2 releases (1 stable)
|1.0.0||May 10, 2019|
|0.1.1||Mar 9, 2019|
23 downloads per month
Please see the documentation (online copy).
Source code, issues, etc., are here: https://salsa.debian.org/iwj/rc-dlist-deque
Copyright (C) 2019 Ian Jackson; GNU AGPLv3+; NO WARRANTY.
This crate provides a doubly-linked list implementation for
Rc is suitable for managing the individual
See the module-level documentation
Many programmers new to Rust look for a linked list when another
data structure is better. Consider
A doubly-linked list is good if:
You need to retain and store, long-term, a reference to the middle of your list, and you need quick access to the corresponding item, and
You need to be able to quickly add or remove items in the middle of your list, based on such references; or your references into the middle of the list must remain valid even as you add or remove other items elsewhere in the middle, and
Your lists might be long.
In other circumstances, which is most circumstances, you
VecDeque instead. They have much lower
overhead and are simpler to work with.
If you don't need to add/remove items in the middle, then a
VecDequeworks well. You can use array indices as your references.
If you want a
VecDequewith stable indices, this can be achieved by maintaining a signed counter of elements pushed/popped at the start.
If you don't need to retain long-term references to the middle of the list, then you can use a vector. Adding or removing items in the middle does mean copying to shuffle items up or down, but if you aren't keeping a reference to the modification location you will have to walk along to find the right place anyway.
Note that there are a number of deque-ish alternatives to
std::VecDeque which are not doubly linked lists and
do not aim to support modification in the middle of the list,
at least some of which seem like they might be useful.
Search crates.io for deque,
and also consider
If you do need a doubly-linked list, but do not need your items to
be on more than one list at once, consider
It has a much simpler ownership model and will be faster too.
If you want each item to be able to be on more than one list at
once (perhaps even selecting the linked list link within each
node dynamically at runtime), then this crate
rc-dlist-deque may be what you want.
|Crate or module||Ref to element (aka Index or Cursor)||Other misuse possible, and consequences||List owns (
||Cost of editing in middle||Memory locality||Element can be on multiple lists||API completeness||
|Type||After altering list at front/back||After altering list in middle||After removing ref'd element||Given ref to elem||Without ref to elem|
|Choose one of these approaches|
||wrong element if alteration at start||wrong element||wrong element||Rich API can invalidate indices||
||O(n)||O(n)||sequential||-||++||Yes||Good||Use if you don't need persistent cursors|
||valid||wrong element||wrong element||
||O(n)||O(n)||sequential||-||DIY||Yes||Good||Consider if you need to modify only at ends|
||valid||valid||valid||Specify wrong list for alteration:
||O(1)||O(n)||scattered to heap||Yes||+||-||Safe||Consider if you need each element on multiple lists|
||Specify wrong list for access or alteration: Maybe detected by luck, giving
||O(1)||O(n)||random order in vector||-||+||Yes||Safe (exc.
||Otherwise, use this|
|Use VecDeque instead of any of the following|
||Mutation not possible while any other cursor exists (prevented by lifetimes). This almost entirely defeats the point of using a doubly linked list.||Various||O(1)||O(n)||scattered to heap||Yes||+||Yes||uses
||If this API is enough for you, use
||O(1)||O(n)||random order in vector||-||Yes||Safe (exc.
||O(1)||O(n)||scattered to heap||-||Yes||uses
||Not supported. This defeats the point of using a doubly linked list.||
||O(n)||scattered to heap||-||Yes|
||O(n)||scattered to heap||-||Yes||uses
Not considered here because single-ended, or special purpose):
Not considered here because no Rustdocs, does not build with modern Rust:
It can be hard to implement
IterMut without using
unsafe, so no criticism is intended for those crates
that use unsafe for this.
Last updated May 2019.