查看“Rust”的源代码

[https://www.rust-lang.org/ Rust] 是一门赋予每个人构建可靠且高效软件能力的语言。

== 笔记 ==

=== 更新 <code>HashMap</code> 的值 ===

直接使用 {{code|rust|2=hmap["key"] = 42}} 会报错，说 <code>HashMap</code> 没有 implement <code>IndexMut</code>。可以使用如下的方法 <ref>[https://stackoverflow.com/a/30414450/10974106 How can I update a value in a mutable HashMap?]</ref>

<syntaxhighlight lang=rust>
*hmap.get_mut("key").unwrap() = 42;
// 或者
*hmap.entry("key").or_insert(42) += 10;
</syntaxhighlight>

== 代码片段 ==

=== 将某些不满足要求的 <code>Ok</code> 转化为 <code>Err</code> ===

<syntaxhighlight lang=rust>
/// Turns into an `Err(anyhow::Error)` some `Ok`s that meet the predicate
trait AdjustResult<T, E> {
    fn adjust(self, predicate: impl Fn(&T) -> bool, msg: &str) -> Result<T>
    where
        E: Into<anyhow::Error>;
}

impl<T, E> AdjustResult<T, E> for Result<T, E> {
    fn adjust(self, predicate: impl Fn(&T) -> bool, msg: &str) -> Result<T>
    where
        E: Into<anyhow::Error>,
    {
        match self {
            Ok(o) if predicate(&o) => Err(anyhow!(msg.to_string())),
            Ok(o) => Ok(o),
            Err(e) => Err(e.into()),
        }
    }
}
</syntaxhighlight>

== 参考资料 ==

<references />

[[Category:Rust]]