These changes refactor the whitespace handling logic for Vim's change
surrounds command (`cs`), making its behavior closely match
[tpope/vim-surround](https://github.com/tpope/vim-surround), following
[this
discussion](https://github.com/zed-industries/zed/issues/38169#issuecomment-3304129461).
Zed's current implementation has two main differences when compared to
[tpope/vim-surround](https://github.com/tpope/vim-surround):
- It only considers whether a single space should be added or removed,
instead of all the space that is between the surrounding character and
the content
- It only takes into consideration the new surrounding characters in
order to determine whether to add or remove that space
A review of
[tpope/vim-surround](https://github.com/tpope/vim-surround)'s behavior
reveals these rules for whitespace:
* Quote to Quote
* Whitespace is never changed
* Quote to Bracket
* If opening bracket, add one space
* If closing bracket, do not add space
* Bracket to Bracket
* If opening to opening, keep only one space
* If opening to closing, remove all space
* If closing to opening, add one space
* If closing to closing, do not change space
* Bracket to Quote
* If opening, remove all space
* If closing, preserve all space
Below is a table with examples for each scenario. A new test has also
been added to specifically check the scenarios outlined above,
`vim::surrounds::test::test_change_surrounds_vim`.
| Type | Before | Command | After |
|-------------------|-------------|---------|---------------|
| Quote → Quote | `' a '` | `cs'"` | `" a "` |
| Quote → Quote | `" a "` | `cs"'` | `' a '` |
| Quote → Bracket | `' a '` | `cs'{` | `{ a }` |
| Quote → Bracket | `' a '` | `cs'}` | `{ a }` |
| Bracket → Bracket | `[ a ]` | `cs[{` | `{ a }` |
| Bracket → Bracket | `[ a ]` | `cs[}` | `{a}` |
| Bracket → Bracket | `[ a ]` | `cs]{` | `{ a }` |
| Bracket → Bracket | `[ a ]` | `cs]}` | `{ a }` |
| Bracket → Quote | `[ a ]` | `cs['` | `'a'` |
| Bracket → Quote | `[ a ]` | `cs]'` | `' a '` |
These changes diverge from
[tpope/vim-surround](https://github.com/tpope/vim-surround) when
handling newlines. For example, with the following snippet:
```rust
fn test_surround() {
if 2 > 1 {
println!("place cursor here");
}
};
```
Placing the cursor inside the string and running any combination of
`cs{[`, `cs{]`, `cs}[`, or `cs}]` would previously remove newline
characters. With these changes, using commands like `cs}]` will now
preserve newlines.
Related to #38169Closes#39334
Release Notes:
- Improved Vim’s change surround command to closely match
[tpope/vim-surround](https://github.com/tpope/vim-surround) behavior.
---------
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>