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helix/helix-core/src/surround.rs

408 lines
12 KiB
Rust

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use std::fmt::Display;
use crate::{movement::Direction, search, Range, Selection};
use ropey::RopeSlice;
pub const PAIRS: &[(char, char)] = &[
('(', ')'),
('[', ']'),
('{', '}'),
('<', '>'),
('«', '»'),
('「', '」'),
('', ''),
];
#[derive(Debug, PartialEq, Eq)]
pub enum Error {
PairNotFound,
CursorOverlap,
RangeExceedsText,
CursorOnAmbiguousPair,
}
impl Display for Error {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.write_str(match *self {
Error::PairNotFound => "Surround pair not found around all cursors",
Error::CursorOverlap => "Cursors overlap for a single surround pair range",
Error::RangeExceedsText => "Cursor range exceeds text length",
Error::CursorOnAmbiguousPair => "Cursor on ambiguous surround pair",
})
}
}
type Result<T> = std::result::Result<T, Error>;
/// 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))
}
pub fn find_nth_closest_pairs_pos(
text: RopeSlice,
range: Range,
mut skip: usize,
) -> Result<(usize, usize)> {
let is_open_pair = |ch| PAIRS.iter().any(|(open, _)| *open == ch);
let is_close_pair = |ch| PAIRS.iter().any(|(_, close)| *close == ch);
let mut stack = Vec::with_capacity(2);
let pos = range.from();
let mut close_pos = pos.saturating_sub(1);
for ch in text.chars_at(pos) {
close_pos += 1;
if is_open_pair(ch) {
// Track open pairs encountered so that we can step over
// the corresponding close pairs that will come up further
// down the loop. We want to find a lone close pair whose
// open pair is before the cursor position.
stack.push(ch);
continue;
}
if !is_close_pair(ch) {
// We don't care if this character isn't a brace pair item,
// so short circuit here.
continue;
}
let (open, close) = get_pair(ch);
if stack.last() == Some(&open) {
// If we are encountering the closing pair for an opener
// we just found while traversing, then its inside the
// selection and should be skipped over.
stack.pop();
continue;
}
match find_nth_open_pair(text, open, close, close_pos, 1) {
// Before we accept this pair, we want to ensure that the
// pair encloses the range rather than just the cursor.
Some(open_pos)
if open_pos <= pos.saturating_add(1)
&& close_pos >= range.to().saturating_sub(1) =>
{
// Since we have special conditions for when to
// accept, we can't just pass the skip parameter on
// through to the find_nth_*_pair methods, so we
// track skips manually here.
if skip > 1 {
skip -= 1;
continue;
}
return match range.direction() {
Direction::Forward => Ok((open_pos, close_pos)),
Direction::Backward => Ok((close_pos, open_pos)),
};
}
_ => continue,
}
}
Err(Error::PairNotFound)
}
/// 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,
range: Range,
n: usize,
) -> Result<(usize, usize)> {
if text.len_chars() < 2 {
return Err(Error::PairNotFound);
}
if range.to() >= text.len_chars() {
return Err(Error::RangeExceedsText);
}
let (open, close) = get_pair(ch);
let pos = range.cursor(text);
let (open, close) = if open == close {
if Some(open) == text.get_char(pos) {
// Cursor is directly on match char. We return no match
// because there's no way to know which side of the char
// we should be searching on.
return Err(Error::CursorOnAmbiguousPair);
}
(
search::find_nth_prev(text, open, pos, n),
search::find_nth_next(text, close, pos, n),
)
} else {
(
find_nth_open_pair(text, open, close, pos, n),
find_nth_close_pair(text, open, close, pos, n),
)
};
Option::zip(open, close).ok_or(Error::PairNotFound)
}
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. If `ch` is None, surround pairs
/// are automatically detected around each cursor (note that this may result
/// in them selecting different surround characters for each selection).
pub fn get_surround_pos(
text: RopeSlice,
selection: &Selection,
ch: Option<char>,
skip: usize,
) -> Result<Vec<usize>> {
let mut change_pos = Vec::new();
for &range in selection {
let (open_pos, close_pos) = match ch {
Some(ch) => find_nth_pairs_pos(text, ch, range, skip)?,
None => find_nth_closest_pairs_pos(text, range, skip)?,
};
if change_pos.contains(&open_pos) || change_pos.contains(&close_pos) {
return Err(Error::CursorOverlap);
}
change_pos.extend_from_slice(&[open_pos, close_pos]);
}
Ok(change_pos)
}
#[cfg(test)]
mod test {
use super::*;
use crate::Range;
use ropey::Rope;
use smallvec::SmallVec;
#[test]
fn test_get_surround_pos() {
#[rustfmt::skip]
let (doc, selection, expectations) =
rope_with_selections_and_expectations(
"(some) (chars)\n(newline)",
"_ ^ _ _ ^ _\n_ ^ _"
);
assert_eq!(
get_surround_pos(doc.slice(..), &selection, Some('('), 1).unwrap(),
expectations
);
}
#[test]
fn test_get_surround_pos_bail_different_surround_chars() {
#[rustfmt::skip]
let (doc, selection, _) =
rope_with_selections_and_expectations(
"[some]\n(chars)xx\n(newline)",
" ^ \n ^ \n "
);
assert_eq!(
get_surround_pos(doc.slice(..), &selection, Some('('), 1),
Err(Error::PairNotFound)
);
}
#[test]
fn test_get_surround_pos_bail_overlapping_surround_chars() {
#[rustfmt::skip]
let (doc, selection, _) =
rope_with_selections_and_expectations(
"[some]\n(chars)xx\n(newline)",
" \n ^ \n ^ "
);
assert_eq!(
get_surround_pos(doc.slice(..), &selection, Some('('), 1),
Err(Error::PairNotFound) // overlapping surround chars
);
}
#[test]
fn test_get_surround_pos_bail_cursor_overlap() {
#[rustfmt::skip]
let (doc, selection, _) =
rope_with_selections_and_expectations(
"[some]\n(chars)xx\n(newline)",
" ^^ \n \n "
);
assert_eq!(
get_surround_pos(doc.slice(..), &selection, Some('['), 1),
Err(Error::CursorOverlap)
);
}
#[test]
fn test_find_nth_pairs_pos_quote_success() {
#[rustfmt::skip]
let (doc, selection, expectations) =
rope_with_selections_and_expectations(
"some 'quoted text' on this 'line'\n'and this one'",
" _ ^ _ \n "
);
assert_eq!(2, expectations.len());
assert_eq!(
find_nth_pairs_pos(doc.slice(..), '\'', selection.primary(), 1)
.expect("find should succeed"),
(expectations[0], expectations[1])
)
}
#[test]
fn test_find_nth_pairs_pos_nested_quote_success() {
#[rustfmt::skip]
let (doc, selection, expectations) =
rope_with_selections_and_expectations(
"some 'nested 'quoted' text' on this 'line'\n'and this one'",
" _ ^ _ \n "
);
assert_eq!(2, expectations.len());
assert_eq!(
find_nth_pairs_pos(doc.slice(..), '\'', selection.primary(), 2)
.expect("find should succeed"),
(expectations[0], expectations[1])
)
}
#[test]
fn test_find_nth_pairs_pos_inside_quote_ambiguous() {
#[rustfmt::skip]
let (doc, selection, _) =
rope_with_selections_and_expectations(
"some 'nested 'quoted' text' on this 'line'\n'and this one'",
" ^ \n "
);
assert_eq!(
find_nth_pairs_pos(doc.slice(..), '\'', selection.primary(), 1),
Err(Error::CursorOnAmbiguousPair)
)
}
// Create a Rope and a matching Selection using a specification language.
// ^ is a single-point selection.
// _ is an expected index. These are returned as a Vec<usize> for use in assertions.
fn rope_with_selections_and_expectations(
text: &str,
spec: &str,
) -> (Rope, Selection, Vec<usize>) {
if text.len() != spec.len() {
panic!("specification must match text length -- are newlines aligned?");
}
let rope = Rope::from(text);
let selections: SmallVec<[Range; 1]> = spec
.match_indices('^')
.map(|(i, _)| Range::point(i))
.collect();
let expectations: Vec<usize> = spec.match_indices('_').map(|(i, _)| i).collect();
(rope, Selection::new(selections, 0), expectations)
}
}