Added CancellationToken support for the context actions.

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/AddAnotherAccessor.cs

@@ -23,6 +23,7 @@
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -31,7 +32,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	/// </summary>
 	public class AddAnotherAccessor : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var pdecl = GetPropertyDeclaration (context);
 			if (pdecl == null)

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CheckIfParameterIsNull.cs

@@ -25,6 +25,7 @@
 // THE SOFTWARE.
 
 using ICSharpCode.NRefactory.PatternMatching;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -34,7 +35,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	public class CheckIfParameterIsNull : IContextAction
 	{
 		//TODO: Create 'multiple' null checks when more than 1 parameter is selected.
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var parameter = GetParameterDeclaration (context);
 			if (parameter == null)

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/ConvertDecToHex.cs

@@ -23,6 +23,7 @@
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -31,7 +32,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	/// </summary>
 	public class ConvertDecToHex : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var pexpr = context.GetNode<PrimitiveExpression> ();
 			if (pexpr == null || pexpr.LiteralValue.StartsWith ("0X", System.StringComparison.OrdinalIgnoreCase))

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/ConvertForeachToFor.cs

@@ -26,6 +26,7 @@
 using System;
 using System.Linq;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -34,9 +35,9 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	/// </summary>
 	public class ConvertForeachToFor : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
-			return GetForeachStatement (context) != null;
+			return GetForeachStatement (context, cancellationToken) != null;
 		}
 
 		static string GetCountProperty (IType type)
@@ -81,13 +82,13 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			}
 		}
 		
-		static ForeachStatement GetForeachStatement (RefactoringContext context)
+		static ForeachStatement GetForeachStatement (RefactoringContext context, CancellationToken cancellationToken = default (CancellationToken))
 		{
 			var astNode = context.GetNode ();
 			if (astNode == null)
 				return null;
 			var result = (astNode as ForeachStatement) ?? astNode.Parent as ForeachStatement;
-			if (result == null || context.Resolve (result.InExpression) == null)
+			if (result == null || context.Resolve (result.InExpression, cancellationToken) == null)
 				return null;
 			return result;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/ConvertHexToDec.cs

@@ -23,6 +23,7 @@
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -31,7 +32,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	/// </summary>
 	public class ConvertHexToDec: IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var pexpr = context.GetNode<PrimitiveExpression> ();
 			if (pexpr == null || !pexpr.LiteralValue.StartsWith ("0X", System.StringComparison.OrdinalIgnoreCase))

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CreateBackingStore.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class CreateBackingStore : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var propertyDeclaration = context.GetNode<PropertyDeclaration> ();
 			return propertyDeclaration != null && 

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CreateEventInvocator.cs

@@ -27,12 +27,13 @@ using System;
 using System.Linq;
 using System.Collections.Generic;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class CreateEventInvocator : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			VariableInitializer initializer;
 			var eventDeclaration = GetEventDeclaration (context, out initializer);

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CreateField.cs

@@ -28,12 +28,13 @@ using System;
 using ICSharpCode.NRefactory.PatternMatching;
 using System.Linq;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class CreateField : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var identifier = GetIdentifier (context);
 			if (identifier == null)

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CreateLocalVariable.cs

@@ -28,6 +28,7 @@ using ICSharpCode.NRefactory.PatternMatching;
 using System.Linq;
 using System.Collections.Generic;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -58,7 +59,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			return expressions;
 		}
 		
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			if (GetUnresolvedArguments (context).Count > 0)
 				return true;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/CreateProperty.cs

@@ -26,12 +26,13 @@
 using System;
 using ICSharpCode.NRefactory.PatternMatching;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class CreateProperty : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var identifier = CreateField.GetIdentifier (context);
 			if (identifier == null)

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/FlipOperatorArguments.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class FlipOperatorArguments : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			return GetBinaryOperatorExpression (context) != null;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/GenerateGetter.cs

@@ -27,12 +27,13 @@
 using System;
 using ICSharpCode.NRefactory.PatternMatching;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class GenerateGetter : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var initializer = GetVariableInitializer (context);
 			if (initializer == null || !initializer.NameToken.Contains (context.Location.Line, context.Location.Column))

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/GenerateProperty.cs

@@ -26,12 +26,13 @@
 using System;
 using ICSharpCode.NRefactory.PatternMatching;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class GenerateProperty : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var initializer = GetVariableInitializer (context);
 			if (initializer == null || !initializer.NameToken.Contains (context.Location.Line, context.Location.Column))

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/GenerateSwitchLabels.cs

@@ -25,17 +25,18 @@
 // THE SOFTWARE.
 using System;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class GenerateSwitchLabels : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var switchStatement = GetSwitchStatement (context);
 			if (switchStatement == null)
 				return false;
-			var result = context.Resolve (switchStatement.Expression);
+			var result = context.Resolve (switchStatement.Expression, cancellationToken);
 			if (result == null)
 				return false;
 			return result.Type.Kind == TypeKind.Enum;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/InsertAnonymousMethodSignature.cs

@@ -27,15 +27,16 @@ using System;
 using ICSharpCode.NRefactory.TypeSystem;
 using System.Linq;
 using System.Text;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class InsertAnonymousMethodSignature : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			IType type;
-			return GetAnonymousMethodExpression (context, out type) != null;
+			return GetAnonymousMethodExpression (context, out type, cancellationToken) != null;
 		}
 		
 		public void Run (RefactoringContext context)
@@ -63,7 +64,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			}
 		}
 		
-		static AnonymousMethodExpression GetAnonymousMethodExpression (RefactoringContext context, out IType delegateType)
+		static AnonymousMethodExpression GetAnonymousMethodExpression (RefactoringContext context, out IType delegateType, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			delegateType = null;
 			
@@ -75,9 +76,9 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			var parent = anonymousMethodExpression.Parent;
 			
 			if (parent is AssignmentExpression) {
-				resolvedType = context.Resolve (((AssignmentExpression)parent).Left).Type;
+				resolvedType = context.Resolve (((AssignmentExpression)parent).Left, cancellationToken).Type;
 			} else if (parent is VariableInitializer) {
-				resolvedType = context.Resolve (((VariableDeclarationStatement)parent.Parent).Type).Type;
+				resolvedType = context.Resolve (((VariableDeclarationStatement)parent.Parent).Type, cancellationToken).Type;
 			} else if (parent is InvocationExpression) {
 				// TODO: handle invocations
 			}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/IntroduceFormatItem.cs

@@ -28,6 +28,7 @@ using System;
 using ICSharpCode.NRefactory.PatternMatching;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -39,7 +40,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 	{
 		readonly static MemberReferenceExpression PrototypeFormatReference = new MemberReferenceExpression (new TypeReferenceExpression (new PrimitiveType ("string")), "Format");
 		
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			if (!context.IsSomethingSelected)
 				return false;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/InvertIf.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class InvertIf : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			var ifStatement = GetIfElseStatement (context);
 			return ifStatement != null && !ifStatement.TrueStatement.IsNull && !ifStatement.FalseStatement.IsNull;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/RemoveBackingStore.cs

@@ -28,14 +28,15 @@ using System.Linq;
 using ICSharpCode.NRefactory.CSharp.Resolver;
 using ICSharpCode.NRefactory.Semantics;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class RemoveBackingStore : IContextAction
 	{
-		public bool  IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
-			return GetBackingField (context) != null;
+			return GetBackingField (context, cancellationToken) != null;
 		}
 		
 		public void Run (RefactoringContext context)
@@ -75,7 +76,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 //			}
 //		}
 //		
-		static IField GetBackingField (RefactoringContext context)
+		static IField GetBackingField (RefactoringContext context, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			var propertyDeclaration = context.GetNode<PropertyDeclaration> ();
 			// automatic properties always need getter & setter
@@ -83,10 +84,10 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 				return null;
 			if (!context.HasCSharp3Support || propertyDeclaration.HasModifier (ICSharpCode.NRefactory.CSharp.Modifiers.Abstract) || ((TypeDeclaration)propertyDeclaration.Parent).ClassType == ClassType.Interface)
 				return null;
-			var getterField = ScanGetter (context, propertyDeclaration);
+			var getterField = ScanGetter (context, propertyDeclaration, cancellationToken);
 			if (getterField == null)
 				return null;
-			var setterField = ScanSetter (context, propertyDeclaration);
+			var setterField = ScanSetter (context, propertyDeclaration, cancellationToken);
 			if (setterField == null)
 				return null;
 			if (getterField.Region != setterField.Region)
@@ -94,20 +95,20 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			return getterField;
 		}
 		
-		internal static IField ScanGetter (RefactoringContext context, PropertyDeclaration propertyDeclaration)
+		internal static IField ScanGetter (RefactoringContext context, PropertyDeclaration propertyDeclaration, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			if (propertyDeclaration.Getter.Body.Statements.Count != 1)
 				return null;
 			var returnStatement = propertyDeclaration.Getter.Body.Statements.First () as ReturnStatement;
 			if (returnStatement == null)
 				return null;
-			var result = context.Resolve (returnStatement.Expression);
+			var result = context.Resolve (returnStatement.Expression, cancellationToken);
 			if (result == null || !(result is MemberResolveResult))
 				return null;
 			return ((MemberResolveResult)result).Member as IField;
 		}
 		
-		internal static IField ScanSetter (RefactoringContext context, PropertyDeclaration propertyDeclaration)
+		internal static IField ScanSetter (RefactoringContext context, PropertyDeclaration propertyDeclaration, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			if (propertyDeclaration.Setter.Body.Statements.Count != 1)
 				return null;
@@ -115,7 +116,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			var assignment = setAssignment != null ? setAssignment.Expression as AssignmentExpression : null;
 			if (assignment == null || assignment.Operator != AssignmentOperatorType.Assign)
 				return null;
-			var result = context.Resolve (assignment.Left);
+			var result = context.Resolve (assignment.Left, cancellationToken);
 			if (result == null || !(result is MemberResolveResult))
 				return null;
 			return ((MemberResolveResult)result).Member as IField;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/RemoveBraces.cs

@@ -25,12 +25,13 @@
 // THE SOFTWARE.
 using System;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class RemoveBraces : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			return GetBlockStatement (context) != null;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/RemoveRegion.cs

@@ -25,12 +25,13 @@
 // THE SOFTWARE.
 using System;
 using System.Linq;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class RemoveRegion : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			return GetDirective (context) != null;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/ReplaceEmptyString.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class ReplaceEmptyString : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			return GetEmptyString (context) != null;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/SplitDeclarationAndAssignment.cs

@@ -26,15 +26,16 @@
 using System;
 using System.Linq;
 using ICSharpCode.NRefactory.PatternMatching;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class SplitDeclarationAndAssignment : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			AstType type;
-			return GetVariableDeclarationStatement (context, out type) != null;
+			return GetVariableDeclarationStatement (context, out type, cancellationToken) != null;
 		}
 		
 		public void Run (RefactoringContext context)
@@ -57,7 +58,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 			}
 		}
 		
-		static VariableDeclarationStatement GetVariableDeclarationStatement (RefactoringContext context, out AstType resolvedType)
+		static VariableDeclarationStatement GetVariableDeclarationStatement (RefactoringContext context, out AstType resolvedType, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			var result = context.GetNode<VariableDeclarationStatement> ();
 			if (result != null && result.Variables.Count == 1 && !result.Variables.First ().Initializer.IsNull && result.Variables.First ().NameToken.Contains (context.Location.Line, context.Location.Column)) {

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/SplitString.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class SplitString: IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			if (context.IsSomethingSelected)
 				return false;

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/UseExplicitType.cs

@@ -27,23 +27,24 @@ using System;
 using System.Linq;
 using ICSharpCode.NRefactory.PatternMatching;
 using ICSharpCode.NRefactory.TypeSystem;
+using System.Threading;
 
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class UseExplicitType: IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
-			var varDecl = GetVariableDeclarationStatement (context);
+			var varDecl = GetVariableDeclarationStatement (context, cancellationToken);
 			IType type;
 			if (varDecl != null) {
-				type = context.Resolve (varDecl.Variables.First ().Initializer).Type;
+				type = context.Resolve (varDecl.Variables.First ().Initializer, cancellationToken).Type;
 			} else {
 				var foreachStatement = GetForeachStatement (context);
 				if (foreachStatement == null)
 					return false;
-				type = context.Resolve (foreachStatement.VariableType).Type;
+				type = context.Resolve (foreachStatement.VariableType, cancellationToken).Type;
 			}
 			
 			return !type.Equals (SpecialType.NullType) && !type.Equals (SpecialType.UnknownType);
@@ -66,11 +67,11 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		
 		static readonly AstType varType = new SimpleType ("var");
 
-		static VariableDeclarationStatement GetVariableDeclarationStatement (RefactoringContext context)
+		static VariableDeclarationStatement GetVariableDeclarationStatement (RefactoringContext context, CancellationToken cancellationToken = default(CancellationToken))
 		{
 			var result = context.GetNode<VariableDeclarationStatement> ();
 			if (result != null && result.Variables.Count == 1 && !result.Variables.First ().Initializer.IsNull && result.Type.Contains (context.Location.Line, context.Location.Column) && result.Type.IsMatch (varType)) {
-				if (context.Resolve (result.Variables.First ().Initializer) == null)
+				if (context.Resolve (result.Variables.First ().Initializer, cancellationToken) == null)
 					return null;
 				return result;
 			}

ICSharpCode.NRefactory.CSharp/Refactoring/ContextAction/UseVarKeyword.cs

@@ -26,12 +26,13 @@
 using System;
 using System.Linq;
 using ICSharpCode.NRefactory.PatternMatching;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public class UseVarKeyword : IContextAction
 	{
-		public bool IsValid (RefactoringContext context)
+		public bool IsValid (RefactoringContext context, CancellationToken cancellationToken)
 		{
 			return GetVariableDeclarationStatement (context) != null || GetForeachStatement (context) != null;
 		}

ICSharpCode.NRefactory.CSharp/Refactoring/IContextAction.cs

@@ -24,12 +24,13 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 using System;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
 	public interface IContextAction
 	{
-		bool IsValid (RefactoringContext context);
+		bool IsValid (RefactoringContext context, CancellationToken cancellationToken);
 		void Run (RefactoringContext context);
 	}
 }

ICSharpCode.NRefactory.CSharp/Refactoring/RefactoringContext.cs

@@ -30,6 +30,7 @@ using ICSharpCode.NRefactory.Semantics;
 using ICSharpCode.NRefactory.TypeSystem;
 using ICSharpCode.NRefactory.TypeSystem.Implementation;
 using ICSharpCode.NRefactory.Editor;
+using System.Threading;
 
 namespace ICSharpCode.NRefactory.CSharp.Refactoring
 {
@@ -122,7 +123,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		#endregion
 		
 		#region Resolving
-		public abstract ResolveResult Resolve (AstNode expression);
+		public abstract ResolveResult Resolve (AstNode expression, CancellationToken cancellationToken = default (CancellationToken));
 		#endregion
 		
 		public string GetNameProposal (string name, bool camelCase = true)