如何在 Rust 中实现 C 灵活数组成员模式? [英] How to implement the C flexible array member pattern in Rust?

问题描述

我想实现这个使用灵活数组成员(在 Rust 中有时称为 结构黑客):

struct test {
  int key;
  int dataSize;
  int data[];
};

struct test* t = malloc(sizeof(struct test) + sizeOfData)

结构末尾的空数组允许您一次性分配元字段和数据.不幸的是，我不知道如何在 Rust 中做这样的事情.

The empty array at the end of structure allows you to allocate your meta fields and data all at once. Unfortunately, I can't figure out how to do such thing in Rust.

推荐答案

该结构的 Rust 等价物将使用切片:

The Rust equivalent of this struct would use a slice:

struct test {
  key: i32,
  dataSize: i32,
  data: [i32],
}

然而，这些类型目前使用起来并不方便，因为没有安全的方法来构造它们.

however, these types are not really convenient to use at the moment as there is no safe way to construct them.

更实用的方法是使用泛型:

A more practical way to do this is to use a generic:

struct test<T: ?Sized> {
  key: i32,
  dataSize: i32,
  data: T,
}

然后确保仅在 T 是数组或切片(只能通过强制创建)时才使用 test.

and then to make sure that you only use test when T is an array or a slice (which you could only create through coercion).

另见:

• 动态大小类型 (DST)经济体

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