toggling of block comments

book/src/keymap.md

@@ -12,6 +12,7 @@
     - [Match mode](#match-mode)
     - [Window mode](#window-mode)
     - [Space mode](#space-mode)
+      - [Comment mode](#comment-mode)
       - [Popup](#popup)
     - [Unimpaired](#unimpaired)
 - [Insert mode](#insert-mode)
@@ -289,6 +290,9 @@ This layer is a kludge of mappings, mostly pickers.
 | `h`     | Select symbol references (**LSP**)                                      | `select_references_to_symbol_under_cursor` |
 | `'`     | Open last fuzzy picker                                                  | `last_picker`                              |
 | `w`     | Enter [window mode](#window-mode)                                       | N/A                                        |
+| `c`     | Comment/uncomment selections                                            | `toggle_comments`                          |
+| `C`     | Block comment/uncomment selections                                      | `toggle_block_comments`                    |
+| `Alt-c` | Line comment/uncomment selections                                       | `toggle_line_comments`                     |
 | `p`     | Paste system clipboard after selections                                 | `paste_clipboard_after`                    |
 | `P`     | Paste system clipboard before selections                                | `paste_clipboard_before`                   |
 | `y`     | Yank selections to clipboard                                            | `yank_to_clipboard`                        |

book/src/languages.md

@@ -42,7 +42,7 @@ name = "mylang"
 scope = "source.mylang"
 injection-regex = "mylang"
 file-types = ["mylang", "myl"]
-comment-token = "#"
+comment-tokens = "#"
 indent = { tab-width = 2, unit = "  " }
 formatter = { command = "mylang-formatter" , args = ["--stdin"] }
 language-servers = [ "mylang-lsp" ]
@@ -61,7 +61,8 @@ These configuration keys are available:
 | `roots`               | A set of marker files to look for when trying to find the workspace root. For example `Cargo.lock`, `yarn.lock` |
 | `auto-format`         | Whether to autoformat this language when saving               |
 | `diagnostic-severity` | Minimal severity of diagnostic for it to be displayed. (Allowed values: `Error`, `Warning`, `Info`, `Hint`) |
-| `comment-token`       | The token to use as a comment-token                           |
+| `comment-tokens`      | The tokens to use as a comment token, either a single token `"//"` or an array `["//", "///", "//!"]` (the first token will be used for commenting). Also configurable as `comment-token` for backwards compatibility|
+| `block-comment-tokens`| The start and end tokens for a multiline comment either an array or single table of `{ start = "/*", end = "*/"}`. The first set of tokens will be used for commenting, any pairs in the array can be uncommented |
 | `indent`              | The indent to use. Has sub keys `unit` (the text inserted into the document when indenting; usually set to N spaces or `"\t"` for tabs) and `tab-width` (the number of spaces rendered for a tab) |
 | `language-servers`    | The Language Servers used for this language. See below for more information in the section [Configuring Language Servers for a language](#configuring-language-servers-for-a-language)   |
 | `grammar`             | The tree-sitter grammar to use (defaults to the value of `name`) |

helix-core/src/comment.rs

@@ -1,8 +1,11 @@
 //! This module contains the functionality toggle comments on lines over the selection
 //! using the comment character defined in the user's `languages.toml`
 
+use smallvec::SmallVec;
+
 use crate::{
-    find_first_non_whitespace_char, Change, Rope, RopeSlice, Selection, Tendril, Transaction,
+    find_first_non_whitespace_char, syntax::BlockCommentToken, Change, Range, Rope, RopeSlice,
+    Selection, Tendril, Transaction,
 };
 use std::borrow::Cow;
 
@@ -94,6 +97,229 @@ pub fn toggle_line_comments(doc: &Rope, selection: &Selection, token: Option<&st
     Transaction::change(doc, changes.into_iter())
 }
 
+fn find_last_non_whitespace_char(text: RopeSlice) -> Option<usize> {
+    text.chars_at(text.len_chars())
+        .reversed()
+        .position(|ch| !ch.is_whitespace())
+        .map(|pos| text.len_chars() - pos - 1)
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum CommentChange {
+    Commented {
+        range: Range,
+        start_pos: usize,
+        end_pos: usize,
+        start_margin: bool,
+        end_margin: bool,
+        start_token: String,
+        end_token: String,
+    },
+    Uncommented {
+        range: Range,
+        start_pos: usize,
+        end_pos: usize,
+        start_token: String,
+        end_token: String,
+    },
+    Whitespace {
+        range: Range,
+    },
+}
+
+pub fn find_block_comments(
+    tokens: &[BlockCommentToken],
+    text: RopeSlice,
+    selection: &Selection,
+) -> (bool, Vec<CommentChange>) {
+    let mut commented = true;
+    let mut only_whitespace = true;
+    let mut comment_changes = Vec::with_capacity(selection.len());
+    let default_tokens = tokens.first().cloned().unwrap_or_default();
+    // TODO: check if this can be removed on MSRV bump
+    #[allow(clippy::redundant_clone)]
+    let mut start_token = default_tokens.start.clone();
+    #[allow(clippy::redundant_clone)]
+    let mut end_token = default_tokens.end.clone();
+
+    let mut tokens = tokens.to_vec();
+    // sort the tokens by length, so longer tokens will match first
+    tokens.sort_by(|a, b| {
+        if a.start.len() == b.start.len() {
+            b.end.len().cmp(&a.end.len())
+        } else {
+            b.start.len().cmp(&a.start.len())
+        }
+    });
+    for range in selection {
+        let selection_slice = range.slice(text);
+        if let (Some(start_pos), Some(end_pos)) = (
+            find_first_non_whitespace_char(selection_slice),
+            find_last_non_whitespace_char(selection_slice),
+        ) {
+            let mut line_commented = false;
+            let mut after_start = 0;
+            let mut before_end = 0;
+            let len = (end_pos + 1) - start_pos;
+
+            for BlockCommentToken { start, end } in &tokens {
+                let start_len = start.chars().count();
+                let end_len = end.chars().count();
+                after_start = start_pos + start_len;
+                before_end = end_pos.saturating_sub(end_len);
+
+                if len >= start_len + end_len {
+                    let start_fragment = selection_slice.slice(start_pos..after_start);
+                    let end_fragment = selection_slice.slice(before_end + 1..end_pos + 1);
+
+                    // block commented with these tokens
+                    if start_fragment == start.as_str() && end_fragment == end.as_str() {
+                        start_token = start.to_string();
+                        end_token = end.to_string();
+                        line_commented = true;
+                        break;
+                    }
+                }
+            }
+
+            if !line_commented {
+                comment_changes.push(CommentChange::Uncommented {
+                    range: *range,
+                    start_pos,
+                    end_pos,
+                    start_token: default_tokens.start.clone(),
+                    end_token: default_tokens.end.clone(),
+                });
+                commented = false;
+            } else {
+                comment_changes.push(CommentChange::Commented {
+                    range: *range,
+                    start_pos,
+                    end_pos,
+                    start_margin: selection_slice
+                        .get_char(after_start)
+                        .map_or(false, |c| c == ' '),
+                    end_margin: after_start != before_end
+                        && selection_slice
+                            .get_char(before_end)
+                            .map_or(false, |c| c == ' '),
+                    start_token: start_token.to_string(),
+                    end_token: end_token.to_string(),
+                });
+            }
+            only_whitespace = false;
+        } else {
+            comment_changes.push(CommentChange::Whitespace { range: *range });
+        }
+    }
+    if only_whitespace {
+        commented = false;
+    }
+    (commented, comment_changes)
+}
+
+#[must_use]
+pub fn create_block_comment_transaction(
+    doc: &Rope,
+    selection: &Selection,
+    commented: bool,
+    comment_changes: Vec<CommentChange>,
+) -> (Transaction, SmallVec<[Range; 1]>) {
+    let mut changes: Vec<Change> = Vec::with_capacity(selection.len() * 2);
+    let mut ranges: SmallVec<[Range; 1]> = SmallVec::with_capacity(selection.len());
+    let mut offs = 0;
+    for change in comment_changes {
+        if commented {
+            if let CommentChange::Commented {
+                range,
+                start_pos,
+                end_pos,
+                start_token,
+                end_token,
+                start_margin,
+                end_margin,
+            } = change
+            {
+                let from = range.from();
+                changes.push((
+                    from + start_pos,
+                    from + start_pos + start_token.len() + start_margin as usize,
+                    None,
+                ));
+                changes.push((
+                    from + end_pos - end_token.len() - end_margin as usize + 1,
+                    from + end_pos + 1,
+                    None,
+                ));
+            }
+        } else {
+            // uncommented so manually map ranges through changes
+            match change {
+                CommentChange::Uncommented {
+                    range,
+                    start_pos,
+                    end_pos,
+                    start_token,
+                    end_token,
+                } => {
+                    let from = range.from();
+                    changes.push((
+                        from + start_pos,
+                        from + start_pos,
+                        Some(Tendril::from(format!("{} ", start_token))),
+                    ));
+                    changes.push((
+                        from + end_pos + 1,
+                        from + end_pos + 1,
+                        Some(Tendril::from(format!(" {}", end_token))),
+                    ));
+
+                    let offset = start_token.chars().count() + end_token.chars().count() + 2;
+                    ranges.push(
+                        Range::new(from + offs, from + offs + end_pos + 1 + offset)
+                            .with_direction(range.direction()),
+                    );
+                    offs += offset;
+                }
+                CommentChange::Commented { range, .. } | CommentChange::Whitespace { range } => {
+                    ranges.push(Range::new(range.from() + offs, range.to() + offs));
+                }
+            }
+        }
+    }
+    (Transaction::change(doc, changes.into_iter()), ranges)
+}
+
+#[must_use]
+pub fn toggle_block_comments(
+    doc: &Rope,
+    selection: &Selection,
+    tokens: &[BlockCommentToken],
+) -> Transaction {
+    let text = doc.slice(..);
+    let (commented, comment_changes) = find_block_comments(tokens, text, selection);
+    let (mut transaction, ranges) =
+        create_block_comment_transaction(doc, selection, commented, comment_changes);
+    if !commented {
+        transaction = transaction.with_selection(Selection::new(ranges, selection.primary_index()));
+    }
+    transaction
+}
+
+pub fn split_lines_of_selection(text: RopeSlice, selection: &Selection) -> Selection {
+    let mut ranges = SmallVec::new();
+    for range in selection.ranges() {
+        let (line_start, line_end) = range.line_range(text.slice(..));
+        let mut pos = text.line_to_char(line_start);
+        for line in text.slice(pos..text.line_to_char(line_end + 1)).lines() {
+            let start = pos;
+            pos += line.len_chars();
+            ranges.push(Range::new(start, pos));
+        }
+    }
+    Selection::new(ranges, 0)
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -149,4 +375,49 @@ mod test {
 
         // TODO: account for uncommenting with uneven comment indentation
     }
+
+    #[test]
+    fn test_find_block_comments() {
+        // three lines 5 characters.
+        let mut doc = Rope::from("1\n2\n3");
+        // select whole document
+        let selection = Selection::single(0, doc.len_chars());
+
+        let text = doc.slice(..);
+
+        let res = find_block_comments(&[BlockCommentToken::default()], text, &selection);
+
+        assert_eq!(
+            res,
+            (
+                false,
+                vec![CommentChange::Uncommented {
+                    range: Range::new(0, 5),
+                    start_pos: 0,
+                    end_pos: 4,
+                    start_token: "/*".to_string(),
+                    end_token: "*/".to_string(),
+                }]
+            )
+        );
+
+        // comment
+        let transaction = toggle_block_comments(&doc, &selection, &[BlockCommentToken::default()]);
+        transaction.apply(&mut doc);
+
+        assert_eq!(doc, "/* 1\n2\n3 */");
+
+        // uncomment
+        let selection = Selection::single(0, doc.len_chars());
+        let transaction = toggle_block_comments(&doc, &selection, &[BlockCommentToken::default()]);
+        transaction.apply(&mut doc);
+        assert_eq!(doc, "1\n2\n3");
+
+        // don't panic when there is just a space in comment
+        doc = Rope::from("/* */");
+        let selection = Selection::single(0, doc.len_chars());
+        let transaction = toggle_block_comments(&doc, &selection, &[BlockCommentToken::default()]);
+        transaction.apply(&mut doc);
+        assert_eq!(doc, "");
+    }
 }