7 releases
0.0.8 | Aug 16, 2023 |
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0.0.7 | Aug 14, 2023 |
0.0.5 | Nov 1, 2022 |
0.0.4 | Oct 26, 2022 |
#1823 in Data structures
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Used in char-list
30KB
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front-vec
Efficiently-prependable Vec and String types.
Exposes two types: FrontVec<T>
and FrontString
. Each implements a push_front
method which efficiently prepends a value onto the front of the data structure.
The types implement Deref
so that they can be used like slices/&str
s.
Unstable Warning
This crate uses the following unstable features, and therefore requires the nightly compiler.
#![feature(ptr_internals, maybe_uninit_slice)]
unsafe
Warning
This is an "in-development" crate. I'm not certain all uses of unsafe
are valid yet. Please don't use this for anything important yet.
Potential Use Cases
Efficient Cons-Lists
My use-case is for packing data together in memory more eficiently than a cons-list, but with the same API as one.
Representation in Memory
my_front_vec =
[len: usize = 3]
[cap: usize = 8]
[buf: Unique<T> = *]
|
|
v
[?, ?, ?, ?, ?, x1, x2, x3]
This diagram shows the memory representation of a FrontVec<T>
which corresponds to the the Vec
vec![x1, x2, x3]
. The question marks (?
) represent uninitialized data.
Downsides
This representation (I believe) does not allow the use of the realloc
function, which assumes memory at the front of the buffer is initialized. So a Front{Vec,String}
is slightly less efficient because of that.
Disclaimer
This is my first time writing unsafe
code, so any safety audit contributions are certainly welcome!