[Rust] Traverse and consume the vector in the given order

consume_vec_in_order.rs

use std::mem::{self, ManuallyDrop};
use std::ptr;

/// Traverse the vector in the given order. The vector will be consumed, and its
/// elements will be moved in when calling the closure. `order` must contain all
/// values in the range `0..vec.len()` without repetition or omission, but the
/// order of elements can be arbitrary.
/// 
/// # Example
/// ```
/// use {YOUR CRATE NAME}::consume_vec_in_order;
/// 
/// let src = vec![
///     "0".to_string(),
///     "1".to_string(),
///     "2".to_string(),
///     "3".to_string(),
///     "4".to_string(),
/// ];
/// let mut dst = vec![];
/// 
/// consume_vec_in_order(
///     src,
///     &[2, 1, 3, 0, 4],
///     |elem| dst.push(elem),
/// );
/// assert_eq!(dst, vec!["2", "1", "3", "0", "4"]);
/// ```
pub fn consume_vec_in_order<T>(vec: Vec<T>, order: &[usize], mut cb: impl FnMut(T)) {
    // Check whether `order` contains all numbers in 0..len without repetition
    // or omission.
    if cfg!(debug_assertions) {
        use std::collections::HashSet;

        let n = order.len();
        if n != vec.len() {
            panic!("The length of `order` is not equal to that of `vec`.");
        }
        let mut set = HashSet::<usize>::new();
        for &idx in order {
            if idx >= n {
                panic!("`{idx}` in the `order` is out of range (0..{n}).");
            } else if set.contains(&idx) {
                panic!("`order` contains the repeated element `{idx}`");
            } else {
                set.insert(idx);
            }
        }
    }

    unsafe {
        for &idx in order {
            let s = ptr::read(vec.get_unchecked(idx));
            cb(s);
        }
        let vec: Vec<ManuallyDrop<T>> = mem::transmute(vec);
        drop(vec);
    }
}