diff options
Diffstat (limited to 'helix-core/src/selection.rs')
| -rw-r--r-- | helix-core/src/selection.rs | 182 |
1 files changed, 126 insertions, 56 deletions
diff --git a/helix-core/src/selection.rs b/helix-core/src/selection.rs index 370a1f6e..35ad9845 100644 --- a/helix-core/src/selection.rs +++ b/helix-core/src/selection.rs @@ -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, @@ -103,22 +115,20 @@ 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); - Self { - anchor: self.anchor, - head: if abs_difference(from, self.anchor) > abs_difference(to, self.anchor) { - from - } else { - to - }, - horiz: None, + if self.anchor <= self.head { + Self { + anchor: self.anchor.min(from), + head: self.head.max(to), + horiz: None, + } + } else { + Self { + anchor: self.anchor.max(to), + head: self.head.min(from), + horiz: None, + } } } @@ -126,7 +136,7 @@ impl Range { #[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] @@ -489,35 +504,90 @@ 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] fn test_split_on_matches() { use crate::regex::Regex; - let text = Rope::from("abcd efg wrs xyz 123 456"); + 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"] ); } } |