DeltaResolver
DeltaResolver 是一个抽象合约（Abstract Contract），用于向 PoolManager 合约同步（sync）、转移代币（send）以及结算资金（settle）。
方法定义
_pay
DeltaResolver 定义了一个抽象方法 _pay，实现将指定数量的代币支付给 poolManager。所有继承 DeltaResolver 的合约都需要实现 _pay 方法。
如 PositionManager 合约继承了 DeltaResolver 合约，并实现了 _pay 方法。
输入参数：
Currency token：需要支付的代币address payer：支付者地址uint256 amount：支付数量
/// @notice Abstract function for contracts to implement paying tokens to the poolManager
/// @dev The recipient of the payment should be the poolManager
/// @param token The token to settle. This is known not to be the native currency
/// @param payer The address who should pay tokens
/// @param amount The number of tokens to send
function _pay(Currency token, address payer, uint256 amount) internal virtual;
_getFullDebt
获取当前合约在 PoolManager 的全部欠款（负 delta）。取反后，返回值为 uint256 类型。
输入参数：
/// @notice Obtain the full amount owed by this contract (negative delta)
/// @param currency Currency to get the delta for
/// @return amount The amount owed by this contract as a uint256
function _getFullDebt(Currency currency) internal view returns (uint256 amount) {
int256 _amount = poolManager.currencyDelta(address(this), currency);
// If the amount is positive, it should be taken not settled.
if (_amount > 0) revert DeltaNotNegative(currency);
// Casting is safe due to limits on the total supply of a pool
amount = uint256(-_amount);
}
_getFullCredit
获取当前合约在 PoolManager 全部可取回金额（正 delta）。返回值为 uint256 类型。
输入参数：
/// @notice Obtain the full credit owed to this contract (positive delta)
/// @param currency Currency to get the delta for
/// @return amount The amount owed to this contract as a uint256
function _getFullCredit(Currency currency) internal view returns (uint256 amount) {
int256 _amount = poolManager.currencyDelta(address(this), currency);
// If the amount is negative, it should be settled not taken.
if (_amount < 0) revert DeltaNotPositive(currency);
amount = uint256(_amount);
}
_take
提取单个代币的余额。由 PoolManager 合约向 recipient 转移代币。
输入参数：
currency：代币recipient：接收者amount：提取金额
/// @notice Take an amount of currency out of the PoolManager
/// @param currency Currency to take
/// @param recipient Address to receive the currency
/// @param amount Amount to take
/// @dev Returns early if the amount is 0
function _take(Currency currency, address recipient, uint256 amount) internal {
if (amount == 0) return;
poolManager.take(currency, recipient, amount);
}
如果 amount 为 0，直接返回。
调用 PoolManager.take 方法，从 poolManager 提取指定数量的代币。
_settle
结算单个代币的欠款。需要向 PoolManager 支付代币。
在 PoolManager.settle 方法中，我们介绍了结算欠款的流程：
- 调用 PoolManager.sync 方法，同步代币余额；
- 向
PoolManager 转移代币；
- 调用 PoolManager.settle 方法，结算记账余额。
输入参数：
currency：代币payer：支付者amount：支付金额
/// @notice Pay and settle a currency to the PoolManager
/// @dev The implementing contract must ensure that the `payer` is a secure address
/// @param currency Currency to settle
/// @param payer Address of the payer
/// @param amount Amount to send
/// @dev Returns early if the amount is 0
function _settle(Currency currency, address payer, uint256 amount) internal {
if (amount == 0) return;
poolManager.sync(currency);
if (currency.isAddressZero()) {
poolManager.settle{value: amount}();
} else {
_pay(currency, payer, amount);
poolManager.settle();
}
}
如果 amount 为 0，直接返回。
调用 poolManager.sync 方法，同步 poolManager 中的代币余额。
如果 currency 为 ADDRESS_ZERO，即原生 ETH，通过 {value: amount} 向 poolManager 转入 ETH，调用 PoolManager.settle 方法，结算记账余额。
否则，对于 ERC20 代币，调用 _pay 方法，向 poolManager 转移代币，然后调用 PoolManager.settle 方法，结算记账余额。
_mapSettleAmount
_mapSettleAmount 方法根据 amount 和 currency 计算待结算的代币数量：
- 如果
amount 为 1 << 255，即 ActionConstants.CONTRACT_BALANCE，则表示使用当前合约的代币余额进行结算
- 否则，如果
amount 为 0，即 ActionConstants.OPEN_DELTA，则表示结算所有欠款
- 否则，表示结算指定
amount 数量的代币
/// @notice Calculates the amount for a settle action
function _mapSettleAmount(uint256 amount, Currency currency) internal view returns (uint256) {
if (amount == ActionConstants.CONTRACT_BALANCE) {
return currency.balanceOfSelf();
} else if (amount == ActionConstants.OPEN_DELTA) {
return _getFullDebt(currency);
} else {
return amount;
}
}
_mapTakeAmount
_mapTakeAmount 方法根据 amount 和 currency 计算提取的代币数量：
- 如果
amount 为 0，则表示提取当前合约在 PoolManager 中的所有可提取余额
- 否则，表示提取指定
amount 数量的代币
/// @notice Calculates the amount for a take action
function _mapTakeAmount(uint256 amount, Currency currency) internal view returns (uint256) {
if (amount == ActionConstants.OPEN_DELTA) {
return _getFullCredit(currency);
} else {
return amount;
}
}
_mapWrapUnwrapAmount
计算包装/解包的代币数量。
输入参数：
inputCurrency：输入的代币，可以是原生代币或包装代币amount：包装/解包的数量，可以是 CONTRACT_BALANCE、OPEN_DELTA 或具体数量outputCurrency：包装/解包后的代币，用户在 PoolManager 上可能欠费的代币
/// @notice Calculates the sanitized amount before wrapping/unwrapping.
/// @param inputCurrency The currency, either native or wrapped native, that this contract holds
/// @param amount The amount to wrap or unwrap. Can be CONTRACT_BALANCE, OPEN_DELTA or a specific amount
/// @param outputCurrency The currency after the wrap/unwrap that the user may owe a balance in on the poolManager
function _mapWrapUnwrapAmount(Currency inputCurrency, uint256 amount, Currency outputCurrency)
internal
view
returns (uint256)
{
// if wrapping, the balance in this contract is in ETH
// if unwrapping, the balance in this contract is in WETH
uint256 balance = inputCurrency.balanceOf(address(this));
if (amount == ActionConstants.CONTRACT_BALANCE) {
// return early to avoid unnecessary balance check
return balance;
}
if (amount == ActionConstants.OPEN_DELTA) {
// if wrapping, the open currency on the PoolManager is WETH.
// if unwrapping, the open currency on the PoolManager is ETH.
// note that we use the DEBT amount. Positive deltas can be taken and then wrapped.
amount = _getFullDebt(outputCurrency);
}
if (amount > balance) revert InsufficientBalance();
return amount;
}
获取当前合约的 inputCurrency 代币余额。
如果 amount 为 1 << 255，则表示使用当前合约的代币余额作为包装/解包的数量。
如果 amount 为 0，则表示使用当前合约在 PoolManager 上 outputCurrency 的欠款作为包装/解包的数量。
确保欠款数量小于 inputCurrency 代币余额。
