From 5fe51129f23ee454142a8b7a2a1d1d2e560f562b Mon Sep 17 00:00:00 2001
From: Eduardo Trujillo <ed@chromabits.com>
Date: Sun, 16 Mar 2025 00:01:42 +0000
Subject: [PATCH] feat(rangeset): Introduce a range set data structure
---
src/lib.rs | 2 +
src/rangeset.rs | 110 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+)
create mode 100644 src/rangeset.rs
diff --git a/src/lib.rs b/src/lib.rs
index 6cd57b8..9b5b4f1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,6 +8,8 @@ pub mod cli;
pub mod config;
/// Range dictionary data structure
pub mod rangedict;
+/// Range set data structure
+pub mod rangeset;
/// Ephemeral working directories.
pub mod rundir;
/// String utilities.
diff --git a/src/rangeset.rs b/src/rangeset.rs
new file mode 100644
index 0000000..f6e8ee3
--- /dev/null
+++ b/src/rangeset.rs
@@ -0,0 +1,110 @@
+use std::collections::BTreeMap;
+
+use thiserror::Error;
+
+/// Error type for [`RangeSet`]
+#[derive(Error, Debug, PartialEq)]
+pub enum RangeSetError {
+ /// Used when an invalid range is provided (e.g. End is before start).
+ #[error("Invalid range provided")]
+ InvalidRange,
+ /// Used when an insertion would result in an overlap.
+ #[error("Overlapping ranges")]
+ RangeOverlap,
+}
+
+/// A set of non-overlapping ranges.
+#[derive(Debug)]
+pub struct RangeSet<RK: Ord + Copy> {
+ ranges: BTreeMap<RK, RK>, // Maps start -> end
+}
+
+impl<RK: Ord + Copy> RangeSet<RK> {
+ /// Creates a new empty `RangeSet`.
+ pub fn new() -> Self {
+ Self {
+ ranges: BTreeMap::new(),
+ }
+ }
+
+ /// Inserts a new range `[start, end)`, ensuring no overlaps.
+ pub fn insert(&mut self, start: RK, end: RK) -> Result<(), RangeSetError> {
+ if start >= end {
+ return Err(RangeSetError::InvalidRange);
+ }
+
+ // Find adjacent or overlapping ranges
+ if let Some((&_prev_start, &prev_end)) = self.ranges.range(..=start).next_back() {
+ if prev_end >= start {
+ return Err(RangeSetError::RangeOverlap);
+ }
+ }
+ if let Some((&next_start, _)) = self.ranges.range(start..).next() {
+ if next_start < end {
+ return Err(RangeSetError::RangeOverlap);
+ }
+ }
+
+ self.ranges.insert(start, end);
+ Ok(())
+ }
+
+ /// Checks if a value exists in any range.
+ pub fn contains(&self, value: RK) -> bool {
+ if let Some((&_start, &end)) = self.ranges.range(..=value).next_back() {
+ return value < end;
+ }
+ false
+ }
+
+ /// Removes a range if it exists.
+ pub fn remove(&mut self, start: RK, end: RK) -> bool {
+ if let Some(range_end) = self.ranges.get(&start) {
+ if *range_end == end {
+ self.ranges.remove(&start);
+ return true;
+ }
+ }
+
+ false
+ }
+
+ /// Returns all stored ranges.
+ pub fn iter(&self) -> impl Iterator<Item = (RK, RK)> + '_ {
+ self.ranges.iter().map(|(&s, &e)| (s, e))
+ }
+}
+
+impl<RK: Copy + Ord> Default for RangeSet<RK> {
+ fn default() -> Self {
+ RangeSet::new()
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use crate::rangeset::{RangeSet, RangeSetError};
+
+ #[test]
+ fn test_insertions() {
+ let mut rs = RangeSet::new();
+
+ assert_eq!(rs.insert(10, 20), Ok(()));
+ assert_eq!(rs.insert(30, 40), Ok(()));
+ assert_eq!(rs.insert(15, 25), Err(RangeSetError::RangeOverlap));
+ assert_eq!(rs.contains(15), true);
+ assert_eq!(rs.contains(25), false);
+ }
+
+ #[test]
+ fn test_removal() {
+ let mut rs = RangeSet::new();
+
+ assert_eq!(rs.insert(10, 20), Ok(()));
+ assert_eq!(rs.insert(30, 40), Ok(()));
+ assert_eq!(rs.remove(10, 11), false);
+ assert_eq!(rs.remove(10, 20), true);
+ assert_eq!(rs.remove(30, 40), true);
+ assert_eq!(rs.remove(30, 40), false);
+ }
+}
--
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