// // ConditionalToNullCoalescingInspector.cs // // Author: // Mike Krüger // // Copyright (c) 2012 Xamarin // // 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; using System.Collections.Generic; using System.Linq; using ICSharpCode.NRefactory.PatternMatching; namespace ICSharpCode.NRefactory.CSharp.Refactoring { /// /// Checks for "a != null ? a : other" /// Converts to: "a ?? other" /// [IssueDescription("'?:' expression can be converted to '??' expression", Description="'?:' expression can be converted to '??' expression.", Category = IssueCategories.Opportunities, Severity = Severity.Suggestion)] public class ConditionalToNullCoalescingIssue : ICodeIssueProvider { static readonly Pattern pattern = new Choice { // a != null ? a : other new ConditionalExpression( PatternHelper.CommutativeOperator(new AnyNode("a"), BinaryOperatorType.InEquality, new NullReferenceExpression()), new Backreference("a"), new AnyNode("other") ), // a == null ? other : a new ConditionalExpression( PatternHelper.CommutativeOperator(new AnyNode("a"), BinaryOperatorType.Equality, new NullReferenceExpression()), new AnyNode("other"), new Backreference("a") ), }; public IEnumerable GetIssues(BaseRefactoringContext context) { return new GatherVisitor(context, this).GetIssues(); } class GatherVisitor : GatherVisitorBase { readonly ConditionalToNullCoalescingIssue inspector; public GatherVisitor (BaseRefactoringContext ctx, ConditionalToNullCoalescingIssue inspector) : base (ctx) { this.inspector = inspector; } public override void VisitConditionalExpression(ConditionalExpression conditionalExpression) { Match m = pattern.Match(conditionalExpression); if (m.Success) { var a = m.Get("a").Single(); var other = m.Get("other").Single(); AddIssue(conditionalExpression, ctx.TranslateString("Convert to '??' expression"), script => { var expr = new BinaryOperatorExpression (a.Clone (), BinaryOperatorType.NullCoalescing, other.Clone ()); script.Replace (conditionalExpression, expr); }); } base.VisitConditionalExpression (conditionalExpression); } } } }