println!("scores after doubling: {:?}", scores);
// double scores of immutable hashmap (rebuild it)
- let collect_scores: HashMap<_, _> = collect_scores.iter()
+ let collect_scores: HashMap<_, _> = collect_scores.into_iter()
.map(|(k, v)| (k, 2 * v))
.collect();
println!("collect_scores after rebuilding with doubling: {:?}", collect_scores);
println!("longest string: {}", l);
}
+fn test_closures() {
+ let mut expensive_int_result = Cacher::new(|x| {
+ println!("calculating expensive int result for {}", x);
+ 2 * x
+ });
+
+ println!("1st int call for value 1: {}", expensive_int_result.value(1));
+ println!("2nd int call for value 1: {}", expensive_int_result.value(1));
+ println!("1st int call for value 2: {}", expensive_int_result.value(2));
+
+ let mut expensive_str_result = Cacher::new(|x: &str| {
+ println!("calculating expensive str result for {}", x);
+ x.len()
+ });
+
+ println!("1st int call for value abc: {}", expensive_str_result.value("abc"));
+ println!("2nd int call for value abc: {}", expensive_str_result.value("abc"));
+ println!("1st int call for value defg: {}", expensive_str_result.value("defg"));
+}
+
+fn test_iterators() {
+ let v1 = vec!["Hello", "good", "world"];
+ // implied default is .into_iter() which consumes v1
+ for s in v1.iter() {
+ println!("element: {}", s);
+ }
+ // can still use it now
+ println!("v1: {:?}", &v1);
+
+ // manual iteration
+ let mut v1_iter = v1.iter();
+ while let Some(e) = v1_iter.next() {
+ println!("while loop over iter: {}", e);
+ }
+
+ for l_element in v1.iter().filter(|x| x.contains('l')) {
+ println!("v1 element containing 'l': {}", l_element);
+ }
+
+ let v2 = vec![1, 2, 3];
+ let double_v2: Vec<_> = v2.iter().map(|x| x * 2).collect();
+ println!("doubled v2: {:?}", double_v2);
+
+ for i in v2.into_iter().map(|x| x * 3) {
+ println!("for loop triplicating v2: {}", i);
+ }
+
+ for i in Counter5::new() {
+ println!("Counter 5 value: {}", i);
+ }
+}
+
fn main() {
test_strings();
test_vectors();
test_hashmaps();
test_files();
test_generics();
+ test_closures();
+ test_iterators();
}