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pair.ts
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pair.ts
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import { Price } from './fractions/price'
import { TokenAmount } from './fractions/tokenAmount'
import invariant from 'tiny-invariant'
import JSBI from 'jsbi'
import { pack, keccak256 } from '@ethersproject/solidity'
import { getCreate2Address } from '@ethersproject/address'
import {
BigintIsh,
FACTORY_ADDRESS,
INIT_CODE_HASH,
MINIMUM_LIQUIDITY,
ZERO,
ONE,
FIVE,
_997,
_1000,
ChainId
} from '../constants'
import { sqrt, parseBigintIsh } from '../utils'
import { InsufficientReservesError, InsufficientInputAmountError } from '../errors'
import { Token } from './token'
let PAIR_ADDRESS_CACHE: { [token0Address: string]: { [token1Address: string]: string } } = {}
export class Pair {
public readonly liquidityToken: Token
private readonly tokenAmounts: [TokenAmount, TokenAmount]
public static getAddress(tokenA: Token, tokenB: Token): string {
const tokens = tokenA.sortsBefore(tokenB) ? [tokenA, tokenB] : [tokenB, tokenA] // does safety checks
if (PAIR_ADDRESS_CACHE?.[tokens[0].address]?.[tokens[1].address] === undefined) {
PAIR_ADDRESS_CACHE = {
...PAIR_ADDRESS_CACHE,
[tokens[0].address]: {
...PAIR_ADDRESS_CACHE?.[tokens[0].address],
[tokens[1].address]: getCreate2Address(
FACTORY_ADDRESS,
keccak256(['bytes'], [pack(['address', 'address'], [tokens[0].address, tokens[1].address])]),
INIT_CODE_HASH
)
}
}
}
return PAIR_ADDRESS_CACHE[tokens[0].address][tokens[1].address]
}
public constructor(tokenAmountA: TokenAmount, tokenAmountB: TokenAmount) {
const tokenAmounts = tokenAmountA.token.sortsBefore(tokenAmountB.token) // does safety checks
? [tokenAmountA, tokenAmountB]
: [tokenAmountB, tokenAmountA]
this.liquidityToken = new Token(
tokenAmounts[0].token.chainId,
Pair.getAddress(tokenAmounts[0].token, tokenAmounts[1].token),
18,
'UNI-V2',
'Uniswap V2'
)
this.tokenAmounts = tokenAmounts as [TokenAmount, TokenAmount]
}
/**
* Returns true if the token is either token0 or token1
* @param token to check
*/
public involvesToken(token: Token): boolean {
return token.equals(this.token0) || token.equals(this.token1)
}
/**
* Returns the current mid price of the pair in terms of token0, i.e. the ratio of reserve1 to reserve0
*/
public get token0Price(): Price {
return new Price(this.token0, this.token1, this.tokenAmounts[0].raw, this.tokenAmounts[1].raw)
}
/**
* Returns the current mid price of the pair in terms of token1, i.e. the ratio of reserve0 to reserve1
*/
public get token1Price(): Price {
return new Price(this.token1, this.token0, this.tokenAmounts[1].raw, this.tokenAmounts[0].raw)
}
/**
* Return the price of the given token in terms of the other token in the pair.
* @param token token to return price of
*/
public priceOf(token: Token): Price {
invariant(this.involvesToken(token), 'TOKEN')
return token.equals(this.token0) ? this.token0Price : this.token1Price
}
/**
* Returns the chain ID of the tokens in the pair.
*/
public get chainId(): ChainId {
return this.token0.chainId
}
public get token0(): Token {
return this.tokenAmounts[0].token
}
public get token1(): Token {
return this.tokenAmounts[1].token
}
public get reserve0(): TokenAmount {
return this.tokenAmounts[0]
}
public get reserve1(): TokenAmount {
return this.tokenAmounts[1]
}
public reserveOf(token: Token): TokenAmount {
invariant(this.involvesToken(token), 'TOKEN')
return token.equals(this.token0) ? this.reserve0 : this.reserve1
}
public getOutputAmount(inputAmount: TokenAmount): [TokenAmount, Pair] {
invariant(this.involvesToken(inputAmount.token), 'TOKEN')
if (JSBI.equal(this.reserve0.raw, ZERO) || JSBI.equal(this.reserve1.raw, ZERO)) {
throw new InsufficientReservesError()
}
const inputReserve = this.reserveOf(inputAmount.token)
const outputReserve = this.reserveOf(inputAmount.token.equals(this.token0) ? this.token1 : this.token0)
const inputAmountWithFee = JSBI.multiply(inputAmount.raw, _997)
const numerator = JSBI.multiply(inputAmountWithFee, outputReserve.raw)
const denominator = JSBI.add(JSBI.multiply(inputReserve.raw, _1000), inputAmountWithFee)
const outputAmount = new TokenAmount(
inputAmount.token.equals(this.token0) ? this.token1 : this.token0,
JSBI.divide(numerator, denominator)
)
if (JSBI.equal(outputAmount.raw, ZERO)) {
throw new InsufficientInputAmountError()
}
return [outputAmount, new Pair(inputReserve.add(inputAmount), outputReserve.subtract(outputAmount))]
}
public getInputAmount(outputAmount: TokenAmount): [TokenAmount, Pair] {
invariant(this.involvesToken(outputAmount.token), 'TOKEN')
if (
JSBI.equal(this.reserve0.raw, ZERO) ||
JSBI.equal(this.reserve1.raw, ZERO) ||
JSBI.greaterThanOrEqual(outputAmount.raw, this.reserveOf(outputAmount.token).raw)
) {
throw new InsufficientReservesError()
}
const outputReserve = this.reserveOf(outputAmount.token)
const inputReserve = this.reserveOf(outputAmount.token.equals(this.token0) ? this.token1 : this.token0)
const numerator = JSBI.multiply(JSBI.multiply(inputReserve.raw, outputAmount.raw), _1000)
const denominator = JSBI.multiply(JSBI.subtract(outputReserve.raw, outputAmount.raw), _997)
const inputAmount = new TokenAmount(
outputAmount.token.equals(this.token0) ? this.token1 : this.token0,
JSBI.add(JSBI.divide(numerator, denominator), ONE)
)
return [inputAmount, new Pair(inputReserve.add(inputAmount), outputReserve.subtract(outputAmount))]
}
public getLiquidityMinted(
totalSupply: TokenAmount,
tokenAmountA: TokenAmount,
tokenAmountB: TokenAmount
): TokenAmount {
invariant(totalSupply.token.equals(this.liquidityToken), 'LIQUIDITY')
const tokenAmounts = tokenAmountA.token.sortsBefore(tokenAmountB.token) // does safety checks
? [tokenAmountA, tokenAmountB]
: [tokenAmountB, tokenAmountA]
invariant(tokenAmounts[0].token.equals(this.token0) && tokenAmounts[1].token.equals(this.token1), 'TOKEN')
let liquidity: JSBI
if (JSBI.equal(totalSupply.raw, ZERO)) {
liquidity = JSBI.subtract(sqrt(JSBI.multiply(tokenAmounts[0].raw, tokenAmounts[1].raw)), MINIMUM_LIQUIDITY)
} else {
const amount0 = JSBI.divide(JSBI.multiply(tokenAmounts[0].raw, totalSupply.raw), this.reserve0.raw)
const amount1 = JSBI.divide(JSBI.multiply(tokenAmounts[1].raw, totalSupply.raw), this.reserve1.raw)
liquidity = JSBI.lessThanOrEqual(amount0, amount1) ? amount0 : amount1
}
if (!JSBI.greaterThan(liquidity, ZERO)) {
throw new InsufficientInputAmountError()
}
return new TokenAmount(this.liquidityToken, liquidity)
}
public getLiquidityValue(
token: Token,
totalSupply: TokenAmount,
liquidity: TokenAmount,
feeOn: boolean = false,
kLast?: BigintIsh
): TokenAmount {
invariant(this.involvesToken(token), 'TOKEN')
invariant(totalSupply.token.equals(this.liquidityToken), 'TOTAL_SUPPLY')
invariant(liquidity.token.equals(this.liquidityToken), 'LIQUIDITY')
invariant(JSBI.lessThanOrEqual(liquidity.raw, totalSupply.raw), 'LIQUIDITY')
let totalSupplyAdjusted: TokenAmount
if (!feeOn) {
totalSupplyAdjusted = totalSupply
} else {
invariant(!!kLast, 'K_LAST')
const kLastParsed = parseBigintIsh(kLast)
if (!JSBI.equal(kLastParsed, ZERO)) {
const rootK = sqrt(JSBI.multiply(this.reserve0.raw, this.reserve1.raw))
const rootKLast = sqrt(kLastParsed)
if (JSBI.greaterThan(rootK, rootKLast)) {
const numerator = JSBI.multiply(totalSupply.raw, JSBI.subtract(rootK, rootKLast))
const denominator = JSBI.add(JSBI.multiply(rootK, FIVE), rootKLast)
const feeLiquidity = JSBI.divide(numerator, denominator)
totalSupplyAdjusted = totalSupply.add(new TokenAmount(this.liquidityToken, feeLiquidity))
} else {
totalSupplyAdjusted = totalSupply
}
} else {
totalSupplyAdjusted = totalSupply
}
}
return new TokenAmount(
token,
JSBI.divide(JSBI.multiply(liquidity.raw, this.reserveOf(token).raw), totalSupplyAdjusted.raw)
)
}
}