C#.NET源生成器如何处理XML注释文档

博客园 - xiangji

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xiangji · 2026-08-15 · via 博客园 - xiangji

1. 前言

1.1 Roslyn支持XML注释文档

Roslyn支持从ISymbol获取XML注释文档

Roslyn支持从SyntaxTree节点获取XML注释文档

Roslyn支持对SyntaxTree节点添加XML注释文档

1.2 源生成器需要生成XML注释文档

XML注释文档是源代码很重要的一部分

可用于代码提示

用于提高代码可读性

用于生成API文档

如果源生成器不支持XML注释文档,大多只能停留在demo层面用于装十三

2. 注释

2.1 单行注释

SyntaxTrivia comment = SyntaxFactory.Comment("// singleLine Comment");
Assert.True(comment.IsKind(SyntaxKind.SingleLineCommentTrivia));

2.2 多行注释

SyntaxTrivia comment = SyntaxFactory.Comment("/* MultiLine\r\n Comment */");
Assert.True(comment.IsKind(SyntaxKind.MultiLineCommentTrivia));

3. XmlElementSyntax

XmlElementSyntax是构成 XML文档注释的核心部分之一

3.1 XmlElementSyntax定义

由开始标签(StartTag)、子元素(Content)和结束标签(EndTag)组成

是个标准的XML结构

class XmlElementSyntax : XmlNodeSyntax
{
    XmlElementStartTagSyntax StartTag { get; }
    SyntaxList<XmlNodeSyntax> Content { get; }
    XmlElementEndTagSyntax EndTag { get; }
}

3.2 XmlElementSyntax简单的Case

通过 SyntaxFactory.XmlElement方法构造 XmlElementSyntax

SyntaxList<XmlNodeSyntax> content = [SyntaxFactory.XmlText("用户名")];
XmlElementSyntax summary = SyntaxFactory.XmlElement("summary", content);
Assert.Equal("<summary>", summary.StartTag.ToFullString());
Assert.Equal("</summary>", summary.EndTag.ToFullString());
Assert.Equal("<summary>用户名</summary>", summary.ToFullString());

4. XmlNameAttributeSyntax

XmlNameAttributeSyntax是表示 XML文档中的属性主要的类之一

XmlAttributeSyntax是属性的抽象基类

4.1 XmlNameAttributeSyntax定义

由属性名(Name)、等号(EqualsToken)、引号(StartQuoteToken和EndQuoteToken)和属性值(Identifier)组成

class XmlNameAttributeSyntax : XmlAttributeSyntax
{
    XmlNameSyntax Name { get; }
    SyntaxToken EqualsToken { get; }
    SyntaxToken StartQuoteToken { get; }
    IdentifierNameSyntax Identifier { get; }
    SyntaxToken EndQuoteToken { get; }
}

4.2 XmlNameAttributeSyntax的Case

使用SyntaxFactory.XmlNameAttribute方法构造XmlNameAttributeSyntax

XmlNameAttributeSyntax attribute = SyntaxFactory.XmlNameAttribute("id");
Assert.Equal(" name=\"id\"", attribute.ToFullString());

4.3 XmlNameAttributeSyntax结合XmlElementSyntax的Case

XmlNameAttributeSyntax一般都是结合XmlElementSyntax来使用的

XmlElementSyntax通过StartTag的AddAttributes方法添加属性

SyntaxList<XmlNodeSyntax> content = [SyntaxFactory.XmlText("用户")];
XmlElementSyntax element = SyntaxFactory.XmlElement("param", content);
XmlNameAttributeSyntax attribute = SyntaxFactory.XmlNameAttribute("userId");
element = element.WithStartTag(element.StartTag.AddAttributes(attribute));
Assert.Equal("<param name=\"userId\">", element.StartTag.ToFullString());
Assert.Equal("</param>", element.EndTag.ToFullString());
Assert.Equal("<param name=\"userId\">用户</param>", element.ToFullString());

5. XML注释文档

XML注释文档是单行注释

DocumentationCommentTriviaSyntax是用于表示XML注释文档的类

DocumentationCommentTriviaSyntax主要是包含子元素(Content)

class DocumentationCommentTriviaSyntax : StructuredTriviaSyntax
{
    SyntaxList<XmlNodeSyntax> Content { get; }
}

5.2 Summary注释简单的Case

调用SyntaxFactory.XmlSummaryElement方法生成XmlElementSyntax

SyntaxFactory.XmlSummaryElement方法是对上面SyntaxFactory.XmlElement方法的封装

调用SyntaxGenerator.CreateDocumentation生成

SyntaxList<XmlNodeSyntax> context = [SyntaxFactory.XmlText("用户名")];
XmlElementSyntax summary = SyntaxFactory.XmlSummaryElement(context);
Assert.Equal("<summary>", summary.StartTag.ToFullString());
Assert.Equal("</summary>", summary.EndTag.ToFullString());
Assert.Equal("<summary>用户名</summary>", summary.ToFullString());
DocumentationCommentTriviaSyntax documentation = SyntaxGenerator.CreateDocumentation(summary);
Assert.True(documentation.IsKind(SyntaxKind.SingleLineDocumentationCommentTrivia));
Assert.Equal("/// <summary>用户名</summary>\r\n", documentation.ToFullString());

5.3 大部分XML注释文档有换行

换行XML注释文档如下

这样的XML注释文档也是可以实现的

/// <summary>
/// 用户名
/// </summary>

5.4 Summary换行注释的Case

context对比4.2前后多了XmlNewLine(true)

SyntaxList<XmlNodeSyntax> context = [XmlNewLine(true), SyntaxFactory.XmlText("用户名"), XmlNewLine(true)];
XmlElementSyntax summary = SyntaxFactory.XmlSummaryElement(context);
Assert.Equal("<summary>", summary.StartTag.ToFullString());
Assert.Equal("</summary>", summary.EndTag.ToFullString());
Assert.Equal("<summary>\r\n/// 用户名\r\n/// </summary>", summary.ToFullString());
DocumentationCommentTriviaSyntax documentation = SyntaxGenerator.CreateDocumentation(summary);
Assert.True(documentation.IsKind(SyntaxKind.SingleLineDocumentationCommentTrivia));
Assert.Equal("/// <summary>\r\n/// 用户名\r\n/// </summary>\r\n", documentation.ToFullString());

static XmlTextSyntax XmlNewLine(bool continueComment)
    => SyntaxFactory.XmlText(SyntaxFactory.XmlTextNewLine("\r\n", continueComment));

6. 复杂XML注释文档

6.1 含复杂XML注释文档的代码的Case

EntityKey类的XML注释文档含summary、typeparam和param

其中typeparam和param还都含name属性

/// <summary>
/// 实体主键
/// </summary>
/// <typeparam name="TKey">主键类型</typeparam>
/// <param name="key">主键</param>
public class EntityKey<TKey>(TKey key)
{
    /// <summary>
    /// 主键
    /// </summary>
    public TKey Key { get; } = key;
}

6.2 使用Roslyn生成EntityKey类的XML注释文档

构造summary、typeparam和paramd等3个XmlElementSyntax

使用换行符line分割3个XmlElementSyntax及XmlNewLine(false)作为documentation的子元素

调用SyntaxFactory.DocumentationComment构造XML注释文档

var line = XmlNewLine(true);
XmlElementSyntax summary = XmlSummary("实体主键", separator);
XmlElementSyntax typeparam = NamedXmlElement("typeparam", "TKey", "主键类型");
XmlElementSyntax param = NamedXmlElement("param", "key", "主键");
XmlNodeSyntax[] content = [summary, separator, typeparam, separator, param, XmlNewLine(false)];
DocumentationCommentTriviaSyntax documentation = SyntaxFactory.DocumentationComment(content);
var code = documentation.ToFullString();
Assert.Contains("<summary>", code);


static XmlElementSyntax NamedXmlElement(string elementName, string name, string text)
{
    SyntaxList<XmlNodeSyntax> content = [SyntaxFactory.XmlText(text)];
    XmlElementSyntax element = SyntaxFactory.XmlElement(elementName, content);
    XmlNameAttributeSyntax attribute = SyntaxFactory.XmlNameAttribute(name);
    return element.WithStartTag(element.StartTag.AddAttributes(attribute));
}
static XmlElementSyntax XmlSummary(string summary, XmlTextSyntax line)
{
    SyntaxList<XmlNodeSyntax> summaryContext = [line, SyntaxFactory.XmlText(summary), line];
    return SyntaxFactory.XmlSummaryElement(summaryContext);
}
static XmlTextSyntax XmlNewLine(bool continueComment)
    => SyntaxFactory.XmlText(SyntaxFactory.XmlTextNewLine("\r\n", continueComment));

6.3 以上代码生成的XML注释文档

生成的XML注释文档与源代码中的还原度为100%

/// <summary>
/// 实体主键
/// </summary>
/// <typeparam name="TKey">主键类型</typeparam>
/// <param name="key">主键</param>

6.4 生成复杂XML注释文档更通用的方法

先构造Comment对象

Comment支持Summary、多个TypeParams、多个Params及Returns

调用SyntaxGenerator.CreateDocumentation生成XML注释文档

该示例生成结果与5.2完全一致

var comment = new Comment() 
{
    Summary = "实体主键",
    TypeParams = { { "TKey", "主键类型" } },
    Params = { { "key", "主键" } }
};
DocumentationCommentTriviaSyntax? documentation = SyntaxGenerator.CreateDocumentation(comment);
Assert.NotNull(documentation);
var code = documentation.ToFullString();
Assert.Contains("<summary>", code);

7. 单行注释生成XML注释文档

单行注释生成XML注释文档是可行的

但是不推荐

7.1 单行注释生成XML注释文档的Case

SyntaxFactory.Comment生成单行注释

这种方式生成复杂文档大概率、需要大量字符串拼接

SyntaxTrivia comment = SyntaxFactory.Comment("/// <summary>This is  comment</summary>");
var method = SyntaxGenerator.VoidType.Method("Test")
    .WithBody(SyntaxFactory.Block())
    .WithLeadingTrivia(comment);
var code = method.ToFullString();
Assert.Contains("<summary>", code);

7.2 生成的代码如下

/// <summary>This is  comment</summary>
void Test()
{
}

8. 从ISymbol解析XML注释文档

8.1 读取XML注释文档

通过方法GetDocumentationCommentXml读取XML注释文档

var sourceCode = @"
    /// <summary>
    /// C
    /// </summary>
    /// <param name=""Id"">Id</param>
    /// <param name=""Name"">Name</param>
    record C(int Id, string Name);";
var compilation = SyntaxTreeDriver.CreateDefaultDriver()
    .Compile(sourceCode);
INamedTypeSymbol? classSymbol = compilation.GetTypeByMetadataName("C");
Assert.NotNull(classSymbol);
string? xml = classSymbol.GetDocumentationCommentXml();
Assert.NotNull(xml);

8.2 读取XML注释文档的结果

结果是一个完整的XML节点member

<member name="T:C">
    <summary>
    C
    </summary>
    <param name="Id">Id</param>
    <param name="Name">Name</param>
</member>

8.3 解析XML注释文档

CommentParser.GetSummary解析Summary

CommentParser.Comment解析Summary及参数

var sourceCode = @"
    /// <summary>
    /// C
    /// </summary>
    /// <param name=""Id"">Id</param>
    /// <param name=""Name"">Name</param>
    record C(int Id, string Name);";
var compilation = SyntaxTreeDriver.CreateDefaultDriver()
    .Compile(sourceCode);
INamedTypeSymbol? classSymbol = compilation.GetTypeByMetadataName("C");
Assert.NotNull(classSymbol);
string? xml = classSymbol.GetDocumentationCommentXml();
Assert.NotNull(xml);
string summary = CommentParser.GetSummary(xml);
Assert.Equal("C", summary);
Comment comment = CommentParser.Instance.Get(xml);
Assert.Equal("C", comment.Summary.Trim());
Assert.Equal(2, comment.Params.Count);
Comment comment2 = CommentParser.Comment(classSymbol);
Assert.Equal("C", comment2.Summary.Trim());
Assert.Equal(2, comment2.Params.Count);

8.4 解析XML注释文档结果

9. 把ISymbol的XML注释文档用于生成代码的注释文档

9.1 生成代码的Case

使用 SyntaxGenerator.Clone复制类型信息

使用 SymbolReflection.GetPublicPropertiesWithBase遍历属性

CommentParser.GetSummary解析XML注释文档的Summary

WithSummary扩展方法添加XML注释文档的Summary

var sourceCode = @"
    namespace ExampleNamespace;

    /// <summary>
    /// 用户
    /// </summary>
    /// <param name=""UserName"">用户名</param>
    public record User(string UserName);
    public partial class UserDTO;
    ";
var compilation = SyntaxTreeDriver.DefaultDriver.Compile(sourceCode);
var syntaxTree = compilation.SyntaxTrees.FirstOrDefault();
Assert.NotNull(syntaxTree);
var classDeclaration = syntaxTree.GetRoot().DescendantNodes().OfType<ClassDeclarationSyntax>().LastOrDefault();
Assert.NotNull(classDeclaration);
var semanticModel = compilation.GetSemanticModel(syntaxTree);
var symbol = semanticModel.GetDeclaredSymbol(classDeclaration);
Assert.NotNull(symbol);
var sourceSymbol = compilation.GetTypeByMetadataName("ExampleNamespace.User");
Assert.NotNull(sourceSymbol);
var generator = SyntaxGenerator.Clone(classDeclaration);
foreach (var propertySymbol in SymbolReflection.GetPublicPropertiesWithBase(sourceSymbol))
{
    string propertySummary = CommentParser.GetSummary(propertySymbol);
    var propertyType = propertySymbol.Type.ToSyntax();
    var property = propertyType.GetSetProperty(propertySymbol.Name)
        .Public()
        .WithSummary(propertySummary);
    generator.AddProperty(property);
}
string sourceSummary = CommentParser.GetSummary(sourceSymbol);
generator.Apply(type => type.WithSummary(sourceSummary));
var code = generator.Build().ToFullString();
Assert.Contains("<summary>", code);

9.2 生成的代码如下

namespace ExampleNamespace;
///<summary>
///用户
///</summary>
partial class UserDTO
{
    ///<summary>
    ///用户名
    ///</summary>
    public string UserName { get; set; }
}

10. 示例说明

10.1 示例执行说明

以上代码执行依赖开源项目EasySyntax、Hand.GenerateCore和Hand.Generators.SyntaxScripting,nuget包如下

Hand.Generators.EasySyntax --version 0.2.1.5

Hand.GenerateCore --version 0.2.1.7

Hand.Generators.SyntaxScripting --version 0.2.1.5-alpha

10.2 示例代码及开源源码

源码托管地址: https://github.com/donetsoftwork/Hand.Generators ，欢迎大家直接查看源码。

gitee同步更新:https://gitee.com/donetsoftwork/hand.-generators

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博客园 - xiangji

1. 前言

1.1 Roslyn支持XML注释文档

1.2 源生成器需要生成XML注释文档

2. 注释

2.1 单行注释

2.2 多行注释

3. XmlElementSyntax

3.1 XmlElementSyntax定义

3.2 XmlElementSyntax简单的Case

4. XmlNameAttributeSyntax

4.1 XmlNameAttributeSyntax定义

4.2 XmlNameAttributeSyntax的Case

4.3 XmlNameAttributeSyntax结合XmlElementSyntax的Case

5. XML注释文档

5.2 Summary注释简单的Case

5.3 大部分XML注释文档有换行

5.4 Summary换行注释的Case

6. 复杂XML注释文档

6.1 含复杂XML注释文档的代码的Case

6.2 使用Roslyn生成EntityKey类的XML注释文档

6.3 以上代码生成的XML注释文档

6.4 生成复杂XML注释文档更通用的方法

7. 单行注释生成XML注释文档

7.1 单行注释生成XML注释文档的Case

7.2 生成的代码如下

8. 从ISymbol解析XML注释文档

8.1 读取XML注释文档

8.2 读取XML注释文档的结果

8.3 解析XML注释文档

8.4 解析XML注释文档结果

9. 把ISymbol的XML注释文档用于生成代码的注释文档

9.1 生成代码的Case

9.2 生成的代码如下

10. 示例说明

10.1 示例执行说明

10.2 示例代码及开源源码