Add MemberThis rule. Rule explicitly adds 'this.' before local member access.

Author: richardstanton

src/Microsoft.DotNet.CodeFormatting/Microsoft.DotNet.CodeFormatting.csproj

@@ -72,6 +72,7 @@
     <Compile Include="NameHelper.cs" />
     <Compile Include="ResponseFileWorkspace.cs" />
     <Compile Include="Rules\MarkReadonlyFieldsRule.cs" />
+    <Compile Include="Rules\MemberThisRule.cs" />
     <Compile Include="SemaphoreLock.cs" />
     <Compile Include="SyntaxUtil.cs" />
     <Compile Include="Filters\FilenameFilter.cs" />

src/Microsoft.DotNet.CodeFormatting/Rules/MemberThisRule.cs

@@ -0,0 +1,178 @@
+// 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.
+
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Microsoft.DotNet.CodeFormatting.Rules
+{
+    [LocalSemanticRule(MemberThisRule.Name, MemberThisRule.Description, LocalSemanticRuleOrder.MemberThisRule, DefaultRule = false)]
+    internal sealed class MemberThisRule : CSharpOnlyFormattingRule, ILocalSemanticFormattingRule
+    {
+        internal const string Name = "MemberThis";
+        internal const string Description = "Add this/Me prefixes on all member references";
+
+        private sealed class MemberThisRewriter : CSharpSyntaxRewriter
+        {
+            private SemanticModel semanticModel;
+            private readonly CancellationToken cancellationToken;
+
+            internal bool AddedAnnotations
+            {
+                get; private set;
+            }
+
+            internal MemberThisRewriter(SemanticModel semanticModel, CancellationToken cancellationToken)
+            {
+                this.semanticModel = semanticModel;
+                this.cancellationToken = cancellationToken;
+            }
+
+            public override SyntaxNode VisitGenericName(GenericNameSyntax name)
+            {
+                if (this.ShouldModify(name))
+                {
+                    this.AddedAnnotations = true;
+
+                    // Create a copy of this name
+                    GenericNameSyntax newName = SyntaxFactory.GenericName(name.Identifier, name.TypeArgumentList);
+
+                    // Add the "this" to the expression
+                    return SyntaxFactory.MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        SyntaxFactory.ThisExpression(),
+                        newName.WithoutTrivia())
+                        .WithLeadingTrivia(name.GetLeadingTrivia())
+                        .WithTrailingTrivia(name.GetTrailingTrivia());
+                }
+
+                return base.VisitGenericName(name);
+            }
+
+            public override SyntaxNode VisitIdentifierName(IdentifierNameSyntax name)
+            {
+                if (this.ShouldModify(name))
+                {
+                    this.AddedAnnotations = true;
+
+                    // Create a copy of this name
+                    IdentifierNameSyntax newName = SyntaxFactory.IdentifierName(name.Identifier);
+
+                    // Add the "this" to the expression
+                    return SyntaxFactory.MemberAccessExpression(
+                        SyntaxKind.SimpleMemberAccessExpression,
+                        SyntaxFactory.ThisExpression(),
+                        newName.WithoutTrivia())
+                        .WithLeadingTrivia(name.GetLeadingTrivia())
+                        .WithTrailingTrivia(name.GetTrailingTrivia());
+                }
+
+                return base.VisitIdentifierName(name);
+            }
+
+            private bool ShouldModify(SimpleNameSyntax name)
+            {
+                // Ignore cases that don't make sense
+                if (name.Parent is MemberAccessExpressionSyntax)
+                {
+                    MemberAccessExpressionSyntax parent = (MemberAccessExpressionSyntax)name.Parent;
+                    if (parent.Name == name)
+                    {
+                        return false;
+                    }
+                }
+                else if (name.Parent is QualifiedNameSyntax)
+                {
+                    QualifiedNameSyntax parent = (QualifiedNameSyntax)name.Parent;
+                    if (parent.Left == name)
+                    {
+                        return false;
+                    }
+                }
+                else if (name.Parent is MemberBindingExpressionSyntax || name.Parent is AliasQualifiedNameSyntax)
+                {
+                    return false;
+                }
+
+                return this.IsLocalMember(name);
+            }
+
+            // Check if the name referes to a non-static member on the same type.
+            private bool IsLocalMember(SimpleNameSyntax name)
+            {
+                ISymbol symbol = semanticModel.GetSymbolInfo(name, this.cancellationToken).Symbol;
+
+                // Only add the "this" to non-static member references
+                if (symbol == null || symbol.IsStatic || !IsMember(symbol))
+                {
+                    return false;
+                }
+
+                // Make sure the reference is in the same type
+                return IsDerivedType(this.GetParentType(name), symbol.ContainingType);
+            }
+
+            private static bool IsDerivedType(INamedTypeSymbol type, INamedTypeSymbol baseType)
+            {
+                if (type == null)
+                    return false;
+                if (object.Equals(type, baseType))
+                    return true;
+                return IsDerivedType(type.BaseType, baseType);
+            }
+
+            private static bool IsMember(ISymbol symbol)
+            {
+                switch (symbol.Kind)
+                {
+                    case SymbolKind.Event:
+                    case SymbolKind.Field:
+                    case SymbolKind.Method:
+                    case SymbolKind.Property:
+                        return true;
+                    default:
+                        return false;
+                }
+            }
+
+            // Find the type this node resides in
+            private INamedTypeSymbol GetParentType(SyntaxNode node)
+            {
+                while (node != null)
+                {
+                    if (node.IsKind(SyntaxKind.ClassDeclaration) || node.IsKind(SyntaxKind.StructDeclaration))
+                    {
+                        return (INamedTypeSymbol)semanticModel.GetDeclaredSymbol(node);
+                    }
+
+                    node = node.Parent;
+                }
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Entry point to the rule
+        /// </summary>
+        public async Task<SyntaxNode> ProcessAsync(Document document, SyntaxNode syntaxNode, CancellationToken cancellationToken)
+        {
+            SemanticModel semanticModel = await document.GetSemanticModelAsync(cancellationToken);
+
+            // Visit all the nodes in the model
+            MemberThisRewriter rewriter = new MemberThisRewriter(semanticModel, cancellationToken);
+            SyntaxNode newNode = rewriter.Visit(syntaxNode);
+
+            // If changes are not mode return the original model
+            if (!rewriter.AddedAnnotations)
+            {
+                return syntaxNode;
+            }
+
+            return newNode;
+        }
+    }
+}

src/Microsoft.DotNet.CodeFormatting/Rules/RuleOrder.cs

@@ -29,6 +29,7 @@ internal static class LocalSemanticRuleOrder
         public const int IsFormattedFormattingRule = 3;
         public const int RemoveExplicitThisRule = 4;
         public const int AssertArgumentOrderRule = 5;
+        public const int MemberThisRule = 6;
     }
 
     // Please keep these values sorted by number, not rule name.