aboutsummaryrefslogtreecommitdiff
path: root/docs/dev/lsp-extensions.md
blob: 2a966a96da9d324fe02dbc7f964744cfa1b7a0b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
<!---
lsp_ext.rs hash: 8f1ae8530f69e3a3

If you need to change the above hash to make the test pass, please check if you
need to adjust this doc as well and ping this  issue:

  https://github.com/rust-analyzer/rust-analyzer/issues/4604

--->

# LSP Extensions

This document describes LSP extensions used by rust-analyzer.
It's a best effort document, when in doubt, consult the source (and send a PR with clarification ;-) ).
We aim to upstream all non Rust-specific extensions to the protocol, but this is not a top priority.
All capabilities are enabled via `experimental` field of `ClientCapabilities` or `ServerCapabilities`.
Requests which we hope to upstream live under `experimental/` namespace.
Requests, which are likely to always remain specific to `rust-analyzer` are under `rust-analyzer/` namespace.

If you want to be notified about the changes to this document, subscribe to [#4604](https://github.com/rust-analyzer/rust-analyzer/issues/4604).

## `initializationOptions`

For `initializationOptions`, `rust-analyzer` expects `"rust-analyzer"` section of the configuration.
That is, `rust-analyzer` usually sends `"workspace/configuration"` request with `{ "items": ["rust-analyzer"] }` payload.
`initializationOptions` should contain the same data that would be in the first item of the result.
If a language client does not know about `rust-analyzer`'s configuration options it can get sensible defaults by doing any of the following:
 * Not sending `initializationOptions`
 * Send `"initializationOptions": null`
 * Send `"initializationOptions": {}`

## Snippet `TextEdit`

**Issue:** https://github.com/microsoft/language-server-protocol/issues/724

**Client Capability:** `{ "snippetTextEdit": boolean }`

If this capability is set, `WorkspaceEdit`s returned from `codeAction` requests might contain `SnippetTextEdit`s instead of usual `TextEdit`s:

```typescript
interface SnippetTextEdit extends TextEdit {
    insertTextFormat?: InsertTextFormat;
}
```

```typescript
export interface TextDocumentEdit {
	textDocument: OptionalVersionedTextDocumentIdentifier;
	edits: (TextEdit | SnippetTextEdit)[];
}
```

When applying such code action, the editor should insert snippet, with tab stops and placeholder.
At the moment, rust-analyzer guarantees that only a single edit will have `InsertTextFormat.Snippet`.

### Example

"Add `derive`" code action transforms `struct S;` into `#[derive($0)] struct S;`

### Unresolved Questions

* Where exactly are `SnippetTextEdit`s allowed (only in code actions at the moment)?
* Can snippets span multiple files (so far, no)?

## `CodeAction` Groups

**Issue:** https://github.com/microsoft/language-server-protocol/issues/994

**Client Capability:** `{ "codeActionGroup": boolean }`

If this capability is set, `CodeAction` returned from the server contain an additional field, `group`:

```typescript
interface CodeAction {
    title: string;
    group?: string;
    ...
}
```

All code-actions with the same `group` should be grouped under single (extendable) entry in lightbulb menu.
The set of actions `[ { title: "foo" }, { group: "frobnicate", title: "bar" }, { group: "frobnicate", title: "baz" }]` should be rendered as

```
💡
  +-------------+
  | foo         |
  +-------------+-----+
  | frobnicate >| bar |
  +-------------+-----+
                | baz |
                +-----+
```

Alternatively, selecting `frobnicate` could present a user with an additional menu to choose between `bar` and `baz`.

### Example

```rust
fn main() {
    let x: Entry/*cursor here*/ = todo!();
}
```

Invoking code action at this position will yield two code actions for importing `Entry` from either `collections::HashMap` or `collection::BTreeMap`, grouped under a single "import" group.

### Unresolved Questions

* Is a fixed two-level structure enough?
* Should we devise a general way to encode custom interaction protocols for GUI refactorings?

## Parent Module

**Issue:** https://github.com/microsoft/language-server-protocol/issues/1002

**Server Capability:** `{ "parentModule": boolean }`

This request is sent from client to server to handle "Goto Parent Module" editor action.

**Method:** `experimental/parentModule`

**Request:** `TextDocumentPositionParams`

**Response:** `Location | Location[] | LocationLink[] | null`


### Example

```rust
// src/main.rs
mod foo;
// src/foo.rs

/* cursor here*/
```

`experimental/parentModule` returns a single `Link` to the `mod foo;` declaration.

### Unresolved Question

* An alternative would be to use a more general "gotoSuper" request, which would work for super methods, super classes and super modules.
  This is the approach IntelliJ Rust is takeing.
  However, experience shows that super module (which generally has a feeling of navigation between files) should be separate.
  If you want super module, but the cursor happens to be inside an overriden function, the behavior with single "gotoSuper" request is surprising.

## Join Lines

**Issue:** https://github.com/microsoft/language-server-protocol/issues/992

**Server Capability:** `{ "joinLines": boolean }`

This request is sent from client to server to handle "Join Lines" editor action.

**Method:** `experimental/joinLines`

**Request:**

```typescript
interface JoinLinesParams {
    textDocument: TextDocumentIdentifier,
    /// Currently active selections/cursor offsets.
    /// This is an array to support multiple cursors.
    ranges: Range[],
}
```

**Response:** `TextEdit[]`

### Example

```rust
fn main() {
    /*cursor here*/let x = {
        92
    };
}
```

`experimental/joinLines` yields (curly braces are automagically removed)

```rust
fn main() {
    let x = 92;
}
```

### Unresolved Question

* What is the position of the cursor after `joinLines`?
  Currently this is left to editor's discretion, but it might be useful to specify on the server via snippets.
  However, it then becomes unclear how it works with multi cursor.

## On Enter

**Issue:** https://github.com/microsoft/language-server-protocol/issues/1001

**Server Capability:** `{ "onEnter": boolean }`

This request is sent from client to server to handle <kbd>Enter</kbd> keypress.

**Method:** `experimental/onEnter`

**Request:**: `TextDocumentPositionParams`

**Response:**

```typescript
SnippetTextEdit[]
```

### Example

```rust
fn main() {
    // Some /*cursor here*/ docs
    let x = 92;
}
```

`experimental/onEnter` returns the following snippet

```rust
fn main() {
    // Some
    // $0 docs
    let x = 92;
}
```

The primary goal of `onEnter` is to handle automatic indentation when opening a new line.
This is not yet implemented.
The secondary goal is to handle fixing up syntax, like continuing doc strings and comments, and escaping `\n` in string literals.

As proper cursor positioning is raison-d'etat for `onEnter`, it uses `SnippetTextEdit`.

### Unresolved Question

* How to deal with synchronicity of the request?
  One option is to require the client to block until the server returns the response.
  Another option is to do a OT-style merging of edits from client and server.
  A third option is to do a record-replay: client applies heuristic on enter immediately, then applies all user's keypresses.
  When the server is ready with the response, the client rollbacks all the changes and applies the recorded actions on top of the correct response.
* How to deal with multiple carets?
* Should we extend this to arbitrary typed events and not just `onEnter`?

## Structural Search Replace (SSR)

**Server Capability:** `{ "ssr": boolean }`

This request is sent from client to server to handle structural search replace -- automated syntax tree based transformation of the source.

**Method:** `experimental/ssr`

**Request:**

```typescript
interface SsrParams {
    /// Search query.
    /// The specific syntax is specified outside of the protocol.
    query: string,
    /// If true, only check the syntax of the query and don't compute the actual edit.
    parseOnly: bool,
    /// The current text document. This and `position` will be used to determine in what scope
    /// paths in `query` should be resolved.
    textDocument: lc.TextDocumentIdentifier;
    /// Position where SSR was invoked.
    position: lc.Position;
}
```

**Response:**

```typescript
WorkspaceEdit
```

### Example

SSR with query `foo($a, $b) ==>> ($a).foo($b)` will transform, eg `foo(y + 5, z)` into `(y + 5).foo(z)`.

### Unresolved Question

* Probably needs search without replace mode
* Needs a way to limit the scope to certain files.

## Matching Brace

**Issue:** https://github.com/microsoft/language-server-protocol/issues/999

**Server Capability:** `{ "matchingBrace": boolean }`

This request is sent from client to server to handle "Matching Brace" editor action.

**Method:** `experimental/matchingBrace`

**Request:**

```typescript
interface MatchingBraceParams {
    textDocument: TextDocumentIdentifier,
    /// Position for each cursor
    positions: Position[],
}
```

**Response:**

```typescript
Position[]
```

### Example

```rust
fn main() {
    let x: Vec<()>/*cursor here*/ = vec![]
}
```

`experimental/matchingBrace` yields the position of `<`.
In many cases, matching braces can be handled by the editor.
However, some cases (like disambiguating between generics and comparison operations) need a real parser.
Moreover, it would be cool if editors didn't need to implement even basic language parsing

### Unresolved Question

* Should we return a a nested brace structure, to allow paredit-like actions of jump *out* of the current brace pair?
  This is how `SelectionRange` request works.
* Alternatively, should we perhaps flag certain `SelectionRange`s as being brace pairs?

## Runnables

**Issue:** https://github.com/microsoft/language-server-protocol/issues/944

**Server Capability:** `{ "runnables": { "kinds": string[] } }`

This request is sent from client to server to get the list of things that can be run (tests, binaries, `cargo check -p`).

**Method:** `experimental/runnables`

**Request:**

```typescript
interface RunnablesParams {
    textDocument: TextDocumentIdentifier;
    /// If null, compute runnables for the whole file.
    position?: Position;
}
```

**Response:** `Runnable[]`

```typescript
interface Runnable {
    label: string;
    /// If this Runnable is associated with a specific function/module, etc, the location of this item
    location?: LocationLink;
    /// Running things is necessary technology specific, `kind` needs to be advertised via server capabilities,
    // the type of `args` is specific to `kind`. The actual running is handled by the client.
    kind: string;
    args: any;
}
```

rust-analyzer supports only one `kind`, `"cargo"`. The `args` for `"cargo"` look like this:

```typescript
{
    workspaceRoot?: string;
    cargoArgs: string[];
    cargoExtraArgs: string[];
    executableArgs: string[];
    expectTest?: boolean;
    overrideCargo?: string;
}
```

## Open External Documentation

This request is sent from client to server to get a URL to documentation for the symbol under the cursor, if available.

**Method** `experimental/externalDocs`

**Request:**: `TextDocumentPositionParams`

**Response** `string | null`


## Analyzer Status

**Method:** `rust-analyzer/analyzerStatus`

**Request:**

```typescript
interface AnalyzerStatusParams {
    /// If specified, show dependencies of the current file.
    textDocument?: TextDocumentIdentifier;
}
```

**Response:** `string`

Returns internal status message, mostly for debugging purposes.

## Reload Workspace

**Method:** `rust-analyzer/reloadWorkspace`

**Request:** `null`

**Response:** `null`

Reloads project information (that is, re-executes `cargo metadata`).

## Status Notification

**Client Capability:** `{ "statusNotification": boolean }`

**Method:** `rust-analyzer/status`

**Notification:**

```typescript
interface StatusParams {
    status: "loading" | "readyPartial" | "ready" | "invalid" | "needsReload",
}
```

This notification is sent from server to client.
The client can use it to display persistent status to the user (in modline).
For `needsReload` state, the client can provide a context-menu action to run `rust-analyzer/reloadWorkspace` request.

## Syntax Tree

**Method:** `rust-analyzer/syntaxTree`

**Request:**

```typescript
interface SyntaxTeeParams {
    textDocument: TextDocumentIdentifier,
    range?: Range,
}
```

**Response:** `string`

Returns textual representation of a parse tree for the file/selected region.
Primarily for debugging, but very useful for all people working on rust-analyzer itself.

## View Hir

**Method:** `rust-analyzer/viewHir`

**Request:** `TextDocumentPositionParams`

**Response:** `string`

Returns a textual representation of the HIR of the function containing the cursor.
For debugging or when working on rust-analyzer itself.

## Expand Macro

**Method:** `rust-analyzer/expandMacro`

**Request:**

```typescript
interface ExpandMacroParams {
    textDocument: TextDocumentIdentifier,
    position: Position,
}
```

**Response:**

```typescript
interface ExpandedMacro {
    name: string,
    expansion: string,
}
```

Expands macro call at a given position.

## Inlay Hints

**Method:** `rust-analyzer/inlayHints`

This request is sent from client to server to render "inlay hints" -- virtual text inserted into editor to show things like inferred types.
Generally, the client should re-query inlay hints after every modification.
Note that we plan to move this request to `experimental/inlayHints`, as it is not really Rust-specific, but the current API is not necessary the right one.
Upstream issue: https://github.com/microsoft/language-server-protocol/issues/956

**Request:**

```typescript
interface InlayHintsParams {
    textDocument: TextDocumentIdentifier,
}
```

**Response:** `InlayHint[]`

```typescript
interface InlayHint {
    kind: "TypeHint" | "ParameterHint" | "ChainingHint",
    range: Range,
    label: string,
}
```

## Hover Actions

**Client Capability:** `{ "hoverActions": boolean }`

If this capability is set, `Hover` request returned from the server might contain an additional field, `actions`:

```typescript
interface Hover {
    ...
    actions?: CommandLinkGroup[];
}

interface CommandLink extends Command {
    /**
     * A tooltip for the command, when represented in the UI.
     */
    tooltip?: string;
}

interface CommandLinkGroup {
    title?: string;
    commands: CommandLink[];
}
```

Such actions on the client side are appended to a hover bottom as command links:
```
  +-----------------------------+
  | Hover content               |
  |                             |
  +-----------------------------+
  | _Action1_ | _Action2_       |  <- first group, no TITLE
  +-----------------------------+
  | TITLE _Action1_ | _Action2_ |  <- second group
  +-----------------------------+
  ...
```

## Open Cargo.toml

**Issue:** https://github.com/rust-analyzer/rust-analyzer/issues/6462

This request is sent from client to server to open the current project's Cargo.toml

**Method:** `experimental/openCargoToml`

**Request:** `OpenCargoTomlParams`

**Response:** `Location | null`


### Example

```rust
// Cargo.toml
[package]
// src/main.rs

/* cursor here*/
```

`experimental/openCargoToml` returns a single `Link` to the start of the `[package]` keyword.