# 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`.

## `SnippetTextEdit`

**Capability**

```typescript
{
    "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: VersionedTextDocumentIdentifier;
	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`.