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use crate::graphemes::{nth_next_grapheme_boundary, nth_prev_grapheme_boundary, RopeGraphemes};
use crate::{Buffer, Rope, RopeSlice, Selection, SelectionRange};
/// A state represents the current editor state of a single buffer.
pub struct State {
pub doc: Buffer,
pub selection: Selection,
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum Direction {
Forward,
Backward,
}
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum Granularity {
Character,
Word,
Line,
// LineBoundary
}
impl State {
#[must_use]
pub fn new(doc: Buffer) -> Self {
Self {
doc,
selection: Selection::single(0, 0),
}
}
// TODO: buf/selection accessors
// 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_pos(
&self,
pos: usize,
dir: Direction,
granularity: Granularity,
count: usize,
) -> usize {
let text = &self.doc.contents;
match (dir, granularity) {
// TODO: clamp movement to line, prevent moving onto \n at the end
(Direction::Backward, Granularity::Character) => {
nth_prev_grapheme_boundary(&text.slice(..), pos, count)
}
(Direction::Forward, Granularity::Character) => {
nth_next_grapheme_boundary(&text.slice(..), pos, count)
}
(_, Granularity::Line) => move_vertically(&text.slice(..), dir, pos, count),
_ => pos,
}
}
pub fn move_selection(
&self,
sel: Selection,
dir: Direction,
granularity: Granularity,
count: usize,
) -> Selection {
// TODO: move all selections according to normal cursor move semantics by collapsing it
// into cursors and moving them vertically
let ranges = sel.ranges.into_iter().map(|range| {
// let pos = if !range.is_empty() {
// // if selection already exists, bump it to the start or end of current select first
// if dir == Direction::Backward {
// range.from()
// } else {
// range.to()
// }
// } else {
let pos = self.move_pos(range.head, dir, granularity, count);
// };
SelectionRange::new(pos, pos)
});
Selection::new(ranges.collect(), sel.primary_index)
// TODO: update selection in state via transaction
}
pub fn extend_selection(
&self,
sel: Selection,
dir: Direction,
granularity: Granularity,
count: usize,
) -> Selection {
let ranges = sel.ranges.into_iter().map(|range| {
let pos = self.move_pos(range.head, dir, granularity, count);
SelectionRange::new(range.anchor, pos)
});
Selection::new(ranges.collect(), sel.primary_index)
// TODO: update selection in state via transaction
}
pub fn file(&self) -> &Rope {
// used to access file contents for rendering to screen
&self.doc.contents
}
}
/// Coordinates are a 0-indexed line and column pair.
type Coords = (usize, usize); // line, col
/// Convert a character index to (line, column) coordinates.
pub fn coords_at_pos(text: &RopeSlice, pos: usize) -> Coords {
let line = text.char_to_line(pos);
let line_start = text.line_to_char(line);
let col = text.slice(line_start..pos).len_chars();
(line, col)
}
/// Convert (line, column) coordinates to a character index.
pub fn pos_at_coords(text: &RopeSlice, coords: Coords) -> usize {
let (line, col) = coords;
let line_start = text.line_to_char(line);
nth_next_grapheme_boundary(text, line_start, col)
}
fn move_vertically(text: &RopeSlice, dir: Direction, pos: usize, count: usize) -> usize {
let (line, col) = coords_at_pos(text, pos);
let new_line = match dir {
Direction::Backward => line.saturating_sub(count),
Direction::Forward => std::cmp::min(line.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 = if new_line_len < col {
// TODO: preserve horiz here
new_line_len
} else {
col
};
pos_at_coords(text, (new_line, new_col))
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_coords_at_pos() {
let text = Rope::from("ḧëḷḷö\nẅöṛḷḋ");
assert_eq!(coords_at_pos(&text.slice(..), 0), (0, 0));
// TODO: what is the coordinate of newline?
assert_eq!(coords_at_pos(&text.slice(..), 5), (0, 5)); // position on \n
assert_eq!(coords_at_pos(&text.slice(..), 6), (1, 0)); // position on w
assert_eq!(coords_at_pos(&text.slice(..), 7), (1, 1)); // position on o
assert_eq!(coords_at_pos(&text.slice(..), 10), (1, 4)); // position on d
}
#[test]
fn test_pos_at_coords() {
let text = Rope::from("ḧëḷḷö\nẅöṛḷḋ");
assert_eq!(pos_at_coords(&text.slice(..), (0, 0)), 0);
assert_eq!(pos_at_coords(&text.slice(..), (0, 5)), 5); // position on \n
assert_eq!(pos_at_coords(&text.slice(..), (1, 0)), 6); // position on w
assert_eq!(pos_at_coords(&text.slice(..), (1, 1)), 7); // position on o
assert_eq!(pos_at_coords(&text.slice(..), (1, 4)), 10); // position on d
}
#[test]
fn test_vertical_move() {
let text = Rope::from("abcd\nefg\nwrs");
let pos = pos_at_coords(&text.slice(..), (0, 4));
let slice = text.slice(..);
assert_eq!(
coords_at_pos(&slice, move_vertically(&slice, Direction::Forward, pos, 1)),
(1, 2)
);
}
}
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