从 Roslyn ClassDeclarationSyntax 获取类全名（包括命名空间）

Question

我有一个来自 roslyn 语法树的 ClassDeclarationSyntax。 我是这样读的：

var tree = SyntaxTree.ParseText(sourceCode);
var root = (CompilationUnitSyntax)tree.GetRoot();

var classes = root.DescendantNodes().OfType<ClassDeclarationSyntax>();

标识符仅包含类的名称，但没有有关命名空间的信息，因此缺少 fullType Name。像“MyClass”，但不是“Namespace1.MyClass”

获取语法的命名空间/FulltypeName 的推荐方法是什么？

Answer 1

你可以使用我写的帮助类来做到这一点：

NamespaceDeclarationSyntax namespaceDeclarationSyntax = null;
if (!SyntaxNodeHelper.TryGetParentSyntax(classDeclarationSyntax, out namespaceDeclarationSyntax))
{
    return; // or whatever you want to do in this scenario
}

var namespaceName = namespaceDeclarationSyntax.Name.ToString();
var fullClassName = namespaceName + "." + classDeclarationSyntax.Identifier.ToString();

和助手：

static class SyntaxNodeHelper
{
    public static bool TryGetParentSyntax<T>(SyntaxNode syntaxNode, out T result) 
        where T : SyntaxNode
    {
        // set defaults
        result = null;

        if (syntaxNode == null)
        {
            return false;
        }

        try
        {
            syntaxNode = syntaxNode.Parent;

            if (syntaxNode == null)
            {
                return false;
            }

            if (syntaxNode.GetType() == typeof (T))
            {
                result = syntaxNode as T;
                return true;
            }

            return TryGetParentSyntax<T>(syntaxNode, out result);
        }
        catch
        {
            return false;
        }
    }
}

这里没有什么太复杂的事情......命名空间将在语法树“向上”是有道理的（因为该类包含在命名空间中）所以您只需要在语法树“向上”移动直到找到命名空间并将其附加到 ClassDeclarationSyntax 的标识符。

Answer 2

我知道我在游戏中比较晚，但我偶然发现了one of given the answers，这在我必须处理嵌套类的情况下不起作用。因此，这里有一个也可以处理嵌套类的方法：

public static class ClassDeclarationSyntaxExtensions
{
    public const string NESTED_CLASS_DELIMITER = "+";
    public const string NAMESPACE_CLASS_DELIMITER = ".";

    public static string GetFullName(this ClassDeclarationSyntax source)
    {
        Contract.Requires(null != source);

        var items = new List<string>();
        var parent = source.Parent;
        while (parent.IsKind(SyntaxKind.ClassDeclaration))
        {
            var parentClass = parent as ClassDeclarationSyntax;
            Contract.Assert(null != parentClass);
            items.Add(parentClass.Identifier.Text);

            parent = parent.Parent;
        }

        var nameSpace = parent as NamespaceDeclarationSyntax;
        Contract.Assert(null != nameSpace);
        var sb = new StringBuilder().Append(nameSpace.Name).Append(NAMESPACE_CLASS_DELIMITER);
        items.Reverse();
        items.ForEach(i => { sb.Append(i).Append(NESTED_CLASS_DELIMITER); });
        sb.Append(source.Identifier.Text);

        var result = sb.ToString();
        return result;
    }
}

Answer 3

基于the answer by Ronald，我添加了对嵌套命名空间、结构体和泛型的支持。

它使用generics CLR naming convention 允许将输出用作Compilation.GetTypeByMetadataName() 的输入

public static class TypeDeclarationSyntaxExtensions
{
    const char NESTED_CLASS_DELIMITER = '+';
    const char NAMESPACE_CLASS_DELIMITER = '.';
    const char TYPEPARAMETER_CLASS_DELIMITER = '`';

    public static string GetFullName(this TypeDeclarationSyntax source)
    {
        if (source is null)
            throw new ArgumentNullException(nameof(source));

        var namespaces = new LinkedList<NamespaceDeclarationSyntax>();
        var types = new LinkedList<TypeDeclarationSyntax>();
        for (var parent = source.Parent; parent is object; parent = parent.Parent)
        {
            if (parent is NamespaceDeclarationSyntax @namespace)
            {
                namespaces.AddFirst(@namespace);
            }
            else if (parent is TypeDeclarationSyntax type)
            {
                types.AddFirst(type);
            }
        }

        var result = new StringBuilder();
        for (var item = namespaces.First; item is object; item = item.Next)
        {
            result.Append(item.Value.Name).Append(NAMESPACE_CLASS_DELIMITER);
        }
        for (var item = types.First; item is object; item = item.Next)
        {
            var type = item.Value;
            AppendName(result, type);
            result.Append(NESTED_CLASS_DELIMITER);
        }
        AppendName(result, source);

        return result.ToString();
    }

    static void AppendName(StringBuilder builder, TypeDeclarationSyntax type)
    {
        builder.Append(type.Identifier.Text);
        var typeArguments = type.TypeParameterList?.ChildNodes()
            .Count(node => node is TypeParameterSyntax) ?? 0;
        if (typeArguments != 0)
            builder.Append(TYPEPARAMETER_CLASS_DELIMITER).Append(typeArguments);
    }
}

Answer 4

试试这个代码

public static string GetFullName(NamespaceDeclarationSyntax node)
{
    if (node.Parent is NamespaceDeclarationSyntax)
        return String.Format("{0}.{1}",
            GetFullName((NamespaceDeclarationSyntax)node.Parent),
            ((IdentifierNameSyntax)node.Name).Identifier.ToString());
    else
        return ((IdentifierNameSyntax)node.Name).Identifier.ToString();
}

Answer 5

使用模式匹配+递归还有一种优雅的方式：

// method with pattern matching
public static string GetNamespaceFrom(SyntaxNode s) =>
    s.Parent switch
    {
        NamespaceDeclarationSyntax namespaceDeclarationSyntax => namespaceDeclarationSyntax.Name.ToString(),
        null => string.Empty, // or whatever you want to do
        _ => GetNamespaceFrom(s.Parent)
    };

// somewhere call it passing the class declaration syntax:
string ns = GetNamespaceFrom(classDeclarationSyntax);

Answer 6

这是我获取命名空间的方法。您必须针对您的情况稍微修改我的代码：

        public static async Task<NamespaceDeclarationSyntax> GetNamespaceAsync(this Document document, CancellationToken cancellationToken = default(CancellationToken))
        {
            SyntaxNode documentRoot = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
            var rootCompUnit = (CompilationUnitSyntax)documentRoot;
            return (NamespaceDeclarationSyntax)rootCompUnit.Members.Where(m => m.IsKind(SyntaxKind.NamespaceDeclaration)).Single();
        }

Answer 7

另一个答案.. 这个实用程序类也支持嵌套命名空间和嵌套类。

public static class SyntaxNodeHelper
{
    public static string GetPrefix(SyntaxNode member)
    {
        if (member == null) {
            return "";
        }

        StringBuilder sb = new StringBuilder();
        SyntaxNode node = member;

        while(node.Parent != null) {
            node = node.Parent;

            if (node is NamespaceDeclarationSyntax) {
                var namespaceDeclaration = (NamespaceDeclarationSyntax) node;

                sb.Insert(0, ".");
                sb.Insert(0, namespaceDeclaration.Name.ToString());
            } else if (node is ClassDeclarationSyntax) {
                var classDeclaration = (ClassDeclarationSyntax) node;

                sb.Insert(0, ".");
                sb.Insert(0, classDeclaration.Identifier.ToString());
            }
        }

        return sb.ToString();
    }
}

Answer 8

这段代码可以解决你的问题。

public static string ClassFullName(this ClassDeclarationSyntax varClassDec)
{
    SyntaxNode tempCurCls = varClassDec;
    var tempFullName = new Stack<string>();
    
    do
    {
        if (tempCurCls.Kind() == SyntaxKind.ClassDeclaration)
        {
            tempFullName.Push(((ClassDeclarationSyntax)tempCurCls).Identifier.ToString());
        }
        else if (tempCurCls.Kind() == SyntaxKind.NamespaceDeclaration)
        {
            tempFullName.Push(((NamespaceDeclarationSyntax)tempCurCls).Name.ToString());
        }
        
        tempCurCls = tempCurCls.Parent;
    } while (tempCurCls != null);
    
    return string.Join(".", tempFullName);
}