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rustlings-exercises-completed/exercises/iterators/iterators5.rs

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// 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. 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.
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// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a hint.
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//
// Make the code compile and the tests pass.
use std::collections::HashMap;
#[derive(Clone, Copy, PartialEq, Eq)]
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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
}
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fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
// map is a hashmap with String keys and Progress values.
// map = { "variables1": Complete, "from_str": None, ... }
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map.values()
.map(|x| match x {
Progress::Complete => 1,
_ => 0,
})
.sum()
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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() {
if val == &value {
count += 1;
}
}
}
count
}
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fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
// collection is a slice of hashmaps.
// collection = [{ "variables1": Complete, "from_str": None, ... },
// { "variables2": Complete, ... }, ... ]
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collection.iter().map(|x| count_iterator(x, value)).sum()
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}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn count_complete() {
let map = get_map();
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assert_eq!(3, count_iterator(&map, Progress::Complete));
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}
#[test]
fn count_equals_for() {
let map = get_map();
assert_eq!(
count_for(&map, Progress::Complete),
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count_iterator(&map, Progress::Complete)
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);
}
#[test]
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fn count_collection_complete() {
let collection = get_vec_map();
assert_eq!(
6,
count_collection_iterator(&collection, Progress::Complete)
);
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}
#[test]
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fn count_collection_equals_for() {
let collection = get_vec_map();
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assert_eq!(
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count_collection_for(&collection, Progress::Complete),
count_collection_iterator(&collection, Progress::Complete)
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);
}
fn get_map() -> HashMap<String, Progress> {
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
}
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fn get_vec_map() -> Vec<HashMap<String, Progress>> {
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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]
}
}