Editor context actions - added context action which inserts null checks - for expressions like "a.b.c" inserts "if (a != null && a.b != null)".

src/AddIns/Misc/SharpRefactoring/Project/SharpRefactoring.addin

@@ -48,6 +48,7 @@
 		<Class class="SharpRefactoring.ContextActions.CheckAssignmentNotNull" />
 		<Class class="SharpRefactoring.ContextActions.ParamCheckForNull" />
 		<Class class="SharpRefactoring.ContextActions.ParamRangeCheck" />
+		<Class class="SharpRefactoring.ContextActions.CheckMemberNotNull" />
 	</Path>
 
 	<Path name="/SharpDevelop/ViewContent/TextEditor/OverrideCompletionHandler">

src/AddIns/Misc/SharpRefactoring/Project/SharpRefactoring.csproj

@@ -77,6 +77,7 @@
     <Compile Include="Src\ContextActions\CheckAssignmentCache.cs" />
     <Compile Include="Src\ContextActions\CheckAssignmentNull.cs" />
     <Compile Include="Src\ContextActions\CheckAssignmentNotNull.cs" />
+    <Compile Include="Src\ContextActions\CheckMemberNotNull.cs" />
     <Compile Include="Src\ContextActions\Extensions.cs" />
     <Compile Include="Src\ContextActions\FindTypeDeclarationsVisitor.cs" />
     <Compile Include="Src\ContextActions\GenerateMember.cs" />

src/AddIns/Misc/SharpRefactoring/Project/Src/ContextActions/CheckAssignmentCache.cs

@@ -19,7 +19,8 @@ namespace SharpRefactoring.ContextActions
 		{
 			this.VariableName = GetVariableName(context);
 			this.CodeGenerator = GetCodeGenerator(context);
-			this.ElementRegion = GetStatementRegion(context);
+			this.Element = GetElement(context);
+			this.ElementRegion = (Element == null) ? DomRegion.Empty : DomRegion.FromLocation(Element.StartLocation, Element.EndLocation);
 		}
 		
 		public bool IsActionAvailable
@@ -33,13 +34,17 @@ namespace SharpRefactoring.ContextActions
 		
 		public CodeGenerator CodeGenerator { get; private set; }
 		
+		/// <summary>
+		/// Either AssignmentExpression or LocalVariableDeclaration.
+		/// </summary>
+		public AbstractNode Element { get; private set; }
+		
 		public DomRegion ElementRegion { get; private set; }
 		
 		protected string GetVariableName(EditorContext context)
 		{
 			// a = Foo()      : AssignmentExpression.Left == IdentifierExpression(*identifier*)
 			// var a = Foo()  : VariableDeclaration(*name*).Initializer != empty
-			
 			var variableName = GetVariableNameFromAssignment(context.GetContainingElement<AssignmentExpression>());
 			if (variableName != null)
 				return variableName;
@@ -50,19 +55,18 @@ namespace SharpRefactoring.ContextActions
 			return null;
 		}
 		
-		protected DomRegion GetStatementRegion(EditorContext context)
+		protected AbstractNode GetElement(EditorContext context)
 		{
 			// a = Foo()      : AssignmentExpression.Left == IdentifierExpression(*identifier*)
 			// var a = Foo()  : VariableDeclaration(*name*).Initializer != empty
-			
 			var assignment = context.GetContainingElement<AssignmentExpression>();
 			if (assignment != null)
-				return DomRegion.FromLocation(assignment.StartLocation, assignment.EndLocation);
+				return assignment;
 			var declaration = context.GetContainingElement<LocalVariableDeclaration>();
 			if (declaration != null)
-				return DomRegion.FromLocation(declaration.StartLocation, declaration.EndLocation);
+				return declaration;
 			
-			return DomRegion.Empty;
+			return null;
 		}
 		
 		string GetVariableNameFromAssignment(AssignmentExpression assignment)

src/AddIns/Misc/SharpRefactoring/Project/Src/ContextActions/CheckAssignmentNotNull.cs

@@ -32,12 +32,12 @@ namespace SharpRefactoring.ContextActions
 			var ifStatement = GenerateAstToInsert(cache.VariableName);
 			
 			var editor = context.Editor;
-			string indent = DocumentUtilitites.GetWhitespaceAfter(editor.Document, editor.Document.GetLineStartOffset(cache.ElementRegion.GetStart()));
-			string code = cache.CodeGenerator.GenerateCode(ifStatement, indent);
-			int insertOffset = editor.Document.GetLineEndOffset(cache.ElementRegion.GetEnd());
+			var doc = editor.Document;
+			
 			using (var undoGroup = editor.Document.OpenUndoGroup()) {
-				editor.Document.Insert(insertOffset, code);
-				var caretPos = editor.Document.Text.IndexOf(caretMarker, insertOffset);
+				editor.InsertCodeAfter(cache.Element, ifStatement);
+				// set caret to the position of the special marker
+				var caretPos = doc.Text.IndexOf(caretMarker, doc.GetLineEndOffset(cache.Element.EndLocation));
 				editor.Caret.Offset = caretPos;
 				editor.Document.RemoveRestOfLine(caretPos);
 			}
@@ -46,6 +46,7 @@ namespace SharpRefactoring.ContextActions
 		AbstractNode GenerateAstToInsert(string variableName)
 		{
 			var block = new BlockStatement();
+			// mark the place where to put caret
 			block.AddChild(new ExpressionStatement(new IdentifierExpression(caretMarker)));
 			return new IfElseStatement(
 				new BinaryOperatorExpression(new IdentifierExpression(variableName), BinaryOperatorType.InEquality, new PrimitiveExpression(null)),

src/AddIns/Misc/SharpRefactoring/Project/Src/ContextActions/CheckAssignmentNull.cs

@@ -29,13 +29,7 @@ namespace SharpRefactoring.ContextActions
 			var cache = context.GetCached<CheckAssignmentCache>();
 			
 			var ifStatement = GenerateAstToInsert(cache.VariableName);
-
-			var editor = context.Editor;
-			string indent = DocumentUtilitites.GetWhitespaceAfter(editor.Document, editor.Document.GetLineStartOffset(cache.ElementRegion.GetStart()));
-			string code = cache.CodeGenerator.GenerateCode(ifStatement, indent);
-			int insertOffset = editor.Document.GetLineEndOffset(cache.ElementRegion.GetEnd());
-			editor.Document.Insert(insertOffset, code);
-			editor.Caret.Offset = insertOffset + code.Length - 1;
+			context.Editor.InsertCodeAfter(cache.Element, ifStatement, true);
 		}
 		
 		AbstractNode GenerateAstToInsert(string variableName)

src/AddIns/Misc/SharpRefactoring/Project/Src/ContextActions/CheckMemberNotNull.cs

@@ -0,0 +1,133 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.Ast;
+using ICSharpCode.SharpDevelop.Dom;
+using ICSharpCode.SharpDevelop.Editor;
+using ICSharpCode.SharpDevelop.Refactoring;
+
+namespace SharpRefactoring.ContextActions
+{
+	/// <summary>
+	/// For expressions like "a.b.c" adds checks for null "if (a != null && a.b != null)".
+	/// </summary>
+	public class CheckMemberNotNull : ContextAction
+	{
+		public override string Title {
+			get { return "Add null checks"; }
+		}
+		
+		/// <summary>
+		/// Expression at caret.
+		/// </summary>
+		Expression currentExpr;
+		/// <summary>
+		/// Expression to be checked for null.
+		/// </summary>
+		Expression targetExpr;
+		
+		public override bool IsAvailable(EditorContext context)
+		{
+			this.currentExpr = context.GetContainingElement<Expression>();
+			if (currentExpr is InvocationExpression) {
+				// InvocationExpression (e.g. "e.Foo()") has MemberReferenceExpression as TargetObject (e.g. "e.Foo")
+				// "e.Foo() -> e"
+				this.targetExpr = GetTarget(((InvocationExpression)currentExpr).TargetObject);
+			} else {
+				// "a.b" -> "a"
+				this.targetExpr = GetTarget(currentExpr);
+			}
+			return 
+				this.targetExpr is MemberReferenceExpression ||
+				this.targetExpr is CastExpression ||
+				this.targetExpr is ParenthesizedExpression;
+				//this.targetExpr is IdentifierExpression;		// "don't offer the action for just a.b, only for a.b.c"
+		}
+		
+		/// <summary>
+		/// Gets "a.b" from "a.b.c"
+		/// </summary>
+		Expression GetTarget(Expression memberReferenceExpr)
+		{
+			if (memberReferenceExpr is MemberReferenceExpression) {
+				return ((MemberReferenceExpression)memberReferenceExpr).TargetObject;
+			}
+			return null;
+		}
+		
+		public override void Execute(EditorContext context)
+		{
+			var conditionExpr = BuildCondition(this.targetExpr);
+			if (conditionExpr == null)
+				return;
+			var ifExpr = new IfElseStatement(conditionExpr, new BlockStatement());
+			
+			context.Editor.InsertCodeBefore(this.currentExpr, ifExpr);
+		}
+		
+		/// <summary>
+		/// Turns "(a.b as T).d.e" into "(a != null) && (a.b is T) && ((a.b as T).d != null)"
+		/// </summary>
+		Expression BuildCondition(Expression targetExpr)
+		{
+			var parts = GetConditionParts(targetExpr);
+			Expression condition = null;
+			foreach (var part in parts) {
+				if (condition == null) {
+					// first
+					condition = new ParenthesizedExpression(part);
+				} else {
+					condition = new BinaryOperatorExpression(new ParenthesizedExpression(part), BinaryOperatorType.LogicalAnd, condition);
+				}
+			}
+			return condition;
+		}
+		
+		List<Expression> GetConditionParts(Expression targetExpr)
+		{
+			var result = new List<Expression>();
+			Expression current = targetExpr;
+			while (current != null)
+			{
+				// process current expr
+				if (current is MemberReferenceExpression) {
+					var memberExpr = (MemberReferenceExpression)current;
+					// expr != null
+					result.Add(new BinaryOperatorExpression(memberExpr, BinaryOperatorType.InEquality, new PrimitiveExpression(null)));
+				} else if (current is CastExpression) {
+					var castExpr = (CastExpression)current;
+					// expr is T
+					result.Add(new TypeOfIsExpression(castExpr.Expression, castExpr.CastTo));
+					// no need to check (a != null) && (a is T): (a is T) is enough - skip the "a"
+					current = StepIn(current);
+				}
+				else if (current is IdentifierExpression) {
+					result.Add(new BinaryOperatorExpression((IdentifierExpression)current, BinaryOperatorType.InEquality, new PrimitiveExpression(null)));
+				}
+				
+				// step down the AST (e.g. from "a as T" to "a")
+				current = StepIn(current);
+			}
+			return result;
+		}
+		
+		Expression StepIn(Expression expr)
+		{
+			if (expr is MemberReferenceExpression) {
+				return ((MemberReferenceExpression)expr).TargetObject;
+			} else if (expr is CastExpression) {
+				return ((CastExpression)expr).Expression;
+			}
+			else if (expr is ParenthesizedExpression) {
+				return ((ParenthesizedExpression)expr).Expression;
+			}
+			else if (expr is IdentifierExpression) {
+				return null;
+			} else {
+				return null;
+			}
+		}
+	}
+}

src/AddIns/Misc/SharpRefactoring/Project/Src/ContextActions/Extensions.cs

@@ -4,9 +4,9 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
-
 using ICSharpCode.NRefactory;
 using ICSharpCode.NRefactory.Ast;
+using ICSharpCode.NRefactory.Visitors;
 using ICSharpCode.SharpDevelop;
 using ICSharpCode.SharpDevelop.Dom;
 using ICSharpCode.SharpDevelop.Dom.Refactoring;
@@ -77,6 +77,15 @@ namespace SharpRefactoring.ContextActions
 			return line.Offset + line.TotalLength;
 		}
 		
+		public static int GetPreviousLineEndOffset(this IDocument document, Location location)
+		{
+			var line = document.GetLineForOffset(document.PositionToOffset(location));
+			if (line.LineNumber == 1)
+				return -1;
+			var previousLine = document.GetLine(line.LineNumber - 1);
+			return previousLine.Offset + previousLine.TotalLength;
+		}
+		
 		public static void RemoveRestOfLine(this IDocument document, int offset)
 		{
 			var line = document.GetLineForOffset(offset);
@@ -84,6 +93,47 @@ namespace SharpRefactoring.ContextActions
 			document.Remove(offset, lineEndOffset - offset);
 		}
 		
+		public static DomRegion DomRegion(this INode node)
+		{
+			return new DomRegion(node.StartLocation.Line, node.StartLocation.Column, node.EndLocation.Line, node.EndLocation.Column);
+		}
+		
+		/// <summary>
+		/// Inserts code at the next line after target AST node.
+		/// </summary>
+		public static void InsertCodeAfter(this ITextEditor editor, AbstractNode target, AbstractNode insert, bool updateCaretPos = false)
+		{
+			InsertCode(editor, target, insert, editor.Document.GetLineEndOffset(target.EndLocation), updateCaretPos);
+		}
+		
+		/// <summary>
+		/// Inserts code at the line before target AST node.
+		/// </summary>
+		public static void InsertCodeBefore(this ITextEditor editor, AbstractNode target, AbstractNode insert)
+		{
+			InsertCode(editor, target, insert, editor.Document.GetPreviousLineEndOffset(target.StartLocation), false);
+		}
+		
+		public static void InsertCode(this ITextEditor editor, AbstractNode target, AbstractNode insert, int insertOffset, bool updateCaretPos)
+		{
+			if (insertOffset < 0)
+				return;
+			
+			var regionCorrectVisitor = new SetRegionInclusionVisitor();
+			insert.AcceptVisitor(regionCorrectVisitor, null);
+			
+			var doc = editor.Document;
+			var codeGen = editor.Language.Properties.CodeGenerator;
+			
+			string indent = DocumentUtilitites.GetWhitespaceAfter(doc, doc.GetLineStartOffset(target.StartLocation));
+			string code = codeGen.GenerateCode(insert, indent);
+			
+			doc.Insert(insertOffset, code);
+			if (updateCaretPos) {
+				editor.Caret.Offset = insertOffset + code.Length - 1;
+			}
+		}
+		
 		/// <summary>
 		/// C# only.
 		/// </summary>
@@ -121,4 +171,4 @@ namespace SharpRefactoring.ContextActions
 			return -1;
 		}
 	}
-}
+}

src/Libraries/NRefactory/Project/Src/Visitors/SetRegionInclusionVisitor.cs

@@ -17,6 +17,11 @@ namespace ICSharpCode.NRefactory.Visitors
 	{
 		Stack<INode> parentNodes = new Stack<INode>();
 		
+		/// <summary>
+		/// Sets StartLocation and EndLocation (region) of every node to union of regions of its children.
+		/// Parsers don't do this by default:
+		/// e.g. "a.Foo()" is InvocationExpression, its region includes only the "()" and it has a child MemberReferenceExpression, with region ".Foo".
+		/// </summary>
 		public SetRegionInclusionVisitor()
 		{
 			parentNodes.Push(null);
@@ -34,7 +39,7 @@ namespace ICSharpCode.NRefactory.Visitors
 				if (node is PropertyDeclaration) {
 					// PropertyDeclaration has correctly set BodyStart and BodyEnd by the parser,
 					// but it has no subnode "body", just 2 children GetRegion and SetRegion which don't span
-					// the whole (BodyStart, BodyEnd) region => We have to handle PropertyDeclaration as a special case.
+					// the whole (BodyStart, BodyEnd) region => we have to handle PropertyDeclaration as a special case.
 					node.EndLocation = ((PropertyDeclaration)node).BodyEnd;
 				}
 				
@@ -60,7 +65,7 @@ namespace ICSharpCode.NRefactory.Visitors
 					parent.EndLocation = node.EndLocation;
 			}
 			
-			// Block statement as a special case - we want it without the '{' and '}'
+			// Block statement as a special case - we want block contents without the '{' and '}'
 			if (node is BlockStatement) {
 				var firstSatement = node.Children.FirstOrDefault();
 				if (firstSatement != null) {