3. Querying Expected Output Amount

There is a view function that calculates the amountOut you will receive when you input an amountIn into a book. Alternatively, you can refer to our off-chain TypeScript implementation available in the SDK for additional guidance.

Below is the interface for getExpectedOutput. If you want to allow unlimited slippage, simply set the limitPrice parameter to 0.

/**
 * @notice Struct for the parameters of the take order action
 */
struct TakeOrderParams {
    BookId id;
    uint256 limitPrice;
    uint256 quoteAmount;
    uint256 maxBaseAmount;
    bytes hookData;
}

/**
 * @notice Returns the expected output for a spend order
 * @param params The parameters of the spend order
 * @return takenQuoteAmount The expected taken quote amount
 * @return spentBaseAmount The expected spend base amount
 */
function getExpectedOutput(IController.SpendOrderParams memory params)
    external
    view
    returns (uint256 takenQuoteAmount, uint256 spentBaseAmount);

Books are always matched from higher to lower prices. This means that, for an ETH/USDC bid book, once the price stored in the contract is converted into a human-readable value, the order remains the same. However, for an ask book, the order is reversed.

Below is an example TypeScript implementation of getExpectedOutput: view.ts#L936