64 lines
1.7 KiB
Rust
64 lines
1.7 KiB
Rust
// as_ref_mut.rs
|
|
//
|
|
// AsRef and AsMut allow for cheap reference-to-reference conversions. Read more
|
|
// about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html and
|
|
// https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
|
|
//
|
|
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a
|
|
// hint.
|
|
|
|
// Obtain the number of bytes (not characters) in the given argument.
|
|
// TODO: Add the AsRef trait appropriately as a trait bound.
|
|
fn byte_counter<T: AsRef<str>>(arg: T) -> usize {
|
|
arg.as_ref().as_bytes().len()
|
|
}
|
|
|
|
// Obtain the number of characters (not bytes) in the given argument.
|
|
// TODO: Add the AsRef trait appropriately as a trait bound.
|
|
fn char_counter<T: AsRef<str>>(arg: T) -> usize {
|
|
arg.as_ref().chars().count()
|
|
}
|
|
|
|
// Squares a number using as_mut().
|
|
// TODO: Add the appropriate trait bound.
|
|
fn num_sq<T: AsMut<u32>>(arg: &mut T) {
|
|
// TODO: Implement the function body.
|
|
*arg.as_mut() = *arg.as_mut() * *arg.as_mut()
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn different_counts() {
|
|
let s = "Café au lait";
|
|
assert_ne!(char_counter(s), byte_counter(s));
|
|
}
|
|
|
|
#[test]
|
|
fn same_counts() {
|
|
let s = "Cafe au lait";
|
|
assert_eq!(char_counter(s), byte_counter(s));
|
|
}
|
|
|
|
#[test]
|
|
fn different_counts_using_string() {
|
|
let s = String::from("Café au lait");
|
|
assert_ne!(char_counter(s.clone()), byte_counter(s));
|
|
}
|
|
|
|
#[test]
|
|
fn same_counts_using_string() {
|
|
let s = String::from("Cafe au lait");
|
|
assert_eq!(char_counter(s.clone()), byte_counter(s));
|
|
}
|
|
|
|
#[test]
|
|
fn mut_box() {
|
|
let mut num: Box<u32> = Box::new(3);
|
|
num_sq(&mut num);
|
|
assert_eq!(*num, 9);
|
|
}
|
|
}
|