diff --git a/exercises/standard_library_types/iterators5.rs b/exercises/standard_library_types/iterators5.rs new file mode 100644 index 00000000..2d97bd46 --- /dev/null +++ b/exercises/standard_library_types/iterators5.rs @@ -0,0 +1,124 @@ +// iterators5.rs + +// 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. These counting functions use +// imperative style for loops. Recreate this counting functionality using +// iterators. Only the two iterator methods (count_iterator and +// count_collection_iterator) need to be modified. +// Execute `rustlings hint +// iterators5` for hints. +// +// Make the code compile and the tests pass. + +// I AM NOT DONE + +use std::collections::HashMap; + +#[derive(PartialEq, Eq)] +enum Progress { + None, + Some, + Complete, +} + +fn count_for(map: &HashMap, value: Progress) -> usize { + let mut count = 0; + for val in map.values() { + if val == &value { + count += 1; + } + } + count +} + +fn count_iterator(map: &HashMap, value: Progress) -> usize { + // map is a hashmap with String keys and Progress values. + // map = { "variables1": Complete, "from_str": None, ... } +} + +fn count_collection_for(collection: &[HashMap], value: Progress) -> usize { + let mut count = 0; + for map in collection { + for val in map.values() { + if val == &value { + count += 1; + } + } + } + count +} + +fn count_collection_iterator(collection: &[HashMap], value: Progress) -> usize { + // collection is a slice of hashmaps. + // collection = [{ "variables1": Complete, "from_str": None, ... }, + // { "variables2": Complete, ... }, ... ] +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn count_complete() { + let map = get_map(); + assert_eq!(3, count_iterator(&map, Progress::Complete)); + } + + #[test] + fn count_equals_for() { + let map = get_map(); + assert_eq!( + count_for(&map, Progress::Complete), + count_iterator(&map, Progress::Complete) + ); + } + + #[test] + fn count_collection_complete() { + let collection = get_vec_map(); + assert_eq!( + 6, + count_collection_iterator(&collection, Progress::Complete) + ); + } + + #[test] + fn count_collection_equals_for() { + let collection = get_vec_map(); + assert_eq!( + count_collection_for(&collection, Progress::Complete), + count_collection_iterator(&collection, Progress::Complete) + ); + } + + fn get_map() -> HashMap { + use 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> { + use 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] + } +} diff --git a/info.toml b/info.toml index 4dd23bdc..36dcbe90 100644 --- a/info.toml +++ b/info.toml @@ -744,6 +744,22 @@ a mutable variable. Or, you might write code utilizing recursion and a match clause. In Rust you can take another functional approach, computing the factorial elegantly with ranges and iterators.""" +[[exercises]] +name = "iterators5" +path = "exercises/standard_library_types/iterators5.rs" +mode = "test" +hint = """ +The documentation for the std::iter::Iterator trait contains numerous methods +that would be helpful here. + +Return 0 from count_collection_iterator to make the code compile in order to +test count_iterator. + +The collection variable in count_collection_iterator is a slice of HashMaps. It +needs to be converted into an iterator in order to use the iterator methods. + +The fold method can be useful in the count_collection_iterator function.""" + # THREADS [[exercises]]