如何在C#源生成器生成的成员之间插入空行？

• 核心问题在于不要仅给单个成员加尾随trivia，而是要在成员之间明确插入空行对应的语法 trivia，以下是两种可靠的实现方式：

方式1：给非首成员添加前置空行trivia #

这种方式更直观，确保每个后续成员前都有一个空行，避免末尾多余空行：

// 假设jsonProperties是你从JSON读取的键值对集合
var memberList = new List<MemberDeclarationSyntax>();
foreach (var (index, prop) in jsonProperties.Select((p, i) => (i, p)))
{
    // 构建公共字符串常量字段
    var field = SyntaxFactory.FieldDeclaration(
            SyntaxFactory.VariableDeclaration(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.StringKeyword)))
                .WithVariables(SyntaxFactory.SingletonSeparatedList(
                    SyntaxFactory.VariableDeclarator(prop.Key)
                        .WithInitializer(SyntaxFactory.EqualsValueClause(
                            SyntaxFactory.LiteralExpression(SyntaxKind.StringLiteralExpression, SyntaxFactory.Literal(prop.Value))
                        ))
                ))
        )
        .WithModifiers(SyntaxFactory.TokenList(
            SyntaxFactory.Token(SyntaxKind.PublicKeyword),
            SyntaxFactory.Token(SyntaxKind.ConstKeyword)
        ));

    // 除第一个成员外，添加空行前置trivia
    if (index > 0)
    {
        var emptyLine = SyntaxFactory.SyntaxTriviaList(
            SyntaxFactory.NewLineTrivia(),
            SyntaxFactory.NewLineTrivia()
        );
        field = field.WithLeadingTrivia(emptyLine);
    }

    memberList.Add(field);
}

// 构建最终的静态类
var staticClass = SyntaxFactory.ClassDeclaration("YourStaticClassName")
    .WithModifiers(SyntaxFactory.TokenList(SyntaxFactory.Token(SyntaxKind.StaticKeyword)))
    .WithMembers(SyntaxFactory.List(memberList))
    .NormalizeWhitespace(); // 规范化空白，确保自定义trivia生效

方式2：给非尾成员添加尾随空行trivia #

如果习惯在成员后加空白，可给除最后一个外的所有成员添加尾随空行：

var members = jsonProperties.Select((prop, index) =>
{
    var field = SyntaxFactory.FieldDeclaration(
            SyntaxFactory.VariableDeclaration(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.StringKeyword)))
                .WithVariables(SyntaxFactory.SingletonSeparatedList(
                    SyntaxFactory.VariableDeclarator(prop.Key)
                        .WithInitializer(SyntaxFactory.EqualsValueClause(
                            SyntaxFactory.LiteralExpression(SyntaxKind.StringLiteralExpression, SyntaxFactory.Literal(prop.Value))
                        ))
                ))
        )
        .WithModifiers(SyntaxFactory.TokenList(
            SyntaxFactory.Token(SyntaxKind.PublicKeyword),
            SyntaxFactory.Token(SyntaxKind.ConstKeyword)
        ));

    // 非最后一个成员添加空行尾随trivia
    if (index != jsonProperties.Count - 1)
    {
        field = field.WithTrailingTrivia(
            SyntaxFactory.SyntaxTriviaList(
                SyntaxFactory.NewLineTrivia(),
                SyntaxFactory.NewLineTrivia()
            )
        );
    }
    return field;
}).ToList();

var staticClass = SyntaxFactory.ClassDeclaration("YourStaticClassName")
    .WithModifiers(SyntaxFactory.TokenList(SyntaxFactory.Token(SyntaxKind.StaticKeyword)))
    .WithMembers(SyntaxFactory.List(members))
    .NormalizeWhitespace();

• 注意：如果之前调用NormalizeWhitespace()无效，检查是否是在添加自定义trivia之后调用的——必须先设置trivia，再执行规范化，否则默认空白会覆盖自定义设置。

内容的提问来源于stack exchange，提问作者Axemasta