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@ -1,5 +1,5 @@
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//! Selections are the primary editing construct. Even a single cursor is
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//! defined as a single empty or 1-wide selection range.
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//! Selections are the primary editing construct. Even cursors are
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//! defined as a selection range.
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//!
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//! All positioning is done via `char` offsets into the buffer.
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use crate::{
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@ -14,17 +14,20 @@ use std::borrow::Cow;
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/// A single selection range.
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///
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/// The range consists of an "anchor" and "head" position in
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/// A range consists of an "anchor" and "head" position in
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/// the text. The head is the part that the user moves when
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/// directly extending the selection. The head and anchor
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/// can be in any order: either can precede or follow the
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/// other in the text, and they can share the same position
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/// for a zero-width range.
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/// directly extending a selection. The head and anchor
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/// can be in any order, or even share the same position.
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///
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/// The anchor and head positions use gap indexing, meaning
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/// that their indices represent the the gaps *between* `char`s
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/// rather than the `char`s themselves. For example, 1
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/// represents the position between the first and second `char`.
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///
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/// Below are some example `Range` configurations to better
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/// illustrate. The anchor and head indices are show as
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/// "(anchor, head)", followed by example text with "[" and "]"
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/// inserted to visually represent the anchor and head positions:
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/// inserted to represent the anchor and head positions:
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///
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/// - (0, 3): [Som]e text.
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/// - (3, 0): ]Som[e text.
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@ -37,6 +40,12 @@ use std::borrow::Cow;
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/// are directly adjecent, sharing an edge, do not overlap.
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/// However, a zero-width range will overlap with the shared
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/// left-edge of another range.
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///
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/// By convention, user-facing ranges are considered to have
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/// a block cursor on the head-side of the range that spans a
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/// single grapheme inward from the range's edge. There are a
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/// variety of helper methods on `Range` for working in terms of
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/// that block cursor, all of which have `cursor` in their name.
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub struct Range {
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/// The anchor of the range: the side that doesn't move when extending.
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@ -73,13 +82,6 @@ impl Range {
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std::cmp::max(self.anchor, self.head)
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}
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/// The line number that the block-cursor is on.
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#[inline]
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#[must_use]
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pub fn cursor_line(&self, text: RopeSlice) -> usize {
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text.char_to_line(self.cursor(text))
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}
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/// The (inclusive) range of lines that the range overlaps.
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#[inline]
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#[must_use]
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@ -184,32 +186,16 @@ impl Range {
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}
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}
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/// Compute a possibly new range from this range, attempting to ensure
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/// a minimum range width of 1 char by shifting the head in the forward
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/// direction as needed.
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///
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/// This method will never shift the anchor, and will only shift the
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/// head in the forward direction. Therefore, this method can fail
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/// at ensuring the minimum width if and only if the passed range is
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/// both zero-width and at the end of the `RopeSlice`.
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///
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/// If the input range is grapheme-boundary aligned, the returned range
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/// will also be. Specifically, if the head needs to shift to achieve
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/// the minimum width, it will shift to the next grapheme boundary.
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#[must_use]
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// groupAt
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#[inline]
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pub fn min_width_1(&self, slice: RopeSlice) -> Self {
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if self.anchor == self.head {
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Range {
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anchor: self.anchor,
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head: next_grapheme_boundary(slice, self.head),
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horiz: self.horiz,
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}
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} else {
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*self
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}
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pub fn fragment<'a, 'b: 'a>(&'a self, text: RopeSlice<'b>) -> Cow<'b, str> {
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text.slice(self.from()..self.to()).into()
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}
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//--------------------------------
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// Alignment methods.
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/// Compute a possibly new range from this range, with its ends
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/// shifted as needed to align with grapheme boundaries.
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///
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@ -243,6 +229,35 @@ impl Range {
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}
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}
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/// Compute a possibly new range from this range, attempting to ensure
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/// a minimum range width of 1 char by shifting the head in the forward
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/// direction as needed.
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///
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/// This method will never shift the anchor, and will only shift the
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/// head in the forward direction. Therefore, this method can fail
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/// at ensuring the minimum width if and only if the passed range is
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/// both zero-width and at the end of the `RopeSlice`.
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///
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/// If the input range is grapheme-boundary aligned, the returned range
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/// will also be. Specifically, if the head needs to shift to achieve
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/// the minimum width, it will shift to the next grapheme boundary.
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#[must_use]
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#[inline]
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pub fn min_width_1(&self, slice: RopeSlice) -> Self {
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if self.anchor == self.head {
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Range {
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anchor: self.anchor,
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head: next_grapheme_boundary(slice, self.head),
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horiz: self.horiz,
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}
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} else {
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*self
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}
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}
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//--------------------------------
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// Block-cursor methods.
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/// Gets the left-side position of the block cursor.
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#[must_use]
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#[inline]
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@ -284,11 +299,11 @@ impl Range {
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}
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}
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// groupAt
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/// The line number that the block-cursor is on.
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#[inline]
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pub fn fragment<'a, 'b: 'a>(&'a self, text: RopeSlice<'b>) -> Cow<'b, str> {
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text.slice(self.from()..self.to()).into()
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#[must_use]
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pub fn cursor_line(&self, text: RopeSlice) -> usize {
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text.char_to_line(self.cursor(text))
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}
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}
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