adds a link completer for inline link to post creation

packages/block-editor/package.json

@@ -30,6 +30,7 @@
 	"dependencies": {
 		"@babel/runtime": "^7.12.5",
 		"@wordpress/a11y": "file:../a11y",
+		"@wordpress/api-fetch": "file:../api-fetch",
 		"@wordpress/blob": "file:../blob",
 		"@wordpress/blocks": "file:../blocks",
 		"@wordpress/components": "file:../components",

packages/block-editor/src/autocompleters/link.js

@@ -0,0 +1,49 @@
+/**
+ * WordPress dependencies
+ */
+import apiFetch from '@wordpress/api-fetch';
+import { addQueryArgs } from '@wordpress/url';
+
+const SHOWN_SUGGESTIONS = 10;
+
+/** @typedef {import('@wordpress/components').WPCompleter} WPCompleter */
+
+/**
+ * Creates a suggestion list for links to posts or pages.
+ *
+ * @return {WPCompleter} A links completer.
+ */
+function createLinkCompleter() {
+	return {
+		name: 'links',
+		className: 'block-editor-autocompleters__link',
+		triggerPrefix: '[[',
+		options( letters ) {
+			return apiFetch( {
+				path: addQueryArgs( '/wp/v2/search', {
+					per_page: SHOWN_SUGGESTIONS,
+					search: letters,
+					type: 'post',
+					order_by: 'menu_order',
+				} ),
+			} );
+		},
+		getOptionKeywords( item ) {
+			const expansionWords = item.title.split( /\s+/ );
+			return [ ...expansionWords ];
+		},
+		getOptionLabel( item ) {
+			return item.title;
+		},
+		getOptionCompletion( item ) {
+			return <a href={ item.url }>{ item.title }</a>;
+		},
+	};
+}
+
+/**
+ * Creates a suggestion list for links to posts or pages..
+ *
+ * @return {WPCompleter} A link completer.
+ */
+export default createLinkCompleter();

packages/block-editor/src/autocompleters/style.scss

@@ -5,3 +5,11 @@
 		margin-right: $grid-unit-10;
 	}
 }
+
+.block-editor-autocompleters__link {
+	white-space: nowrap;
+
+	.block-editor-block-icon {
+		margin-right: $grid-unit-10;
+	}
+}

packages/block-editor/src/components/autocomplete/index.js

@@ -16,6 +16,7 @@ import { getDefaultBlockName } from '@wordpress/blocks';
  */
 import { useBlockEditContext } from '../block-edit/context';
 import blockAutocompleter from '../../autocompleters/block';
+import linkAutocompleter from '../../autocompleters/link';
 
 /**
  * Shared reference to an empty array for cases where it is important to avoid
@@ -42,6 +43,7 @@ function BlockEditorAutocomplete( props ) {
 		if ( name === getDefaultBlockName() ) {
 			filteredCompleters = filteredCompleters.concat( [
 				blockAutocompleter,
+				linkAutocompleter,
 			] );
 		}