[CodeIssue] Added ExpressionIsAlwaysOfProvidedTypeIssue

ICSharpCode.NRefactory.CSharp/ICSharpCode.NRefactory.CSharp.csproj

@@ -269,6 +269,7 @@
     <Compile Include="Refactoring\CodeIssues\CompareBooleanWithTrueOrFalseIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\CompareFloatWithEqualityOperatorIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\ConstantConditionIssue.cs" />
+    <Compile Include="Refactoring\CodeIssues\ExpressionIsAlwaysOfProvidedTypeIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\NegativeRelationalExpressionIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\ExplicitConversionInForEachIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\ForControlVariableNotModifiedIssue.cs" />

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/ExpressionIsAlwaysOfProvidedTypeIssue.cs

@@ -0,0 +1,70 @@
+// 
+// ExpressionIsAlwaysOfProvidedTypeIssue.cs
+// 
+// Author:
+//      Mansheng Yang <lightyang0@gmail.com>
+// 
+// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// 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.Collections.Generic;
+using System.Linq;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	[IssueDescription ("CS0183:Given expression is always of the provided type",
+					   Description = "CS0183:Given expression is always of the provided type.",
+					   Category = IssueCategories.CompilerWarnings,
+					   Severity = Severity.Warning,
+					   IssueMarker = IssueMarker.Underline)]
+	public class ExpressionIsAlwaysOfProvidedTypeIssue : ICodeIssueProvider
+	{
+		public IEnumerable<CodeIssue> GetIssues (BaseRefactoringContext context)
+		{
+			return new GatherVisitor (context).GetIssues ();
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			public GatherVisitor (BaseRefactoringContext ctx)
+				: base (ctx)
+			{
+			}
+
+			public override void VisitIsExpression (IsExpression isExpression)
+			{
+				base.VisitIsExpression (isExpression);
+
+				var type = ctx.Resolve (isExpression.Expression).Type;
+				var providedType = ctx.ResolveType (isExpression.Type);
+
+				if (type.GetAllBaseTypes ().All (t => !t.Equals (providedType)))
+					return;
+
+				var action = new CodeAction (ctx.TranslateString ("Compare with 'null'"), 
+					scrpit => scrpit.Replace (isExpression, new BinaryOperatorExpression (
+						isExpression.Expression.Clone (), BinaryOperatorType.InEquality, new PrimitiveExpression (null))));
+				AddIssue (isExpression, ctx.TranslateString ("Given expression is always of the provided type. " +
+					"Consider comparing with 'null' instead"), new [] { action });
+			}
+		}
+	}
+}

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/ExpressionIsAlwaysOfProvidedTypeIssueTests.cs

@@ -0,0 +1,90 @@
+// 
+// ExpressionIsAlwaysOfProvidedTypeIssueTests.cs
+// 
+// Author:
+//      Mansheng Yang <lightyang0@gmail.com>
+// 
+// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.com>
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// 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 ICSharpCode.NRefactory.CSharp.Refactoring;
+using NUnit.Framework;
+
+namespace ICSharpCode.NRefactory.CSharp.CodeIssues
+{
+	[TestFixture]
+	public class ExpressionIsAlwaysOfProvidedTypeIssueTests : InspectionActionTestBase
+	{
+		public void Test (string variableType, string providedType)
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (" + variableType + @" x)
+	{
+		if (x is " + providedType + @") ;
+	}
+}";
+			var output = @"
+class TestClass
+{
+	void TestMethod (" + variableType + @" x)
+	{
+		if (x != null) ;
+	}
+}";
+			Test<ExpressionIsAlwaysOfProvidedTypeIssue> (input, 1, output);
+		}
+
+		[Test]
+		public void TestSameType ()
+		{
+			Test ("int", "int");
+		}
+
+		[Test]
+		public void TestBaseType ()
+		{
+			Test ("int", "object");
+		}
+
+		[Test]
+		public void TestTypeParameter ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod<T> (T x) where T : TestClass
+	{
+		if (x is TestClass) ;
+	}
+}";
+			var output = @"
+class TestClass
+{
+	void TestMethod<T> (T x) where T : TestClass
+	{
+		if (x != null) ;
+	}
+}";
+			Test<ExpressionIsAlwaysOfProvidedTypeIssue> (input, 1, output);
+		}
+	}
+}

ICSharpCode.NRefactory.Tests/ICSharpCode.NRefactory.Tests.csproj

@@ -108,6 +108,7 @@
     <Compile Include="CSharp\CodeIssues\CompareFloatWithEqualityOperatorIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\ConstantConditionIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\ExplicitConversionInForEachIssueTests.cs" />
+    <Compile Include="CSharp\CodeIssues\ExpressionIsAlwaysOfProvidedTypeIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\ForControlVariableNotModifiedIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\IdenticalConditionalBranchIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\LocalVariableHidesMemberIssueTests.cs" />