diff --git a/sdk/src/lib.rs b/sdk/src/lib.rs index f537560b79..ded554312d 100644 --- a/sdk/src/lib.rs +++ b/sdk/src/lib.rs @@ -104,6 +104,15 @@ macro_rules! program_stubs { () => {}; } +/// Convenience macro for `AddAssign` with saturating arithmetic. +/// Replace by `std::num::Saturating` once stable +#[macro_export] +macro_rules! saturating_add_assign { + ($i:expr, $v:expr) => {{ + $i = $i.saturating_add($v) + }}; +} + #[macro_use] extern crate serde_derive; pub extern crate bs58; @@ -111,3 +120,18 @@ extern crate log as logger; #[macro_use] extern crate solana_frozen_abi_macro; + +#[cfg(test)] +mod tests { + #[test] + fn test_saturating_add_assign() { + let mut i = 0u64; + let v = 1; + saturating_add_assign!(i, v); + assert_eq!(i, 1); + + i = u64::MAX; + saturating_add_assign!(i, v); + assert_eq!(i, u64::MAX); + } +}