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//
// RedundantNullCheckIssue.cs
//
// Author:
// Ji Kun <jikun.nus@gmail.com>
//
// Copyright (c) 2013 Ji Kun
//
// 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 ICSharpCode.NRefactory.PatternMatching;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.CSharp.Resolver;
using ICSharpCode.NRefactory.Semantics;
using System.Linq;
using ICSharpCode.NRefactory.TypeSystem.Implementation;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
[IssueDescription("Redundant null check",
Description = "When 'is' keyword is used, which implicitly check null.",
Category = IssueCategories.Redundancies,
Severity = Severity.Suggestion,
ResharperDisableKeyword = "RedundantNullCheck",
IssueMarker = IssueMarker.GrayOut)]
public class RedundantNullCheckIssue : ICodeIssueProvider
{
private static readonly Pattern pattern1
= new Choice {
// x is Record && x!= null
new BinaryOperatorExpression(
new IsExpression
{
Expression = new AnyNode("a"),
Type = new AnyNode("t")
}, BinaryOperatorType.ConditionalAnd,
PatternHelper.CommutativeOperator(new Backreference("a"),
BinaryOperatorType.
InEquality,
new NullReferenceExpression
())
)
};
private static readonly Pattern pattern2
= new Choice {
// x != null && x is Record
new BinaryOperatorExpression (
PatternHelper.CommutativeOperator (new AnyNode("a"),
BinaryOperatorType.InEquality,
new NullReferenceExpression())
, BinaryOperatorType.ConditionalAnd,
new IsExpression {
Expression = new Backreference("a"),
Type = new AnyNode("t")
}
)
};
public IEnumerable<CodeIssue> GetIssues(BaseRefactoringContext context)
{
return new GatherVisitor(context).GetIssues();
}
class GatherVisitor : GatherVisitorBase<RedundantNullCheckIssue>
{
public GatherVisitor(BaseRefactoringContext ctx)
: base(ctx)
{
}
public override void VisitBinaryOperatorExpression(BinaryOperatorExpression binaryOperatorExpression)
{
base.VisitBinaryOperatorExpression(binaryOperatorExpression);
Match m1 = pattern1.Match(binaryOperatorExpression);
if (m1.Success) {
AddIssue(binaryOperatorExpression, ctx.TranslateString("Remove redundant IsNULL check"), script => {
Expression expr = binaryOperatorExpression.Left;
script.Replace(binaryOperatorExpression, expr);
});
return;
}
Match m2 = pattern2.Match(binaryOperatorExpression);
if (m2.Success) {
AddIssue(binaryOperatorExpression, ctx.TranslateString("Remove redundant IsNULL check"), script => {
Expression expr = binaryOperatorExpression.Right;
script.Replace(binaryOperatorExpression, expr);
});
return;
}
}
}
}
}
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