Restore some parts of the progression api some legacy components (like codemap) use. (#78836)

Author: CyrusNajmabadi

src/VisualStudio/CSharp/Impl/Progression/CSharpProgressionLanguageService.cs

@@ -0,0 +1,91 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#nullable disable
+
+using System;
+using System.Collections.Generic;
+using System.Composition;
+using System.Threading;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Symbols;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.PooledObjects;
+using Microsoft.CodeAnalysis.Shared.Extensions;
+using Microsoft.VisualStudio.LanguageServices.Implementation.Progression;
+
+namespace Microsoft.VisualStudio.LanguageServices.CSharp.Progression;
+
+[ExportLanguageService(typeof(IProgressionLanguageService), LanguageNames.CSharp), Shared]
+internal sealed partial class CSharpProgressionLanguageService : IProgressionLanguageService
+{
+    private static readonly SymbolDisplayFormat s_descriptionFormat = new(
+        globalNamespaceStyle: SymbolDisplayGlobalNamespaceStyle.OmittedAsContaining,
+        typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypesAndNamespaces,
+        genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters,
+        memberOptions: SymbolDisplayMemberOptions.IncludeParameters |
+                       SymbolDisplayMemberOptions.IncludeContainingType,
+        parameterOptions: SymbolDisplayParameterOptions.IncludeType |
+                          SymbolDisplayParameterOptions.IncludeParamsRefOut |
+                          SymbolDisplayParameterOptions.IncludeOptionalBrackets,
+        miscellaneousOptions: SymbolDisplayMiscellaneousOptions.UseSpecialTypes);
+
+    private static readonly SymbolDisplayFormat s_labelFormat = new(
+        genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters,
+        memberOptions: SymbolDisplayMemberOptions.IncludeParameters |
+                       SymbolDisplayMemberOptions.IncludeExplicitInterface,
+        parameterOptions: SymbolDisplayParameterOptions.IncludeType |
+                          SymbolDisplayParameterOptions.IncludeParamsRefOut |
+                          SymbolDisplayParameterOptions.IncludeOptionalBrackets,
+        delegateStyle: SymbolDisplayDelegateStyle.NameAndParameters,
+        miscellaneousOptions: SymbolDisplayMiscellaneousOptions.UseSpecialTypes);
+
+    [ImportingConstructor]
+    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
+    public CSharpProgressionLanguageService()
+    {
+    }
+
+    public string GetDescriptionForSymbol(ISymbol symbol, bool includeContainingSymbol)
+        => GetSymbolText(symbol, includeContainingSymbol, s_descriptionFormat);
+
+    public string GetLabelForSymbol(ISymbol symbol, bool includeContainingSymbol)
+        => GetSymbolText(symbol, includeContainingSymbol, s_labelFormat);
+
+    private static string GetSymbolText(ISymbol symbol, bool includeContainingSymbol, SymbolDisplayFormat displayFormat)
+    {
+        var label = symbol.ToDisplayString(displayFormat);
+
+        var typeToShow = GetType(symbol);
+
+        if (typeToShow != null)
+        {
+            label += " : " + typeToShow.ToDisplayString(s_labelFormat);
+        }
+
+        if (includeContainingSymbol && symbol.ContainingSymbol != null)
+        {
+            label += " (" + symbol.ContainingSymbol.ToDisplayString(s_labelFormat) + ")";
+        }
+
+        return label;
+    }
+
+    private static ITypeSymbol GetType(ISymbol symbol)
+    {
+        switch (symbol)
+        {
+            case IEventSymbol f: return f.Type;
+            case IFieldSymbol f: return f.ContainingType.TypeKind == TypeKind.Enum ? null : f.Type;
+            case IMethodSymbol m: return IncludeReturnType(m) ? m.ReturnType : null;
+            case IPropertySymbol p: return p.Type;
+            case INamedTypeSymbol n: return n.IsDelegateType() ? n.DelegateInvokeMethod.ReturnType : null;
+            default: return null;
+        }
+    }
+
+    private static bool IncludeReturnType(IMethodSymbol f)
+        => f.MethodKind is MethodKind.Ordinary or MethodKind.ExplicitInterfaceImplementation;
+}