bitwarden-server/util/Setup/YamlComments.cs

using System.ComponentModel;
using YamlDotNet.Core;
using YamlDotNet.Core.Events;
using YamlDotNet.Serialization;
using YamlDotNet.Serialization.ObjectGraphVisitors;
using YamlDotNet.Serialization.TypeInspectors;

// ref: https://github.com/aaubry/YamlDotNet/issues/152#issuecomment-349034754

namespace Bit.Setup
{
    public class CommentGatheringTypeInspector : TypeInspectorSkeleton
    {
        private readonly ITypeInspector _innerTypeDescriptor;

        public CommentGatheringTypeInspector(ITypeInspector innerTypeDescriptor)
        {
            _innerTypeDescriptor = innerTypeDescriptor ?? throw new ArgumentNullException(nameof(innerTypeDescriptor));
        }

        public override IEnumerable<IPropertyDescriptor> GetProperties(Type type, object container)
        {
            return _innerTypeDescriptor.GetProperties(type, container).Select(d => new CommentsPropertyDescriptor(d));
        }

        private sealed class CommentsPropertyDescriptor : IPropertyDescriptor
        {
            private readonly IPropertyDescriptor _baseDescriptor;

            public CommentsPropertyDescriptor(IPropertyDescriptor baseDescriptor)
            {
                _baseDescriptor = baseDescriptor;
                Name = baseDescriptor.Name;
            }

            public string Name { get; set; }
            public int Order { get; set; }
            public Type Type => _baseDescriptor.Type;
            public bool CanWrite => _baseDescriptor.CanWrite;

            public Type TypeOverride
            {
                get { return _baseDescriptor.TypeOverride; }
                set { _baseDescriptor.TypeOverride = value; }
            }

            public ScalarStyle ScalarStyle
            {
                get { return _baseDescriptor.ScalarStyle; }
                set { _baseDescriptor.ScalarStyle = value; }
            }

            public void Write(object target, object value)
            {
                _baseDescriptor.Write(target, value);
            }

            public T GetCustomAttribute<T>() where T : Attribute
            {
                return _baseDescriptor.GetCustomAttribute<T>();
            }

            public IObjectDescriptor Read(object target)
            {
                var description = _baseDescriptor.GetCustomAttribute<DescriptionAttribute>();
                return description != null ?
                    new CommentsObjectDescriptor(_baseDescriptor.Read(target), description.Description) :
                    _baseDescriptor.Read(target);
            }
        }
    }

    public sealed class CommentsObjectDescriptor : IObjectDescriptor
    {
        private readonly IObjectDescriptor _innerDescriptor;

        public CommentsObjectDescriptor(IObjectDescriptor innerDescriptor, string comment)
        {
            _innerDescriptor = innerDescriptor;
            Comment = comment;
        }

        public string Comment { get; private set; }
        public object Value => _innerDescriptor.Value;
        public Type Type => _innerDescriptor.Type;
        public Type StaticType => _innerDescriptor.StaticType;
        public ScalarStyle ScalarStyle => _innerDescriptor.ScalarStyle;
    }

    public class CommentsObjectGraphVisitor : ChainedObjectGraphVisitor
    {
        public CommentsObjectGraphVisitor(IObjectGraphVisitor<IEmitter> nextVisitor)
            : base(nextVisitor) { }

        public override bool EnterMapping(IPropertyDescriptor key, IObjectDescriptor value, IEmitter context)
        {
            if (value is CommentsObjectDescriptor commentsDescriptor && commentsDescriptor.Comment != null)
            {
                context.Emit(new Comment(string.Empty, false));
                foreach (var comment in commentsDescriptor.Comment.Split(Environment.NewLine))
                {
                    context.Emit(new Comment(comment, false));
                }
            }
            return base.EnterMapping(key, value, context);
        }
    }
}