fix: stable trade currency (#329)

Uses a stable value for the trade's currencies, so that hooks depending on the currency are not rerendered. Practically, this fixes an issue where changing the input amount would reset approval state.

src/state/routing/utils.ts

@@ -1,7 +1,6 @@
 import { Currency, CurrencyAmount, Token, TradeType } from '@uniswap/sdk-core'
 import { Pair, Route as V2Route } from '@uniswap/v2-sdk'
 import { FeeAmount, Pool, Route as V3Route } from '@uniswap/v3-sdk'
-import { nativeOnChain } from 'constants/tokens'
 
 import { InterfaceTrade, QuoteResult, V2PoolInRoute, V3PoolInRoute } from './types'
 
@@ -25,9 +24,6 @@ export function computeRoutes(
   if (parsedTokenIn.address !== currencyIn.wrapped.address) return undefined
   if (parsedTokenOut.address !== currencyOut.wrapped.address) return undefined
 
-  const parsedCurrencyIn = currencyIn.isNative ? nativeOnChain(currencyIn.chainId) : parsedTokenIn
-  const parsedCurrencyOut = currencyOut.isNative ? nativeOnChain(currencyOut.chainId) : parsedTokenOut
-
   try {
     return quoteResult.route.map((route) => {
       if (route.length === 0) {
@@ -41,10 +37,10 @@ export function computeRoutes(
       }
 
       return {
-        routev3: isV3Route(route) ? new V3Route(route.map(parsePool), parsedCurrencyIn, parsedCurrencyOut) : null,
-        routev2: !isV3Route(route) ? new V2Route(route.map(parsePair), parsedCurrencyIn, parsedCurrencyOut) : null,
-        inputAmount: CurrencyAmount.fromRawAmount(parsedCurrencyIn, rawAmountIn),
-        outputAmount: CurrencyAmount.fromRawAmount(parsedCurrencyOut, rawAmountOut),
+        routev3: isV3Route(route) ? new V3Route(route.map(parsePool), currencyIn, currencyOut) : null,
+        routev2: !isV3Route(route) ? new V2Route(route.map(parsePair), currencyIn, currencyOut) : null,
+        inputAmount: CurrencyAmount.fromRawAmount(currencyIn, rawAmountIn),
+        outputAmount: CurrencyAmount.fromRawAmount(currencyOut, rawAmountOut),
       }
     })
   } catch (e) {