Reorgonise extensions docs

Author: matklad

docs/dev/lsp-extensions.md

@@ -3,7 +3,9 @@
 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`.
+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.
 
 ## Snippet `TextEdit`
 
@@ -38,6 +40,53 @@ At the moment, rust-analyzer guarantees that only a single edit will have `Inser
 * 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?
+
 ## Join Lines
 
 **Issue:** https://github.com/microsoft/language-server-protocol/issues/992
@@ -123,50 +172,3 @@ SSR with query `foo($a:expr, $b:expr) ==>> ($a).foo($b)` will transform, eg `foo
 
 * Probably needs search without replace mode
 * Needs a way to limit the scope to certain files.
-
-## `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?