cow-settlement-interface 0.1.1

Account layouts, PDA derivations, and instruction builders for the CoW Protocol Solana settlement program.
Documentation 
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//! Settlement state PDA seed and address derivation.
//!
//! There is a single state PDA per settlement program, derived from
//! [`SETTLEMENT_SEED`] alone. It is the program's central account: it manages
//! solver authentication and holds the SPL token authority over every buffer
//! account (see [`crate::pda::buffer`]).
//!
//! Because that lone seed carries the cargo crate version, a minor
//! version bump moves the state PDA. Users delegate their token accounts to
//! this address, so every delegation has to be renewed after a
//! bump.

use solana_pubkey::Pubkey;

use crate::pda::SETTLEMENT_SEED;

/// Canonical seed components for the settlement state PDA.
pub fn state_pda_seeds<'a>() -> [&'a [u8]; 1] {
    [SETTLEMENT_SEED]
}

/// Canonical seeds for signing as the settlement state PDA with `bump`. The
/// on-chain settlement handlers use this to construct the CPI signer.
pub fn state_pda_signer_seeds(bump: &[u8; 1]) -> [&[u8]; 2] {
    let [seed] = state_pda_seeds();
    [seed, bump]
}

/// Derive the canonical settlement state PDA address (and bump).
pub fn find_state_pda(program_id: &Pubkey) -> (Pubkey, u8) {
    Pubkey::find_program_address(&state_pda_seeds(), program_id)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::pda::tests::assert_distinct_versions_yield_distinct_pdas;

    #[test]
    fn find_state_pda_uses_canonical_seeds() {
        crate::pda::tests::assert_canonical_bump(find_state_pda, state_pda_seeds());
    }

    #[test]
    fn distinct_versions_yield_distinct_state_pdas() {
        let (pda, _) = find_state_pda(&crate::ID);

        assert_distinct_versions_yield_distinct_pdas(&pda, &[]);
    }
}