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