Add RazorCSharpSourceDocument

Precursor to actual CSharp lowering

src/Microsoft.AspNetCore.Razor.Evolution/RazorCSharpDocument.cs

@@ -0,0 +1,15 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Evolution
+{
+    public class RazorCSharpDocument
+    {
+        public string GeneratedCode { get; set; }
+
+        internal IReadOnlyList<LineMapping> LineMappings { get; set; }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/RazorCodeDocumentExtensions.cs

@@ -47,5 +47,25 @@ namespace Microsoft.AspNetCore.Razor.Evolution
 
             document.Items[typeof(DocumentIRNode)] = irDocument;
         }
+
+        public static RazorCSharpDocument GetCSharpDocument(this RazorCodeDocument document)
+        {
+            if (document == null)
+            {
+                throw new ArgumentNullException(nameof(document));
+            }
+
+            return (RazorCSharpDocument)document.Items[typeof(RazorCSharpDocument)];
+        }
+
+        public static void SetCSharpDocument(this RazorCodeDocument document, RazorCSharpDocument csharp)
+        {
+            if (document == null)
+            {
+                throw new ArgumentNullException(nameof(document));
+            }
+
+            document.Items[typeof(RazorCSharpDocument)] = csharp;
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Evolution.Test/RazorCodeDocumentExtensionsTest.cs

@@ -69,5 +69,36 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             // Assert
             Assert.Same(expected, codeDocument.Items[typeof(DocumentIRNode)]);
         }
+
+        [Fact]
+        public void GetCSharpDocument_ReturnsCSharpDocument()
+        {
+            // Arrange
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+
+            var expected = new RazorCSharpDocument();
+            codeDocument.Items[typeof(RazorCSharpDocument)] = expected;
+
+            // Act
+            var actual = codeDocument.GetCSharpDocument();
+
+            // Assert
+            Assert.Same(expected, actual);
+        }
+
+        [Fact]
+        public void SetCSharpDocument_SetsCSharpDocument()
+        {
+            // Arrange
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+
+            var expected = new RazorCSharpDocument();
+
+            // Act
+            codeDocument.SetCSharpDocument(expected);
+
+            // Assert
+            Assert.Same(expected, codeDocument.Items[typeof(RazorCSharpDocument)]);
+        }
     }
 }