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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,
SyntaxKind.StructDeclaration,
SyntaxKind.EnumDeclaration,
SyntaxKind.InterfaceDeclaration,
SyntaxKindEx.RecordClassDeclaration,
SyntaxKindEx.RecordStructDeclaration
};
protected override ILanguageFacade<SyntaxKind> Language => CSharpFacade.Instance;
protected override SyntaxNode GetScope(VariableDeclaratorSyntax declarator) =>
declarator switch
{
{ Parent: VariableDeclarationSyntax { Parent: LocalDeclarationStatementSyntax { Parent: BlockSyntax block } } } => block,
{ Parent: VariableDeclarationSyntax { Parent: LocalDeclarationStatementSyntax { Parent: GlobalStatementSyntax { Parent: CompilationUnitSyntax compilationUnit } } } } => compilationUnit,
_ => null,
};
protected override ILocalSymbol RetrieveStringBuilderObject(SemanticModel semanticModel, VariableDeclaratorSyntax declarator) =>
declarator is
{
Parent.Parent: LocalDeclarationStatementSyntax,
Initializer.Value: { } expression,
}
&& IsStringBuilderObjectCreation(expression, semanticModel)
? semanticModel.GetDeclaredSymbol(declarator) as ILocalSymbol
: null;
protected override bool IsStringBuilderRead(SemanticModel model, ILocalSymbol symbol, SyntaxNode node) =>
node switch
{
InvocationExpressionSyntax invocation => IsAccessInvocation(invocation.Expression.GetName()) && IsSameReference(model, symbol, invocation.Expression),
ReturnStatementSyntax returnStatement => IsSameReference(model, symbol, returnStatement.Expression),
InterpolationSyntax interpolation => IsSameReference(model, symbol, interpolation.Expression),
ElementAccessExpressionSyntax elementAccess => IsSameReference(model, symbol, elementAccess.Expression),
ArgumentSyntax argument => IsSameReference(model, symbol, argument.Expression),
MemberAccessExpressionSyntax memberAccess => IsAccessExpression(memberAccess.Name.GetName()) && IsSameReference(model, symbol, memberAccess.Expression),
EqualsValueClauseSyntax { Value: IdentifierNameSyntax identifier } => IsSameReference(model, symbol, identifier),
AssignmentExpressionSyntax { Right: IdentifierNameSyntax identifier } => IsSameReference(model, symbol, identifier),
_ => 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);
}