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|
//! 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 crate::{Assoc, ChangeSet};
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]
#[must_use]
pub fn from(&self) -> usize {
std::cmp::min(self.anchor, self.head)
}
/// End of the range.
#[inline]
#[must_use]
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.
#[must_use]
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()
}
}
/// Map a range through a set of changes. Returns a new range representing the same position
/// after the changes are applied.
pub fn map(self, changes: &ChangeSet) -> Self {
let anchor = changes.map_pos(self.anchor, Assoc::Before);
let head = changes.map_pos(self.head, Assoc::Before);
// TODO: possibly unnecessary
if self.anchor == anchor && self.head == head {
return self;
}
Self { anchor, head }
}
/// Extend the range to cover at least `from` `to`.
#[must_use]
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: SmallVec<[Range; 1]>,
primary_index: usize,
}
impl Selection {
// map
// eq
#[must_use]
pub fn primary(&self) -> Range {
self.ranges[self.primary_index]
}
/// Ensure selection containing only the primary selection.
pub fn into_single(self) -> Self {
if self.ranges.len() == 1 {
self
} else {
Self {
ranges: smallvec![self.ranges[self.primary_index]],
primary_index: 0,
}
}
}
// add_range // push
// replace_range
/// Map selections over a set of changes. Useful for adjusting the selection position after
/// applying changes to a document.
pub fn map(self, changes: &ChangeSet) -> Self {
if changes.is_empty() {
return self;
}
Self::new(
self.ranges
.into_iter()
.map(|range| range.map(changes))
.collect(),
self.primary_index,
)
}
#[must_use]
/// Constructs a selection holding a single range.
pub fn single(anchor: usize, head: usize) -> Self {
Self {
ranges: smallvec![Range { anchor, head }],
primary_index: 0,
}
}
#[must_use]
pub fn new(ranges: SmallVec<[Range; 1]>, primary_index: usize) -> Self {
fn normalize(mut ranges: SmallVec<[Range; 1]>, mut primary_index: usize) -> Selection {
let primary = ranges[primary_index];
ranges.sort_unstable_by_key(Range::from);
primary_index = ranges.iter().position(|&range| range == primary).unwrap();
let mut result: SmallVec<[Range; 1]> = SmallVec::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(
smallvec![
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(
smallvec![
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");
}
}
|
