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) ); } }