protected override void Initialize(SonarAnalysisContext context)
{
context.RegisterSyntaxNodeActionInNonGenerated(
c =>
{
var lessThan = (BinaryExpressionSyntax)c.Node;
if (ExpressionNumericConverter.TryGetConstantIntValue(lessThan.Left, out var constValue) &&
constValue == 0 &&
IsIndexOfCall(lessThan.Right, c.SemanticModel))
{
c.ReportDiagnosticWhenActive(Diagnostic.Create(rule, Location.Create(lessThan.SyntaxTree,
TextSpan.FromBounds(lessThan.Left.SpanStart, lessThan.OperatorToken.Span.End))));
}
},
SyntaxKind.LessThanExpression);
context.RegisterSyntaxNodeActionInNonGenerated(
c =>
{
var greaterThan = (BinaryExpressionSyntax)c.Node;
if (ExpressionNumericConverter.TryGetConstantIntValue(greaterThan.Right, out var constValue) &&
constValue == 0 &&
IsIndexOfCall(greaterThan.Left, c.SemanticModel))
{
c.ReportDiagnosticWhenActive(Diagnostic.Create(rule, Location.Create(greaterThan.SyntaxTree,
TextSpan.FromBounds(greaterThan.OperatorToken.SpanStart, greaterThan.Right.Span.End))));
}
},
SyntaxKind.GreaterThanExpression);
}
private static bool CheckExpression(ExpressionSyntax constant, ExpressionSyntax modulus, SemanticModel semanticModel,
out int constantValue)
{
return(ExpressionNumericConverter.TryGetConstantIntValue(constant, out constantValue) &&
constantValue != 0 &&
ExpressionIsModulus(modulus) &&
!ExpressionIsNonNegative(modulus, semanticModel));
}
private static void CheckCountOne(ExpressionSyntax one, ExpressionSyntax count, SyntaxNodeAnalysisContext context)
{
if (ExpressionNumericConverter.TryGetConstantIntValue(one, out var value) &&
value == 1 &&
TryGetCountCall(count, context.SemanticModel, out var reportLocation, out var typeArgument))
{
context.ReportDiagnosticWhenActive(Diagnostic.Create(rule, reportLocation, typeArgument));
}
}
private static void CheckCountZero(ExpressionSyntax zero, ExpressionSyntax count, SyntaxNodeAnalysisContext context)
{
Location reportLocation;
string typeArgument;
int value;
if (ExpressionNumericConverter.TryGetConstantIntValue(zero, out value) &&
value == 0 &&
TryGetCountCall(count, context.SemanticModel, out reportLocation, out typeArgument))
{
context.ReportDiagnosticWhenActive(Diagnostic.Create(rule, reportLocation, typeArgument));
}
}
private static void CheckCountOne(ExpressionSyntax one, ExpressionSyntax count, SyntaxNodeAnalysisContext c)
{
Location reportLocation;
string typeArgument;
int value;
if (ExpressionNumericConverter.TryGetConstantIntValue(one, out value) &&
value == 1 &&
TryGetCountCall(count, c.SemanticModel, out reportLocation, out typeArgument))
{
c.ReportDiagnostic(Diagnostic.Create(Rule, reportLocation, typeArgument));
}
}
/// <summary>
/// We try to retrieve the integer value of an expression. If the expression is an integer literal, we return its value, otherwise if
/// the expression is an identifier, we attempt to retrieve the integer value the variable was initialized with if it exists.
/// </summary>
/// <param name="variableNameToIntegerValue">A dictionary mapping variable names to the integer value they were initialized with if it exists</param>
/// <param name="expression">The expression for which we want to retrieve the integer value</param>
/// <param name="intValue">The output parameter that will hold the integer value if it is found</param>
/// <returns>true if an integer value was found for the expression, false otherwise</returns>
private static bool GetIntValue(IDictionary <string, int> variableNameToIntegerValue, ExpressionSyntax expression, out int intValue)
{
if (ExpressionNumericConverter.TryGetConstantIntValue(expression, out intValue) ||
(
expression is SimpleNameSyntax simpleName &&
variableNameToIntegerValue.TryGetValue(simpleName.Identifier.ValueText, out intValue)
))
{
return(true);
}
intValue = default(int);
return(false);
}
private static void CheckAssignment(SyntaxNodeAnalysisContext context, int constValueToLookFor)
{
var assignment = (AssignmentExpressionSyntax)context.Node;
if (ExpressionNumericConverter.TryGetConstantIntValue(assignment.Right, out var constValue) &&
constValue == constValueToLookFor)
{
var location = assignment.Parent is StatementSyntax
? assignment.Parent.GetLocation()
: GetReportLocation(assignment.OperatorToken.Span, assignment.Right.Span, assignment.SyntaxTree);
context.ReportDiagnosticWhenActive(Diagnostic.Create(rule, location));
}
}
/// <summary>
/// Retrieves the mapping of variable names to their integer value from the variable declaration part of a for loop.
/// This will find the mapping for such cases:
/// <code>
/// for (var i = 0;;) {}
/// </code>
/// </summary>
private static IDictionary <string, int> GetVariableDeclarationMapping(VariableDeclarationSyntax variableDeclarationSyntax)
{
var loopInitializerValues = new Dictionary <string, int>();
if (variableDeclarationSyntax != null)
{
foreach (var variableDeclaration in variableDeclarationSyntax.Variables)
{
if (variableDeclaration.Initializer is EqualsValueClauseSyntax initializer &&
ExpressionNumericConverter.TryGetConstantIntValue(initializer.Value, out var intValue))
{
loopInitializerValues.Add(variableDeclaration.Identifier.ValueText, intValue);
}
}
}
return(loopInitializerValues);
}
/// <summary>
/// Retrieves the mapping of variable names to their integer value from the initializer part of a for loop.
/// This will find the mapping for such cases:
/// <code>
/// int i;
/// for (i = 0;;) {}
/// </code>
/// </summary>
private static IDictionary <string, int> GetLoopInitializerMapping(IEnumerable <ExpressionSyntax> initializers)
{
var loopInitializerValues = new Dictionary <string, int>();
if (initializers != null)
{
foreach (var initializer in initializers)
{
if (initializer.IsKind(SyntaxKind.SimpleAssignmentExpression) &&
initializer is AssignmentExpressionSyntax assignment &&
assignment.Left is SimpleNameSyntax simpleName &&
ExpressionNumericConverter.TryGetConstantIntValue(assignment.Right, out var intValue))
{
loopInitializerValues.Add(simpleName.Identifier.ValueText, intValue);
}
}
}
return(loopInitializerValues);
}
private static void CheckBinary(SyntaxNodeAnalysisContext context, int constValueToLookFor)
{
var binary = (BinaryExpressionSyntax)context.Node;
if (ExpressionNumericConverter.TryGetConstantIntValue(binary.Left, out var constValue) &&
constValue == constValueToLookFor)
{
var location = GetReportLocation(binary.Left.Span, binary.OperatorToken.Span, binary.SyntaxTree);
context.ReportDiagnosticWhenActive(Diagnostic.Create(rule, location, ImmutableDictionary <string, string> .Empty.Add(IsReportingOnLeftKey, true.ToString())));
return;
}
if (ExpressionNumericConverter.TryGetConstantIntValue(binary.Right, out constValue) &&
constValue == constValueToLookFor)
{
var location = GetReportLocation(binary.OperatorToken.Span, binary.Right.Span, binary.SyntaxTree);
context.ReportDiagnosticWhenActive(Diagnostic.Create(rule, location, ImmutableDictionary <string, string> .Empty.Add(IsReportingOnLeftKey, false.ToString())));
}
}
public override void Initialize(AnalysisContext context)
{
context.RegisterSyntaxNodeActionInNonGenerated(
c =>
{
var expression = (BinaryExpressionSyntax)c.Node;
int value;
if (expression.IsKind(SyntaxKind.LeftShiftExpression) &&
ExpressionNumericConverter.TryGetConstantIntValue(expression.Right, out value) &&
value == 1)
{
return;
}
if (EquivalenceChecker.AreEquivalent(expression.Left, expression.Right))
{
c.ReportDiagnostic(Diagnostic.Create(Rule, c.Node.GetLocation(), expression.OperatorToken));
}
},
SyntaxElementsToCheck);
}
private static bool CheckValueTypeDefaultValueInitializer(EqualsValueClauseSyntax initializer, ITypeSymbol type)
{
if (!type.IsValueType)
{
return(false);
}
switch (type.SpecialType)
{
case SpecialType.System_Boolean:
return(EquivalenceChecker.AreEquivalent(initializer.Value, SyntaxHelper.FalseLiteralExpression));
case SpecialType.System_Decimal:
case SpecialType.System_Double:
case SpecialType.System_Single:
{
double constantValue;
return(ExpressionNumericConverter.TryGetConstantDoubleValue(initializer.Value, out constantValue) &&
Math.Abs(constantValue - default(double)) < double.Epsilon);
}
case SpecialType.System_Char:
case SpecialType.System_Byte:
case SpecialType.System_Int16:
case SpecialType.System_Int32:
case SpecialType.System_Int64:
case SpecialType.System_SByte:
case SpecialType.System_UInt16:
case SpecialType.System_UInt32:
case SpecialType.System_UInt64:
{
int constantValue;
return(ExpressionNumericConverter.TryGetConstantIntValue(initializer.Value, out constantValue) &&
constantValue == default(int));
}
default:
return(false);
}
}
private static bool CheckValueTypeDefaultValueInitializer(VariableDeclaratorSyntax variable, IFieldSymbol variableSymbol)
{
if (!variableSymbol.Type.IsValueType)
{
return(false);
}
switch (variableSymbol.Type.SpecialType)
{
case SpecialType.System_Boolean:
return(EquivalenceChecker.AreEquivalent(variable.Initializer.Value, FalseExpression));
case SpecialType.System_Decimal:
case SpecialType.System_Double:
case SpecialType.System_Single:
{
double constantValue;
return(ExpressionNumericConverter.TryGetConstantDoubleValue(variable.Initializer.Value, out constantValue) &&
Math.Abs(constantValue - default(double)) < double.Epsilon);
}
case SpecialType.System_Char:
case SpecialType.System_Byte:
case SpecialType.System_Int16:
case SpecialType.System_Int32:
case SpecialType.System_Int64:
case SpecialType.System_SByte:
case SpecialType.System_UInt16:
case SpecialType.System_UInt32:
case SpecialType.System_UInt64:
{
int constantValue;
return(ExpressionNumericConverter.TryGetConstantIntValue(variable.Initializer.Value, out constantValue) &&
constantValue == default(int));
}
default:
return(false);
}
}