use std::fmt::Display; use crate::{search, Range, Selection}; use ropey::RopeSlice; pub const PAIRS: &[(char, char)] = &[ ('(', ')'), ('[', ']'), ('{', '}'), ('<', '>'), ('«', '»'), ('「', '」'), ('(', ')'), ]; #[derive(Debug, PartialEq)] 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 = std::result::Result; /// 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, 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 { 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 { 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, ) -> Result> { let mut change_pos = Vec::new(); for &range in selection { let (open_pos, close_pos) = find_nth_pairs_pos(text, ch, 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; #[allow(clippy::type_complexity)] fn check_find_nth_pair_pos( text: &str, cases: Vec<(usize, char, usize, Result<(usize, usize)>)>, ) { let doc = Rope::from(text); let slice = doc.slice(..); for (cursor_pos, ch, n, expected_range) in cases { let range = find_nth_pairs_pos(slice, ch, (cursor_pos, cursor_pos + 1).into(), n); assert_eq!( range, expected_range, "Expected {:?}, got {:?}", expected_range, range ); } } #[test] fn test_find_nth_pairs_pos() { check_find_nth_pair_pos( "some (text) here", vec![ // cursor on [t]ext (6, '(', 1, Ok((5, 10))), (6, ')', 1, Ok((5, 10))), // cursor on so[m]e (2, '(', 1, Err(Error::PairNotFound)), // cursor on bracket itself (5, '(', 1, Ok((5, 10))), (10, '(', 1, Ok((5, 10))), ], ); } #[test] fn test_find_nth_pairs_pos_skip() { check_find_nth_pair_pos( "(so (many (good) text) here)", vec![ // cursor on go[o]d (13, '(', 1, Ok((10, 15))), (13, '(', 2, Ok((4, 21))), (13, '(', 3, Ok((0, 27))), ], ); } #[test] fn test_find_nth_pairs_pos_same() { check_find_nth_pair_pos( "'so 'many 'good' text' here'", vec![ // cursor on go[o]d (13, '\'', 1, Ok((10, 15))), (13, '\'', 2, Ok((4, 21))), (13, '\'', 3, Ok((0, 27))), // cursor on the quotes (10, '\'', 1, Err(Error::CursorOnAmbiguousPair)), ], ) } #[test] fn test_find_nth_pairs_pos_step() { check_find_nth_pair_pos( "((so)((many) good (text))(here))", vec![ // cursor on go[o]d (15, '(', 1, Ok((5, 24))), (15, '(', 2, Ok((0, 31))), ], ) } #[test] fn test_find_nth_pairs_pos_mixed() { check_find_nth_pair_pos( "(so [many {good} text] here)", vec![ // cursor on go[o]d (13, '{', 1, Ok((10, 15))), (13, '[', 1, Ok((4, 21))), (13, '(', 1, Ok((0, 27))), ], ) } #[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, 5, 7, 13, 15, 23] ); } #[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), Err(Error::PairNotFound) // 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), Err(Error::PairNotFound) // overlapping surround chars ); let selection = Selection::new(SmallVec::from_slice(&[Range::point(2), Range::point(3)]), 0); // cursor on s[o][m]e assert_eq!( get_surround_pos(slice, &selection, '[', 1), Err(Error::CursorOverlap) ); } }