aspnetcore/src/Microsoft.AspNetCore.Razor.Language/DirectiveRemovalOptimizationPass.cs

// 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.Language.Intermediate;

namespace Microsoft.AspNetCore.Razor.Language
{
    internal class DirectiveRemovalOptimizationPass : IntermediateNodePassBase, IRazorOptimizationPass
    {
        public override int Order => DefaultFeatureOrder + 50;

        protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentIntermediateNode documentNode)
        {
            var visitor = new Visitor();
            visitor.VisitDocument(documentNode);

            foreach (var nodeReference in visitor.DirectiveNodes)
            {
                // Lift the diagnostics in the directive node up to the document node.
                for (var i = 0; i < nodeReference.Node.Diagnostics.Count; i++)
                {
                    documentNode.Diagnostics.Add(nodeReference.Node.Diagnostics[i]);
                }

                nodeReference.Remove();
            }
        }

        private class Visitor : IntermediateNodeWalker
        {
            public IList<IntermediateNodeReference> DirectiveNodes { get; } = new List<IntermediateNodeReference>();

            public override void VisitDirective(DirectiveIntermediateNode node)
            {
                DirectiveNodes.Add(new IntermediateNodeReference(Parent, node));
            }
        }
    }
}