rejoin_slice

This crate provides functions to join two slices that are adjacent in memory. It is useful for rejoining slices that are split from the same slice, but need to be processed as a continous slice later:

let mut values: Vec<_> = util_lib::split_by_streak("aaaaaaabbbbbbbcccccccddddeeeeeeefffggggggggh");
let last_two = &values[values.len()-2].rejoin(&values[values.len()-1]);
assert_eq!(&"ggggggggh", last_two);

Notes about safety.

The API provided by this crate is not sound; I've yanked the published versions. I wrote this crate as a sample/experiment for a Rust RFC that was discussed at the time: rust-lang/rfcs#2806 Please refer to that discussion for why it isn't sound.

(Old, misguided) Notes about safety

This crate internally uses unsafe to achieve its functionality. However, it provides a safe interface. It takes the following precautions for safety:

1. Pointer arithmetic is never explicitly performed. A pointer pointing to the end of the first slice is calculated using safe API's.
2. Equality comparisons between pointers, although undefined behaviour in C in cases where the pointers originate from different objects, can be considered to be safe in Rust. This is ensured by the fact that the standard library provides a safe function std::ptr::eq to compares pointers.
3. unsafe is only used to call std::slice::from_raw_parts to create a new slice after the check that the input slices are adjacent in memory.