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UnusedStringBuilder.cs
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UnusedStringBuilder.cs
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/*
* SonarAnalyzer for .NET
* Copyright (C) 2015-2023 SonarSource SA
* mailto: contact AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
namespace SonarAnalyzer.Rules.CSharp;
[DiagnosticAnalyzer(LanguageNames.CSharp)]
public sealed class UnusedStringBuilder : UnusedStringBuilderBase<SyntaxKind, VariableDeclaratorSyntax, IdentifierNameSyntax>
{
private static readonly SyntaxKind[] SkipChildren =
{
SyntaxKind.ClassDeclaration,
};
protected override ILanguageFacade<SyntaxKind> Language => CSharpFacade.Instance;
protected override string GetName(SyntaxNode declaration) => declaration.GetName();
protected override SyntaxNode GetScope(VariableDeclaratorSyntax declarator) =>
declarator.Parent.Parent is { Parent: GlobalStatementSyntax { Parent: CompilationUnitSyntax } }
? declarator.Parent.Parent.Parent.Parent
: declarator.Parent.Parent.Parent;
protected override ILocalSymbol RetrieveStringBuilderObject(VariableDeclaratorSyntax declarator, SemanticModel semanticModel) =>
declarator is
{
Parent.Parent: LocalDeclarationStatementSyntax,
Initializer.Value: { } expression,
}
&& IsStringBuilderObjectCreation(expression, semanticModel)
? semanticModel.GetDeclaredSymbol(declarator) as ILocalSymbol
: null;
protected override bool IsStringBuilderRead(string name, ILocalSymbol symbol, SyntaxNode node, SemanticModel model) =>
node switch
{
InvocationExpressionSyntax invocation => StringBuilderAccessInvocations.Contains(invocation.Expression.GetName()) && IsSameReference(invocation.Expression, name, symbol, model),
ReturnStatementSyntax returnStatement => IsSameReference(returnStatement.Expression, name, symbol, model),
InterpolationSyntax interpolation => IsSameReference(interpolation.Expression, name, symbol, model),
ElementAccessExpressionSyntax elementAccess => IsSameReference(elementAccess.Expression, name, symbol, model),
ArgumentSyntax argument => IsSameReference(argument.Expression, name, symbol, model),
MemberAccessExpressionSyntax memberAccess => StringBuilderAccessExpressions.Contains(memberAccess.Name.GetName()) && IsSameReference(memberAccess.Expression, name, symbol, model),
_ => false,
};
protected override bool DescendIntoChildren(SyntaxNode node) =>
!(node.IsAnyKind(SkipChildren) && node.IsKind(SyntaxKindEx.LocalFunctionStatement) && ((LocalFunctionStatementSyntaxWrapper)node).Modifiers.Any(SyntaxKind.StaticKeyword));
private static bool IsStringBuilderObjectCreation(ExpressionSyntax expression, SemanticModel semanticModel) =>
ObjectCreationFactory.TryCreate(expression) is { } creation
&& creation.IsKnownType(KnownType.System_Text_StringBuilder, semanticModel);
}