public static void Free(RemoveRedundantAssignmentWalker walker)
{
walker.Symbol = null;
walker.SemanticModel = null;
walker.CancellationToken = default;
_cachedInstance = walker;
}
public static bool GetResultAndFree(RemoveRedundantAssignmentWalker walker)
{
bool result = walker.Result;
walker.Result = false;
walker.Symbol = default;
walker.SemanticModel = default;
walker.CancellationToken = default;
_cachedInstance = walker;
return(result);
}
public static RemoveRedundantAssignmentWalker GetInstance()
{
RemoveRedundantAssignmentWalker walker = _cachedInstance;
if (walker != null)
{
_cachedInstance = null;
}
else
{
walker = new RemoveRedundantAssignmentWalker();
}
return(walker);
}
public static RemoveRedundantAssignmentWalker GetInstance()
{
RemoveRedundantAssignmentWalker walker = _cachedInstance;
if (walker != null)
{
Debug.Assert(walker.Symbol == null);
Debug.Assert(walker.SemanticModel == null);
Debug.Assert(walker.CancellationToken == default);
_cachedInstance = null;
return(walker);
}
return(new RemoveRedundantAssignmentWalker());
}
private static void AnalyzeSimpleAssignment(SyntaxNodeAnalysisContext context)
{
if (context.Node.ContainsDiagnostics)
{
return;
}
if (context.Node.SpanOrTrailingTriviaContainsDirectives())
{
return;
}
var assignment = (AssignmentExpressionSyntax)context.Node;
SimpleAssignmentStatementInfo assignmentInfo = SyntaxInfo.SimpleAssignmentStatementInfo(assignment);
if (!assignmentInfo.Success)
{
return;
}
if (assignmentInfo.Left is not IdentifierNameSyntax identifierName)
{
return;
}
StatementListInfo statementsInfo = SyntaxInfo.StatementListInfo(assignmentInfo.Statement);
if (!statementsInfo.Success)
{
return;
}
int index = statementsInfo.IndexOf(assignmentInfo.Statement);
if (index == statementsInfo.Count - 1)
{
return;
}
if (index > 0)
{
StatementSyntax previousStatement = statementsInfo[index - 1];
SimpleAssignmentStatementInfo assignmentInfo2 = SyntaxInfo.SimpleAssignmentStatementInfo(previousStatement);
if (assignmentInfo2.Success &&
assignmentInfo2.Left is IdentifierNameSyntax identifierName2 &&
string.Equals(identifierName.Identifier.ValueText, identifierName2.Identifier.ValueText, StringComparison.Ordinal))
{
return;
}
}
StatementSyntax nextStatement = statementsInfo[index + 1];
if (nextStatement.SpanOrLeadingTriviaContainsDirectives())
{
return;
}
if (nextStatement is not ReturnStatementSyntax returnStatement)
{
return;
}
if (returnStatement.Expression?.WalkDownParentheses() is not IdentifierNameSyntax identifierName3)
{
return;
}
if (!string.Equals(identifierName.Identifier.ValueText, identifierName3.Identifier.ValueText, StringComparison.Ordinal))
{
return;
}
ISymbol symbol = context.SemanticModel.GetSymbol(identifierName, context.CancellationToken);
switch (symbol?.Kind)
{
case SymbolKind.Local:
{
break;
}
case SymbolKind.Parameter:
{
if (((IParameterSymbol)symbol).RefKind != RefKind.None)
{
return;
}
break;
}
default:
{
return;
}
}
if (IsAssignedInsideAnonymousFunctionButDeclaredOutsideOfIt())
{
return;
}
bool result;
RemoveRedundantAssignmentWalker walker = null;
try
{
walker = RemoveRedundantAssignmentWalker.GetInstance();
walker.Symbol = symbol;
walker.SemanticModel = context.SemanticModel;
walker.CancellationToken = context.CancellationToken;
walker.Result = false;
walker.Visit(assignmentInfo.Right);
result = walker.Result;
}
finally
{
if (walker != null)
{
RemoveRedundantAssignmentWalker.Free(walker);
}
}
if (result)
{
return;
}
if (IsDeclaredInTryStatementOrCatchClauseAndReferencedInFinallyClause(context, assignmentInfo.Statement, symbol))
{
return;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.RemoveRedundantAssignment, assignment);
bool IsAssignedInsideAnonymousFunctionButDeclaredOutsideOfIt()
{
SyntaxNode declaringSyntax = null;
SyntaxNode n = assignment.Parent;
do
{
if (CSharpFacts.IsAnonymousFunctionExpression(n.Kind()))
{
if (declaringSyntax == null)
{
declaringSyntax = symbol.GetSyntaxOrDefault();
Debug.Assert(declaringSyntax != null, "");
if (declaringSyntax == null)
{
break;
}
SyntaxDebug.Assert(declaringSyntax.IsKind(SyntaxKind.VariableDeclarator, SyntaxKind.Parameter), declaringSyntax);
}
SyntaxNode n2 = declaringSyntax.Parent;
do
{
if (CSharpFacts.IsAnonymousFunctionExpression(n2.Kind()))
{
return(!object.ReferenceEquals(n, n2));
}
if (n2 is MemberDeclarationSyntax)
{
break;
}
n2 = n2.Parent;
}while (n2 != null);
return(true);
}
else if (n is MemberDeclarationSyntax)
{
break;
}
n = n.Parent;
}while (n != null);
return(false);
}
}
internal static void AnalyzeSimpleAssignment(SyntaxNodeAnalysisContext context)
{
if (context.Node.ContainsDiagnostics)
{
return;
}
if (context.Node.SpanOrTrailingTriviaContainsDirectives())
{
return;
}
var assignment = (AssignmentExpressionSyntax)context.Node;
SimpleAssignmentStatementInfo assignmentInfo = SyntaxInfo.SimpleAssignmentStatementInfo(assignment);
if (!assignmentInfo.Success)
{
return;
}
if (!(assignmentInfo.Left is IdentifierNameSyntax identifierName))
{
return;
}
StatementListInfo statementsInfo = SyntaxInfo.StatementListInfo(assignmentInfo.Statement);
if (!statementsInfo.Success)
{
return;
}
int index = statementsInfo.IndexOf(assignmentInfo.Statement);
if (index == statementsInfo.Count - 1)
{
return;
}
if (index > 0)
{
StatementSyntax previousStatement = statementsInfo[index - 1];
SimpleAssignmentStatementInfo assignmentInfo2 = SyntaxInfo.SimpleAssignmentStatementInfo(previousStatement);
if (assignmentInfo2.Success &&
assignmentInfo2.Left is IdentifierNameSyntax identifierName2 &&
string.Equals(identifierName.Identifier.ValueText, identifierName2.Identifier.ValueText, StringComparison.Ordinal))
{
return;
}
}
StatementSyntax nextStatement = statementsInfo[index + 1];
if (nextStatement.SpanOrLeadingTriviaContainsDirectives())
{
return;
}
if (!(nextStatement is ReturnStatementSyntax returnStatement))
{
return;
}
if (!(returnStatement.Expression?.WalkDownParentheses() is IdentifierNameSyntax identifierName3))
{
return;
}
if (!string.Equals(identifierName.Identifier.ValueText, identifierName3.Identifier.ValueText, StringComparison.Ordinal))
{
return;
}
ISymbol symbol = context.SemanticModel.GetSymbol(identifierName, context.CancellationToken);
switch (symbol?.Kind)
{
case SymbolKind.Local:
{
break;
}
case SymbolKind.Parameter:
{
if (((IParameterSymbol)symbol).RefKind != RefKind.None)
{
return;
}
break;
}
default:
{
return;
}
}
RemoveRedundantAssignmentWalker walker = RemoveRedundantAssignmentWalker.GetInstance();
walker.Symbol = symbol;
walker.SemanticModel = context.SemanticModel;
walker.CancellationToken = context.CancellationToken;
walker.Result = false;
walker.Visit(assignmentInfo.Right);
bool result = walker.Result;
RemoveRedundantAssignmentWalker.Free(walker);
if (result)
{
return;
}
DiagnosticHelpers.ReportDiagnostic(context, DiagnosticDescriptors.RemoveRedundantAssignment, assignment);
}
