Extract helpers.

src/EditorFeatures/Core.Wpf/NavigateTo/NavigateToItemProvider.Searcher.cs

@@ -71,6 +71,10 @@ internal async void Search()
                         _progress.AddItems(_solution.Projects.Count());
 
                         var workspace = _solution.Workspace;
+
+                        // If the workspace is tracking documents, use that to prioritize our search
+                        // order.  That way we provide results for the documents the user is working
+                        // on faster than the rest of the solution.
                         var docTrackingService = workspace.Services.GetService<IDocumentTrackingService>();
                         if (docTrackingService != null)
                         {
@@ -95,12 +99,9 @@ private async Task SearchProjectsInPriorityOrder(IDocumentTrackingService docTra
             {
                 var processedProjects = new HashSet<Project>();
 
-                var activeDocOpt = _solution.GetDocument(docTrackingService.GetActiveDocument());
-                var visibleDocs = docTrackingService.GetVisibleDocuments()
-                                                    .Select(d => _solution.GetDocument(d))
+                var activeDocOpt = docTrackingService.GetActiveDocument(_solution);
+                var visibleDocs = docTrackingService.GetVisibleDocuments(_solution)
                                                     .Where(d => d != activeDocOpt)
-                                                    .WhereNotNull()
-                                                    .Distinct()
                                                     .ToImmutableArray();
 
                 // First, if there's an active document, search that project first, prioritizing

src/Features/Core/Portable/SolutionCrawler/IDocumentTrackingServiceExtensions.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Linq;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis
+{
+    internal static class IDocumentTrackingServiceExtensions
+    {
+        /// <summary>
+        /// Gets the active <see cref="Document"/> the user is currently working in. May be null if
+        /// there is no active document or the active document is not in this <paramref name="solution"/>.
+        /// </summary>
+        public static Document GetActiveDocument(this IDocumentTrackingService service, Solution solution)
+        {
+            // Note: GetDocument checks that the DocId is contained in the solution, and returns null if not.
+            return solution.GetDocument(service.GetActiveDocument());
+        }
+
+        /// <summary>
+        /// Get a read only collection of all the unique visible documents in the workspace that are
+        /// contained within <paramref name="solution"/>.
+        /// </summary>
+        public static ImmutableArray<Document> GetVisibleDocuments(this IDocumentTrackingService service, Solution solution)
+            => service.GetVisibleDocuments()
+                      .Select(d => solution.GetDocument(d))
+                      .WhereNotNull()
+                      .Distinct()
+                      .ToImmutableArray();
+    }
+}