From 249752087ef841a6ede2a075bf17a6adaa37d1c2 Mon Sep 17 00:00:00 2001
From: Ajay Bhargav Baaskaran <ajaybhargavb@gmail.com>
Date: Tue, 2 Apr 2019 21:55:37 -0700
Subject: [PATCH] Fix csharp intellisense in _Imports.razor
 (dotnet/aspnetcore-tooling#387)

* Fix csharp intellisense in _Imports.razor

* Feedback
\n\nCommit migrated from https://github.com/dotnet/aspnetcore-tooling/commit/229951a5c8640651f9724fda38361601ed5fa286
---
 ...faultRazorIntermediateNodeLoweringPhase.cs | 75 +++++++++++++++++--
 1 file changed, 70 insertions(+), 5 deletions(-)

diff --git a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorIntermediateNodeLoweringPhase.cs b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorIntermediateNodeLoweringPhase.cs
index 232ce738fb..7056b178e7 100644
--- a/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorIntermediateNodeLoweringPhase.cs
+++ b/src/Razor/Microsoft.AspNetCore.Razor.Language/src/DefaultRazorIntermediateNodeLoweringPhase.cs
@@ -1885,36 +1885,101 @@ namespace Microsoft.AspNetCore.Razor.Language
             {
                 _document.Diagnostics.Add(
                     ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
+
+                base.VisitMarkupElement(node);
             }
 
             public override void VisitMarkupCommentBlock(MarkupCommentBlockSyntax node)
             {
                 _document.Diagnostics.Add(
                     ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
+
+                base.VisitMarkupCommentBlock(node);
             }
 
             public override void VisitMarkupTagHelperElement(MarkupTagHelperElementSyntax node)
             {
                 _document.Diagnostics.Add(
                     ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
-            }
 
-            public override void VisitCSharpImplicitExpression(CSharpImplicitExpressionSyntax node)
-            {
-                _document.Diagnostics.Add(
-                    ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
+                base.VisitMarkupTagHelperElement(node);
             }
 
             public override void VisitCSharpExplicitExpression(CSharpExplicitExpressionSyntax node)
             {
                 _document.Diagnostics.Add(
                     ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
+
+                base.VisitCSharpExplicitExpression(node);
+            }
+
+            public override void VisitCSharpImplicitExpression(CSharpImplicitExpressionSyntax node)
+            {
+                // We typically don't want C# in imports files except for directives. But since Razor directive intellisense
+                // is tied to C# intellisense during design time, we want to still generate and IR node for implicit expressions.
+                // Otherwise, there will be no source mapping when someone types an `@` leading to no intellisense.
+                if (node.FirstAncestorOrSelf<SyntaxNode>(n => n is MarkupStartTagSyntax || n is MarkupEndTagSyntax) != null)
+                {
+                    // We don't care about implicit expresssion in attributes.
+                    return;
+                }
+
+                var expressionNode = new CSharpExpressionIntermediateNode();
+
+                _builder.Push(expressionNode);
+
+                base.VisitCSharpImplicitExpression(node);
+
+                _builder.Pop();
+
+                if (expressionNode.Children.Count > 0)
+                {
+                    var sourceRangeStart = expressionNode
+                        .Children
+                        .FirstOrDefault(child => child.Source != null)
+                        ?.Source;
+
+                    if (sourceRangeStart != null)
+                    {
+                        var contentLength = expressionNode.Children.Sum(child => child.Source?.Length ?? 0);
+
+                        expressionNode.Source = new SourceSpan(
+                            sourceRangeStart.Value.FilePath ?? SourceDocument.FilePath,
+                            sourceRangeStart.Value.AbsoluteIndex,
+                            sourceRangeStart.Value.LineIndex,
+                            sourceRangeStart.Value.CharacterIndex,
+                            contentLength);
+                    }
+                }
+
+                _document.Diagnostics.Add(
+                    ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(expressionNode.Source));
+
+                base.VisitCSharpImplicitExpression(node);
+            }
+
+            public override void VisitCSharpExpressionLiteral(CSharpExpressionLiteralSyntax node)
+            {
+                if (node.FirstAncestorOrSelf<SyntaxNode>(n => n is CSharpImplicitExpressionSyntax) == null)
+                {
+                    // We only care about implicit expressions.
+                    return;
+                }
+
+                _builder.Add(new IntermediateToken()
+                {
+                    Content = node.GetContent(),
+                    Kind = TokenKind.CSharp,
+                    Source = BuildSourceSpanFromNode(node),
+                });
             }
 
             public override void VisitCSharpStatement(CSharpStatementSyntax node)
             {
                 _document.Diagnostics.Add(
                     ComponentDiagnosticFactory.Create_UnsupportedComponentImportContent(BuildSourceSpanFromNode(node)));
+
+                base.VisitCSharpStatement(node);
             }
         }