
+  FEED_REGISTRY_MAINNET,
+  FeedRegistryInterface
+);
+
 const feedRegistryFetcher =
   (
     provider: JsonRpcProvider | undefined
   ): Fetcher<FeedRegistryFetcherData, FeedRegistryFetcherKey> =>
   async (tokenAddress, blockTag) => {
+    if (provider === undefined) {
+      return [undefined, undefined];
+    }
+
     // It work works on ethereum mainnet and kovan, see:
     // https://docs.chain.link/docs/feed-registry/
     if (provider!.network.chainId !== 1) {
@@ -38,11 +48,7 @@ const feedRegistryFetcher =
     }
 
     // Let SWR handle error
-    const feedRegistry = new Contract(
-      FEED_REGISTRY_MAINNET,
-      FeedRegistryInterface,
-      provider
-    );
+    const feedRegistry = FEED_REGISTRY_MAINNET_PROTOTYPE.connect(provider);
     const priceData = await feedRegistry.latestRoundData(tokenAddress, USD, {
       blockTag,
     });
@@ -76,6 +82,8 @@ const ethUSDFetcherKey = (blockTag: BlockTag | undefined) => {
   return ["ethusd", blockTag];
 };
 
+const ETH_USD_FEED_PROTOTYPE = new Contract(AddressZero, AggregatorV3Interface);
+
 const ethUSDFetcher =
   (
     provider: JsonRpcProvider | undefined
@@ -84,7 +92,9 @@ const ethUSDFetcher =
     if (provider?.network.chainId !== 1) {
       return undefined;
     }
-    const c = new Contract("eth-usd.data.eth", AggregatorV3Interface, provider);
+
+    const c =
+      ETH_USD_FEED_PROTOTYPE.connect(provider).attach("eth-usd.data.eth");
     const priceData = await c.latestRoundData({ blockTag });
     return priceData;
   };
@@ -120,6 +130,11 @@ const fastGasFetcherKey = (blockTag: BlockTag | undefined) => {
   return ["gasgwei", blockTag];
 };
 
+const FAST_GAS_FEED_PROTOTYPE = new Contract(
+  AddressZero,
+  AggregatorV3Interface
+);
+
 const fastGasFetcher =
   (
     provider: JsonRpcProvider | undefined
@@ -128,10 +143,8 @@ const fastGasFetcher =
     if (provider?.network.chainId !== 1) {
       return undefined;
     }
-    const c = new Contract(
-      "fast-gas-gwei.data.eth",
-      AggregatorV3Interface,
-      provider
+    const c = FAST_GAS_FEED_PROTOTYPE.connect(provider).attach(
+      "fast-gas-gwei.data.eth"
     );
     const priceData = await c.latestRoundData({ blockTag });
     return priceData;