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Diffstat (limited to 'helix-core/src/selection.rs')
| -rw-r--r-- | helix-core/src/selection.rs | 222 |
1 files changed, 222 insertions, 0 deletions
diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs new file mode 100644 index 00000000..24a8be46 --- /dev/null +++ b/helix-core/src/selection.rs @@ -0,0 +1,222 @@ +//! Selections are the primary editing construct. Even a single cursor is defined as an empty +//! single selection range. +//! +//! All positioning is done via `char` offsets into the buffer. +use smallvec::{smallvec, SmallVec}; + +#[inline] +fn abs_difference(x: usize, y: usize) -> usize { + if x < y { + y - x + } else { + x - y + } +} + +/// A single selection range. Anchor-inclusive, head-exclusive. +#[derive(Debug, Clone, Copy, PartialEq, Eq)] +pub struct Range { + // TODO: optimize into u32 + /// The anchor of the range: the side that doesn't move when extending. + pub anchor: usize, + /// The head of the range, moved when extending. + pub head: usize, +} + +impl Range { + pub fn new(anchor: usize, head: usize) -> Self { + Self { anchor, head } + } + + /// Start of the range. + #[inline] + pub fn from(&self) -> usize { + std::cmp::min(self.anchor, self.head) + } + + /// End of the range. + #[inline] + pub fn to(&self) -> usize { + std::cmp::max(self.anchor, self.head) + } + + /// `true` when head and anchor are at the same position. + #[inline] + pub fn is_empty(&self) -> bool { + self.anchor == self.head + } + + /// Check two ranges for overlap. + pub fn overlaps(&self, other: &Self) -> bool { + // cursor overlap is checked differently + if self.is_empty() { + self.from() <= other.to() + } else { + self.from() < other.to() + } + } + + // TODO: map + + /// Extend the range to cover at least `from` `to`. + pub fn extend(&self, from: usize, to: usize) -> Self { + if from <= self.anchor && to >= self.anchor { + return Range { + anchor: from, + head: to, + }; + } + + Range { + anchor: self.anchor, + head: if abs_difference(from, self.anchor) > abs_difference(to, self.anchor) { + from + } else { + to + }, + } + } + + // groupAt +} + +/// A selection consists of one or more selection ranges. +pub struct Selection { + // TODO: decide how many ranges to inline SmallVec<[Range; 1]> + ranges: Vec<Range>, + primary_index: usize, +} + +impl Selection { + // map + // eq + pub fn primary(&self) -> Range { + self.ranges[self.primary_index] + } + + /// Ensure selection containing only the primary selection. + pub fn as_single(self) -> Self { + if self.ranges.len() == 1 { + self + } else { + Self { + ranges: vec![self.ranges[self.primary_index]], + primary_index: 0, + } + } + } + + // add_range // push + // replace_range + + /// Constructs a selection holding a single range. + pub fn single(anchor: usize, head: usize) -> Self { + Self { + ranges: vec![Range { anchor, head }], + primary_index: 0, + } + } + + pub fn new(ranges: Vec<Range>, primary_index: usize) -> Self { + fn normalize(mut ranges: Vec<Range>, primary_index: usize) -> Selection { + let primary = ranges[primary_index]; + ranges.sort_unstable_by_key(|range| range.from()); + let mut primary_index = ranges.iter().position(|&range| range == primary).unwrap(); + + let mut result: Vec<Range> = Vec::new(); + + // TODO: we could do with one vec by removing elements as we mutate + + for (i, range) in ranges.into_iter().enumerate() { + // if previous value exists + if let Some(prev) = result.last_mut() { + // and we overlap it + if range.overlaps(prev) { + let from = prev.from(); + let to = std::cmp::max(range.to(), prev.to()); + + if i <= primary_index { + primary_index -= 1 + } + + // merge into previous + if range.anchor > range.head { + prev.anchor = to; + prev.head = from; + } else { + prev.anchor = from; + prev.head = to; + } + continue; + } + } + + result.push(range) + } + + Selection { + ranges: result, + primary_index, + } + } + + // TODO: only normalize if needed (any ranges out of order) + normalize(ranges, primary_index) + } +} + +// TODO: checkSelection -> check if valid for doc length + +#[cfg(test)] +mod test { + use super::*; + + #[test] + fn test_create_normalizes_and_merges() { + let sel = Selection::new( + vec![ + Range::new(10, 12), + Range::new(6, 7), + Range::new(4, 5), + Range::new(3, 4), + Range::new(0, 6), + Range::new(7, 8), + Range::new(9, 13), + Range::new(13, 14), + ], + 0, + ); + + let res = sel + .ranges + .into_iter() + .map(|range| format!("{}/{}", range.anchor, range.head)) + .collect::<Vec<String>>() + .join(","); + + assert_eq!(res, "0/6,6/7,7/8,9/13,13/14"); + } + + #[test] + fn test_create_merges_adjacent_points() { + let sel = Selection::new( + vec![ + Range::new(10, 12), + Range::new(12, 12), + Range::new(12, 12), + Range::new(10, 10), + Range::new(8, 10), + ], + 0, + ); + + let res = sel + .ranges + .into_iter() + .map(|range| format!("{}/{}", range.anchor, range.head)) + .collect::<Vec<String>>() + .join(","); + + assert_eq!(res, "8/10,10/12"); + } +} |