Improved iterators5.rs explanation.
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@ -1,11 +1,14 @@
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// iterators5.rs
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// Rustling progress is modelled using a hash map. The name of the exercise is
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// the key and the progress is the value. Two counting functions were created
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// to count the number of exercises with a given progress. These counting
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// functions use imperative style for loops. Recreate this counting
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// functionality using iterators.
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// Execute `rustlings hint iterators5` for hints.
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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
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// iterators5` for hints.
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//
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// Make the code compile and the tests pass.
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@ -30,12 +33,14 @@ fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
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count
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}
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fn count(map: &HashMap<String, Progress>, value: Progress) -> usize {
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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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}
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fn count_stack_for(stack: &[HashMap<String, Progress>], value: Progress) -> usize {
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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 stack {
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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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@ -45,7 +50,10 @@ fn count_stack_for(stack: &[HashMap<String, Progress>], value: Progress) -> usiz
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count
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}
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fn count_stack(stack: &[HashMap<String, Progress>], value: Progress) -> usize {
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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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}
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#[cfg(test)]
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@ -55,7 +63,7 @@ mod tests {
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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(&map, Progress::Complete));
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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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@ -63,22 +71,25 @@ mod tests {
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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(&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_stack_complete() {
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let stack = get_map_stack();
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assert_eq!(6, count_stack(&stack, Progress::Complete));
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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_stack_equals_for() {
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let stack = get_map_stack();
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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_stack_for(&stack, Progress::Complete),
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count_stack(&stack, Progress::Complete)
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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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@ -96,7 +107,7 @@ mod tests {
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map
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}
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fn get_map_stack() -> Vec<HashMap<String, Progress>> {
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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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11
info.toml
11
info.toml
@ -694,7 +694,7 @@ Step 2 & step 2.1:
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Very similar to the lines above and below. You've got this!
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Step 3:
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An iterator goes through all elements in a collection, but what if we've run out of
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elements? What should we expect here? If you're stuck, take a look at
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elements? What should we expect here? If you're stuck, take a look at
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https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
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"""
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@ -749,12 +749,13 @@ hint = """
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The documentation for the std::iter::Iterator trait contains numerous methods
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that would be helpful here.
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Return 0 from count_stack to make the code compile in order to test count.
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Return 0 from count_collection_iterator to make the code compile in order to
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test count_iterator.
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The stack variable in count_stack is a slice of HashMaps. It needs to be
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converted into an iterator in order to use the iterator methods.
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The collection variable in count_collection_iterator is a slice of HashMaps. It
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needs to be converted into an iterator in order to use the iterator methods.
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The fold method can be useful in the count_stack function."""
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The fold method can be useful in the count_collection_iterator function."""
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# THREADS
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