[](https://crates.io/crates/any_vec)
[](#license)
[](https://docs.rs/any_vec)
[](https://github.com/tower120/any_vec/actions/workflows/ci.yml)
Type erased vector. All elements have the same type.
Designed to be type-erased as far as possible - most of the operations does not know about concrete type.
Only type-erased destruct and clone operations have additional overhead of indirect call.
# Usage
```rust
let mut vec: AnyVec = AnyVec::new::<String>();
{
// Typed operations.
let mut vec = vec.downcast_mut::<String>().unwrap();
vec.push(String::from("0"));
vec.push(String::from("1"));
vec.push(String::from("2"));
}
let mut other_vec: AnyVec = AnyVec::new::<String>();
// Fully type erased element move from one vec to another
// without intermediate mem-copies.
let element = vec.swap_remove(0);
other_vec.push(element);
// Output 2 1
for s in vec.downcast_ref::<String>().unwrap(){
println!("{}", s);
}
```
See [documentation](https://docs.rs/any_vec) for more.
## Send, Sync, Clone
You can make `AnyVec` `Send`able, `Sync`able, `Clone`able:
```rust
use any_vec::AnyVec;
use any_vec::traits::*;
let v1: AnyVec<dyn Cloneable + Sync + Send> = AnyVec::new::<String>();
let v2 = v1.clone();
```
This constraints will be applied compiletime to element type:
```rust
// This will fail to compile.
let v1: AnyVec<dyn Sync + Send> = AnyVec::new::<Rc<usize>>();
```
## LazyClone
Whenever possible, `any_vec` type erased elements can be lazily cloned:
```rust
let mut v1: AnyVec<dyn Cloneable> = AnyVec::new::<String>();
v1.push(AnyValueWrapper::new(String::from("0")));
let mut v2: AnyVec<dyn Cloneable> = AnyVec::new::<String>();
let e = v1.swap_remove(0);
v2.push(e.lazy_clone());
v2.push(e.lazy_clone());
```
## MemBuilder
`MemBuilder` + `Mem` works like `Allocator` for `AnyVec`. But unlike allocator,
`Mem` container-specialized design allows to perform more optimizations. For example,
it is possible to make stack-allocated `FixedAnyVec` and small-buffer-optimized(SBO) `SmallAnyVec`
from `AnyVec` by just changing `MemBuilder`:
```rust
type FixedAnyVec<Traits = dyn None> = AnyVec<Traits, Stack<512>>;
let mut any_vec: FixedAnyVec = AnyVec::new::<String>();
// This will be on stack, without any allocations.
any_vec.push(AnyValueWrapper::new(String::from("0")))
```
With help of `clone_empty_in` you can use stack allocated, or SBO `AnyVec`
as fast intermediate storage for values of unknown type:
```rust
fn self_push_first_element<T: Trait + Cloneable>(any_vec: &mut AnyVec<T>){
let mut tmp = any_vec.clone_empty_in(StackN::<1, 256>);
tmp.push(any_vec.at(0).lazy_clone());
any_vec.push(tmp.pop().unwrap());
}
```
`MemBuilder` interface, being stateful, allow to make `Mem`, which can work with complex custom allocators.
### Changelog
See [CHANGELOG.md](CHANGELOG.md) for version differences.
# Known alternatives
* [type_erased_vec](https://crates.io/crates/type_erased_vec). Allow to store `Vec<T>` in type erased way,
but you need to perform operations, you need to "cast" to concrete type first.
* [untyped_vec](https://crates.io/crates/untyped_vec). Some operations like `len`, `capacity` performed without type
knowledge; but the rest - require concrete type.