Crate segvec

This crate provides the SegVec data structure.

It is similar to Vec, but allocates memory in chunks of increasing size, referred to as “segments”. This involves a few trade-offs:

Pros:

• Element addresses are stable across push operations even if the SegVec must grow.
• Resizing only allocates the additional space needed, and doesn’t require copying.

Cons:

• Operations are slower (some, like insert, remove, and drain, are much slower) than for a Vec due to the need for multiple pointer dereferences and conversion between linear indexes and (segment, offset) pairs
• Direct slicing is unavailable (i.e. no &[T] or &mut [T]), though slice and slice_mut are available

Use Cases

1. You have a long-lived Vec whose size fluctuates between very large and very small throughout the life of the program.
2. You have a large append-only Vec and would benefit from stable references to the elements

Features

• small-vec - Uses SmallVec instead of Vec to store the list of segments, allowing the first few segment headers to live on the stack. Can speed up access for small SegVec values.
• thin-segments - Uses ThinVec instead of Vec to store the data for each segment, meaning that each segment header takes up the space of a single usize, rathern than 3 when using Vec.

Structs

Drain

Removes and returns elements from a range in a SegVec. Any un-consumed elements are removed and dropped when a Drain is dropped. If a Drain is forgotten (via std::mem::forget), it is unspecified how many elements are removed. The current implementation calls SegVec::remove on a single element on each call to next.

IntoIter

Consuming iterator over items in a SegVec.

Iter

Iterator over immutable references to items in a SegVec.

SegVec

A data structure similar to Vec, but that does not copy on re-size and can release memory when it is truncated.

Slice

Provides an immutable view of elements from a range in SegVec.

SliceIter

Iterator over immutable references to the elements of a Slice.

SliceMut

Provides a mutable view of elements from a range in SegVec.

SliceMutIter

Iterator over mutable references to the elements of a SliceMut.