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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};
#[derive(Copy, Clone, PartialEq, Eq)]
pub enum Direction {
Forward,
Backward,
}
pub fn move_horizontally(
text: RopeSlice,
range: Range,
dir: Direction,
count: usize,
extend: bool,
) -> Range {
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 {
Direction::Backward => {
let start = text.line_to_char(line);
nth_prev_grapheme_boundary(text, pos, count).max(start)
}
Direction::Forward => {
// 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)
}
};
Range::new(if extend { range.anchor } else { pos }, pos)
}
pub fn move_vertically(
text: RopeSlice,
range: Range,
dir: Direction,
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
}
pub fn move_next_word_start(slice: RopeSlice, mut pos: usize, count: usize) -> usize {
for _ in 0..count {
if pos + 1 == slice.len_chars() {
return pos;
}
let mut ch = slice.char(pos);
let next = slice.char(pos + 1);
// if we're at the end of a word, or on whitespce right before new one
if categorize(ch) != categorize(next) {
pos += 1;
ch = next;
}
if is_word(ch) {
skip_over_next(slice, &mut pos, is_word);
} else if ch.is_ascii_punctuation() {
skip_over_next(slice, &mut pos, |ch| ch.is_ascii_punctuation());
}
// TODO: don't include newline?
skip_over_next(slice, &mut pos, |ch| ch.is_ascii_whitespace());
}
pos
}
pub fn move_prev_word_start(slice: RopeSlice, mut pos: usize, count: usize) -> usize {
for _ in 0..count {
if pos == 0 {
return pos;
}
let ch = slice.char(pos);
let prev = slice.char(pos - 1);
if categorize(ch) != categorize(prev) {
pos -= 1;
}
// match (category c1, category c2) => {
// if c1 != c2 {
// }
// }
// TODO: skip while eol
// TODO: don't include newline?
skip_over_prev(slice, &mut pos, |ch| ch.is_ascii_whitespace());
// refetch
let ch = slice.char(pos);
if is_word(ch) {
skip_over_prev(slice, &mut pos, is_word);
} else if ch.is_ascii_punctuation() {
skip_over_prev(slice, &mut pos, |ch| ch.is_ascii_punctuation());
}
pos = pos.saturating_add(1)
}
pos
}
pub fn move_next_word_end(slice: RopeSlice, mut pos: usize, count: usize) -> usize {
for _ in 0..count {
if pos + 1 == slice.len_chars() {
return pos;
}
let ch = slice.char(pos);
let next = slice.char(pos + 1);
if categorize(ch) != categorize(next) {
pos += 1;
}
// TODO: don't include newline?
skip_over_next(slice, &mut pos, |ch| ch.is_ascii_whitespace());
// refetch
let ch = slice.char(pos);
if is_word(ch) {
skip_over_next(slice, &mut pos, is_word);
} else if ch.is_ascii_punctuation() {
skip_over_next(slice, &mut pos, |ch| ch.is_ascii_punctuation());
}
pos -= 1
}
pos
}
// ---- util ------------
// used for by-word movement
fn is_word(ch: char) -> bool {
ch.is_alphanumeric() || ch == '_'
}
#[derive(Debug, Eq, PartialEq)]
enum Category {
Whitespace,
Eol,
Word,
Punctuation,
}
fn categorize(ch: char) -> Category {
if ch == '\n' {
Category::Eol
} else if ch.is_ascii_whitespace() {
Category::Whitespace
} else if ch.is_ascii_punctuation() {
Category::Punctuation
} else if ch.is_ascii_alphanumeric() {
Category::Word
} else {
unreachable!()
}
}
#[inline]
pub fn skip_over_next<F>(slice: RopeSlice, pos: &mut usize, fun: F)
where
F: Fn(char) -> bool,
{
let mut chars = slice.chars_at(*pos);
for ch in chars {
if !fun(ch) {
break;
}
*pos += 1;
}
}
#[inline]
pub fn skip_over_prev<F>(slice: RopeSlice, pos: &mut usize, fun: F)
where
F: Fn(char) -> bool,
{
// need to +1 so that prev() includes current char
let mut chars = slice.chars_at(*pos + 1);
while let Some(ch) = chars.prev() {
if !fun(ch) {
break;
}
*pos = pos.saturating_sub(1);
}
}
#[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, range, Direction::Forward, 1, false).head
),
(1, 2).into()
);
}
}
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