alice pellerin
77 lines
1.6 KiB
Rust
77 lines
1.6 KiB
Rust
use std::{cmp::{max, min}, mem::swap, ops::RangeInclusive};
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mod actions;
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#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
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pub struct Cursor {
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pub head: usize,
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pub tail: usize
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}
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pub enum InCursor {
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Head,
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Rest
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}
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impl Cursor {
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pub const fn at(index: usize) -> Self {
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Self { head: index, tail: index }
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}
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pub fn lower_bound(&self) -> usize {
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min(self.head, self.tail)
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}
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pub fn upper_bound(&self) -> usize {
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max(self.head, self.tail)
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}
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pub fn range(&self) -> RangeInclusive<usize> {
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self.lower_bound()..=self.upper_bound()
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}
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pub fn len(&self) -> usize {
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self.upper_bound() - self.lower_bound() + 1
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}
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pub const fn contains(&self, index: usize) -> Option<InCursor> {
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if index == self.head {
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Some(InCursor::Head)
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} else if (self.head < index && index <= self.tail) ||
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(self.tail <= index && index < self.head)
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{
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Some(InCursor::Rest)
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} else {
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None
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}
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}
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pub const fn contains_space_before(&self, index: usize) -> bool {
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(self.head < index && index <= self.tail) ||
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(self.tail < index && index <= self.head)
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}
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pub const fn collapse(&mut self) {
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self.tail = self.head;
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}
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pub const fn flip(&mut self) {
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swap(&mut self.head, &mut self.tail);
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}
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pub fn clamp(&mut self, min: usize, max: usize) {
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self.head = self.head.clamp(min, max);
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self.tail = self.tail.clamp(min, max);
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}
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pub fn combine_with(&mut self, other: Self) {
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if self.head < self.tail {
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self.head = min(self.head, other.head);
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self.tail = max(self.tail, other.tail);
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} else {
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self.head = max(self.head, other.head);
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self.tail = min(self.tail, other.tail);
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}
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}
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}
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