83 lines
2.5 KiB
TypeScript
83 lines
2.5 KiB
TypeScript
import { BaseProvider } from "@ethersproject/providers";
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import { Contract } from "@ethersproject/contracts";
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import { IAddressResolver } from "./address-resolver";
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import { ChecksummedAddress, TokenMeta } from "../../types";
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import { ERCTokenResolver } from "./ERCTokenResolver";
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const UNISWAP_V2_FACTORY = "0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f";
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const UNISWAP_V2_FACTORY_ABI = [
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"function getPair(address tokenA, address tokenB) external view returns (address pair)",
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];
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const UNISWAP_V2_PAIR_ABI = [
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"function factory() external view returns (address)",
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"function token0() external view returns (address)",
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"function token1() external view returns (address)",
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];
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export type UniswapV2TokenMeta = {
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address: ChecksummedAddress;
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} & TokenMeta;
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export type UniswapV2PairMeta = {
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pair: ChecksummedAddress;
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token0: UniswapV2TokenMeta;
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token1: UniswapV2TokenMeta;
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};
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const ercResolver = new ERCTokenResolver();
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export class UniswapV2Resolver implements IAddressResolver<UniswapV2PairMeta> {
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async resolveAddress(
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provider: BaseProvider,
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address: string
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): Promise<UniswapV2PairMeta | undefined> {
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const pairContract = new Contract(address, UNISWAP_V2_PAIR_ABI, provider);
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const factoryContract = new Contract(
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UNISWAP_V2_FACTORY,
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UNISWAP_V2_FACTORY_ABI,
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provider
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);
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try {
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// First, probe the factory() function; if it responds with UniswapV2 factory
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// address, it may be a pair
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const factoryAddress = (await pairContract.factory()) as string;
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if (factoryAddress !== UNISWAP_V2_FACTORY) {
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return undefined;
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}
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// Probe the token0/token1
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const [token0, token1] = await Promise.all([
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pairContract.token0() as string,
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pairContract.token1() as string,
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]);
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// Probe the factory to ensure it is a legit pair
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const expectedPairAddress = await factoryContract.getPair(token0, token1);
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if (expectedPairAddress !== address) {
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return undefined;
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}
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const [meta0, meta1] = await Promise.all([
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ercResolver.resolveAddress(provider, token0),
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ercResolver.resolveAddress(provider, token1),
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]);
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if (meta0 === undefined || meta1 === undefined) {
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return undefined;
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}
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return {
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pair: address,
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token0: { address: token0, ...meta0 },
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token1: { address: token1, ...meta1 },
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};
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} catch (err) {
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// Ignore on purpose; this indicates the probe failed and the address
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// is not a token
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}
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return undefined;
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}
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}
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