Implement IR lowering phase

This is a first cut of IR lowering and includes the basic node types and
some tests.

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

@@ -0,0 +1,215 @@
+// 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 Microsoft.AspNetCore.Razor.Evolution.Intermediate;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Evolution
+{
+    internal class DefaultRazorIRLoweringPhase : RazorEnginePhaseBase, IRazorIRLoweringPhase
+    {
+        protected override void ExecuteCore(RazorCodeDocument codeDocument)
+        {
+            var syntaxTree = codeDocument.GetSyntaxTree();
+            ThrowForMissingDependency<RazorSyntaxTree>(syntaxTree);
+
+            var visitor = new Visitor();
+
+            visitor.VisitBlock(syntaxTree.Root);
+
+            var irDocument = (DocumentIRNode)visitor.Builder.Build();
+            codeDocument.SetIRDocument(irDocument);
+        }
+
+        private class Visitor : ParserVisitor
+        {
+            public Visitor()
+            {
+                Builder = RazorIRBuilder.Document();
+
+                Namespace = new NamespaceDeclarationIRNode();
+                NamespaceBuilder = RazorIRBuilder.Create(Namespace);
+                Builder.Push(Namespace);
+
+                Class = new ClassDeclarationIRNode();
+                ClassBuilder = RazorIRBuilder.Create(Class);
+                Builder.Push(Class);
+
+                Method = new MethodDeclarationIRNode();
+                Builder.Push(Method);
+            }
+
+            public RazorIRBuilder Builder { get; }
+
+            public NamespaceDeclarationIRNode Namespace { get; }
+
+            public RazorIRBuilder NamespaceBuilder { get; }
+
+            public ClassDeclarationIRNode Class { get; }
+
+            public RazorIRBuilder ClassBuilder { get; }
+
+            public MethodDeclarationIRNode Method { get; }
+
+            public override void VisitStartAttributeBlock(AttributeBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Push(new HtmlAttributeIRNode()
+                {
+                    Name = chunk.Name,
+                    Prefix = chunk.Prefix,
+                    Suffix = chunk.Prefix,
+
+                    SourceLocation = block.Start,
+                });
+            }
+
+            public override void VisitEndAttributeBlock(AttributeBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Pop();
+            }
+
+            public override void VisitStartDynamicAttributeBlock(DynamicAttributeBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Push(new CSharpAttributeValueIRNode()
+                {
+                    Prefix = chunk.Prefix,
+                    SourceLocation = block.Start,
+                });
+            }
+
+            public override void VisitEndDynamicAttributeBlock(DynamicAttributeBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Pop();
+            }
+
+            public override void VisitLiteralAttributeSpan(LiteralAttributeChunkGenerator chunk, Span span)
+            {
+                Builder.Add(new HtmlAttributeValueIRNode()
+                {
+                    Prefix = chunk.Prefix,
+                    SourceLocation = span.Start,
+                });
+            }
+
+            public override void VisitStartTemplateBlock(TemplateBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Push(new TemplateIRNode());
+            }
+
+            public override void VisitEndTemplateBlock(TemplateBlockChunkGenerator chunk, Block block)
+            {
+                Builder.Pop();
+            }
+
+            // CSharp expressions are broken up into blocks and spans because Razor allows Razor comments
+            // inside an expression.
+            // Ex:
+            //      @DateTime.@*This is a comment*@Now
+            //
+            // We need to capture this in the IR so that we can give each piece the correct source mappings
+            public override void VisitStartExpressionBlock(ExpressionChunkGenerator chunk, Block block)
+            {
+                Builder.Push(new CSharpExpressionIRNode()
+                {
+                    SourceLocation = block.Start,
+                });
+            }
+
+            public override void VisitEndExpressionBlock(ExpressionChunkGenerator chunk, Block block)
+            {
+                Builder.Pop();
+            }
+
+            public override void VisitExpressionSpan(ExpressionChunkGenerator chunk, Span span)
+            {
+                Builder.Add(new CSharpTokenIRNode()
+                {
+                    Content = span.Content,
+                    SourceLocation = span.Start,
+                });
+            }
+
+            public override void VisitStartSectionBlock(SectionChunkGenerator chunk, Block block)
+            {
+                Builder.Push(new SectionIRNode()
+                {
+                    Name = chunk.SectionName,
+                });
+            }
+
+            public override void VisitEndSectionBlock(SectionChunkGenerator chunk, Block block)
+            {
+                Builder.Pop();
+            }
+
+            public override void VisitTypeMemberSpan(TypeMemberChunkGenerator chunk, Span span)
+            {
+                ClassBuilder.Add(new CSharpStatementIRNode()
+                {
+                    Content = span.Content,
+                    SourceLocation = span.Start,
+                });
+            }
+
+            public override void VisitAddTagHelperSpan(AddTagHelperChunkGenerator chunk, Span span)
+            {
+                // Empty for now
+            }
+
+            public override void VisitRemoveTagHelperSpan(RemoveTagHelperChunkGenerator chunk, Span span)
+            {
+                // Empty for now
+            }
+
+            public override void VisitTagHelperPrefixSpan(TagHelperPrefixDirectiveChunkGenerator chunk, Span span)
+            {
+                // Empty for now
+            }
+
+            public override void VisitStatementSpan(StatementChunkGenerator chunk, Span span)
+            {
+                Builder.Add(new CSharpStatementIRNode()
+                {
+                    Content = span.Content,
+                    SourceLocation = span.Start,
+                });
+            }
+
+            public override void VisitSetBaseTypeSpan(SetBaseTypeChunkGenerator chunk, Span span)
+            {
+                Class.BaseType = span.Content;
+            }
+
+            public override void VisitMarkupSpan(MarkupChunkGenerator chunk, Span span)
+            {
+                Builder.Add(new HtmlContentIRNode()
+                {
+                    Content = span.Content,
+                    SourceLocation = span.Start,
+                });
+            }
+
+            public override void VisitImportSpan(AddImportChunkGenerator chunk, Span span)
+            {
+                // For prettiness, let's insert the usings before the class declaration.
+                var i = 0;
+                for (; i < Namespace.Children.Count; i++)
+                {
+                    if (Namespace.Children[i] is ClassDeclarationIRNode)
+                    {
+                        break;
+                    }
+                }
+
+                var @using = new UsingStatementIRNode()
+                {
+                    Content = span.Content,
+                    Parent = Namespace,
+                    SourceLocation = span.Start,
+                };
+
+                Namespace.Children.Insert(i, @using);
+            }
+        }
+    }
+}

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

@@ -0,0 +1,9 @@
+// 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.
+
+namespace Microsoft.AspNetCore.Razor.Evolution
+{
+    public interface IRazorIRLoweringPhase : IRazorEnginePhase
+    {
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/BlockDirectiveIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class BlockDirectiveIRNode : RazorIRNode
+    {
+        public string Name { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitBlockDirective(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitBlockDirective(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/CSharpAttributeValueIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class CSharpAttributeValueIRNode : RazorIRNode
+    {
+        public string Prefix { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitCSharpAttributeValue(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitCSharpAttributeValue(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/CSharpExpressionIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class CSharpExpressionIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public string Content { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitCSharpExpression(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitCSharpExpression(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/CSharpStatementIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class CSharpStatementIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public string Content { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitCSharpStatement(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitCSharpStatement(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/CSharpTokenIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class CSharpTokenIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = EmptyArray;
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public string Content { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitCSharpToken(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitCSharpToken(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/ClassDeclarationIRNode.cs

@@ -0,0 +1,36 @@
+// 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;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
+{
+    public class ClassDeclarationIRNode : RazorIRNode
+    {
+        public string AccessModifier { get; set; }
+
+        public string Name { get; set; }
+
+        public string BaseType { get; set; }
+
+        public IList<string> Interfaces { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitClass(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitClass(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/DefaultRazorIRBuilder.cs

@@ -35,6 +35,17 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
             Pop();
         }
 
+        public override RazorIRNode Build()
+        {
+            RazorIRNode node = null;
+            while (_depth > 0)
+            {
+                node = Pop();
+            }
+            
+            return node;
+        }
+        
         public override RazorIRNode Pop()
         {
             if (_depth == 0)

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/DirectiveTokenIRNode.cs

@@ -0,0 +1,27 @@
+// 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.Intermediate
+{
+    public class DirectiveTokenIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitDirectiveToken(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitDirectiveToken(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/DocumentIRNode.cs

@@ -2,22 +2,18 @@
 // 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.Intermediate
 {
-    public sealed class RazorIRDocument : RazorIRNode
+    public sealed class DocumentIRNode : RazorIRNode
     {
-        // Only allow creation of documents through the builder API because
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
-        // they can't be nested.
-        internal RazorIRDocument()
-        {
-            Children = new List<RazorIRNode>();
-        }
-
-        public override IList<RazorIRNode> Children { get; }
 
         public override RazorIRNode Parent { get; set; }
 
+        internal override SourceLocation SourceLocation { get; set; }
+
         public override void Accept(RazorIRNodeVisitor visitor)
         {
             visitor.VisitDocument(this);

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/HtmlAttributeIRNode.cs

@@ -0,0 +1,33 @@
+// 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.Intermediate
+{
+    public class HtmlAttributeIRNode : RazorIRNode
+    {
+        public string Name { get; set; }
+
+        public string Prefix { get; set; }
+
+        public string Suffix { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitHtmlAttribute(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitHtmlAttribute(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/HtmlAttributeValueIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class HtmlAttributeValueIRNode : RazorIRNode
+    {
+        public string Prefix { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitHtmlAttributeValue(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitHtmlAttributeValue(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/HtmlContentIRNode.cs

@@ -0,0 +1,40 @@
+// 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;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
+{
+    public sealed class HtmlContentIRNode : RazorIRNode
+    {
+        public string Content { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            visitor.VisitHtml(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            return visitor.VisitHtml(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/MethodDeclarationIRNode.cs

@@ -0,0 +1,35 @@
+// 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.Intermediate
+{
+    public class MethodDeclarationIRNode : RazorIRNode
+    {
+        public string AccessModifier { get; set; }
+
+        public IList<string> Modifiers { get; set; }
+
+        public string Name { get; set; }
+
+        public string ReturnType { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitMethodDeclaration(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitMethodDeclaration(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/NamespaceDeclarationIRNode.cs

@@ -0,0 +1,27 @@
+// 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.Intermediate
+{
+    public class NamespaceDeclarationIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitNamespace(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitNamespace(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/RazorIRBuilder.cs

@@ -1,14 +1,26 @@
 // 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;
+
 namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
 {
     public abstract class RazorIRBuilder
     {
         public static RazorIRBuilder Document()
         {
+            return Create(new DocumentIRNode());
+        }
+
+        public static RazorIRBuilder Create(RazorIRNode root)
+        {
+            if (root == null)
+            {
+                throw new ArgumentNullException(nameof(root));
+            }
+
             var builder = new DefaultRazorIRBuilder();
-            builder.Push(new RazorIRDocument());
+            builder.Push(root);
             return builder;
         }
 
@@ -16,6 +28,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
 
         public abstract void Add(RazorIRNode node);
 
+        public abstract RazorIRNode Build();
+
         public abstract void Push(RazorIRNode node);
 
         public abstract RazorIRNode Pop();

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/RazorIRNode.cs

@@ -2,6 +2,7 @@
 // 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.Intermediate
 {
@@ -13,6 +14,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
 
         public abstract RazorIRNode Parent { get; set; }
 
+        internal abstract SourceLocation SourceLocation { get; set; }
+
         public abstract void Accept(RazorIRNodeVisitor visitor);
 
         public abstract TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor);

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/RazorIRNodeVisitor.cs

@@ -14,7 +14,87 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
         {
         }
 
-        public virtual void VisitDocument(RazorIRDocument node)
+        public virtual void VisitDirectiveToken(DirectiveTokenIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitTemplate(TemplateIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitSection(SectionIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitCSharpStatement(CSharpStatementIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitCSharpExpression(CSharpExpressionIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitCSharpToken(CSharpTokenIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitHtmlAttributeValue(HtmlAttributeValueIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitCSharpAttributeValue(CSharpAttributeValueIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitHtmlAttribute(HtmlAttributeIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitSingleLineDirective(SingleLineDirectiveIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitBlockDirective(BlockDirectiveIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitClass(ClassDeclarationIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitMethodDeclaration(MethodDeclarationIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitDocument(DocumentIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitHtml(HtmlContentIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitNamespace(NamespaceDeclarationIRNode node)
+        {
+            VisitDefault(node);
+        }
+
+        public virtual void VisitUsingStatement(UsingStatementIRNode node)
         {
             VisitDefault(node);
         }

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/RazorIRNodeVisitorOfT.cs

@@ -15,7 +15,86 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
             return default(TResult);
         }
 
-        public virtual TResult VisitDocument(RazorIRDocument node)
+        public virtual TResult VisitDirectiveToken(DirectiveTokenIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitTemplate(TemplateIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitSection(SectionIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitCSharpStatement(CSharpStatementIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitCSharpExpression(CSharpExpressionIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitCSharpToken(CSharpTokenIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitHtmlAttributeValue(HtmlAttributeValueIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitCSharpAttributeValue(CSharpAttributeValueIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitHtmlAttribute(HtmlAttributeIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitClass(ClassDeclarationIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitSingleLineDirective(SingleLineDirectiveIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitBlockDirective(BlockDirectiveIRNode node)
+        {
+            return VisitDefault(node);
+        }
+        public virtual TResult VisitMethodDeclaration(MethodDeclarationIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitDocument(DocumentIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitHtml(HtmlContentIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitNamespace(NamespaceDeclarationIRNode node)
+        {
+            return VisitDefault(node);
+        }
+
+        public virtual TResult VisitUsingStatement(UsingStatementIRNode node)
         {
             return VisitDefault(node);
         }

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/SectionIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class SectionIRNode : RazorIRNode
+    {
+        public string Name { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitSection(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitSection(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/SingleLineDirectiveIRNode.cs

@@ -0,0 +1,29 @@
+// 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.Intermediate
+{
+    public class SingleLineDirectiveIRNode : RazorIRNode
+    {
+        public string Name { get; set; }
+
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitSingleLineDirective(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitSingleLineDirective(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/TemplateIRNode.cs

@@ -0,0 +1,27 @@
+// 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.Intermediate
+{
+    public class TemplateIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            visitor.VisitTemplate(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            return visitor.VisitTemplate(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Intermediate/UsingStatementIRNode.cs

@@ -0,0 +1,40 @@
+// 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;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
+{
+    public class UsingStatementIRNode : RazorIRNode
+    {
+        public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
+
+        public override RazorIRNode Parent { get; set; }
+
+        internal override SourceLocation SourceLocation { get; set; }
+
+        public string Content { get; set; }
+
+        public override void Accept(RazorIRNodeVisitor visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            visitor.VisitUsingStatement(this);
+        }
+
+        public override TResult Accept<TResult>(RazorIRNodeVisitor<TResult> visitor)
+        {
+            if (visitor == null)
+            {
+                throw new ArgumentNullException(nameof(visitor));
+            }
+
+            return visitor.VisitUsingStatement(this);
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/AddImportChunkGenerator.cs

@@ -14,6 +14,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string Namespace { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitImportSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             var ns = Namespace;

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/AddTagHelperChunkGenerator.cs

@@ -15,6 +15,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string LookupText { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitAddTagHelperSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             //context.ChunkTreeBuilder.AddAddTagHelperChunk(LookupText, target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/AttributeBlockChunkGenerator.cs

@@ -36,6 +36,16 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             //context.ChunkTreeBuilder.EndParentChunk();
         }
 
+        public override void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartAttributeBlock(this, block);
+        }
+
+        public override void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndAttributeBlock(this, block);
+        }
+
         public override string ToString()
         {
             return string.Format(CultureInfo.CurrentCulture, "Attr:{0},{1:F},{2:F}", Name, Prefix, Suffix);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/Block.cs

@@ -176,6 +176,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             return hashCodeCombiner.CombinedHash;
         }
 
+        public override void Accept(ParserVisitor visitor)
+        {
+            visitor.VisitBlock(this);
+        }
+
         private class EquivalenceComparer : IEqualityComparer<SyntaxTreeNode>
         {
             public static readonly EquivalenceComparer Default = new EquivalenceComparer();

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/DynamicAttributeBlockChunkGenerator.cs

@@ -1,6 +1,7 @@
 // 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;
 using System.Globalization;
 
 namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
@@ -22,6 +23,16 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public SourceLocation ValueStart { get; }
 
+        public override void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartDynamicAttributeBlock(this, block);
+        }
+
+        public override void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndDynamicAttributeBlock(this, block);
+        }
+
         public override void GenerateStartParentChunk(Block target, ChunkGeneratorContext context)
         {
             //var chunk = context.ChunkTreeBuilder.StartParentChunk<DynamicCodeAttributeChunk>(target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/ExpressionChunkGenerator.cs

@@ -1,6 +1,8 @@
 // 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;
+
 namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 {
     internal class ExpressionChunkGenerator : ISpanChunkGenerator, IParentChunkGenerator
@@ -22,6 +24,21 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             //context.ChunkTreeBuilder.EndParentChunk();
         }
 
+        public void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitExpressionSpan(this, span);
+        }
+
+        public void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartExpressionBlock(this, block);
+        }
+
+        public void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndExpressionBlock(this, block);
+        }
+
         public override string ToString()
         {
             return "Expr";

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/IParentChunkGenerator.cs

@@ -7,5 +7,7 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
     {
         void GenerateStartParentChunk(Block target, ChunkGeneratorContext context);
         void GenerateEndParentChunk(Block target, ChunkGeneratorContext context);
+        void AcceptStart(ParserVisitor visitor, Block block);
+        void AcceptEnd(ParserVisitor visitor, Block block);
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/ISpanChunkGenerator.cs

@@ -6,5 +6,7 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
     internal interface ISpanChunkGenerator
     {
         void GenerateChunk(Span target, ChunkGeneratorContext context);
+
+        void Accept(ParserVisitor visitor, Span span);
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/LiteralAttributeChunkGenerator.cs

@@ -28,6 +28,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public LocationTagged<SpanChunkGenerator> ValueGenerator { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitLiteralAttributeSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             //var chunk = context.ChunkTreeBuilder.StartParentChunk<LiteralCodeAttributeChunk>(target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/MarkupChunkGenerator.cs

@@ -10,6 +10,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             //context.ChunkTreeBuilder.AddLiteralChunk(target.Content, target);
         }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitMarkupSpan(this, span);
+        }
+
         public override string ToString()
         {
             return "Markup";

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/ParentChunkGenerator.cs

@@ -9,6 +9,9 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public static readonly IParentChunkGenerator Null = new NullParentChunkGenerator();
 
+        public abstract void AcceptStart(ParserVisitor visitor, Block block);
+        public abstract void AcceptEnd(ParserVisitor visitor, Block block);
+
         public virtual void GenerateStartParentChunk(Block target, ChunkGeneratorContext context)
         {
         }
@@ -42,6 +45,14 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             {
                 return "None";
             }
+
+            public void AcceptStart(ParserVisitor visitor, Block block)
+            {
+            }
+
+            public void AcceptEnd(ParserVisitor visitor, Block block)
+            {
+            }
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/ParserVisitor.cs

@@ -0,0 +1,132 @@
+// 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.
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
+{
+    internal abstract class ParserVisitor
+    {
+        public virtual void VisitBlock(Block block)
+        {
+            VisitStartBlock(block);
+            
+            for (var i = 0; i < block.Children.Count; i++)
+            {
+                block.Children[i].Accept(this);
+            }
+
+            VisitEndBlock(block);
+        }
+
+        public virtual void VisitStartBlock(Block block)
+        {
+            if (block.ChunkGenerator != null)
+            {
+                block.ChunkGenerator.AcceptStart(this, block);
+            }
+        }
+
+        public virtual void VisitEndBlock(Block block)
+        {
+            if (block.ChunkGenerator != null)
+            {
+                block.ChunkGenerator.AcceptEnd(this, block);
+            }
+        }
+
+        public virtual void VisitSpan(Span span)
+        {
+            if (span.ChunkGenerator != null)
+            {
+                span.ChunkGenerator.Accept(this, span);
+            }
+        }
+
+        public virtual void VisitStartDynamicAttributeBlock(DynamicAttributeBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitEndDynamicAttributeBlock(DynamicAttributeBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitStartExpressionBlock(ExpressionChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitEndExpressionBlock(ExpressionChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitStartAttributeBlock(AttributeBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitEndAttributeBlock(AttributeBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitExpressionSpan(ExpressionChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitSetBaseTypeSpan(SetBaseTypeChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitTagHelperPrefixSpan(TagHelperPrefixDirectiveChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitTypeMemberSpan(TypeMemberChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitMarkupSpan(MarkupChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitRemoveTagHelperSpan(RemoveTagHelperChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitImportSpan(AddImportChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitAddTagHelperSpan(AddTagHelperChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitStatementSpan(StatementChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitLiteralAttributeSpan(LiteralAttributeChunkGenerator chunk, Span span)
+        {
+        }
+
+        public virtual void VisitEndTemplateBlock(TemplateBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitStartTemplateBlock(TemplateBlockChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitStartSectionBlock(SectionChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitEndSectionBlock(SectionChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitEndCommentBlock(RazorCommentChunkGenerator chunk, Block block)
+        {
+        }
+
+        public virtual void VisitStartCommentBlock(RazorCommentChunkGenerator chunk, Block block)
+        {
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/RazorCommentChunkGenerator.cs

@@ -5,5 +5,14 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 {
     internal class RazorCommentChunkGenerator : ParentChunkGenerator
     {
+        public override void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartCommentBlock(this, block);
+        }
+
+        public override void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndCommentBlock(this, block);
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/RemoveTagHelperChunkGenerator.cs

@@ -15,6 +15,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string LookupText { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitRemoveTagHelperSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             //context.ChunkTreeBuilder.AddRemoveTagHelperChunk(LookupText, target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/SectionChunkGenerator.cs

@@ -14,6 +14,16 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string SectionName { get; }
 
+        public override void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartSectionBlock(this, block);
+        }
+
+        public override void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndSectionBlock(this, block);
+        }
+
         public override void GenerateStartParentChunk(Block target, ChunkGeneratorContext context)
         {
             //var chunk = context.ChunkTreeBuilder.StartParentChunk<SectionChunk>(target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/SetBaseTypeChunkGenerator.cs

@@ -14,6 +14,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string BaseType { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitSetBaseTypeSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
         }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/Span.cs

@@ -131,5 +131,10 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             // Hash code should include only immutable properties but Equals also checks the type.
             return TypeHashCode;
         }
+
+        public override void Accept(ParserVisitor visitor)
+        {
+            visitor.VisitSpan(this);
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/SpanChunkGenerator.cs

@@ -1,6 +1,8 @@
 // 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;
+
 namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 {
     internal abstract class SpanChunkGenerator : ISpanChunkGenerator
@@ -9,6 +11,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public static readonly ISpanChunkGenerator Null = new NullSpanChunkGenerator();
 
+        public abstract void Accept(ParserVisitor visitor, Span span);
+
         public virtual void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
         }
@@ -26,6 +30,10 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         private class NullSpanChunkGenerator : ISpanChunkGenerator
         {
+            public void Accept(ParserVisitor visitor, Span span)
+            {
+            }
+
             public void GenerateChunk(Span target, ChunkGeneratorContext context)
             {
             }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/StatementChunkGenerator.cs

@@ -5,6 +5,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 {
     internal class StatementChunkGenerator : SpanChunkGenerator
     {
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitStatementSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             //context.ChunkTreeBuilder.AddStatementChunk(target.Content, target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/SyntaxTreeNode.cs

@@ -41,5 +41,7 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
         /// <see cref="EquivalentTo"/> comparisons.
         /// </returns>
         public abstract int GetEquivalenceHash();
+
+        public abstract void Accept(ParserVisitor visitor);
     }
 }

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/TagHelperPrefixDirectiveChunkGenerator.cs

@@ -15,6 +15,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 
         public string Prefix { get; }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitTagHelperPrefixSpan(this, span);
+        }
+
         public override void GenerateChunk(Span target, ChunkGeneratorContext context)
         {
             //context.ChunkTreeBuilder.AddTagHelperPrefixDirectiveChunk(Prefix, target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/TemplateBlockChunkGenerator.cs

@@ -5,6 +5,16 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
 {
     internal class TemplateBlockChunkGenerator : ParentChunkGenerator
     {
+        public override void AcceptStart(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitStartTemplateBlock(this, block);
+        }
+
+        public override void AcceptEnd(ParserVisitor visitor, Block block)
+        {
+            visitor.VisitEndTemplateBlock(this, block);
+        }
+
         public override void GenerateStartParentChunk(Block target, ChunkGeneratorContext context)
         {
             //context.ChunkTreeBuilder.StartParentChunk<TemplateChunk>(target);

src/Microsoft.AspNetCore.Razor.Evolution/Legacy/TypeMemberChunkGenerator.cs

@@ -10,6 +10,11 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Legacy
             //context.ChunkTreeBuilder.AddTypeMemberChunk(target.Content, target);
         }
 
+        public override void Accept(ParserVisitor visitor, Span span)
+        {
+            visitor.VisitTypeMemberSpan(this, span);
+        }
+
         public override string ToString()
         {
             return "TypeMember";

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

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using Microsoft.AspNetCore.Razor.Evolution.Intermediate;
 
 namespace Microsoft.AspNetCore.Razor.Evolution
 {
@@ -26,5 +27,25 @@ namespace Microsoft.AspNetCore.Razor.Evolution
 
             document.Items[typeof(RazorSyntaxTree)] = syntaxTree;
         }
+
+        public static DocumentIRNode GetIRDocument(this RazorCodeDocument document)
+        {
+            if (document == null)
+            {
+                throw new ArgumentNullException(nameof(document));
+            }
+
+            return document.Items[typeof(DocumentIRNode)] as DocumentIRNode;
+        }
+
+        public static void SetIRDocument(this RazorCodeDocument document, DocumentIRNode irDocument)
+        {
+            if (document == null)
+            {
+                throw new ArgumentNullException(nameof(document));
+            }
+
+            document.Items[typeof(DocumentIRNode)] = irDocument;
+        }
     }
 }

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

@@ -32,6 +32,7 @@ namespace Microsoft.AspNetCore.Razor.Evolution
         {
             builder.Phases.Add(new DefaultRazorParsingPhase());
             builder.Phases.Add(new DefaultRazorSyntaxTreePhase());
+            builder.Phases.Add(new DefaultRazorIRLoweringPhase());
 
             builder.Features.Add(new TagHelperBinderSyntaxTreePass());
         }

test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRBuilderTest.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
 using Microsoft.AspNetCore.Testing;
 using Xunit;
 
@@ -125,12 +126,34 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
             Assert.Collection(parent.Children, n => Assert.Same(node, n));
         }
 
+        [Fact]
+        public void Build_PopsMultipleLevels()
+        {
+            // Arrange
+            var builder = new DefaultRazorIRBuilder();
+
+            var document = new DocumentIRNode();
+            builder.Push(document);
+
+            var node = new BasicIRNode();
+            builder.Push(node);
+
+            // Act
+            var result = builder.Build();
+
+            // Assert
+            Assert.Same(document, result);
+            Assert.Null(builder.Current);
+        }
+
         private class BasicIRNode : RazorIRNode
         {
             public override IList<RazorIRNode> Children { get; } = new List<RazorIRNode>();
 
             public override RazorIRNode Parent { get; set; }
 
+            internal override SourceLocation SourceLocation { get; set; }
+
             public override void Accept(RazorIRNodeVisitor visitor)
             {
                 throw new NotImplementedException();

test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRLoweringPhaseIntegrationTest.cs

@@ -0,0 +1,118 @@
+// 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 static Microsoft.AspNetCore.Razor.Evolution.Intermediate.RazorIRAssert;
+using Xunit;
+using System;
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
+{
+    public class LoweringIntegrationTest
+    {
+        [Fact]
+        public void Lower_EmptyDocument()
+        {
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+
+            var irDocument = Lower(codeDocument);
+
+            var @namespace = SingleChild<NamespaceDeclarationIRNode>(irDocument);
+            var @class = SingleChild<ClassDeclarationIRNode>(@namespace);
+            var method = SingleChild<MethodDeclarationIRNode>(@class);
+            var html = SingleChild<HtmlContentIRNode>(method);
+
+            Assert.Equal(string.Empty, html.Content);
+        }
+
+        [Fact]
+        public void Lower_HelloWorld()
+        {
+            var codeDocument = TestRazorCodeDocument.Create("Hello, World!");
+
+            var irDocument = Lower(codeDocument);
+
+            var @namespace = SingleChild<NamespaceDeclarationIRNode>(irDocument);
+            var @class = SingleChild<ClassDeclarationIRNode>(@namespace);
+            var method = SingleChild<MethodDeclarationIRNode>(@class);
+            var html = SingleChild<HtmlContentIRNode>(method);
+
+            Assert.Equal("Hello, World!", html.Content);
+        }
+
+        [Fact]
+        public void Lower_HtmlWithAttributes()
+        {
+            var codeDocument = TestRazorCodeDocument.Create(@"
+<html>
+    <body>
+        <span data-val=""@Hello"" />
+    </body>
+</html>");
+            var irDocument = Lower(codeDocument);
+            
+            var @namespace = SingleChild<NamespaceDeclarationIRNode>(irDocument);
+            var @class = SingleChild<ClassDeclarationIRNode>(@namespace);
+            var method = SingleChild<MethodDeclarationIRNode>(@class);
+            Children(method,
+                n => Html(Environment.NewLine, n),
+                n => Html("<html>", n),
+                n => Html(Environment.NewLine + "    ", n),
+                n => Html("<body>", n),
+                n => Html(Environment.NewLine + "        ", n),
+                n => Html("<span", n),
+                n => Html(" data-val=\"", n),
+                n => CSharpExpression("Hello", n),
+                n => Html("\"", n),
+                n => Html(" />", n),
+                n => Html(Environment.NewLine + "    ", n),
+                n => Html("</body>", n),
+                n => Html(Environment.NewLine, n),
+                n => Html("</html>", n));
+        }
+
+        [Fact]
+        public void Lower_WithUsing()
+        {
+            var codeDocument = TestRazorCodeDocument.Create(@"@functions { public int Foo { get; set; }}");
+            var irDocument = Lower(codeDocument);
+
+            var @namespace = SingleChild<NamespaceDeclarationIRNode>(irDocument);
+            var @class = SingleChild<ClassDeclarationIRNode>(@namespace);
+            Children(@class,
+                n => Assert.IsType<MethodDeclarationIRNode>(n),
+                n => Assert.IsType<CSharpStatementIRNode>(n));
+        }
+
+        [Fact]
+        public void Lower_WithFunctions()
+        {
+            var codeDocument = TestRazorCodeDocument.Create(@"@using System");
+            var irDocument = Lower(codeDocument);
+
+            var @namespace = SingleChild<NamespaceDeclarationIRNode>(irDocument);
+            Children(@namespace,
+                n => Using("using System", n),
+                n => Assert.IsType<ClassDeclarationIRNode>(n));
+        }
+
+        private DocumentIRNode Lower(RazorCodeDocument codeDocument)
+        {
+            var engine = RazorEngine.Create();
+
+            for (var i = 0; i < engine.Phases.Count; i++)
+            {
+                var phase = engine.Phases[i];
+                phase.Execute(codeDocument);
+
+                if (phase is IRazorIRLoweringPhase)
+                {
+                    break;
+                }
+            }
+
+            var irDocument = codeDocument.GetIRDocument();
+            Assert.NotNull(irDocument);
+            return irDocument;
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/RazorIRAssert.cs

@@ -0,0 +1,169 @@
+// 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;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+using Xunit.Sdk;
+
+namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
+{
+    public static class RazorIRAssert
+    {
+        public static TNode SingleChild<TNode>(RazorIRNode node)
+        {
+            if (node.Children.Count == 0)
+            {
+                throw new IRAssertException(node, "The node has no children.");
+            }
+            else if (node.Children.Count > 1)
+            {
+                throw new IRAssertException(node, node.Children, "The node has multiple children");
+            }
+
+            var child = node.Children[0];
+            return Assert.IsType<TNode>(child);
+        }
+
+        public static void NoChildren(RazorIRNode node)
+        {
+            if (node.Children.Count > 0)
+            {
+                throw new IRAssertException(node, node.Children, "The node has children.");
+            }
+        }
+
+        public static void Children(RazorIRNode node, params Action<RazorIRNode>[] validators)
+        {
+            var i = 0;
+            for (; i < validators.Length; i++)
+            {
+                if (node.Children.Count == i)
+                {
+                    throw new IRAssertException(node, node.Children, $"The node only has {node.Children.Count} children.");
+                }
+
+                try
+                {
+                    validators[i].Invoke(node.Children[i]);
+                }
+                catch (XunitException e)
+                {
+                    throw new IRAssertException(node, node.Children, $"Failed while validating node {node.Children[i]} at {i}.", e);
+                }
+            }
+
+            if (i < node.Children.Count)
+            {
+                throw new IRAssertException(node, node.Children, $"The node has extra child {node.Children[i]} at {i}.");
+            }
+        }
+
+        public static void Html(string expected, RazorIRNode node)
+        {
+            try
+            {
+                var html = Assert.IsType<HtmlContentIRNode>(node);
+                Assert.Equal(expected, html.Content);
+            }
+            catch (XunitException e)
+            {
+                throw new IRAssertException(node, node.Children, e.Message, e);
+            }
+        }
+
+        public static void Using(string expected, RazorIRNode node)
+        {
+            try
+            {
+                var @using = Assert.IsType<UsingStatementIRNode>(node);
+                Assert.Equal(expected, @using.Content);
+            }
+            catch (XunitException e)
+            {
+                throw new IRAssertException(node, node.Children, e.Message, e);
+            }
+        }
+
+        public static void CSharpExpression(string expected, RazorIRNode node)
+        {
+            try
+            {
+                var cSharp = Assert.IsType<CSharpExpressionIRNode>(node);
+
+                var content = new StringBuilder();
+                for (var i = 0; i < cSharp.Children.Count; i++)
+                {
+                    content.Append(((CSharpTokenIRNode)cSharp.Children[i]).Content);
+                }
+
+                Assert.Equal(expected, content.ToString());
+            }
+            catch (XunitException e)
+            {
+                throw new IRAssertException(node, node.Children, e.Message, e);
+            }
+        }
+
+        private class IRAssertException : XunitException
+        {
+            public IRAssertException(RazorIRNode node, string userMessage) 
+                : base(Format(node, null, userMessage))
+            {
+                Node = node;
+            }
+
+            public IRAssertException(RazorIRNode node, IEnumerable<RazorIRNode> nodes, string userMessage)
+                : base(Format(node, nodes, userMessage))
+            {
+                Node = node;
+                Nodes = nodes;
+            } 
+
+            public IRAssertException(
+                RazorIRNode node,
+                IEnumerable<RazorIRNode> nodes,
+                string userMessage,
+                Exception innerException)
+                : base(Format(node, nodes, userMessage), innerException)
+            {
+            }
+
+            public RazorIRNode Node { get; }
+
+            public IEnumerable<RazorIRNode> Nodes { get; }
+
+            private static string Format(RazorIRNode node, IEnumerable<RazorIRNode> nodes, string userMessage)
+            {
+                var builder = new StringBuilder();
+                builder.AppendLine(userMessage);
+                builder.AppendLine();
+
+                if (nodes != null)
+                {
+                    builder.AppendLine("Nodes:");
+
+                    foreach (var n in nodes)
+                    {
+                        builder.AppendLine(n.ToString());
+                    }
+
+                    builder.AppendLine();
+                }
+
+
+                builder.AppendLine("Path:");
+
+                var current = node;
+                do
+                {
+                    builder.AppendLine(current.ToString());
+                }
+                while ((current = current.Parent) != null);
+
+                return builder.ToString();
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/RazorIRBuilderTest.cs

@@ -14,7 +14,7 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
             var builder = RazorIRBuilder.Document();
 
             // Assert
-            Assert.IsType<RazorIRDocument>(builder.Current);
+            Assert.IsType<DocumentIRNode>(builder.Current);
         }
     }
 }

test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/RazorIRNodeWalkerTest.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using Microsoft.AspNetCore.Razor.Evolution.Legacy;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
@@ -74,6 +75,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
 
             public override RazorIRNode Parent { get; set; }
 
+            internal override SourceLocation SourceLocation { get; set; }
+
             public override void Accept(RazorIRNodeVisitor visitor)
             {
                 ((DerivedIRNodeWalker)visitor).VisitBasic(this);

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

@@ -1,6 +1,7 @@
 // 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 Microsoft.AspNetCore.Razor.Evolution.Intermediate;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Razor.Evolution
@@ -37,5 +38,36 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             // Assert
             Assert.Same(expected, codeDocument.Items[typeof(RazorSyntaxTree)]);
         }
+
+        [Fact]
+        public void GetIRDocument_ReturnsIRDocument()
+        {
+            // Arrange
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+
+            var expected = RazorIRBuilder.Document().Build();
+            codeDocument.Items[typeof(DocumentIRNode)] = expected;
+
+            // Act
+            var actual = codeDocument.GetIRDocument();
+
+            // Assert
+            Assert.Same(expected, actual);
+        }
+
+        [Fact]
+        public void SetIRDocument_SetsIRDocument()
+        {
+            // Arrange
+            var codeDocument = TestRazorCodeDocument.CreateEmpty();
+
+            var expected = RazorIRBuilder.Document().Build();
+
+            // Act
+            codeDocument.SetIRDocument((DocumentIRNode)expected);
+
+            // Assert
+            Assert.Same(expected, codeDocument.Items[typeof(DocumentIRNode)]);
+        }
     }
 }

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

@@ -84,7 +84,8 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             Assert.Collection(
                 phases,
                 phase => Assert.IsType<DefaultRazorParsingPhase>(phase),
-                phase => Assert.IsType<DefaultRazorSyntaxTreePhase>(phase));
+                phase => Assert.IsType<DefaultRazorSyntaxTreePhase>(phase),
+                phase => Assert.IsType<DefaultRazorIRLoweringPhase>(phase));
         }
     }
 }

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

@@ -11,6 +11,12 @@ namespace Microsoft.AspNetCore.Razor.Evolution
             return new TestRazorCodeDocument(source);
         }
 
+        public static TestRazorCodeDocument Create(string content)
+        {
+            var source = TestRazorSourceDocument.Create(content);
+            return new TestRazorCodeDocument(source);
+        }
+
         private TestRazorCodeDocument(RazorSourceDocument source)
             : base(source)
         {