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/// Reverse a collection, returning a new vector with the elements in reverse order.
///
/// This function takes a slice of items and returns a new `Vec<T>` containing all the elements
/// from the input collection in reverse order.
///
/// **Time Complexity:**
/// O(n), where n is the number of elements in the collection.
///
/// # Arguments
///
/// * `collection` - A slice of items to be reversed.
///
/// # Type Parameters
///
/// * `T` - The type of elements in the collection. Must implement `Clone`.
///
/// # Returns
///
/// * `Vec<T>` - A new vector containing all elements from the input collection in reverse order.
///
/// # Examples
///
/// ```rust
/// use lowdash::reverse;
///
/// let numbers = vec![1, 2, 3, 4, 5];
/// let reversed = reverse(&numbers);
/// assert_eq!(reversed, vec![5, 4, 3, 2, 1]);
/// ```
///
/// ```rust
/// use lowdash::reverse;
///
/// #[derive(Debug, PartialEq, Clone)]
/// struct Person {
/// name: String,
/// age: u32,
/// }
///
/// let people = vec![
/// Person { name: "Alice".to_string(), age: 25 },
/// Person { name: "Bob".to_string(), age: 30 },
/// Person { name: "Carol".to_string(), age: 35 },
/// ];
///
/// let reversed_people = reverse(&people);
/// assert_eq!(reversed_people, vec![
/// Person { name: "Carol".to_string(), age: 35 },
/// Person { name: "Bob".to_string(), age: 30 },
/// Person { name: "Alice".to_string(), age: 25 },
/// ]);
/// ```
pub fn reverse<T>(collection: &[T]) -> Vec<T>
where
T: Clone,
{
collection.iter().rev().cloned().collect()
}
#[cfg(test)]
mod tests {
use super::*;
#[derive(Debug, PartialEq, Clone)]
struct Person {
name: String,
age: u32,
}
#[test]
fn test_reverse_integers() {
let numbers = vec![1, 2, 3, 4, 5];
let reversed = reverse(&numbers);
assert_eq!(reversed, vec![5, 4, 3, 2, 1]);
}
#[test]
fn test_reverse_strings() {
let strings = vec!["apple", "banana", "cherry", "date"];
let reversed = reverse(&strings);
assert_eq!(reversed, vec!["date", "cherry", "banana", "apple"]);
}
#[test]
fn test_reverse_with_structs() {
let people = vec![
Person {
name: "Alice".to_string(),
age: 25,
},
Person {
name: "Bob".to_string(),
age: 30,
},
Person {
name: "Carol".to_string(),
age: 35,
},
];
let reversed_people = reverse(&people);
assert_eq!(
reversed_people,
vec![
Person {
name: "Carol".to_string(),
age: 35
},
Person {
name: "Bob".to_string(),
age: 30
},
Person {
name: "Alice".to_string(),
age: 25
},
]
);
}
#[test]
fn test_reverse_empty_collection() {
let empty: Vec<i32> = vec![];
let reversed = reverse(&empty);
assert_eq!(reversed, Vec::<i32>::new());
}
#[test]
fn test_reverse_single_element() {
let single = vec![42];
let reversed = reverse(&single);
assert_eq!(reversed, single);
}
#[test]
fn test_reverse_preserves_elements() {
let elements = vec![10, 20, 30, 40, 50];
let reversed = reverse(&elements);
assert_eq!(reversed, vec![50, 40, 30, 20, 10]);
}
#[test]
fn test_reverse_with_duplicates() {
let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let reversed = reverse(&numbers);
assert_eq!(reversed, vec![5, 3, 4, 3, 2, 2, 1]);
}
#[test]
fn test_reverse_with_optionals() {
let collection = vec![Some(1), None, Some(2), Some(3), None];
let reversed = reverse(&collection);
assert_eq!(reversed, vec![None, Some(3), Some(2), None, Some(1)]);
}
#[test]
fn test_reverse_with_floats() {
let float_collection = vec![1.1, 2.2, 3.3, 4.4, 5.5];
let reversed = reverse(&float_collection);
assert_eq!(reversed, vec![5.5, 4.4, 3.3, 2.2, 1.1]);
}
#[test]
fn test_reverse_with_nan_floats() {
let float_collection = vec![std::f64::NAN, 2.2, std::f64::NAN, 4.4];
let reversed = reverse(&float_collection);
assert_eq!(reversed.len(), float_collection.len());
// Verify each element is reversed correctly
for i in 0..float_collection.len() {
if float_collection[i].is_nan() {
assert!(reversed[float_collection.len() - 1 - i].is_nan());
} else {
assert_eq!(
reversed[float_collection.len() - 1 - i],
float_collection[i]
);
}
}
}
}