Mikhail Pertsev
05154a14af
# Objective - Preserve Helix mode selections after surround-related commands such as adding, deleting, and replacing surrounds. - Add Helix-compatible closest-pair behavior for `m i m` / `m a m` and surround commands that target `m`. - Avoid long stalls in Helix text-object boundary scans by removing repeated syntax-scope classification during textual scans. - Keep workflows like selecting text with `m i w`, applying `m s`, and continuing with `i`, `a`, or another surround command aligned with Helix behavior. ## Solution - Add selection anchors that preserve each pre-edit selection range and direction through surround edits. - Update Helix surround add so the resulting selection includes the added delimiters, allowing surround commands to compose and insert/append actions to land outside the pair. - Apply preserved selections to Helix surround delete and replace so non-empty selections are not collapsed to the cursor after the edit. - Add Helix-specific text-object bindings so `m` selects the closest surrounding pair, `t` selects types/classes, `c` selects comments, and `x` selects XML/HTML elements in Helix mode. - Match the current closest pair through language bracket queries, so delimiters inside strings or comments do not count as surrounding pairs. - Resolve the textual boundary scanner's `CharClassifier` once per scan and pass it by reference instead of recomputing the same classifier for every scanned character. Word and subword boundaries still clone it only to apply the `ignore_punctuation` flag. ## Performance The textual boundary scanner previously called `char_classifier_at(from.0)` inside the per-character comparison closures for the four `ImmediateBoundary` scan methods and `FuzzyBoundary::to_boundary`. That lookup resolves the language scope through the syntax layers, and the value was loop-invariant because every iteration used the scan's starting offset. Local debug benchmark, using `] m` in a roughly 540 KB buffer with no pair characters so the scan runs to EOF across all pair boundaries: | | `] m` | | ------ | -----: | | Before | 36.3 s | | After | 210 ms | This speeds up the remaining textual scanner paths, including `m i (` / `m i "`-style pair objects, word/sentence/paragraph objects, `]` / `[` text-object navigation, and `] m` / `[ m`. The current-pair `m i m`, `m a m`, `m d m`, and `m r m` paths use the tree-sitter closest-pair path instead. ## Testing - Ran `cargo test -p vim test_helix_surround -- --nocapture`. - The focused Helix surround test filter passed: 10 passed, 0 failed. - Added coverage for closest-pair selection, Helix-specific text-object keys, and surround selection preservation. ## Self-Review Checklist: - [x] I've reviewed my own diff for quality, security, and reliability - [x] Unsafe blocks (if any) have justifying comments - [x] The content adheres to Zed's UI standards ([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) and [icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md) guidelines) - [x] Tests cover the new/changed behavior - [x] Performance impact has been considered and is acceptable --- Release Notes: - Added Helix mode support for closest-pair text objects with `m i m` and `m a m`. - Fixed Helix mode surround commands to preserve selections after edits and avoid slow textual boundary scans.
This contains the code for Zed's Vim emulation mode.
Vim mode in Zed is supposed to primarily "do what you expect": it mostly tries to copy vim exactly, but will use Zed-specific functionality when available to make things smoother. This means Zed will never be 100% vim compatible, but should be 100% vim familiar!
The backlog is maintained in the #vim channel notes.
Testing against Neovim
If you are making a change to make Zed's behavior more closely match vim/nvim, you can create a test using the NeovimBackedTestContext.
For example, the following test checks that Zed and Neovim have the same behavior when running * in visual mode:
#[gpui::test]
async fn test_visual_star_hash(cx: &mut gpui::TestAppContext) {
let mut cx = NeovimBackedTestContext::new(cx).await;
cx.set_shared_state("ˇa.c. abcd a.c. abcd").await;
cx.simulate_shared_keystrokes(["v", "3", "l", "*"]).await;
cx.assert_shared_state("a.c. abcd ˇa.c. abcd").await;
}
To keep CI runs fast, by default the neovim tests use a cached JSON file that records what neovim did (see crates/vim/test_data), but while developing this test you'll need to run it with the neovim flag enabled:
cargo test -p vim --features neovim test_visual_star_hash
This will run your keystrokes against a headless neovim and cache the results in the test_data directory. Note that neovim must be installed and reachable on your $PATH in order to run the feature.
Testing zed-only behavior
Zed does more than vim/neovim in their default modes. The VimTestContext can be used instead. This lets you test integration with the language server and other parts of zed's UI that don't have a NeoVim equivalent.