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Change the `Range` type and associated functions to gap indexing.

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pull/376/head
Nathan Vegdahl 3 years ago
parent 79f096963c
commit c1b0a71975
1 changed files with 126 additions and 56 deletions
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174
helix-core/src/selection.rs
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@ -1,5 +1,5 @@
//! Selections are the primary editing construct. Even a single cursor is defined as an empty
//! single selection range.
//! Selections are the primary editing construct. Even a single cursor is
//! defined as a single empty or 1-wide selection range.
//!
//! All positioning is done via `char` offsets into the buffer.
use crate::{Assoc, ChangeSet, Rope, RopeSlice};
@ -15,16 +15,39 @@ fn abs_difference(x: usize, y: usize) -> usize {
}
}
/// A single selection range. Anchor-inclusive, head-exclusive.
/// A single selection range.
///
/// The range consists of an "anchor" and "head" position in
/// the text. The head is the part that the user moves when
/// directly extending the selection. The head and anchor
/// can be in any order: either can precede or follow the
/// other in the text, and they can share the same position
/// for a zero-width range.
///
/// Below are some example `Range` configurations to better
/// illustrate. The anchor and head indices are show as
/// "(anchor, head)", followed by example text with "[" and "]"
/// inserted to visually represent the anchor and head positions:
///
/// - (0, 3): [Som]e text.
/// - (3, 0): ]Som[e text.
/// - (2, 7): So[me te]xt.
/// - (1, 1): S[]ome text.
///
/// Ranges are considered to be inclusive on the left and
/// exclusive on the right, regardless of anchor-head ordering.
/// This means, for example, that non-zero-width ranges that
/// are directly adjecent, sharing an edge, do not overlap.
/// However, a zero-width range will overlap with the shared
/// left-edge of another range.
#[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,
pub horiz: Option<u32>,
} // TODO: might be cheaper to store normalized as from/to and an inverted flag
}
impl Range {
pub fn new(anchor: usize, head: usize) -> Self {
@ -62,25 +85,14 @@ impl Range {
/// Check two ranges for overlap.
#[must_use]
pub fn overlaps(&self, other: &Self) -> bool {
// cursor overlap is checked differently
if self.is_empty() {
let pos = self.head;
pos >= other.from() && other.to() >= pos
} else {
self.to() > other.from() && other.to() > self.from()
}
// To my eye, it's non-obvious why this works, but I arrived
// at it after transforming the slower version that explicitly
// enumerated more cases. The unit tests are thorough.
self.from() == other.from() || (self.to() > other.from() && other.to() > self.from())
}
pub fn contains(&self, pos: usize) -> bool {
if self.is_empty() {
return false;
}
if self.anchor < self.head {
self.anchor <= pos && pos < self.head
} else {
self.head < pos && pos <= self.anchor
}
self.from() <= pos && pos < self.to()
}
/// Map a range through a set of changes. Returns a new range representing the same position
@ -89,10 +101,10 @@ impl Range {
let anchor = changes.map_pos(self.anchor, Assoc::After);
let head = changes.map_pos(self.head, Assoc::After);
// TODO: possibly unnecessary
if self.anchor == anchor && self.head == head {
return self;
}
// We want to return a new `Range` with `horiz == None` every time,
// even if the anchor and head haven't changed, because we don't
// know if the *visual* position hasn't changed due to
// character-width or grapheme changes earlier in the text.
Self {
anchor,
head,
@ -103,30 +115,28 @@ impl Range {
/// 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 Self {
anchor: from,
head: to,
horiz: None,
};
}
debug_assert!(from <= to);
if self.anchor <= self.head {
Self {
anchor: self.anchor,
head: if abs_difference(from, self.anchor) > abs_difference(to, self.anchor) {
from
anchor: self.anchor.min(from),
head: self.head.max(to),
horiz: None,
}
} else {
to
},
Self {
anchor: self.anchor.max(to),
head: self.head.min(from),
horiz: None,
}
}
}
// groupAt
#[inline]
pub fn fragment<'a, 'b: 'a>(&'a self, text: RopeSlice<'b>) -> Cow<'b, str> {
Cow::from(text.slice(self.from()..self.to() + 1))
text.slice(self.from()..self.to()).into()
}
}
@ -355,7 +365,7 @@ pub fn select_on_matches(
let start = text.byte_to_char(start_byte + mat.start());
let end = text.byte_to_char(start_byte + mat.end());
result.push(Range::new(start, end.saturating_sub(1)));
result.push(Range::new(start, end));
}
}
@ -376,6 +386,12 @@ pub fn split_on_matches(
let mut result = SmallVec::with_capacity(selection.len());
for sel in selection {
// Special case: zero-width selection.
if sel.from() == sel.to() {
result.push(*sel);
continue;
}
// TODO: can't avoid occasional allocations since Regex can't operate on chunks yet
let fragment = sel.fragment(text);
@ -388,13 +404,12 @@ pub fn split_on_matches(
for mat in regex.find_iter(&fragment) {
// TODO: retain range direction
let end = text.byte_to_char(start_byte + mat.start());
result.push(Range::new(start, end.saturating_sub(1)));
result.push(Range::new(start, end));
start = text.byte_to_char(start_byte + mat.end());
}
if start <= sel_end {
if start < sel_end {
result.push(Range::new(start, sel_end));
}
}
@ -475,7 +490,7 @@ mod test {
.collect::<Vec<String>>()
.join(",");
assert_eq!(res, "8/10,10/12");
assert_eq!(res, "8/10,10/12,12/12");
}
#[test]
@ -489,9 +504,56 @@ mod test {
assert_eq!(range.contains(13), false);
let range = Range::new(9, 6);
assert_eq!(range.contains(9), true);
assert_eq!(range.contains(9), false);
assert_eq!(range.contains(7), true);
assert_eq!(range.contains(6), false);
assert_eq!(range.contains(6), true);
}
#[test]
fn test_overlaps() {
// Two non-zero-width ranges, no overlap.
assert!(!Range::new(0, 3).overlaps(&Range::new(3, 6)));
assert!(!Range::new(0, 3).overlaps(&Range::new(6, 3)));
assert!(!Range::new(3, 0).overlaps(&Range::new(3, 6)));
assert!(!Range::new(3, 0).overlaps(&Range::new(6, 3)));
assert!(!Range::new(3, 6).overlaps(&Range::new(0, 3)));
assert!(!Range::new(3, 6).overlaps(&Range::new(3, 0)));
assert!(!Range::new(6, 3).overlaps(&Range::new(0, 3)));
assert!(!Range::new(6, 3).overlaps(&Range::new(3, 0)));
// Two non-zero-width ranges, overlap.
assert!(Range::new(0, 4).overlaps(&Range::new(3, 6)));
assert!(Range::new(0, 4).overlaps(&Range::new(6, 3)));
assert!(Range::new(4, 0).overlaps(&Range::new(3, 6)));
assert!(Range::new(4, 0).overlaps(&Range::new(6, 3)));
assert!(Range::new(3, 6).overlaps(&Range::new(0, 4)));
assert!(Range::new(3, 6).overlaps(&Range::new(4, 0)));
assert!(Range::new(6, 3).overlaps(&Range::new(0, 4)));
assert!(Range::new(6, 3).overlaps(&Range::new(4, 0)));
// Zero-width and non-zero-width range, no overlap.
assert!(!Range::new(0, 3).overlaps(&Range::new(3, 3)));
assert!(!Range::new(3, 0).overlaps(&Range::new(3, 3)));
assert!(!Range::new(3, 3).overlaps(&Range::new(0, 3)));
assert!(!Range::new(3, 3).overlaps(&Range::new(3, 0)));
// Zero-width and non-zero-width range, overlap.
assert!(Range::new(1, 4).overlaps(&Range::new(1, 1)));
assert!(Range::new(4, 1).overlaps(&Range::new(1, 1)));
assert!(Range::new(1, 1).overlaps(&Range::new(1, 4)));
assert!(Range::new(1, 1).overlaps(&Range::new(4, 1)));
assert!(Range::new(1, 4).overlaps(&Range::new(3, 3)));
assert!(Range::new(4, 1).overlaps(&Range::new(3, 3)));
assert!(Range::new(3, 3).overlaps(&Range::new(1, 4)));
assert!(Range::new(3, 3).overlaps(&Range::new(4, 1)));
// Two zero-width ranges, no overlap.
assert!(!Range::new(0, 0).overlaps(&Range::new(1, 1)));
assert!(!Range::new(1, 1).overlaps(&Range::new(0, 0)));
// Two zero-width ranges, overlap.
assert!(Range::new(1, 1).overlaps(&Range::new(1, 1)));
}
#[test]
@ -500,24 +562,32 @@ mod test {
let text = Rope::from(" abcd efg wrs xyz 123 456");
let selection = Selection::new(smallvec![Range::new(0, 8), Range::new(10, 19),], 0);
let selection = Selection::new(smallvec![Range::new(0, 9), Range::new(11, 20),], 0);
let result = split_on_matches(text.slice(..), &selection, &Regex::new(r"\s+").unwrap());
assert_eq!(
result.ranges(),
&[
Range::new(0, 3),
Range::new(5, 7),
Range::new(10, 11),
Range::new(15, 17),
Range::new(19, 19),
// We get a leading zero-width range when there's
// a leading match because ranges are inclusive on
// the left. Imagine, for example, if the entire
// selection range were matched: you'd still want
// at least one range to remain after the split.
Range::new(0, 0),
Range::new(1, 5),
Range::new(6, 9),
Range::new(11, 13),
Range::new(16, 19),
// In contrast to the comment above, there is no
// _trailing_ zero-width range despite the trailing
// match, because ranges are exclusive on the right.
]
);
assert_eq!(
result.fragments(text.slice(..)).collect::<Vec<_>>(),
&["abcd", "efg", "rs", "xyz", "1"]
&["", "abcd", "efg", "rs", "xyz"]
);
}
}

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