74 lines
2.1 KiB
Rust
74 lines
2.1 KiB
Rust
use std::ops::Index;
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/// OrderedIterator allows iterating with specific order specified
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pub struct OrderedIterator<'a, T: 'a> {
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element_order: Option<&'a [usize]>,
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current: usize,
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vec: &'a [T],
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}
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impl<'a, T> OrderedIterator<'a, T> {
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pub fn new(vec: &'a [T], element_order: Option<&'a [usize]>) -> OrderedIterator<'a, T> {
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if let Some(custom_order) = element_order {
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assert!(custom_order.len() == vec.len());
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}
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OrderedIterator {
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element_order,
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current: 0,
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vec,
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}
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}
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}
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impl<'a, T> Iterator for OrderedIterator<'a, T> {
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type Item = &'a T;
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fn next(&mut self) -> Option<Self::Item> {
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if self.current >= self.vec.len() {
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None
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} else {
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let index: usize;
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if let Some(custom_order) = self.element_order {
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index = custom_order[self.current];
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} else {
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index = self.current;
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}
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self.current += 1;
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Some(self.vec.index(index))
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_ordered_iterator_custom_order() {
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let vec: Vec<usize> = vec![1, 2, 3, 4];
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let custom_order: Vec<usize> = vec![3, 1, 0, 2];
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let ordered_iterator = OrderedIterator::new(&vec, Some(&custom_order));
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let expected_response: Vec<usize> = vec![4, 2, 1, 3];
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let resp: Vec<(&usize, &usize)> = ordered_iterator
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.zip(expected_response.iter())
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.filter(|(actual_elem, expected_elem)| *actual_elem == *expected_elem)
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.collect();
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assert_eq!(resp.len(), custom_order.len());
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}
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#[test]
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fn test_ordered_iterator_original_order() {
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let vec: Vec<usize> = vec![1, 2, 3, 4];
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let ordered_iterator = OrderedIterator::new(&vec, None);
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let resp: Vec<(&usize, &usize)> = ordered_iterator
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.zip(vec.iter())
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.filter(|(actual_elem, expected_elem)| *actual_elem == *expected_elem)
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.collect();
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assert_eq!(resp.len(), vec.len());
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}
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}
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