# Quoter

Allows getting the expected amount out or amount in for a given swap without executing the swap

*These functions are not gas efficient and should not be called on chain. Instead, optimistically execute the swap and check the amounts in the callback.*

### State Variables <a href="#state-variables" id="state-variables"></a>

#### amountOutCached <a href="#amountoutcached" id="amountoutcached"></a>

*Transient storage variable used to check a safety condition in exact output swaps.*

```solidity
uint256 private amountOutCached;
```

### Functions <a href="#functions" id="functions"></a>

#### constructor <a href="#constructor" id="constructor"></a>

```solidity
constructor(address _factory, address _WSEI) PeripheryImmutableState(_factory, _WSEI);
```

#### getPool <a href="#getpool" id="getpool"></a>

```solidity
function getPool(address tokenA, address tokenB, uint24 fee) private view returns (IDragonswapV2Pool);
```

#### dragonswapV2SwapCallback <a href="#dragonswapv2swapcallback" id="dragonswapv2swapcallback"></a>

Called to `msg.sender` after executing a swap via IDragonswapV2Pool#swap.

*In the implementation you must pay the pool tokens owed for the swap. The caller of this method must be checked to be a DragonswapV2Pool deployed by the canonical DragonswapV2Factory. amount0Delta and amount1Delta can both be 0 if no tokens were swapped.*

```solidity
function dragonswapV2SwapCallback(int256 amount0Delta, int256 amount1Delta, bytes memory path) external view override;
```

**Parameters**

| Name           | Type     | Description                                                                                                                                                                             |
| -------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `amount0Delta` | `int256` | The amount of token0 that was sent (negative) or must be received (positive) by the pool by the end of the swap. If positive, the callback must send that amount of token0 to the pool. |
| `amount1Delta` | `int256` | The amount of token1 that was sent (negative) or must be received (positive) by the pool by the end of the swap. If positive, the callback must send that amount of token1 to the pool. |
| `path`         | `bytes`  |                                                                                                                                                                                         |

#### parseRevertReason <a href="#parserevertreason" id="parserevertreason"></a>

*Parses a revert reason that should contain the numeric quote*

```solidity
function parseRevertReason(bytes memory reason) private pure returns (uint256);
```

#### quoteExactInputSingle <a href="#quoteexactinputsingle" id="quoteexactinputsingle"></a>

Returns the amount out received for a given exact input but for a swap of a single pool

```solidity
function quoteExactInputSingle(
    address tokenIn,
    address tokenOut,
    uint24 fee,
    uint256 amountIn,
    uint160 sqrtPriceLimitX96
) public override returns (uint256 amountOut);
```

**Parameters**

| Name                | Type      | Description                                                     |
| ------------------- | --------- | --------------------------------------------------------------- |
| `tokenIn`           | `address` | The token being swapped in                                      |
| `tokenOut`          | `address` | The token being swapped out                                     |
| `fee`               | `uint24`  | The fee of the token pool to consider for the pair              |
| `amountIn`          | `uint256` | The desired input amount                                        |
| `sqrtPriceLimitX96` | `uint160` | The price limit of the pool that cannot be exceeded by the swap |

**Returns**

| Name        | Type      | Description                                     |
| ----------- | --------- | ----------------------------------------------- |
| `amountOut` | `uint256` | The amount of `tokenOut` that would be received |

#### quoteExactInput <a href="#quoteexactinput" id="quoteexactinput"></a>

Returns the amount out received for a given exact input swap without executing the swap

```solidity
function quoteExactInput(bytes memory path, uint256 amountIn) external override returns (uint256 amountOut);
```

**Parameters**

| Name       | Type      | Description                                                 |
| ---------- | --------- | ----------------------------------------------------------- |
| `path`     | `bytes`   | The path of the swap, i.e. each token pair and the pool fee |
| `amountIn` | `uint256` | The amount of the first token to swap                       |

**Returns**

| Name        | Type      | Description                                         |
| ----------- | --------- | --------------------------------------------------- |
| `amountOut` | `uint256` | The amount of the last token that would be received |

#### quoteExactOutputSingle <a href="#quoteexactoutputsingle" id="quoteexactoutputsingle"></a>

Returns the amount in required to receive the given exact output amount but for a swap of a single pool

```solidity
function quoteExactOutputSingle(
    address tokenIn,
    address tokenOut,
    uint24 fee,
    uint256 amountOut,
    uint160 sqrtPriceLimitX96
) public override returns (uint256 amountIn);
```

**Parameters**

| Name                | Type      | Description                                                     |
| ------------------- | --------- | --------------------------------------------------------------- |
| `tokenIn`           | `address` | The token being swapped in                                      |
| `tokenOut`          | `address` | The token being swapped out                                     |
| `fee`               | `uint24`  | The fee of the token pool to consider for the pair              |
| `amountOut`         | `uint256` | The desired output amount                                       |
| `sqrtPriceLimitX96` | `uint160` | The price limit of the pool that cannot be exceeded by the swap |

**Returns**

| Name       | Type      | Description                                                                   |
| ---------- | --------- | ----------------------------------------------------------------------------- |
| `amountIn` | `uint256` | The amount required as the input for the swap in order to receive `amountOut` |

#### quoteExactOutput <a href="#quoteexactoutput" id="quoteexactoutput"></a>

Returns the amount in required for a given exact output swap without executing the swap

```solidity
function quoteExactOutput(bytes memory path, uint256 amountOut) external override returns (uint256 amountIn);
```

**Parameters**

| Name        | Type      | Description                                                                                         |
| ----------- | --------- | --------------------------------------------------------------------------------------------------- |
| `path`      | `bytes`   | The path of the swap, i.e. each token pair and the pool fee. Path must be provided in reverse order |
| `amountOut` | `uint256` | The amount of the last token to receive                                                             |

**Returns**

| Name       | Type      | Description                                   |
| ---------- | --------- | --------------------------------------------- |
| `amountIn` | `uint256` | The amount of first token required to be paid |