Remove duplicate ifs, in if/else chains in case that the expression is duplicated. It can happen in copy/paste cases.

Fixes formatting of the previous commit to match K&R style.

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

@@ -538,6 +538,7 @@
     <Compile Include="Refactoring\CodeIssues\ParameterCanBeDemotedIssue\ParameterCanBeIEnumerableIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\DuplicateBodyMethodIssue.cs" />
     <Compile Include="Refactoring\CodeIssues\DuplicateExpressionsInConditionsIssue.cs" />
+    <Compile Include="Refactoring\CodeIssues\DuplicateIfInIfChainIssue.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ICSharpCode.NRefactory\ICSharpCode.NRefactory.csproj">

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

@@ -92,7 +92,7 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
                 }
             }
 
-		    private static void RemoveRedundantExpression(Script script, Expression expressionRight)
+		    private static void RemoveRedundantExpression(Script script, AstNode expressionRight)
 		    {
                 var parent = expressionRight.Parent as BinaryOperatorExpression;
                 if(parent==null) //should never happen!
@@ -118,6 +118,5 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		        return expressions;
 		    }
 		}
-	}
-	
+	}	
 }

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

@@ -0,0 +1,111 @@
+//
+// DuplicateIfInIfChainIssue.cs
+//
+// Author:
+//       Ciprian Khlud <ciprian.mustiata@yahoo.com>
+//
+// Copyright (c) 2013 Ciprian Khlud
+//
+// 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 ICSharpCode.NRefactory.PatternMatching;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	[IssueDescription("Else branch has some redundant if",
+	                  Description = "One Else-if was checked before so is not be true",
+	                  Category = IssueCategories.CodeQualityIssues,
+	                  Severity = Severity.Warning,
+	                  IssueMarker = IssueMarker.GrayOut,
+	                  ResharperDisableKeyword = "ConditionalTernaryEqualBranch")]
+	public class DuplicateIfInIfChainIssue : ICodeIssueProvider
+	{
+		public IEnumerable<CodeIssue> GetIssues (BaseRefactoringContext context)
+		{
+			return new GatherVisitor (context).GetIssues ();
+		}
+		
+		class GatherVisitor : GatherVisitorBase<IdenticalConditionalBranchIssue>
+		{
+			public GatherVisitor (BaseRefactoringContext ctx)
+				: base (ctx)
+			{
+			}
+			
+			public override void VisitIfElseStatement(IfElseStatement ifStatement)
+			{
+				base.VisitIfElseStatement(ifStatement);
+				var parentExpression = ifStatement.Parent as IfElseStatement;
+				//handle only parent sequence
+				if (parentExpression != null)
+					return;
+				var expressions = GetExpressions(ifStatement);
+				for(var i=0;i<expressions.Count-1;i++) {
+					for (var j = i+1; j < expressions.Count; j++) {
+						var leftCondition = expressions[i].Condition;
+                        var rightIf = expressions[j];
+                        var rightCondition = rightIf.Condition;
+					    
+						if (!leftCondition.IsMatch(rightCondition))
+							continue;
+						var action = new CodeAction(ctx.TranslateString("Remove redundant expression"),
+                                                    script => RemoveRedundantIf(script, rightIf),
+						                            rightCondition);
+						
+						AddIssue(rightCondition,
+						         ctx.TranslateString(string.Format("The expression '{0}' is identical in the left branch",
+						                                  rightCondition)), action);
+						
+					}
+				}
+			}
+
+            private static void RemoveRedundantIf(Script script, IfElseStatement expressionRight)
+            {
+                var parent = expressionRight.Parent as IfElseStatement;
+                if(parent==null) { //should never happen!
+                    return;
+                }
+                if (expressionRight.FalseStatement.IsNull) {
+                    script.Remove(parent.ElseToken);
+                    script.Remove(parent.FalseStatement);
+                    script.FormatText(parent);
+				} else {
+					script.Replace(parent.FalseStatement, expressionRight.FalseStatement.Clone());
+				}
+            }
+
+		    private static List<IfElseStatement> GetExpressions(IfElseStatement expression)
+			{
+				var baseExpression = expression;
+				var falseExpression = baseExpression.FalseStatement as IfElseStatement;
+                var expressions = new List<IfElseStatement>();
+				while (falseExpression != null) {
+					expressions.Add(baseExpression);
+					baseExpression = falseExpression;
+					falseExpression = falseExpression.FalseStatement as IfElseStatement;
+				}
+				expressions.Add(baseExpression);
+				return expressions;
+			}
+		}
+	}
+	
+}

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

@@ -29,8 +29,7 @@ using ICSharpCode.NRefactory.CSharp.Refactoring;
 using NUnit.Framework;
 
 namespace ICSharpCode.NRefactory.CSharp.CodeIssues
-{
-	
+{	
 	[TestFixture]
 	public class DuplicateExpressionsInConditionsIssueTests : InspectionActionTestBase
 	{

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

@@ -0,0 +1,120 @@
+//
+// DuplicateIfInIfChainIssueTests.cs
+//
+// Author:
+//       Ciprian Khlud <ciprian.mustiata@yahoo.com>
+//
+// Copyright (c) 2013 Ciprian Khlud
+//
+// 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 DuplicateIfInIfChainIssueTests : InspectionActionTestBase
+	{
+		[Test]
+		public void TestSimple ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if(i > 0) {}else if (i > 0){}
+	}
+}";
+			var output = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if (i > 0) {
+        }
+	}
+}";
+            Test<DuplicateIfInIfChainIssue>(input, output);
+		}
+		
+		[Test]
+		public void Test ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if(i > 0) {
+		} else 
+		if (i % 2 == 0){
+		} else 
+		if (i > 0) {
+		}
+	}
+}";
+			var output = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if(i > 0) {
+		} else if (i % 2 == 0) {
+		} 
+	}
+}";
+            Test<DuplicateIfInIfChainIssue>(input, output);
+		}
+
+		[Test]
+		public void TestComplexWithMoreBranches ()
+		{
+			var input = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if(i > 0) {
+		} else 
+		if (i % 2 == 0){
+		} else 
+		if (i > 0) {
+		} else 
+		if (i > 1) {
+		}
+	}
+}";
+			var output = @"
+class TestClass
+{
+	void TestMethod (int i)
+	{
+		if(i > 0) {
+		} else if (i % 2 == 0) {
+		} else if (i > 1) {
+		} 
+	}
+}";
+			Test<DuplicateIfInIfChainIssue>(input, output);
+		}
+	}
+	
+}

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

@@ -413,6 +413,7 @@
     <Compile Include="CSharp\CodeIssues\ParameterCanBeDemotedIssue\ParameterCanBeIEnumerableTests.cs" />
     <Compile Include="CSharp\CodeIssues\DuplicateBodyMethodIssueTests.cs" />
     <Compile Include="CSharp\CodeIssues\DuplicateExpressionsInConditionsIssueTests.cs" />
+    <Compile Include="CSharp\CodeIssues\DuplicateIfInIfChainIssueTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\cecil\Mono.Cecil.csproj">