diff --git a/exercises/standard_library_types/iterators5.rs b/exercises/standard_library_types/iterators5.rs new file mode 100644 index 00000000..65c50e62 --- /dev/null +++ b/exercises/standard_library_types/iterators5.rs @@ -0,0 +1,113 @@ +// iterators5.rs + +// Rustling progress is 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. +// 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(map: &HashMap, value: Progress) -> usize { +} + +fn count_stack_for(stack: &[HashMap], value: Progress) -> usize { + let mut count = 0; + for map in stack { + for val in map.values() { + if val == &value { + count += 1; + } + } + } + count +} + +fn count_stack(stack: &[HashMap], value: Progress) -> usize { +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn count_complete() { + let map = get_map(); + assert_eq!(3, count(&map, Progress::Complete)); + } + + #[test] + fn count_equals_for() { + let map = get_map(); + assert_eq!( + count_for(&map, Progress::Complete), + count(&map, Progress::Complete) + ); + } + + #[test] + fn count_stack_complete() { + let stack = get_map_stack(); + assert_eq!(6, count_stack(&stack, Progress::Complete)); + } + + #[test] + fn count_stack_equals_for() { + let stack = get_map_stack(); + assert_eq!( + count_stack_for(&stack, Progress::Complete), + count_stack(&stack, 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_map_stack() -> 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 f0fed934..646bb5a5 100644 --- a/info.toml +++ b/info.toml @@ -741,6 +741,21 @@ 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_stack to make the code compile in order to test count. + +The stack variable in count_stack 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_stack function.""" + # THREADS [[exercises]]