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//
// ConditionalToNullCoalescingInspector.cs
//
// Author:
// Mike Krüger <mkrueger@xamarin.com>
//
// Copyright (c) 2012 Xamarin <http://xamarin.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;
using System.Collections.Generic;
using System.Linq;
using ICSharpCode.NRefactory.PatternMatching;
using ICSharpCode.NRefactory.Refactoring;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
/// <summary>
/// Checks for "a != null ? a : other"<expr>
/// Converts to: "a ?? other"<expr>
/// </summary>
[IssueDescription("'?:' expression can be converted to '??' expression",
Description="'?:' expression can be converted to '??' expression.",
Category = IssueCategories.Opportunities,
Severity = Severity.Suggestion,
ResharperDisableKeyword = "ConvertConditionalTernaryToNullCoalescing")]
public class ConvertConditionalTernaryToNullCoalescingIssue : 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<CodeIssue> GetIssues(BaseRefactoringContext context)
{
return new GatherVisitor(context, this).GetIssues();
}
class GatherVisitor : GatherVisitorBase<ConvertConditionalTernaryToNullCoalescingIssue>
{
// readonly ConvertConditionalTernaryToNullCoalescingIssue inspector;
public GatherVisitor (BaseRefactoringContext ctx, ConvertConditionalTernaryToNullCoalescingIssue inspector) : base (ctx)
{
// this.inspector = inspector;
}
public override void VisitConditionalExpression(ConditionalExpression conditionalExpression)
{
Match m = pattern.Match(conditionalExpression);
if (m.Success) {
var a = m.Get<Expression>("a").Single();
var other = m.Get<Expression>("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);
}
}
}
}
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