.NET Decompiler with support for PDB generation, ReadyToRun, Metadata (&more) - cross-platform!
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//
// CompareFloatWithEqualityOperatorIssue.cs
//
// Author:
// Mansheng Yang <lightyang0@gmail.com>
//
// Copyright (c) 2012 Mansheng Yang <lightyang0@gmail.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.Collections.Generic;
using ICSharpCode.NRefactory.TypeSystem;
namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
[IssueDescription ("Compare floating point numbers with equality operator",
Description = "Comparison of floating point numbers with equality operator.",
Category = IssueCategories.CodeQualityIssues,
Severity = Severity.Warning,
IssueMarker = IssueMarker.Underline)]
public class CompareFloatWithEqualityOperatorIssue : ICodeIssueProvider
{
public IEnumerable<CodeIssue> GetIssues (BaseRefactoringContext context)
{
return new GatherVisitor (context).GetIssues ();
}
class GatherVisitor : GatherVisitorBase
{
public GatherVisitor (BaseRefactoringContext ctx)
: base(ctx)
{
}
static bool IsFloatingPointType (IType type)
{
var typeDef = type.GetDefinition ();
return typeDef != null &&
(typeDef.KnownTypeCode == KnownTypeCode.Single || typeDef.KnownTypeCode == KnownTypeCode.Double);
}
bool IsFloatingPoint(AstNode node)
{
return IsFloatingPointType (ctx.Resolve (node).Type);
}
bool IsNaN (AstNode node, out string floatType)
{
floatType = "";
var rr = ctx.Resolve (node);
if (!rr.IsCompileTimeConstant)
return false;
if (rr.ConstantValue is double && double.IsNaN ((double)rr.ConstantValue)) {
floatType = "double";
return true;
}
if (rr.ConstantValue is float && float.IsNaN ((float)rr.ConstantValue)) {
floatType = "float";
return true;
}
return false;
}
void AddIsNaNIssue(BinaryOperatorExpression binaryOperatorExpr, Expression argExpr, string floatType)
{
if (ctx.Resolve (argExpr).Type.ReflectionName != "System.Single")
floatType = "double";
AddIssue (binaryOperatorExpr, string.Format(ctx.TranslateString ("Use {0}.IsNan()"), floatType),
script => {
Expression expr = new InvocationExpression (new MemberReferenceExpression (
new TypeReferenceExpression (new PrimitiveType (floatType)), "IsNaN"), argExpr.Clone ());
if (binaryOperatorExpr.Operator == BinaryOperatorType.InEquality)
expr = new UnaryOperatorExpression (UnaryOperatorType.Not, expr);
script.Replace (binaryOperatorExpr, expr);
});
}
public override void VisitBinaryOperatorExpression (BinaryOperatorExpression binaryOperatorExpression)
{
base.VisitBinaryOperatorExpression (binaryOperatorExpression);
if (binaryOperatorExpression.Operator != BinaryOperatorType.Equality &&
binaryOperatorExpression.Operator != BinaryOperatorType.InEquality)
return;
string floatType;
if (IsNaN(binaryOperatorExpression.Left, out floatType)) {
AddIsNaNIssue (binaryOperatorExpression, binaryOperatorExpression.Right, floatType);
} else if (IsNaN (binaryOperatorExpression.Right, out floatType)) {
AddIsNaNIssue (binaryOperatorExpression, binaryOperatorExpression.Left, floatType);
} else if (IsFloatingPoint(binaryOperatorExpression.Left) || IsFloatingPoint(binaryOperatorExpression.Right)) {
AddIssue (binaryOperatorExpression, ctx.TranslateString ("Compare a difference with EPSILON"),
script => {
// Math.Abs(diff) op EPSILON
var diff = new BinaryOperatorExpression (binaryOperatorExpression.Left.Clone (),
BinaryOperatorType.Subtract, binaryOperatorExpression.Right.Clone ());
var abs = new InvocationExpression (
new MemberReferenceExpression (
new TypeReferenceExpression (new SimpleType ("System.Math")),
"Abs"),
diff);
var op = binaryOperatorExpression.Operator == BinaryOperatorType.Equality ?
BinaryOperatorType.LessThan : BinaryOperatorType.GreaterThan;
var epsilon = new IdentifierExpression ("EPSILON");
var compare = new BinaryOperatorExpression (abs, op, epsilon);
script.Replace (binaryOperatorExpression, compare);
script.Link (epsilon);
});
}
}
}
}
}