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helix/helix-core/src/surround.rs

289 lines
8.3 KiB
Rust

use crate::graphemes::next_grapheme_boundary;
use crate::{search, Selection};
use ropey::RopeSlice;
pub const PAIRS: &[(char, char)] = &[
('(', ')'),
('[', ']'),
('{', '}'),
('<', '>'),
('«', '»'),
('「', '」'),
('', ''),
];
/// Given any char in [PAIRS], return the open and closing chars. If not found in
/// [PAIRS] return (ch, ch).
///
/// ```
/// use helix_core::surround::get_pair;
///
/// assert_eq!(get_pair('['), ('[', ']'));
/// assert_eq!(get_pair('}'), ('{', '}'));
/// assert_eq!(get_pair('"'), ('"', '"'));
/// ```
pub fn get_pair(ch: char) -> (char, char) {
PAIRS
.iter()
.find(|(open, close)| *open == ch || *close == ch)
.copied()
.unwrap_or((ch, ch))
}
/// Find the position of surround pairs of `ch` which can be either a closing
/// or opening pair. `n` will skip n - 1 pairs (eg. n=2 will discard (only)
/// the first pair found and keep looking)
pub fn find_nth_pairs_pos(
text: RopeSlice,
ch: char,
pos: usize,
n: usize,
) -> Option<(usize, usize)> {
let (open, close) = get_pair(ch);
if text.len_chars() < 2 || pos >= text.len_chars() {
return None;
}
if open == close {
if Some(open) == text.get_char(pos) {
// Special case: cursor is directly on a matching char.
match pos {
0 => Some((pos, search::find_nth_next(text, close, pos + 1, n, true)?)),
_ if (pos + 1) == text.len_chars() => Some((
search::find_nth_prev(text, open, pos, n, true)?,
text.len_chars(),
)),
// We return no match because there's no way to know which
// side of the char we should be searching on.
_ => None,
}
} else {
Some((
search::find_nth_prev(text, open, pos, n, true)?,
search::find_nth_next(text, close, pos, n, true)?,
))
}
} else {
Some((
find_nth_open_pair(text, open, close, pos, n)?,
next_grapheme_boundary(text, find_nth_close_pair(text, open, close, pos, n)?),
))
}
}
fn find_nth_open_pair(
text: RopeSlice,
open: char,
close: char,
mut pos: usize,
n: usize,
) -> Option<usize> {
let mut chars = text.chars_at(pos + 1);
// Adjusts pos for the first iteration, and handles the case of the
// cursor being *on* the close character which will get falsely stepped over
// if not skipped here
if chars.prev()? == open {
return Some(pos);
}
for _ in 0..n {
let mut step_over: usize = 0;
loop {
let c = chars.prev()?;
pos = pos.saturating_sub(1);
// ignore other surround pairs that are enclosed *within* our search scope
if c == close {
step_over += 1;
} else if c == open {
if step_over == 0 {
break;
}
step_over = step_over.saturating_sub(1);
}
}
}
Some(pos)
}
fn find_nth_close_pair(
text: RopeSlice,
open: char,
close: char,
mut pos: usize,
n: usize,
) -> Option<usize> {
if pos >= text.len_chars() {
return None;
}
let mut chars = text.chars_at(pos);
if chars.next()? == close {
return Some(pos);
}
for _ in 0..n {
let mut step_over: usize = 0;
loop {
let c = chars.next()?;
pos += 1;
if c == open {
step_over += 1;
} else if c == close {
if step_over == 0 {
break;
}
step_over = step_over.saturating_sub(1);
}
}
}
Some(pos)
}
/// Find position of surround characters around every cursor. Returns None
/// if any positions overlap. Note that the positions are in a flat Vec.
/// Use get_surround_pos().chunks(2) to get matching pairs of surround positions.
/// `ch` can be either closing or opening pair.
pub fn get_surround_pos(
text: RopeSlice,
selection: &Selection,
ch: char,
skip: usize,
) -> Option<Vec<usize>> {
let mut change_pos = Vec::new();
for range in selection {
let (open_pos, close_pos) = find_nth_pairs_pos(text, ch, range.head, skip)?;
if change_pos.contains(&open_pos) || change_pos.contains(&close_pos) {
return None;
}
change_pos.extend_from_slice(&[open_pos, close_pos]);
}
Some(change_pos)
}
#[cfg(test)]
mod test {
use super::*;
use crate::Range;
use ropey::Rope;
use smallvec::SmallVec;
#[test]
fn test_find_nth_pairs_pos() {
let doc = Rope::from("some (text) here");
let slice = doc.slice(..);
// cursor on [t]ext
assert_eq!(find_nth_pairs_pos(slice, '(', 6, 1), Some((5, 11)));
assert_eq!(find_nth_pairs_pos(slice, ')', 6, 1), Some((5, 11)));
// cursor on so[m]e
assert_eq!(find_nth_pairs_pos(slice, '(', 2, 1), None);
// cursor on bracket itself
assert_eq!(find_nth_pairs_pos(slice, '(', 5, 1), Some((5, 11)));
assert_eq!(find_nth_pairs_pos(slice, '(', 10, 1), Some((5, 11)));
}
#[test]
fn test_find_nth_pairs_pos_skip() {
let doc = Rope::from("(so (many (good) text) here)");
let slice = doc.slice(..);
// cursor on go[o]d
assert_eq!(find_nth_pairs_pos(slice, '(', 13, 1), Some((10, 16)));
assert_eq!(find_nth_pairs_pos(slice, '(', 13, 2), Some((4, 22)));
assert_eq!(find_nth_pairs_pos(slice, '(', 13, 3), Some((0, 28)));
}
#[test]
fn test_find_nth_pairs_pos_same() {
let doc = Rope::from("'so 'many 'good' text' here'");
let slice = doc.slice(..);
// cursor on go[o]d
assert_eq!(find_nth_pairs_pos(slice, '\'', 13, 1), Some((10, 16)));
assert_eq!(find_nth_pairs_pos(slice, '\'', 13, 2), Some((4, 22)));
assert_eq!(find_nth_pairs_pos(slice, '\'', 13, 3), Some((0, 28)));
// cursor on the quotes
assert_eq!(find_nth_pairs_pos(slice, '\'', 10, 1), None);
// this is the best we can do since opening and closing pairs are same
assert_eq!(find_nth_pairs_pos(slice, '\'', 0, 1), Some((0, 5)));
assert_eq!(find_nth_pairs_pos(slice, '\'', 27, 1), Some((21, 28)));
}
#[test]
fn test_find_nth_pairs_pos_step() {
let doc = Rope::from("((so)((many) good (text))(here))");
let slice = doc.slice(..);
// cursor on go[o]d
assert_eq!(find_nth_pairs_pos(slice, '(', 15, 1), Some((5, 25)));
assert_eq!(find_nth_pairs_pos(slice, '(', 15, 2), Some((0, 32)));
}
#[test]
fn test_find_nth_pairs_pos_mixed() {
let doc = Rope::from("(so [many {good} text] here)");
let slice = doc.slice(..);
// cursor on go[o]d
assert_eq!(find_nth_pairs_pos(slice, '{', 13, 1), Some((10, 16)));
assert_eq!(find_nth_pairs_pos(slice, '[', 13, 1), Some((4, 22)));
assert_eq!(find_nth_pairs_pos(slice, '(', 13, 1), Some((0, 28)));
}
#[test]
fn test_get_surround_pos() {
let doc = Rope::from("(some) (chars)\n(newline)");
let slice = doc.slice(..);
let selection = Selection::new(
SmallVec::from_slice(&[Range::point(2), Range::point(9), Range::point(20)]),
0,
);
// cursor on s[o]me, c[h]ars, newl[i]ne
assert_eq!(
get_surround_pos(slice, &selection, '(', 1)
.unwrap()
.as_slice(),
&[0, 6, 7, 14, 15, 24]
);
}
#[test]
fn test_get_surround_pos_bail() {
let doc = Rope::from("[some]\n(chars)xx\n(newline)");
let slice = doc.slice(..);
let selection =
Selection::new(SmallVec::from_slice(&[Range::point(2), Range::point(9)]), 0);
// cursor on s[o]me, c[h]ars
assert_eq!(
get_surround_pos(slice, &selection, '(', 1),
None // different surround chars
);
let selection = Selection::new(
SmallVec::from_slice(&[Range::point(14), Range::point(24)]),
0,
);
// cursor on [x]x, newli[n]e
assert_eq!(
get_surround_pos(slice, &selection, '(', 1),
None // overlapping surround chars
);
}
}