#memoization #memo #lazy-evaluation #cache #derive-debug

no-std core_memo

零成本、兼容no_std的懒加载和缓存库

1个不稳定版本

使用旧的Rust 2015

0.1.0 2018年6月15日

#275 in 缓存

MIT/Apache

25KB
288

简单的缓存库

core_memo 是一个简单、直接、零成本的Rust缓存库,用于懒加载和缓存。它不进行内存分配或动态分发,且与 #![no_std] 兼容。它没有依赖项。

更多信息请查看 docs

示例

use core_memo::{Memoize, Memo, MemoExt};

#[derive(Debug, PartialEq, Eq)] // for assert_eq! later
struct MemoSum(i32);

impl Memoize for MemoSum {
    type Param = [i32];

    fn memoize(p: &[i32]) -> MemoSum {
        MemoSum(p.iter().sum())
    }
}


// The `Memo` type holds ownership over the parameter for the calculation
// There are also the `MemoExt` and `MemoOnce` types with different semantics

let mut memo: Memo<MemoSum, _> = Memo::new(vec![1, 2]);

// Our `memoize` method is called the first time we call `memo.get()`
assert_eq!(memo.get(), &MemoSum(3));

// Further calls to `memo.get()` return the cached value without reevaluating
assert_eq!(memo.get(), &MemoSum(3));


// We can mutate the parameter held inside the `Memo`:

// via a mutable reference
memo.param_mut().push(3);
// via a closure
memo.update_param(|p| p.push(4));

// either way, the `Memo` forgets any cached value and it will be
// reevaluated on the next call to `memo.get()`

assert_eq!(memo.get(), &MemoSum(10)); // the vec is now `[1, 2, 3, 4]`

无运行时依赖