public static void Free(UseExceptionFilterWalker walker)
{
walker.CanUseExceptionFilter = true;
walker.SemanticModel = null;
walker.CancellationToken = default;
_cachedInstance = walker;
}
private static void AnalyzeCatchClause(SyntaxNodeAnalysisContext context)
{
var catchClause = (CatchClauseSyntax)context.Node;
if (catchClause.Filter != null)
{
return;
}
if (!(catchClause.Block.Statements.FirstOrDefault() is IfStatementSyntax ifStatement))
{
return;
}
if (IsThrowStatementWithoutExpression(ifStatement.Statement.SingleNonBlockStatementOrDefault())
^ IsThrowStatementWithoutExpression(ifStatement.Else?.Statement.SingleNonBlockStatementOrDefault()))
{
bool canUseExceptionFilter;
UseExceptionFilterWalker walker = null;
try
{
walker = UseExceptionFilterWalker.GetInstance();
walker.SemanticModel = context.SemanticModel;
walker.CancellationToken = context.CancellationToken;
walker.Visit(ifStatement.Condition);
canUseExceptionFilter = walker.CanUseExceptionFilter;
}
finally
{
if (walker != null)
{
UseExceptionFilterWalker.Free(walker);
}
}
if (!canUseExceptionFilter)
{
return;
}
if (ifStatement.ContainsUnbalancedIfElseDirectives())
{
return;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.UseExceptionFilter, ifStatement.IfKeyword);
}
}
public static UseExceptionFilterWalker GetInstance()
{
UseExceptionFilterWalker walker = _cachedInstance;
if (walker != null)
{
Debug.Assert(walker.CanUseExceptionFilter = true);
Debug.Assert(walker.SemanticModel == null);
Debug.Assert(walker.CancellationToken == default);
_cachedInstance = null;
return(walker);
}
return(new UseExceptionFilterWalker());
}
