Break out code for index building into its own service.

src/Workspaces/Core/Portable/FindSymbols/SyntaxTree/SyntaxTreeIndex_Create.cs

@@ -5,6 +5,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.ErrorReporting;
+using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.LanguageServices;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Shared.Utilities;
@@ -12,6 +13,11 @@
 
 namespace Microsoft.CodeAnalysis.FindSymbols
 {
+    internal interface IDeclaredSymbolInfoFactoryService : ILanguageService
+    {
+        bool TryGetDeclaredSymbolInfo(Project project, SyntaxNode node, out DeclaredSymbolInfo declaredSymbolInfo);
+    }
+
     internal sealed partial class SyntaxTreeIndex
     {
         // The probability of getting a false positive when calling ContainsIdentifier.
@@ -28,6 +34,7 @@ internal sealed partial class SyntaxTreeIndex
         {
             var project = document.Project;
             var syntaxFacts = document.GetLanguageService<ISyntaxFactsService>();
+            var infoFactory = document.GetLanguageService<IDeclaredSymbolInfoFactoryService>();
             var ignoreCase = syntaxFacts != null && !syntaxFacts.IsCaseSensitive;
             var isCaseSensitive = !ignoreCase;
 
@@ -68,6 +75,7 @@ internal sealed partial class SyntaxTreeIndex
                             containsQueryExpression = containsQueryExpression || syntaxFacts.IsQueryExpression(node);
                             containsElementAccess = containsElementAccess || syntaxFacts.IsElementAccessExpression(node);
                             containsIndexerMemberCref = containsIndexerMemberCref || syntaxFacts.IsIndexerMemberCRef(node);
+
                             // We've received a number of error reports where DeclaredSymbolInfo.GetSymbolAsync() will
                             // crash because the document's syntax root doesn't contain the span of the node returned
                             // by TryGetDeclaredSymbolInfo().  There are two possibilities for this crash:
@@ -78,7 +86,7 @@ internal sealed partial class SyntaxTreeIndex
                             // the future then we know the problem lies in (2).  If, however, the problem is really in
                             // TryGetDeclaredSymbolInfo, then this will at least prevent us from returning bad spans
                             // and will prevent the crash from occurring.
-                            if (syntaxFacts.TryGetDeclaredSymbolInfo(project, node, out var declaredSymbolInfo))
+                            if (infoFactory.TryGetDeclaredSymbolInfo(project, node, out var declaredSymbolInfo))
                             {
                                 if (root.FullSpan.Contains(declaredSymbolInfo.Span))
                                 {

src/Workspaces/Core/Portable/LanguageServices/SyntaxFactsService/AbstractSyntaxFactsService.cs

@@ -2,19 +2,20 @@
 
 using System;
 using System.Collections.Generic;
-using Microsoft.CodeAnalysis.Shared.Extensions;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
+using System.Text;
 using System.Threading;
+using Microsoft.CodeAnalysis.FindSymbols;
+using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Shared.Utilities;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
-using System.Text;
 
 namespace Microsoft.CodeAnalysis.LanguageServices
 {
-    internal abstract class AbstractSyntaxFactsService
+    internal abstract class AbstractDeclaredSymbolInfoFactoryService : IDeclaredSymbolInfoFactoryService
     {
         private readonly static ObjectPool<List<Dictionary<string, string>>> s_aliasMapListPool =
             new ObjectPool<List<Dictionary<string, string>>>(() => new List<Dictionary<string, string>>());
@@ -27,6 +28,53 @@ internal abstract class AbstractSyntaxFactsService
         private readonly static ObjectPool<Dictionary<string, string>> s_aliasMapPool =
             new ObjectPool<Dictionary<string, string>>(() => new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase));
 
+        protected static List<Dictionary<string, string>> AllocateAliasMapList()
+            => s_aliasMapListPool.Allocate();
+
+        protected static void FreeAliasMapList(List<Dictionary<string, string>> list)
+        {
+            if (list != null)
+            {
+                foreach (var aliasMap in list)
+                {
+                    FreeAliasMap(aliasMap);
+                }
+
+                s_aliasMapListPool.ClearAndFree(list);
+            }
+        }
+
+        protected static void FreeAliasMap(Dictionary<string, string> aliasMap)
+        {
+            if (aliasMap != null)
+            {
+                s_aliasMapPool.ClearAndFree(aliasMap);
+            }
+        }
+
+        protected static Dictionary<string, string> AllocateAliasMap()
+            => s_aliasMapPool.Allocate();
+
+        protected static void AppendTokens(SyntaxNode node, StringBuilder builder)
+        {
+            foreach (var child in node.ChildNodesAndTokens())
+            {
+                if (child.IsToken)
+                {
+                    builder.Append(child.AsToken().Text);
+                }
+                else
+                {
+                    AppendTokens(child.AsNode(), builder);
+                }
+            }
+        }
+
+        public abstract bool TryGetDeclaredSymbolInfo(Project project, SyntaxNode node, out DeclaredSymbolInfo declaredSymbolInfo);
+    }
+
+    internal abstract class AbstractSyntaxFactsService
+    {
         private readonly static ObjectPool<Stack<(SyntaxNodeOrToken nodeOrToken, bool leading, bool trailing)>> s_stackPool =
             new ObjectPool<Stack<(SyntaxNodeOrToken nodeOrToken, bool leading, bool trailing)>>(() => new Stack<(SyntaxNodeOrToken nodeOrToken, bool leading, bool trailing)>());
 
@@ -77,33 +125,6 @@ protected AbstractSyntaxFactsService()
         public abstract bool IsShebangDirectiveTrivia(SyntaxTrivia trivia);
         public abstract bool IsPreprocessorDirective(SyntaxTrivia trivia);
 
-        protected static List<Dictionary<string, string>> AllocateAliasMapList()
-            => s_aliasMapListPool.Allocate();
-
-        protected static void FreeAliasMapList(List<Dictionary<string, string>> list)
-        {
-            if (list != null)
-            {
-                foreach (var aliasMap in list)
-                {
-                    FreeAliasMap(aliasMap);
-                }
-
-                s_aliasMapListPool.ClearAndFree(list);
-            }
-        }
-
-        protected static void FreeAliasMap(Dictionary<string, string> aliasMap)
-        {
-            if (aliasMap != null)
-            {
-                s_aliasMapPool.ClearAndFree(aliasMap);
-            }
-        }
-
-        protected static Dictionary<string, string> AllocateAliasMap()
-            => s_aliasMapPool.Allocate();
-
         public bool IsOnSingleLine(SyntaxNode node, bool fullSpan)
         {
             // Use an actual Stack so we can write out deeply recursive structures without overflowing.
@@ -392,20 +413,5 @@ public string GetBannerText(SyntaxNode documentationCommentTriviaSyntax, Cancell
             => DocumentationCommentService.GetBannerText(documentationCommentTriviaSyntax, cancellationToken);
 
         protected abstract IDocumentationCommentService DocumentationCommentService { get; }
-
-        protected static void AppendTokens(SyntaxNode node, StringBuilder builder)
-        {
-            foreach (var child in node.ChildNodesAndTokens())
-            {
-                if (child.IsToken)
-                {
-                    builder.Append(child.AsToken().Text);
-                }
-                else
-                {
-                    AppendTokens(child.AsNode(), builder);
-                }
-            }
-        }
     }
 }
\ No newline at end of file

src/Workspaces/Core/Portable/LanguageServices/SyntaxFactsService/ISyntaxFactsService.cs

@@ -4,7 +4,6 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading;
-using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.Host;
 using Microsoft.CodeAnalysis.Text;
 
@@ -224,8 +223,6 @@ internal interface ISyntaxFactsService : ILanguageService
         bool AreEquivalent(SyntaxToken token1, SyntaxToken token2);
         bool AreEquivalent(SyntaxNode node1, SyntaxNode node2);
 
-        bool TryGetDeclaredSymbolInfo(Project project, SyntaxNode node, out DeclaredSymbolInfo declaredSymbolInfo);
-
         string GetDisplayName(SyntaxNode node, DisplayNameOptions options, string rootNamespace = null);
 
         SyntaxNode GetContainingTypeDeclaration(SyntaxNode root, int position);