> ## Documentation Index
> Fetch the complete documentation index at: https://docs.krokoswap.io/llms.txt
> Use this file to discover all available pages before exploring further.

# V2 Factory 与 Pair

> V2 流动性池创建和 Pair 合约接口

# V2 Factory 与 Pair

## V2 Factory

V2 Factory 负责创建和索引 V2 交易对。每个唯一的代币对只有一个 V2 流动性池。

### 核心函数

#### getPair

返回两个代币的 Pair 合约地址，如果不存在则返回零地址。

```solidity theme={null}
function getPair(
    address tokenA,
    address tokenB
) external view returns (address pair);
```

<Note>
  代币顺序无关紧要 — `getPair(A, B)` 与 `getPair(B, A)` 返回相同结果。
</Note>

#### allPairs

返回给定索引处的 Pair 地址。用于枚举遍历。

```solidity theme={null}
function allPairs(uint256 index) external view returns (address pair);
function allPairsLength() external view returns (uint256);
```

### ABI

```json theme={null}
[
  "function getPair(address tokenA, address tokenB) view returns (address pair)",
  "function allPairs(uint256 index) view returns (address pair)",
  "function allPairsLength() view returns (uint256)"
]
```

***

## V2 Pair

每个 V2 Pair 是一个 ERC-20 合约（LP 代币），同时持有池的储备量并执行兑换。

### 核心函数

#### getReserves

返回当前的代币储备量和最后一个区块的时间戳。

```solidity theme={null}
function getReserves() external view returns (
    uint112 reserve0,
    uint112 reserve1,
    uint32 blockTimestampLast
);
```

`token0` 始终是地址较小的代币。

#### token0 / token1

返回池中代币的地址。

```solidity theme={null}
function token0() external view returns (address);
function token1() external view returns (address);
```

#### totalSupply / balanceOf

用于 LP 代币记账的标准 ERC-20 函数。

```solidity theme={null}
function totalSupply() external view returns (uint256);
function balanceOf(address owner) external view returns (uint256);
```

### ABI

```json theme={null}
[
  "function getReserves() view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast)",
  "function token0() view returns (address)",
  "function token1() view returns (address)",
  "function totalSupply() view returns (uint256)",
  "function balanceOf(address owner) view returns (uint256)",
  "function approve(address spender, uint256 value) returns (bool)",
  "function transfer(address to, uint256 value) returns (bool)"
]
```

### 示例：读取池状态

```typescript theme={null}
const FACTORY_ABI = [
  "function getPair(address, address) view returns (address)"
];
const PAIR_ABI = [
  "function getReserves() view returns (uint112, uint112, uint32)",
  "function token0() view returns (address)",
  "function token1() view returns (address)",
  "function totalSupply() view returns (uint256)"
];

const factory = new ethers.Contract(V2_FACTORY, FACTORY_ABI, provider);
const pairAddress = await factory.getPair(tokenA, tokenB);

if (pairAddress === ethers.ZeroAddress) {
  console.log("Pool does not exist");
} else {
  const pair = new ethers.Contract(pairAddress, PAIR_ABI, provider);
  const [reserve0, reserve1] = await pair.getReserves();
  const token0 = await pair.token0();

  console.log(`Reserve ${token0 === tokenA ? 'A' : 'B'}: ${reserve0}`);
  console.log(`Reserve ${token0 === tokenA ? 'B' : 'A'}: ${reserve1}`);
}
```