Enum TransferMode 

#[non_exhaustive]
pub enum TransferMode {
    Standard,
    Fast {
        max_fee: U256,
    },
    StandardWithHook {
        hook_data: Bytes,
    },
    FastWithHook {
        max_fee: U256,
        hook_data: Bytes,
    },
}

Selects which CCTP v2 burn variant the bridge sends.

Replaces the legacy independent fast_transfer / hook_data / max_fee fields. The enum captures the exact wire shape of the four valid configurations and makes the relationship between fee, finality, and hook data unambiguous at the type level.

Examples

use cctp_rs::{FinalityThreshold, TransferMode};
use alloy_primitives::{Bytes, U256};

let standard = TransferMode::Standard;
assert_eq!(standard.finality_threshold(), FinalityThreshold::Standard);
assert!(standard.hook_data().is_none());

let fast = TransferMode::Fast { max_fee: U256::from(500) };
assert_eq!(fast.finality_threshold(), FinalityThreshold::Fast);
assert_eq!(fast.max_fee(), U256::from(500));

let fast_with_hook = TransferMode::FastWithHook {
    max_fee: U256::from(500),
    hook_data: Bytes::from(vec![0xde, 0xad]),
};
assert!(fast_with_hook.is_fast());
assert_eq!(fast_with_hook.hook_data().map(|b| b.len()), Some(2));

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Standard

Plain burn at finalized finality (threshold 2000), no hooks.

Settlement matches v1 timing (13–19 min). No fast-transfer fee.

Fast

Fast burn at confirmed finality (threshold 1000), no hooks.

max_fee caps the fast-transfer fee Circle’s relayers may deduct from the minted amount. A fee below the chain’s minimum will leave the burn pending until enough finality accrues for the standard path.

Fields

max_fee: U256

Maximum fast-transfer fee, in USDC atomic units.

StandardWithHook

Burn carrying hook data at finalized finality.

The hook data is opaque to CCTP and runs on the destination chain after the mint.

Fields

hook_data: Bytes

Hook payload forwarded to the destination chain.

FastWithHook

Burn carrying hook data at confirmed (fast) finality.

Combines a fast-finality attestation with a post-mint hook. Both maxFee and hookData are passed through to depositForBurnWithHook on-chain.

Fields

max_fee: U256

Maximum fast-transfer fee, in USDC atomic units.

hook_data: Bytes

Hook payload forwarded to the destination chain.

Implementations

impl TransferMode

pub const fn finality_threshold(&self) -> FinalityThreshold

Returns the finality threshold this mode requests from Circle.

pub const fn is_fast(&self) -> bool

Returns true when the mode requests fast (confirmed) finality.

pub const fn has_hook(&self) -> bool

Returns true when the mode carries hook data.

pub fn max_fee(&self) -> U256

Returns the fast-transfer fee cap.

Defaults to U256::ZERO for standard modes, which is what the on-chain call expects when fast transfer is not requested.

pub const fn hook_data(&self) -> Option<&Bytes>

Returns the hook payload, if any.

Trait Implementations

impl Clone for TransferMode

fn clone(&self) -> TransferMode

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TransferMode

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TransferMode

fn default() -> TransferMode

Returns the “default value” for a type.

impl Eq for TransferMode

impl PartialEq for TransferMode

fn eq(&self, other: &TransferMode) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for TransferMode