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authorJordan Gong <jordan.gong@protonmail.com>2020-09-08 20:18:34 +0800
committerJordan Gong <jordan.gong@protonmail.com>2020-09-08 20:18:34 +0800
commit66e7b9956833678a7911abc362031774f31ed211 (patch)
treebecae9f3212b4ffe321ce15af0487c9d49a89a2b /iterators/src/lib.rs
parent20dd593509db111575a370a156d716a0bc851312 (diff)
Iterate with closures
Diffstat (limited to 'iterators/src/lib.rs')
-rw-r--r--iterators/src/lib.rs125
1 files changed, 125 insertions, 0 deletions
diff --git a/iterators/src/lib.rs b/iterators/src/lib.rs
new file mode 100644
index 0000000..01ffec3
--- /dev/null
+++ b/iterators/src/lib.rs
@@ -0,0 +1,125 @@
+#[derive(PartialEq, Debug)]
+struct Shoe {
+ size: u32,
+ style: String,
+}
+
+fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
+ shoes.into_iter().filter(|s| s.size == shoe_size).collect()
+}
+
+struct Counter {
+ count: u32,
+}
+
+impl Counter {
+ fn new() -> Counter {
+ Counter { count: 0 }
+ }
+}
+
+impl Iterator for Counter {
+ type Item = u32;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.count < 5 {
+ self.count += 1;
+ Some(self.count)
+ } else {
+ None
+ }
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ #[test]
+ fn interator_demostration() {
+ let v1 = vec![1, 2, 3];
+
+ let mut v1_iter = v1.iter();
+
+ assert_eq!(v1_iter.next(), Some(&1));
+ assert_eq!(v1_iter.next(), Some(&2));
+ assert_eq!(v1_iter.next(), Some(&3));
+ assert_eq!(v1_iter.next(), None);
+ }
+
+ #[test]
+ fn iterator_sum() {
+ let v1 = vec![1, 2, 3];
+
+ let v1_iter = v1.iter();
+
+ let total: i32 = v1_iter.sum();
+
+ assert_eq!(total, 6);
+ }
+
+ #[test]
+ fn iterator_adaptor() {
+ let v1: Vec<i32> = vec![1, 2, 3];
+
+ let v2: Vec<_> = v1.iter().map(|x| x + 1).collect();
+
+ assert_eq!(v2, vec![2, 3, 4]);
+ }
+
+ use super::*;
+ #[test]
+ fn filter_by_size() {
+ let shoes = vec![
+ Shoe {
+ size: 10,
+ style: String::from("sneaker"),
+ },
+ Shoe {
+ size: 13,
+ style: String::from("sandal"),
+ },
+ Shoe {
+ size: 10,
+ style: String::from("boot"),
+ },
+ ];
+
+ let in_my_size = shoes_in_my_size(shoes, 10);
+
+ assert_eq!(
+ in_my_size,
+ vec![
+ Shoe {
+ size: 10,
+ style: String::from("sneaker"),
+ },
+ Shoe {
+ size: 10,
+ style: String::from("boot"),
+ },
+ ]
+ );
+ }
+
+ #[test]
+ fn calling_next_directly() {
+ let mut counter = Counter::new();
+
+ assert_eq!(counter.next(), Some(1));
+ assert_eq!(counter.next(), Some(2));
+ assert_eq!(counter.next(), Some(3));
+ assert_eq!(counter.next(), Some(4));
+ assert_eq!(counter.next(), Some(5));
+ assert_eq!(counter.next(), None);
+ }
+
+ #[test]
+ fn using_other_iterator_trait_methods() {
+ let sum: u32 = Counter::new()
+ .zip(Counter::new().skip(1))
+ .map(|(a, b)| a * b)
+ .filter(|x| x % 3 == 0)
+ .sum();
+
+ assert_eq!(sum, 18);
+ }
+}