86 lines
2.5 KiB
Rust
86 lines
2.5 KiB
Rust
use rand::prelude::*;
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use std::cmp::Ordering;
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pub fn post_inc(value: &mut usize) -> usize {
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let prev = *value;
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*value += 1;
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prev
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}
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/// Extend a sorted vector with a sorted sequence of items, maintaining the vector's sort order and
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/// enforcing a maximum length. Sort the items according to the given callback. Before calling this,
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/// both `vec` and `new_items` should already be sorted according to the `cmp` comparator.
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pub fn extend_sorted<T, I, F>(vec: &mut Vec<T>, new_items: I, limit: usize, mut cmp: F)
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where
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I: IntoIterator<Item = T>,
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F: FnMut(&T, &T) -> Ordering,
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{
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let mut start_index = 0;
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for new_item in new_items {
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if let Err(i) = vec[start_index..].binary_search_by(|m| cmp(m, &new_item)) {
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let index = start_index + i;
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if vec.len() < limit {
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vec.insert(index, new_item);
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} else if index < vec.len() {
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vec.pop();
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vec.insert(index, new_item);
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}
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start_index = index;
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}
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}
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}
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pub struct RandomCharIter<T: Rng>(T);
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impl<T: Rng> RandomCharIter<T> {
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#[cfg(test)]
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pub fn new(rng: T) -> Self {
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Self(rng)
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}
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}
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impl<T: Rng> Iterator for RandomCharIter<T> {
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type Item = char;
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fn next(&mut self) -> Option<Self::Item> {
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if self.0.gen_bool(1.0 / 5.0) {
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Some('\n')
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}
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// two-byte greek letters
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else if self.0.gen_bool(1.0 / 8.0) {
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Some(std::char::from_u32(self.0.gen_range(('α' as u32)..('ω' as u32 + 1))).unwrap())
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}
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// three-byte characters
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else if self.0.gen_bool(1.0 / 10.0) {
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['✋', '✅', '❌', '❎', '⭐'].choose(&mut self.0).cloned()
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}
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// four-byte characters
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else if self.0.gen_bool(1.0 / 12.0) {
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['🍐', '🏀', '🍗', '🎉'].choose(&mut self.0).cloned()
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}
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// ascii letters
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else {
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Some(self.0.gen_range(b'a'..b'z' + 1).into())
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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_extend_sorted() {
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let mut vec = vec![];
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extend_sorted(&mut vec, vec![21, 17, 13, 8, 1, 0], 5, |a, b| b.cmp(a));
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assert_eq!(vec, &[21, 17, 13, 8, 1]);
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extend_sorted(&mut vec, vec![101, 19, 17, 8, 2], 8, |a, b| b.cmp(a));
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assert_eq!(vec, &[101, 21, 19, 17, 13, 8, 2, 1]);
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extend_sorted(&mut vec, vec![1000, 19, 17, 9, 5], 8, |a, b| b.cmp(a));
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assert_eq!(vec, &[1000, 101, 21, 19, 17, 13, 9, 8]);
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}
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}
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