Add primitives for converting between char offset indices and coords.
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387fb57c94
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2 changed files with 44 additions and 3 deletions
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@ -5,7 +5,7 @@ mod selection;
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mod state;
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mod transaction;
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pub use ropey::Rope;
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pub use ropey::{Rope, RopeSlice};
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pub use tendril::StrTendril as Tendril;
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pub use buffer::Buffer;
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@ -1,5 +1,5 @@
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use crate::graphemes::{nth_next_grapheme_boundary, nth_prev_grapheme_boundary};
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use crate::{Buffer, Selection, SelectionRange};
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use crate::graphemes::{nth_next_grapheme_boundary, nth_prev_grapheme_boundary, RopeGraphemes};
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use crate::{Buffer, Rope, RopeSlice, Selection, SelectionRange};
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/// A state represents the current editor state of a single buffer.
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pub struct State {
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@ -117,3 +117,44 @@ impl State {
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// TODO: update selection in state via transaction
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}
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}
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/// Coordinates are a 0-indexed line and column pair.
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type Coords = (usize, usize); // line, col
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/// Convert a character index to (line, column) coordinates.
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pub fn coords_at_pos(text: &RopeSlice, pos: usize) -> Coords {
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let line = text.char_to_line(pos);
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let line_start = text.line_to_char(line);
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let col = RopeGraphemes::new(&text.slice(line_start..pos)).count();
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(line, col)
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}
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/// Convert (line, column) coordinates to a character index.
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pub fn pos_at_coords(text: &RopeSlice, coords: Coords) -> usize {
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let (line, col) = coords;
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let line_start = text.line_to_char(line);
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nth_next_grapheme_boundary(text, line_start, col)
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_coords_at_pos() {
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let text = Rope::from("ḧëḷḷö\nẅöṛḷḋ");
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assert_eq!(coords_at_pos(&text.slice(..), 0), (0, 0));
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assert_eq!(coords_at_pos(&text.slice(..), 5), (0, 5)); // position on \n
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assert_eq!(coords_at_pos(&text.slice(..), 6), (1, 0)); // position on w
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assert_eq!(coords_at_pos(&text.slice(..), 11), (1, 5)); // position on d
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}
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#[test]
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fn test_pos_at_coords() {
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let text = Rope::from("ḧëḷḷö\nẅöṛḷḋ");
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assert_eq!(pos_at_coords(&text.slice(..), (0, 0)), 0);
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assert_eq!(pos_at_coords(&text.slice(..), (0, 5)), 5); // position on \n
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assert_eq!(pos_at_coords(&text.slice(..), (1, 0)), 6); // position on w
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assert_eq!(pos_at_coords(&text.slice(..), (1, 5)), 11); // position on d
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}
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}
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