70ecd6caa0
Transaction Science open standards monorepo. Each subdirectory is a self-contained reference protocol with its own README and licence. - openpay/ Apache-2.0 payment-acceptance stack (Rust, 26 crates) - smart-byte/ CC-BY-4.0 content-addressed value carrier (spec) - eoc/ CC-BY-4.0 energy-optimised compute (spec) The wire format and the right to fork are public. The optional hosted services are the offer; the protocols are not.
91 lines
2.8 KiB
Rust
91 lines
2.8 KiB
Rust
//! Balance — what an account holds at a point in time.
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//!
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//! Three balance views per Modern Treasury convention:
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//!
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//! - **Posted** — sum of posted transactions only. The settled state.
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//! - **Pending** — sum of posted AND pending transactions. The
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//! "balance after everything in flight settles" projection.
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//! - **Available** — context-dependent; for OpenPay's reference
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//! model it equals `posted` (we don't model holds beyond pending).
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//!
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//! Balances are derived (never stored). They're computed by walking
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//! the ledger's entries; the [`LedgerStore`](crate::LedgerStore)
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//! does the iteration.
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//!
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//! ## Why a struct instead of `(i64, i64)`?
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//!
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//! Type-safety. `Balance::pending` and `Balance::posted` are clearly
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//! labeled; you can't accidentally pass posted where pending is
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//! expected. The struct also carries the currency so the caller
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//! doesn't have to refetch the account to format the amount.
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use op_core::{Currency, Money};
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/// Balance for a single account at a point in time.
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///
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/// All three views carry the account's currency. They're always in
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/// the SAME currency (one account → one currency, fixed at
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/// creation).
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#[derive(Copy, Clone, Debug, PartialEq, Eq)]
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pub struct Balance {
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/// Currency. Always matches the account's currency.
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pub currency: Currency,
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/// Sum of posted-transaction entries, signed by the account's
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/// normal balance so it's natural-positive for a healthy account.
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pub posted: Money,
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/// Sum of posted-and-pending entries, signed the same way.
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pub pending: Money,
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}
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impl Balance {
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/// Construct a zero balance in the given currency.
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#[must_use]
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pub fn zero(currency: Currency) -> Self {
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Self {
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currency,
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posted: Money::from_minor(0, currency),
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pending: Money::from_minor(0, currency),
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}
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}
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/// True if both views are zero.
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#[must_use]
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pub fn is_zero(&self) -> bool {
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self.posted.is_zero() && self.pending.is_zero()
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn zero_constructs_zero_money_for_each_view() {
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let b = Balance::zero(Currency::USD);
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assert!(b.is_zero());
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assert_eq!(b.posted.minor_units, 0);
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assert_eq!(b.pending.minor_units, 0);
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assert_eq!(b.currency, Currency::USD);
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}
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#[test]
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fn non_zero_pending_is_not_zero() {
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let b = Balance {
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currency: Currency::USD,
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posted: Money::from_minor(0, Currency::USD),
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pending: Money::from_minor(100, Currency::USD),
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};
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assert!(!b.is_zero());
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}
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#[test]
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fn equality_requires_all_three_fields() {
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let a = Balance::zero(Currency::USD);
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let b = Balance::zero(Currency::USD);
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assert_eq!(a, b);
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let c = Balance::zero(Currency::EUR);
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assert_ne!(a, c);
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}
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}
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