aspnetcore/Microsoft.AspNet.Mvc.Razor/RazorView.cs

using System;
using System.Globalization;
using System.IO;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNet.CoreServices;
using Microsoft.Owin;

namespace Microsoft.AspNet.Mvc.Razor
{
    public abstract class RazorView : IView
    {
        public IOwinContext Context { get; set; }

        public object Model { get; set; }

        public string Layout { get; set; }

        protected TextWriter Output { get; set; }

        private string BodyContent { get; set; }

        public async Task RenderAsync(ViewContext context, TextWriter writer)
        {
            Model = context.Model;

            var contentBuilder = new StringBuilder(1024);
            using (var bodyWriter = new StringWriter(contentBuilder))
            {
                Output = bodyWriter;
                Execute();
            }

            string bodyContent = contentBuilder.ToString();
            if (!String.IsNullOrEmpty(Layout))
            {
                await RenderLayoutAsync(context, writer, bodyContent);
            }
            else
            {
                await writer.WriteAsync(bodyContent);
            }
        }

        private async Task RenderLayoutAsync(ViewContext context, TextWriter writer, string bodyContent)
        {
            var virtualPathFactory = context.ServiceProvider.GetService<IVirtualPathFactory>();
            RazorView razorView = (RazorView)(await virtualPathFactory.CreateInstance(Layout));
            if (razorView == null)
            {
                string message = String.Format(CultureInfo.CurrentCulture, "The layout view '{0}' could not be located.", Layout);
                throw new InvalidOperationException(message);
            }

            razorView.BodyContent = bodyContent;
            await razorView.RenderAsync(context, writer);
        }

        protected abstract void Execute();

        public virtual void Write(object value)
        {
            WriteTo(Output, value);
        }

        public virtual void WriteTo(TextWriter writer, object content)
        {
            if (content != null)
            {
                var htmlString = content as HtmlString;
                if (htmlString != null)
                {
                    writer.Write(content.ToString());
                }
                else
                {
                    WebUtility.HtmlEncode(content.ToString(), writer);
                }
            }
        }

        public void WriteLiteral(object value)
        {
            WriteLiteralTo(Output, value);
        }

        public virtual void WriteLiteralTo(TextWriter writer, object text)
        {
            if (text != null)
            {
                writer.Write(text.ToString());
            }
        }

        protected virtual void RenderBody()
        {
            if (BodyContent != null)
            {
                WriteLiteral(BodyContent);
            }
        }
    }
}