Adapter Trait

AdapterTrait, the interface every protocol adapter implements so the aggregator can route through it.

Every adapter implements AdapterTrait, defined in contracts/adapters/interface. That single interface is what lets the aggregator treat Soroswap, Phoenix, Aqua and Comet the same way, and it is all you need to implement to add a protocol.

Interface

pub trait AdapterTrait {
    fn initialize(
        e: Env,
        protocol_id: String,
        protocol_address: Address,
    ) -> Result<(), AdapterError>;

    /// Swaps an exact amount of input tokens for as many output tokens as possible,
    /// along the route given by `path`.
    fn swap_exact_tokens_for_tokens(
        env: Env,
        amount_in: i128,
        amount_out_min: i128,
        path: Vec<Address>,
        to: Address,
        deadline: u64,
        bytes: Option<Vec<BytesN<32>>>,
    ) -> Result<Vec<i128>, AdapterError>;

    /// Swaps as few input tokens as possible for an exact amount of output token.
    fn swap_tokens_for_exact_tokens(
        e: Env,
        amount_out: i128,
        amount_in_max: i128,
        path: Vec<Address>,
        to: Address,
        deadline: u64,
        bytes: Option<Vec<BytesN<32>>>,
    ) -> Result<Vec<i128>, AdapterError>;

    /*  *** Read only functions: *** */
    fn get_protocol_id(e: &Env) -> Result<String, AdapterError>;
    fn get_protocol_address(e: &Env) -> Result<Address, AdapterError>;
}

Notes on the parameters

path is the route through the underlying protocol. The first element is the input token, the last is the output token, and anything between them is an intermediate hop to trade through when no direct pair exists.

bytes is the escape hatch for protocols that need something the common interface does not carry. Aqua uses it for pool hashes, which is why AdapterError has MissingPoolHashes and WrongPoolHashesLength. Adapters that need nothing extra take None.

Both swap functions return the amounts at each step of the route, not just the final amount.

Errors

Code	Variant	Meaning
401	NotInitialized	The adapter has not been initialized.
402	AlreadyInitialized	initialize was called twice.
403	NegativeNotAllowed	An amount was negative.
404	ProtocolAddressNotFound	No protocol address is stored.
405	DeadlineExpired	The ledger passed deadline.
406	MissingPoolHashes	Aqua: bytes was required and not supplied.
407	WrongMinimumPathLength	path is shorter than the protocol needs.
408	WrongPoolHashesLength	Aqua: the pool hash count does not match the path.