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use crate::graphemes::{nth_next_grapheme_boundary, nth_prev_grapheme_boundary, RopeGraphemes};
use crate::{coords_at_pos, pos_at_coords, ChangeSet, Position, Range, Rope, RopeSlice, Selection};
/// A state represents the current editor state of a single buffer.
#[derive(Clone)]
pub struct State {
// TODO: fields should be private but we need to refactor commands.rs first
pub doc: Rope,
pub selection: Selection,
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum Direction {
Forward,
Backward,
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum Granularity {
Character,
Line,
}
impl State {
#[must_use]
pub fn new(doc: Rope) -> Self {
Self {
doc,
selection: Selection::point(0),
}
}
// update/transact:
// update(desc) => transaction ? transaction.doc() for applied doc
// transaction.apply(doc)
// doc.transact(fn -> ... end)
// replaceSelection (transaction that replaces selection)
// changeByRange
// changes
// slice
//
// getters:
// tabSize
// indentUnit
// languageDataAt()
//
// config:
// indentation
// tabSize
// lineUnit
// syntax
// foldable
// changeFilter/transactionFilter
pub fn move_range(
&self,
range: Range,
dir: Direction,
granularity: Granularity,
count: usize,
extend: bool,
) -> Range {
let text = self.doc.slice(..);
let pos = range.head;
let line = text.char_to_line(pos);
// TODO: we can optimize clamping by passing in RopeSlice limited to current line. that way
// we stop calculating past start/end of line.
let pos = match (dir, granularity) {
(Direction::Backward, Granularity::Character) => {
let start = text.line_to_char(line);
nth_prev_grapheme_boundary(text, pos, count).max(start)
}
(Direction::Forward, Granularity::Character) => {
// Line end is pos at the start of next line - 1
// subtract another 1 because the line ends with \n
let end = text.line_to_char(line + 1).saturating_sub(2);
nth_next_grapheme_boundary(text, pos, count).min(end)
}
(_, Granularity::Line) => return move_vertically(text, dir, range, count, extend),
};
Range::new(if extend { range.anchor } else { pos }, pos)
}
pub fn move_selection(
&self,
dir: Direction,
granularity: Granularity,
count: usize,
) -> Selection {
self.selection
.transform(|range| self.move_range(range, dir, granularity, count, false))
}
pub fn extend_selection(
&self,
dir: Direction,
granularity: Granularity,
count: usize,
) -> Selection {
self.selection
.transform(|range| self.move_range(range, dir, granularity, count, true))
}
}
fn move_vertically(
text: RopeSlice,
dir: Direction,
range: Range,
count: usize,
extend: bool,
) -> Range {
let Position { row, col } = coords_at_pos(text, range.head);
let horiz = range.horiz.unwrap_or(col as u32);
let new_line = match dir {
Direction::Backward => row.saturating_sub(count),
Direction::Forward => std::cmp::min(row.saturating_add(count), text.len_lines() - 1),
};
// convert to 0-indexed, subtract another 1 because len_chars() counts \n
let new_line_len = text.line(new_line).len_chars().saturating_sub(2);
let new_col = std::cmp::min(horiz as usize, new_line_len);
let pos = pos_at_coords(text, Position::new(new_line, new_col));
let mut range = Range::new(if extend { range.anchor } else { pos }, pos);
range.horiz = Some(horiz);
range
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_vertical_move() {
let text = Rope::from("abcd\nefg\nwrs");
let slice = text.slice(..);
let pos = pos_at_coords(slice, (0, 4).into());
let range = Range::new(pos, pos);
assert_eq!(
coords_at_pos(
slice,
move_vertically(slice, Direction::Forward, range, 1, false).head
),
(1, 2).into()
);
}
}
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