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-rw-r--r--rustlings/solutions/18_iterators/iterators5.rs168
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diff --git a/rustlings/solutions/18_iterators/iterators5.rs b/rustlings/solutions/18_iterators/iterators5.rs
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-// Let's define a simple model to track Rustlings' exercise progress. Progress
-// will be modelled using a hash map. The name of the exercise is the key and
-// the progress is the value. Two counting functions were created to count the
-// number of exercises with a given progress. Recreate this counting
-// functionality using iterators. Try to not use imperative loops (for/while).
-
-use std::collections::HashMap;
-
-#[derive(Clone, Copy, PartialEq, Eq)]
-enum Progress {
- None,
- Some,
- Complete,
-}
-
-fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
- let mut count = 0;
- for val in map.values() {
- if *val == value {
- count += 1;
- }
- }
- count
-}
-
-fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
- // `map` is a hash map with `String` keys and `Progress` values.
- // map = { "variables1": Complete, "from_str": None, … }
- map.values().filter(|val| **val == value).count()
-}
-
-fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
- let mut count = 0;
- for map in collection {
- count += count_for(map, value);
- }
- count
-}
-
-fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
- // `collection` is a slice of hash maps.
- // collection = [{ "variables1": Complete, "from_str": None, … },
- // { "variables2": Complete, … }, … ]
- collection
- .iter()
- .map(|map| count_iterator(map, value))
- .sum()
-}
-
-// Equivalent to `count_collection_iterator` and `count_iterator`, iterating as
-// if the collection was a single container instead of a container of containers
-// (and more accurately, a single iterator instead of an iterator of iterators).
-fn count_collection_iterator_flat(
- collection: &[HashMap<String, Progress>],
- value: Progress,
-) -> usize {
- // `collection` is a slice of hash maps.
- // collection = [{ "variables1": Complete, "from_str": None, … },
- // { "variables2": Complete, … }, … ]
- collection
- .iter()
- .flat_map(HashMap::values) // or just `.flatten()` when wanting the default iterator (`HashMap::iter`)
- .filter(|val| **val == value)
- .count()
-}
-
-fn main() {
- // You can optionally experiment here.
-}
-
-#[cfg(test)]
-mod tests {
- use super::*;
- use Progress::*;
-
- fn get_map() -> HashMap<String, Progress> {
- let mut map = HashMap::new();
- map.insert(String::from("variables1"), Complete);
- map.insert(String::from("functions1"), Complete);
- map.insert(String::from("hashmap1"), Complete);
- map.insert(String::from("arc1"), Some);
- map.insert(String::from("as_ref_mut"), None);
- map.insert(String::from("from_str"), None);
-
- map
- }
-
- fn get_vec_map() -> Vec<HashMap<String, Progress>> {
- let map = get_map();
-
- let mut other = HashMap::new();
- other.insert(String::from("variables2"), Complete);
- other.insert(String::from("functions2"), Complete);
- other.insert(String::from("if1"), Complete);
- other.insert(String::from("from_into"), None);
- other.insert(String::from("try_from_into"), None);
-
- vec![map, other]
- }
-
- #[test]
- fn count_complete() {
- let map = get_map();
- assert_eq!(count_iterator(&map, Complete), 3);
- }
-
- #[test]
- fn count_some() {
- let map = get_map();
- assert_eq!(count_iterator(&map, Some), 1);
- }
-
- #[test]
- fn count_none() {
- let map = get_map();
- assert_eq!(count_iterator(&map, None), 2);
- }
-
- #[test]
- fn count_complete_equals_for() {
- let map = get_map();
- let progress_states = [Complete, Some, None];
- for progress_state in progress_states {
- assert_eq!(
- count_for(&map, progress_state),
- count_iterator(&map, progress_state),
- );
- }
- }
-
- #[test]
- fn count_collection_complete() {
- let collection = get_vec_map();
- assert_eq!(count_collection_iterator(&collection, Complete), 6);
- assert_eq!(count_collection_iterator_flat(&collection, Complete), 6);
- }
-
- #[test]
- fn count_collection_some() {
- let collection = get_vec_map();
- assert_eq!(count_collection_iterator(&collection, Some), 1);
- assert_eq!(count_collection_iterator_flat(&collection, Some), 1);
- }
-
- #[test]
- fn count_collection_none() {
- let collection = get_vec_map();
- assert_eq!(count_collection_iterator(&collection, None), 4);
- assert_eq!(count_collection_iterator_flat(&collection, None), 4);
- }
-
- #[test]
- fn count_collection_equals_for() {
- let collection = get_vec_map();
- let progress_states = [Complete, Some, None];
-
- for progress_state in progress_states {
- assert_eq!(
- count_collection_for(&collection, progress_state),
- count_collection_iterator(&collection, progress_state),
- );
- assert_eq!(
- count_collection_for(&collection, progress_state),
- count_collection_iterator_flat(&collection, progress_state),
- );
- }
- }
-}