From 5849e59afd9d598666426f2640dfbd173eace02d Mon Sep 17 00:00:00 2001
From: "Jeremy A. Kolb" <jkolb@ara.com>
Date: Tue, 7 Apr 2020 12:28:02 -0400
Subject: [PATCH] Document rust-analyzer's inlay hints implementation

---
 protocol/src/protocol.inlayHints.proposed.md | 109 +++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 protocol/src/protocol.inlayHints.proposed.md

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+
+#### Inlay Hints
+
+The LSP provides retrieving inlay hints information with the following request.
+
+_Client Capabilities_:
+
+```ts
+InlayHintsClientCapabilities {
+    /**
+     * The text document client capabilities
+     */
+    textDocument?: {
+        /**
+         * Capabilities specific to the `textDocument/inlayHints`
+         */
+        inlayHints?: {
+            /**
+             * Whether implementation supports dynamic registration. If this is set to `true`
+             * the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
+             * return value for the corresponding server capability as well.
+             */
+            dynamicRegistration?: boolean;
+        };
+    }
+}
+```
+
+_Server Capabilities_:
+
+```ts
+InlayHintsServerCapabilities {
+    /**
+     * The server provides Inlay Hint support.
+     */
+    inlayHintsProvider?: boolean | (TextDocumentRegistrationOptions & StaticRegistrationOptions);
+}
+```
+
+##### Inlay Hints Request
+
+_Request_:
+
+The `textDocument/inlayHints` request is sent from the client to the server to request the hints for a given
+text document.
+
+Returns a collection of hints for the text document.
+
+* method: ‘textDocument/inlayHints'
+* params: `InlayHintsParams` defined as follows:
+
+```ts
+export interface InlayHintsParams {
+    /**
+     * The text document
+     */
+    textDocument: TextDocumentIdentifier;
+}
+```
+
+_Response_:
+
+The server will send a collection of `InlayHint` objects, or `null` if no hints are found.
+
+Each `InlayHint` object defines a range and kind corresponding to the hint and a label
+to be displayed inline in the editor.
+
+* result: `InlayHint[]` | `null`
+
+```ts
+export interface InlayHint {
+
+    /**
+     * The source range of the hint.
+     */
+    range: Range;
+
+    /**
+    * The type of hint.
+     */
+    kind: InlayHintKind;
+
+    /**
+     * The label that is displayed the in editor
+    */
+    label: string;
+}
+
+/**
+ * A set of predefined hint kinds
+ */
+export interface InlayHintKind {
+
+	/**
+	 * The hint is for type information
+	 */
+	export const TypeHint: InlayHintKind = 'TypeHint';
+
+	/**
+	 * The hint corresponds to parameter information
+	 */
+	export const ParameterHint: InlayHintKind = 'ParameterHint';
+
+	/**
+	 * The hint corresponds to method chaining
+	 */
+	export const ChainingHint: InlayHintKind = 'ChainingHint';
+}
+```
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