/*
In Rust, slicing a dynamically sized collection (like a Vec<T>, a dynamic array,
or a sub-slice) allows you to use slice patterns at runtime.
*/
/// Analyzes a dynamic slice of integers (`&[i32]`) using runtime slice patterns.
pub fn analyze_dynamic_slice(slice: &[i32]) -> String {
match slice {
// Pattern 1: Matches an empty slice (length 0)
[] => String::from("The slice is empty."),
// Pattern 2: Matches a slice with exactly one element
[x] => format!("Single element slice: {}", x),
// Pattern 3: Matches a slice with exactly two elements
[first, second] => format!("Two elements: first = {}, second = {}", first, second),
// Pattern 4: Matches a slice starting with 0 and ending with 9,
// capturing all intermediate values into a sub-slice `middle` using `@`.
[0, middle @ .., 9] => {
format!("Bounded slice (starts with 0, ends with 9). Middle elements: {:?}", middle)
}
// Pattern 5: Matches a slice starting with 42, capturing everything else into `rest`.
[42, rest @ ..] => {
format!("Special prefix (42). Remaining elements: {:?}", rest)
}
// Pattern 6: General catch-all for any other slice of length 3 or more,
// capturing the first and last elements while ignoring or bridging the rest.
[first, .., last] => {
format!("General slice (length >= 3). First = {}, Last = {}", first, last)
}
}
}
fn main() {
// Example 1: Empty slice
let empty: &[i32] = &[];
println!("{}", analyze_dynamic_slice(empty));
// Example 2: Single element slice from a vector
let vec_data = vec![7];
println!("{}", analyze_dynamic_slice(&vec_data));
// Example 3: Two-element slice
let pair = &[10, 20];
println!("{}", analyze_dynamic_slice(pair));
// Example 4: Bounded slice matching pattern with `middle @ ..`
let bounded = &[0, 4, 5, 6, 9];
println!("{}", analyze_dynamic_slice(bounded));
// Example 5: Specific prefix matching with `rest @ ..`
let custom = &[42, 100, 200, 300];
println!("{}", analyze_dynamic_slice(custom));
// Example 6: General catch-all slice
let general = &[5, 12, 18, 25];
println!("{}", analyze_dynamic_slice(general));
}
/*
run:
The slice is empty.
Single element slice: 7
Two elements: first = 10, second = 20
Bounded slice (starts with 0, ends with 9). Middle elements: [4, 5, 6]
Special prefix (42). Remaining elements: [100, 200, 300]
General slice (length >= 3). First = 5, Last = 25
*/
