Add expression body syntax for getter-only properties.

ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -866,7 +866,7 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 				lambdaExpression.Parameters.Single().AcceptVisitor(this);
 			}
 			Space();
-			WriteToken(LambdaExpression.ArrowRole);
+			WriteToken(Roles.Arrow);
 			if (lambdaExpression.Body is BlockStatement) {
 				WriteBlock((BlockStatement)lambdaExpression.Body, policy.AnonymousMethodBraceStyle);
 			} else {
@@ -2179,22 +2179,30 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 			Space();
 			WritePrivateImplementationType(propertyDeclaration.PrivateImplementationType);
 			WriteIdentifier(propertyDeclaration.NameToken);
-			OpenBrace(policy.PropertyBraceStyle);
-			// output get/set in their original order
-			foreach (AstNode node in propertyDeclaration.Children) {
-				if (node.Role == IndexerDeclaration.GetterRole || node.Role == IndexerDeclaration.SetterRole) {
-					node.AcceptVisitor(this);
+			if (propertyDeclaration.ExpressionBody.IsNull) {
+				OpenBrace(policy.PropertyBraceStyle);
+				// output get/set in their original order
+				foreach (AstNode node in propertyDeclaration.Children) {
+					if (node.Role == IndexerDeclaration.GetterRole || node.Role == IndexerDeclaration.SetterRole) {
+						node.AcceptVisitor(this);
+					}
 				}
-			}
-			CloseBrace(policy.PropertyBraceStyle);
-			if (!propertyDeclaration.Initializer.IsNull) {
-				Space(policy.SpaceAroundAssignment);
-				WriteToken(Roles.Assign);
-				Space(policy.SpaceAroundAssignment);
-				propertyDeclaration.Initializer.AcceptVisitor(this);
+				CloseBrace(policy.PropertyBraceStyle);
+				if (!propertyDeclaration.Initializer.IsNull) {
+					Space(policy.SpaceAroundAssignment);
+					WriteToken(Roles.Assign);
+					Space(policy.SpaceAroundAssignment);
+					propertyDeclaration.Initializer.AcceptVisitor(this);
+					Semicolon();
+				}
+				NewLine();
+			} else {
+				Space();
+				WriteToken(Roles.Arrow);
+				Space();
+				propertyDeclaration.ExpressionBody.AcceptVisitor(this);
 				Semicolon();
 			}
-			NewLine();
 			EndNode(propertyDeclaration);
 		}
 

ICSharpCode.Decompiler/CSharp/Syntax/Expressions/LambdaExpression.cs

@@ -32,7 +32,6 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 	public class LambdaExpression : Expression
 	{
 		public readonly static TokenRole AsyncModifierRole = new TokenRole ("async");
-		public readonly static TokenRole ArrowRole = new TokenRole ("=>");
 		public static readonly Role<AstNode> BodyRole = new Role<AstNode>("Body", AstNode.Null);
 		
 		bool isAsync;
@@ -55,7 +54,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		}
 
 		public CSharpTokenNode ArrowToken {
-			get { return GetChildByRole (ArrowRole); }
+			get { return GetChildByRole (Roles.Arrow); }
 		}
 		
 		public AstNode Body {

ICSharpCode.Decompiler/CSharp/Syntax/Roles.cs

@@ -66,6 +66,7 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public static readonly TokenRole Assign = new TokenRole ("=");
 		public static readonly TokenRole Colon = new TokenRole (":");
 		public static readonly TokenRole DoubleColon = new TokenRole ("::");
+		public static readonly TokenRole Arrow = new TokenRole("=>");
 		public static readonly Role<Comment> Comment = new Role<Comment> ("Comment");
 		public static readonly Role<NewLineNode> NewLine = new Role<NewLineNode> ("NewLine");
 		public static readonly Role<WhitespaceNode> Whitespace = new Role<WhitespaceNode> ("Whitespace");

ICSharpCode.Decompiler/CSharp/Syntax/TypeMembers/PropertyDeclaration.cs

@@ -34,7 +34,8 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public static readonly TokenRole SetKeywordRole = new TokenRole ("set");
 		public static readonly Role<Accessor> GetterRole = new Role<Accessor>("Getter", Accessor.Null);
 		public static readonly Role<Accessor> SetterRole = new Role<Accessor>("Setter", Accessor.Null);
-		
+		public static readonly Role<Expression> ExpressionBodyRole = new Role<Expression>("ExpressionBody", Expression.Null);
+
 		public override SymbolKind SymbolKind {
 			get { return SymbolKind.Property; }
 		}
@@ -75,6 +76,11 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 			set { SetChildByRole(Roles.Expression, value); }
 		}
 
+		public Expression ExpressionBody {
+			get { return GetChildByRole(ExpressionBodyRole); }
+			set { SetChildByRole(ExpressionBodyRole, value); }
+		}
+
 		public override void AcceptVisitor (IAstVisitor visitor)
 		{
 			visitor.VisitPropertyDeclaration (this);
@@ -97,7 +103,8 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 				&& this.MatchAttributesAndModifiers(o, match) && this.ReturnType.DoMatch(o.ReturnType, match)
 				&& this.PrivateImplementationType.DoMatch(o.PrivateImplementationType, match)
 				&& this.Getter.DoMatch(o.Getter, match) && this.Setter.DoMatch(o.Setter, match)
-				&& this.Initializer.DoMatch(o.Initializer, match);
+				&& this.Initializer.DoMatch(o.Initializer, match)
+				&& this.ExpressionBody.DoMatch(o.ExpressionBody, match);
 		}
 	}
 }

ICSharpCode.Decompiler/CSharp/Transforms/NormalizeBlockStatements.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using ICSharpCode.Decompiler.CSharp.Syntax;
+using ICSharpCode.Decompiler.CSharp.Syntax.PatternMatching;
 
 namespace ICSharpCode.Decompiler.CSharp.Transforms
 {
@@ -116,5 +117,28 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			this.context = context;
 			rootNode.AcceptVisitor(this);
 		}
+
+		public override void VisitPropertyDeclaration(PropertyDeclaration propertyDeclaration)
+		{
+			if (context.Settings.UseExpressionBodyForCalculatedGetterOnlyProperties) {
+				SimplifyPropertyDeclaration(propertyDeclaration);
+			}
+			base.VisitPropertyDeclaration(propertyDeclaration);
+		}
+
+		static readonly PropertyDeclaration CalculatedGetterOnlyPropertyPattern = new PropertyDeclaration() {
+			Modifiers = Modifiers.Any,
+			Name = Pattern.AnyString,
+			ReturnType = new AnyNode(),
+			Getter = new Accessor() { Body = new BlockStatement() { new ReturnStatement(new AnyNode("expression")) } }
+		};
+
+		void SimplifyPropertyDeclaration(PropertyDeclaration propertyDeclaration)
+		{
+			var m = CalculatedGetterOnlyPropertyPattern.Match(propertyDeclaration);
+			if (!m.Success)
+				return;
+			propertyDeclaration.ExpressionBody = m.Get<Expression>("expression").Single().Detach();
+		}
 	}
 }

ICSharpCode.Decompiler/DecompilerSettings.cs

@@ -421,6 +421,21 @@ namespace ICSharpCode.Decompiler
 			}
 		}
 
+		bool useExpressionBodyForCalculatedGetterOnlyProperties = true;
+
+		/// <summary>
+		/// Gets/Sets whether simple calculated getter-only property declarations should use expression body syntax.
+		/// </summary>
+		public bool UseExpressionBodyForCalculatedGetterOnlyProperties {
+			get { return useExpressionBodyForCalculatedGetterOnlyProperties; }
+			set {
+				if (useExpressionBodyForCalculatedGetterOnlyProperties != value) {
+					useExpressionBodyForCalculatedGetterOnlyProperties = value;
+					OnPropertyChanged();
+				}
+			}
+		}
+
 		#region Options to aid VB decompilation
 		bool introduceIncrementAndDecrement = true;