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//! This module contains the functionality toggle comments on lines over the selection
//! using the comment character defined in the user's `languages.toml`
use crate::{
find_first_non_whitespace_char, Change, Rope, RopeSlice, Selection, Tendril, Transaction,
};
use std::borrow::Cow;
/// Given text, a comment token, and a set of line indices, returns the following:
/// - Whether the given lines should be considered commented
/// - If any of the lines are uncommented, all lines are considered as such.
/// - The lines to change for toggling comments
/// - This is all provided lines excluding blanks lines.
/// - The column of the comment tokens
/// - Column of existing tokens, if the lines are commented; column to place tokens at otherwise.
/// - The margin to the right of the comment tokens
/// - Defaults to `1`. If any existing comment token is not followed by a space, changes to `0`.
fn find_line_comment(
token: &str,
text: RopeSlice,
lines: impl IntoIterator<Item = usize>,
) -> (bool, Vec<usize>, usize, usize) {
let mut commented = true;
let mut to_change = Vec::new();
let mut min = usize::MAX; // minimum col for find_first_non_whitespace_char
let mut margin = 1;
let token_len = token.chars().count();
for line in lines {
let line_slice = text.line(line);
if let Some(pos) = find_first_non_whitespace_char(line_slice) {
let len = line_slice.len_chars();
if pos < min {
min = pos;
}
// line can be shorter than pos + token len
let fragment = Cow::from(line_slice.slice(pos..std::cmp::min(pos + token.len(), len)));
if fragment != token {
// as soon as one of the non-blank lines doesn't have a comment, the whole block is
// considered uncommented.
commented = false;
}
// determine margin of 0 or 1 for uncommenting; if any comment token is not followed by a space,
// a margin of 0 is used for all lines.
if !matches!(line_slice.get_char(pos + token_len), Some(c) if c == ' ') {
margin = 0;
}
// blank lines don't get pushed.
to_change.push(line);
}
}
(commented, to_change, min, margin)
}
#[must_use]
pub fn toggle_line_comments(doc: &Rope, selection: &Selection, token: Option<&str>) -> Transaction {
let text = doc.slice(..);
let token = token.unwrap_or("//");
let comment = Tendril::from(format!("{} ", token));
let mut lines: Vec<usize> = Vec::with_capacity(selection.len());
let mut min_next_line = 0;
for selection in selection {
let (start, end) = selection.line_range(text);
let start = start.clamp(min_next_line, text.len_lines());
let end = (end + 1).min(text.len_lines());
lines.extend(start..end);
min_next_line = end;
}
let (commented, to_change, min, margin) = find_line_comment(token, text, lines);
let mut changes: Vec<Change> = Vec::with_capacity(to_change.len());
for line in to_change {
let pos = text.line_to_char(line) + min;
if !commented {
// comment line
changes.push((pos, pos, Some(comment.clone())));
} else {
// uncomment line
changes.push((pos, pos + token.len() + margin, None));
}
}
Transaction::change(doc, changes.into_iter())
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_find_line_comment() {
// four lines, two space indented, except for line 1 which is blank.
let mut doc = Rope::from(" 1\n\n 2\n 3");
// select whole document
let mut selection = Selection::single(0, doc.len_chars() - 1);
let text = doc.slice(..);
let res = find_line_comment("//", text, 0..3);
// (commented = true, to_change = [line 0, line 2], min = col 2, margin = 0)
assert_eq!(res, (false, vec![0, 2], 2, 0));
// comment
let transaction = toggle_line_comments(&doc, &selection, None);
transaction.apply(&mut doc);
selection = selection.map(transaction.changes());
assert_eq!(doc, " // 1\n\n // 2\n // 3");
// uncomment
let transaction = toggle_line_comments(&doc, &selection, None);
transaction.apply(&mut doc);
selection = selection.map(transaction.changes());
assert_eq!(doc, " 1\n\n 2\n 3");
assert!(selection.len() == 1); // to ignore the selection unused warning
// 0 margin comments
doc = Rope::from(" //1\n\n //2\n //3");
// reset the selection.
selection = Selection::single(0, doc.len_chars() - 1);
let transaction = toggle_line_comments(&doc, &selection, None);
transaction.apply(&mut doc);
selection = selection.map(transaction.changes());
assert_eq!(doc, " 1\n\n 2\n 3");
assert!(selection.len() == 1); // to ignore the selection unused warning
// 0 margin comments, with no space
doc = Rope::from("//");
// reset the selection.
selection = Selection::single(0, doc.len_chars() - 1);
let transaction = toggle_line_comments(&doc, &selection, None);
transaction.apply(&mut doc);
selection = selection.map(transaction.changes());
assert_eq!(doc, "");
assert!(selection.len() == 1); // to ignore the selection unused warning
// TODO: account for uncommenting with uneven comment indentation
}
}
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