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//
// CheckIfParameterIsNull.cs
//
// Author:
// Mike Krüger <mkrueger@novell.com>
//
// Copyright (c) 2011 Mike Krüger <mkrueger@novell.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.PatternMatching;
using System.Collections.Generic;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
/// <summary>
/// Creates a 'if (param == null) throw new System.ArgumentNullException ();' contruct for a parameter.
/// </summary>
[ContextAction("Check if parameter is null", Description = "Checks function parameter is not null.")]
public class CheckIfParameterIsNullAction : SpecializedCodeAction<ParameterDeclaration>
{
protected override CodeAction GetAction(RefactoringContext context, ParameterDeclaration parameter)
{
BlockStatement bodyStatement;
if (parameter.Parent is LambdaExpression) {
bodyStatement = parameter.Parent.GetChildByRole (LambdaExpression.BodyRole) as BlockStatement;
} else {
bodyStatement = parameter.Parent.GetChildByRole (Roles.Body);
}
if (bodyStatement == null || bodyStatement.IsNull)
return null;
var type = context.ResolveType(parameter.Type);
if (type.IsReferenceType == false || HasNullCheck(parameter))
return null;
return new CodeAction(context.TranslateString("Add null check for parameter"), script => {
var statement = new IfElseStatement() {
Condition = new BinaryOperatorExpression (new IdentifierExpression (parameter.Name), BinaryOperatorType.Equality, new NullReferenceExpression ()),
TrueStatement = new ThrowStatement (new ObjectCreateExpression (context.CreateShortType("System", "ArgumentNullException"), new PrimitiveExpression (parameter.Name)))
};
script.AddTo(bodyStatement, statement);
}, parameter.NameToken);
}
static bool HasNullCheck (ParameterDeclaration parameter)
{
var visitor = new CheckNullVisitor (parameter);
parameter.Parent.AcceptVisitor (visitor, null);
return visitor.ContainsNullCheck;
}
class CheckNullVisitor : DepthFirstAstVisitor<object, object>
{
readonly Expression pattern;
internal bool ContainsNullCheck;
public CheckNullVisitor (ParameterDeclaration parameter)
{
pattern = PatternHelper.CommutativeOperator(new IdentifierExpression(parameter.Name), BinaryOperatorType.Any, new NullReferenceExpression());
}
public override object VisitIfElseStatement (IfElseStatement ifElseStatement, object data)
{
if (ifElseStatement.Condition is BinaryOperatorExpression) {
var binOp = ifElseStatement.Condition as BinaryOperatorExpression;
if ((binOp.Operator == BinaryOperatorType.Equality || binOp.Operator == BinaryOperatorType.InEquality) && pattern.IsMatch(binOp)) {
ContainsNullCheck = true;
}
}
return base.VisitIfElseStatement (ifElseStatement, data);
}
}
}
}
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