c# - 使用语句 Roslyn 脚本/代码排序和删除（未使用）？

Question

使用语句 Roslyn 脚本/代码排序和删除（未使用）？我正在寻找一些可以在项目中运行并对未使用的 using 语句进行排序和删除的 .NET/Roslyn（编译器即服务）代码。我相信罗斯林有可能吗？谁能指出我可以重写的代码？

Answer 1

这是 Visual Studio 中的一个功能，但在学术上我认为你会使用 SyntaxTree 中的语句来收集，如下所示：

var usings = syntaxTree.Root.DescendentNodes().Where(node is UsingDirectiveSyntax);

...并将其与符号表解析的命名空间进行比较，如下所示：

private static IEnumerable<INamespaceSymbol> GetNamespaceSymbol(ISymbol symbol)
{
    if (symbol != null && symbol.ContainingNamespace != null)
        yield return symbol.ContainingNamespace;
}

var ns = semanticModel.SyntaxTree.Root.DescendentNodes().SelectMany(node =>
    GetNamespaceSymbol(semanticModel.GetSemanticInfo(node).Symbol)).Distinct();

Answer 2

Roslyn CTP September 2012 提供了一种GetUnusedImportDirectives()方法，在这里很有用。

通过修改 Matt 引用的OrganizeSolution示例项目，您可以使用指令实现（未使用）的排序和删除。可以在此处找到此项目的（过时）版本：http: //go.microsoft.com/fwlink/ ?LinkId=263977 。它已经过时了，因为 document.GetUpdatedDocument()不再存在，

var document = newSolution.GetDocument(documentId);
var transformation = document.OrganizeImports();
var newDocument = transformation.GetUpdatedDocument();

可以简化为

var document = newSolution.GetDocument(documentId);
var newDocument = document.OrganizeImports();

添加newDocument = RemoveUnusedImportDirectives(newDocument);并提供以下方法可以解决问题。

private static IDocument RemoveUnusedImportDirectives(IDocument document)
{
    var root = document.GetSyntaxRoot();
    var semanticModel = document.GetSemanticModel();

    // An IDocument can refer to both a CSharp as well as a VisualBasic source file.
    // Therefore we need to distinguish those cases and provide appropriate casts.  
    // Since the question was tagged c# only the CSharp way is provided.
    switch (document.LanguageServices.Language)
    {
        case LanguageNames.CSharp:
            var oldUsings = ((CompilationUnitSyntax)root).Usings;
            var unusedUsings = ((SemanticModel)semanticModel).GetUnusedImportDirectives();
            var newUsings = Syntax.List(oldUsings.Where(item => !unusedUsings.Contains(item)));
            root = ((CompilationUnitSyntax)root).WithUsings(newUsings);
            document = document.UpdateSyntaxRoot(root);
            break;

        case LanguageNames.VisualBasic:
            // TODO
            break;
    }
    return document;
}

Answer 3

我使用以下扩展方法对 usings 进行排序

internal static SyntaxList<UsingDirectiveSyntax> Sort(this SyntaxList<UsingDirectiveSyntax> usingDirectives, bool placeSystemNamespaceFirst = false) =>
    SyntaxFactory.List(
        usingDirectives
        .OrderBy(x => x.StaticKeyword.IsKind(SyntaxKind.StaticKeyword) ? 1 : x.Alias == null ? 0 : 2)
        .ThenBy(x => x.Alias?.ToString())
        .ThenByDescending(x => placeSystemNamespaceFirst && x.Name.ToString().StartsWith(nameof(System) + "."))
        .ThenBy(x => x.Name.ToString()));

和

compilationUnit = compilationUnit.WithUsings(SortUsings(compilationUnit.Usings))

Answer 4

查看 Roslyn 附带的 OrganizeSolution 示例项目。它做的事情类似于你想要的。它执行排序部分。您还必须使用 Jeff 展示的 SemanticModel 来确定源中是否没有对特定命名空间的引用。

Answer 5

For removing statements, check out the FAQ item 30 in the solution in the following directory, in the FAQ.cs file: (Note this is for the June 2012 CTP version of Roslyn).

%userprofile%\Documents\Microsoft Roslyn CTP - June 2012\CSharp\APISampleUnitTestsCS

There is also a FAQ which refers to this project:

http://www.codeplex.com/Download?ProjectName=dlr&DownloadId=386858

Here is the sample rewriter from the sample code, which removes assignment statements.

// Below SyntaxRewriter removes multiple assignement statements from under the 
// SyntaxNode being visited.
public class AssignmentStatementRemover : SyntaxRewriter
{
    public override SyntaxNode VisitExpressionStatement(ExpressionStatementSyntax node)
    {
        SyntaxNode updatedNode = base.VisitExpressionStatement(node);

        if (node.Expression.Kind == SyntaxKind.AssignExpression)
        {
            if (node.Parent.Kind == SyntaxKind.Block)
            {
                // There is a parent block so it is ok to remove the statement completely.
                updatedNode = null;
            }
            else
            {
                // The parent context is some statement like an if statement without a block.
                // Return an empty statement.
                updatedNode = Syntax.EmptyStatement()
                    .WithLeadingTrivia(updatedNode.GetLeadingTrivia())
                    .WithTrailingTrivia(updatedNode.GetTrailingTrivia());
            }
        }
     return updatedNode;
    }
}