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116 lines
2.8 KiB
Rust
116 lines
2.8 KiB
Rust
5 years ago
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use std::iter::Extend;
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use std::ops::Index;
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#[derive(Debug)]
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pub struct StackVec<T: Default + Copy + std::fmt::Debug> {
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len: usize,
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array: [T; 32],
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heap_vec: Vec<T>,
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}
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impl<T: Default + Copy + std::fmt::Debug> StackVec<T> {
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pub fn new() -> Self {
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StackVec {
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len: 0,
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array: [T::default(); 32],
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heap_vec: Vec::new(),
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}
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}
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pub fn push(&mut self, ind: T) {
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if self.len == self.array.len() {
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if self.heap_vec.is_empty() {
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self.heap_vec.reserve(32);
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for _ in 0..8 {
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self.heap_vec.push(T::default());
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}
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}
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self.heap_vec[0..8].copy_from_slice(&self.array);
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self.heap_vec.push(ind);
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} else if self.len > self.array.len() {
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self.heap_vec.push(ind);
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} else {
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self.array[self.len] = ind;
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}
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self.len += 1;
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}
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pub fn pop(&mut self) -> Option<T> {
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if self.len == 0 {
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return None;
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}
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if self.len >= self.array.len() {
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self.len -= 1;
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self.heap_vec.pop()
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} else {
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let ret = self.array[self.len - 1];
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self.len = self.len - 1;
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Some(ret)
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}
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}
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pub fn len(&self) -> usize {
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self.len
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}
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pub fn is_empty(&self) -> bool {
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self.len == 0
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}
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pub fn iter(&self) -> StackVecIter<T> {
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StackVecIter {
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stack: &self,
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range: 0..self.len,
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}
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}
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}
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pub struct StackVecIter<'a, T: Default + Copy + std::fmt::Debug> {
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stack: &'a StackVec<T>,
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range: std::ops::Range<usize>,
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}
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impl<'a, T: Default + Copy + std::fmt::Debug> Iterator for StackVecIter<'a, T> {
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type Item = &'a T;
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fn next(&mut self) -> Option<&'a T> {
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if self.range.len() == 0 {
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None
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} else {
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let idx = self.range.start;
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self.range.start += 1;
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Some(&self.stack[idx])
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}
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}
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}
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impl<'a, T: Default + Copy + std::fmt::Debug> std::iter::DoubleEndedIterator
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for StackVecIter<'a, T>
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{
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fn next_back(&mut self) -> Option<&'a T> {
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if self.range.len() == 0 {
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None
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} else {
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let idx = self.range.end - 1;
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self.range.end -= 1;
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Some(&self.stack[idx])
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}
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}
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}
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impl<T: Default + Copy + std::fmt::Debug> Index<usize> for StackVec<T> {
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type Output = T;
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fn index(&self, idx: usize) -> &T {
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if self.len >= self.array.len() {
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&self.heap_vec[idx]
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} else {
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&self.array[idx]
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}
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}
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}
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impl<T: Default + Copy + std::fmt::Debug> Extend<T> for StackVec<T> {
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fn extend<I>(&mut self, iter: I)
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where
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I: IntoIterator<Item = T>,
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{
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for elem in iter {
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self.push(elem);
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}
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}
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}
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