use cosmwasm_std::{StdResult, Storage};
use crate::Singleton;
pub fn sequence<'a, S: Storage>(storage: &'a mut S, key: &[u8]) -> Singleton<'a, S, u64> {
Singleton::new(storage, key)
}
pub fn currval<S: Storage>(seq: &Singleton<S, u64>) -> StdResult<u64> {
Ok(seq.may_load()?.unwrap_or_default())
}
pub fn nextval<S: Storage>(seq: &mut Singleton<S, u64>) -> StdResult<u64> {
let val = currval(&seq)? + 1;
seq.save(&val)?;
Ok(val)
}
#[cfg(test)]
mod test {
use super::*;
use cosmwasm_std::testing::MockStorage;
#[test]
fn walk_through_sequence() {
let mut store = MockStorage::new();
let mut seq = sequence(&mut store, b"seq");
assert_eq!(currval(&seq).unwrap(), 0);
assert_eq!(nextval(&mut seq).unwrap(), 1);
assert_eq!(nextval(&mut seq).unwrap(), 2);
assert_eq!(nextval(&mut seq).unwrap(), 3);
assert_eq!(currval(&seq).unwrap(), 3);
assert_eq!(currval(&seq).unwrap(), 3);
}
#[test]
fn sequences_independent() {
let mut store = MockStorage::new();
let mut seq = sequence(&mut store, b"seq");
assert_eq!(nextval(&mut seq).unwrap(), 1);
assert_eq!(nextval(&mut seq).unwrap(), 2);
assert_eq!(nextval(&mut seq).unwrap(), 3);
let mut seq2 = sequence(&mut store, b"seq2");
assert_eq!(nextval(&mut seq2).unwrap(), 1);
assert_eq!(nextval(&mut seq2).unwrap(), 2);
let mut seq3 = sequence(&mut store, b"seq");
assert_eq!(nextval(&mut seq3).unwrap(), 4);
}
#[test]
fn set_sequence() {
let mut store = MockStorage::new();
let mut seq = sequence(&mut store, b"seq");
assert_eq!(nextval(&mut seq).unwrap(), 1);
assert_eq!(nextval(&mut seq).unwrap(), 2);
seq.save(&20).unwrap();
assert_eq!(currval(&seq).unwrap(), 20);
assert_eq!(nextval(&mut seq).unwrap(), 21);
}
}