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"Strings and Iterators" solution that uses let-else (#833)

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Add "Strings and Iterators" solution that uses let-else.
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Victor Costan 2023-06-28 23:52:58 -07:00 committed by GitHub
parent b83dd9a1f9
commit 0c867c952f
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1 changed files with 15 additions and 13 deletions
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28
src/exercises/day-2/strings-iterators.rs
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@ -15,23 +15,25 @@
// ANCHOR: prefix_matches // ANCHOR: prefix_matches
pub fn prefix_matches(prefix: &str, request_path: &str) -> bool { pub fn prefix_matches(prefix: &str, request_path: &str) -> bool {
// ANCHOR_END: prefix_matches // ANCHOR_END: prefix_matches
let prefixes = prefix.split('/');
let request_paths = request_path
.split('/')
.map(|p| Some(p))
.chain(std::iter::once(None));
for (prefix, request_path) in prefixes.zip(request_paths) { let mut request_segments = request_path.split('/');
match request_path {
Some(request_path) => { for prefix_segment in prefix.split('/') {
if (prefix != "*") && (prefix != request_path) { let Some(request_segment) = request_segments.next() else {
return false; return false;
} };
} if request_segment != prefix_segment && prefix_segment != "*" {
None => return false, return false;
} }
} }
true true
// Alternatively, Iterator::zip() lets us iterate simultaneously over prefix
// and request segments. The zip() iterator is finished as soon as one of
// the source iterators is finished, but we need to iterate over all request
// segments. A neat trick that makes zip() work is to use map() and chain()
// to produce an iterator that returns Some(str) for each pattern segments,
// and then returns None indefinitely.
} }
// ANCHOR: unit-tests // ANCHOR: unit-tests