123 lines
3.6 KiB
Rust
123 lines
3.6 KiB
Rust
// iterators5.rs
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// Let's define a simple model to track Rustlings exercise progress. Progress
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// will be modelled using a hash map. The name of the exercise is the key and
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// the progress is the value. Two counting functions were created to count the
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// number of exercises with a given progress. These counting functions use
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// imperative style for loops. Recreate this counting functionality using
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// iterators. Only the two iterator methods (count_iterator and
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// count_collection_iterator) need to be modified.
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// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a hint.
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//
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// Make the code compile and the tests pass.
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use std::collections::HashMap;
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#[derive(Clone, Copy, PartialEq, Eq)]
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enum Progress {
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None,
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Some,
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Complete,
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}
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fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
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let mut count = 0;
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for val in map.values() {
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if val == &value {
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count += 1;
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}
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}
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count
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}
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fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
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// map is a hashmap with String keys and Progress values.
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// map = { "variables1": Complete, "from_str": None, ... }
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map.values().filter(|v| v == &&value).count()
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}
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fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
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let mut count = 0;
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for map in collection {
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for val in map.values() {
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if val == &value {
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count += 1;
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}
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}
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}
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count
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}
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fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
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// collection is a slice of hashmaps.
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// collection = [{ "variables1": Complete, "from_str": None, ... },
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// { "variables2": Complete, ... }, ... ]
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collection.iter().map(|hm| count_iterator(&hm, value)).fold(0, |a, b| a + b)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn count_complete() {
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let map = get_map();
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assert_eq!(3, count_iterator(&map, Progress::Complete));
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}
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#[test]
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fn count_equals_for() {
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let map = get_map();
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assert_eq!(
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count_for(&map, Progress::Complete),
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count_iterator(&map, Progress::Complete)
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);
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}
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#[test]
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fn count_collection_complete() {
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let collection = get_vec_map();
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assert_eq!(
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6,
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count_collection_iterator(&collection, Progress::Complete)
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);
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}
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#[test]
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fn count_collection_equals_for() {
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let collection = get_vec_map();
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assert_eq!(
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count_collection_for(&collection, Progress::Complete),
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count_collection_iterator(&collection, Progress::Complete)
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);
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}
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fn get_map() -> HashMap<String, Progress> {
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use Progress::*;
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let mut map = HashMap::new();
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map.insert(String::from("variables1"), Complete);
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map.insert(String::from("functions1"), Complete);
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map.insert(String::from("hashmap1"), Complete);
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map.insert(String::from("arc1"), Some);
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map.insert(String::from("as_ref_mut"), None);
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map.insert(String::from("from_str"), None);
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map
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}
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fn get_vec_map() -> Vec<HashMap<String, Progress>> {
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use Progress::*;
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let map = get_map();
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let mut other = HashMap::new();
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other.insert(String::from("variables2"), Complete);
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other.insert(String::from("functions2"), Complete);
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other.insert(String::from("if1"), Complete);
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other.insert(String::from("from_into"), None);
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other.insert(String::from("try_from_into"), None);
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vec![map, other]
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}
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}
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