private static NullCheckExpressionInfo Create(
BinaryExpressionSyntax binaryExpression,
SyntaxKind binaryExpressionKind,
ExpressionSyntax expression1,
ExpressionSyntax expression2,
NullCheckKind allowedKinds,
bool allowMissing,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
switch (expression1.Kind())
{
case SyntaxKind.NullLiteralExpression:
{
NullCheckKind kind = (binaryExpressionKind == SyntaxKind.EqualsExpression) ? NullCheckKind.EqualsToNull : NullCheckKind.NotEqualsToNull;
if ((allowedKinds & kind) == 0)
{
break;
}
return(new NullCheckExpressionInfo(
binaryExpression,
expression2,
kind));
}
case SyntaxKind.TrueLiteralExpression:
{
NullCheckKind kind = (binaryExpressionKind == SyntaxKind.EqualsExpression) ? NullCheckKind.HasValue : NullCheckKind.NotHasValue;
return(Create(
binaryExpression,
expression2,
kind,
allowedKinds,
allowMissing,
semanticModel,
cancellationToken));
}
case SyntaxKind.FalseLiteralExpression:
{
NullCheckKind kind = (binaryExpressionKind == SyntaxKind.EqualsExpression) ? NullCheckKind.NotHasValue : NullCheckKind.HasValue;
return(Create(
binaryExpression,
expression2,
kind,
allowedKinds,
allowMissing,
semanticModel,
cancellationToken));
}
}
return(Default);
}
public NullCheckExpression(
ExpressionSyntax containingNode,
ExpressionSyntax expression,
NullCheckKind kind)
{
ContainingNode = containingNode;
Expression = expression;
Kind = kind;
}
private NullCheckExpressionInfo(
ExpressionSyntax containingExpression,
ExpressionSyntax expression,
NullCheckKind kind)
{
ContainingExpression = containingExpression;
Expression = expression;
Kind = kind;
}
public static NullCheckExpressionInfo NullCheckExpressionInfo(
SyntaxNode node,
NullCheckKind allowedKinds = NullCheckKind.All,
bool walkDownParentheses = true,
bool allowMissing = false,
SemanticModel semanticModel = null,
CancellationToken cancellationToken = default(CancellationToken))
{
return(Syntax.NullCheckExpressionInfo.Create(
node,
allowedKinds,
walkDownParentheses,
allowMissing,
semanticModel,
cancellationToken));
}
private static NullCheckExpressionInfo Create(
BinaryExpressionSyntax binaryExpression,
ExpressionSyntax expression,
NullCheckKind kind,
NullCheckKind allowedKinds,
bool allowMissing,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
if ((allowedKinds & (NullCheckKind.HasValueProperty)) == 0)
{
return(Default);
}
if (!(expression is MemberAccessExpressionSyntax memberAccessExpression))
{
return(Default);
}
if (memberAccessExpression.Kind() != SyntaxKind.SimpleMemberAccessExpression)
{
return(Default);
}
if (!IsPropertyOfNullableOfT(memberAccessExpression.Name, "HasValue", semanticModel, cancellationToken))
{
return(Default);
}
if ((allowedKinds & kind) == 0)
{
return(Default);
}
ExpressionSyntax expression2 = memberAccessExpression.Expression;
if (!Check(expression2, allowMissing))
{
return(Default);
}
return(new NullCheckExpressionInfo(binaryExpression, expression2, kind));
}
private static void Analyze(SyntaxNodeAnalysisContext context, BinaryExpressionSyntax binaryExpression, NullCheckKind allowedKinds)
{
NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(binaryExpression, allowedKinds: allowedKinds);
if (nullCheck.Success &&
IsUnconstrainedTypeParameter(context.SemanticModel.GetTypeSymbol(nullCheck.Expression, context.CancellationToken)) &&
!binaryExpression.SpanContainsDirectives())
{
context.ReportDiagnostic(DiagnosticDescriptors.UnconstrainedTypeParameterCheckedForNull, binaryExpression);
}
}
internal static NullCheckExpressionInfo Create(
SyntaxNode node,
NullCheckKind allowedKinds = NullCheckKind.All,
bool walkDownParentheses = true,
bool allowMissing = false,
SemanticModel semanticModel = null,
CancellationToken cancellationToken = default(CancellationToken))
{
if (semanticModel == null &&
(allowedKinds & NullCheckKind.HasValueProperty) != 0)
{
return(Default);
}
ExpressionSyntax expression = WalkAndCheck(node, allowMissing, walkDownParentheses);
if (expression == null)
{
return(Default);
}
SyntaxKind kind = expression.Kind();
switch (kind)
{
case SyntaxKind.EqualsExpression:
case SyntaxKind.NotEqualsExpression:
{
var binaryExpression = (BinaryExpressionSyntax)expression;
ExpressionSyntax left = WalkAndCheck(binaryExpression.Left, allowMissing, walkDownParentheses);
if (left == null)
{
break;
}
ExpressionSyntax right = WalkAndCheck(binaryExpression.Right, allowMissing, walkDownParentheses);
if (right == null)
{
break;
}
NullCheckExpressionInfo info = Create(binaryExpression, kind, left, right, allowedKinds, allowMissing, semanticModel, cancellationToken);
if (info.Success)
{
return(info);
}
else
{
return(Create(binaryExpression, kind, right, left, allowedKinds, allowMissing, semanticModel, cancellationToken));
}
}
case SyntaxKind.SimpleMemberAccessExpression:
{
if ((allowedKinds & NullCheckKind.HasValue) == 0)
{
break;
}
var memberAccessExpression = (MemberAccessExpressionSyntax)expression;
if (!IsPropertyOfNullableOfT(memberAccessExpression.Name, "HasValue", semanticModel, cancellationToken))
{
break;
}
return(new NullCheckExpressionInfo(expression, memberAccessExpression.Expression, NullCheckKind.HasValue));
}
case SyntaxKind.LogicalNotExpression:
{
if ((allowedKinds & NullCheckKind.NotHasValue) == 0)
{
break;
}
var logicalNotExpression = (PrefixUnaryExpressionSyntax)expression;
ExpressionSyntax operand = WalkAndCheck(logicalNotExpression.Operand, allowMissing, walkDownParentheses);
if (!(operand is MemberAccessExpressionSyntax memberAccessExpression))
{
break;
}
if (memberAccessExpression.Kind() != SyntaxKind.SimpleMemberAccessExpression)
{
break;
}
if (!IsPropertyOfNullableOfT(memberAccessExpression.Name, "HasValue", semanticModel, cancellationToken))
{
break;
}
return(new NullCheckExpressionInfo(expression, memberAccessExpression.Expression, NullCheckKind.NotHasValue));
}
}
return(Default);
}
