Add support for PreventDefault and StopPropagation in event handlers

\n\nCommit migrated from ae5be3e

Commit migrated from dotnet/aspnetcore@5badd9418263

src/Microsoft.AspNetCore.Razor.Language/src/ComponentResources.resx

@@ -162,6 +162,12 @@
   <data name="EventHandlerTagHelper_Documentation" xml:space="preserve">
     <value>Sets the '{0}' attribute to the provided string or delegate value. A delegate value should be of type '{1}'.</value>
   </data>
+  <data name="EventHandlerTagHelper_PreventDefault_Documentation" xml:space="preserve">
+    <value>Specifies whether to cancel(if cancelable) the default action that belongs to the '{0}' event.</value>
+  </data>
+  <data name="EventHandlerTagHelper_StopPropagation_Documentation" xml:space="preserve">
+    <value>Specifies whether to prevent further propagation of the '{0}' event in the capturing and bubbling phases.</value>
+  </data>
   <data name="ImplementsDirective_Description" xml:space="preserve">
     <value>Declares an interface implementation for the current class.</value>
   </data>

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDesignTimeNodeWriter.cs

@@ -700,10 +700,11 @@ private void WriteComponentAttributeInnards(CodeRenderingContext context, Compon
                 }
             }
 
-            bool NeedsTypeCheck(ComponentAttributeIntermediateNode n)
+            static bool NeedsTypeCheck(ComponentAttributeIntermediateNode n)
             {
-                return n.BoundAttribute != null && !n.BoundAttribute.IsWeaklyTyped();
-            }   
+                // Weakly typed attributes will have their TypeName set to null.
+                return n.BoundAttribute != null && n.TypeName != null;
+            }
         }
 
         private IReadOnlyList<IntermediateToken> GetCSharpTokens(IntermediateNode node)

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentDiagnosticFactory.cs

@@ -438,5 +438,21 @@ public static RazorDiagnostic Create_InconsistentStartAndEndTagName(string start
                 startTagName,
                 endTagName);
         }
+
+        public static readonly RazorDiagnosticDescriptor EventHandlerParameter_Duplicates =
+            new RazorDiagnosticDescriptor(
+            $"{DiagnosticPrefix}10014",
+            () => "The attribute '{0}' was matched by multiple event handlers parameter attributes. Duplicates:{1}",
+            RazorDiagnosticSeverity.Error);
+
+        public static RazorDiagnostic CreateEventHandlerParameter_Duplicates(SourceSpan? source, string attribute, TagHelperDirectiveAttributeParameterIntermediateNode[] attributes)
+        {
+            var diagnostic = RazorDiagnostic.Create(
+                EventHandlerParameter_Duplicates,
+                source ?? SourceSpan.Undefined,
+                attribute,
+                Environment.NewLine + string.Join(Environment.NewLine, attributes.Select(p => p.TagHelper.DisplayName)));
+            return diagnostic;
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentEventHandlerLoweringPass.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.Collections.Generic;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language.Extensions;
@@ -31,12 +32,17 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
             // Each usage will be represented by a tag helper property that is a descendant of either
             // a component or element.
             var references = documentNode.FindDescendantReferences<TagHelperDirectiveAttributeIntermediateNode>();
+            var parameterReferences = documentNode.FindDescendantReferences<TagHelperDirectiveAttributeParameterIntermediateNode>();
 
             var parents = new HashSet<IntermediateNode>();
             for (var i = 0; i < references.Count; i++)
             {
                 parents.Add(references[i].Parent);
             }
+            for (var i = 0; i < parameterReferences.Count; i++)
+            {
+                parents.Add(parameterReferences[i].Parent);
+            }
 
             foreach (var parent in parents)
             {
@@ -59,6 +65,23 @@ protected override void ExecuteCore(RazorCodeDocument codeDocument, DocumentInte
                     reference.Replace(RewriteUsage(reference.Parent, node));
                 }
             }
+
+            for (var i = 0; i < parameterReferences.Count; i++)
+            {
+                var reference = parameterReferences[i];
+                var node = (TagHelperDirectiveAttributeParameterIntermediateNode)reference.Node;
+
+                if (!reference.Parent.Children.Contains(node))
+                {
+                    // This node was removed as a duplicate, skip it.
+                    continue;
+                }
+
+                if (node.TagHelper.IsEventHandlerTagHelper())
+                {
+                    reference.Replace(RewriteParameterUsage(reference.Parent, node));
+                }
+            }
         }
 
         private void ProcessDuplicates(IntermediateNode parent)
@@ -109,6 +132,24 @@ private void ProcessDuplicates(IntermediateNode parent)
                     parent.Children.Remove(property);
                 }
             }
+
+            var parameterDuplicates = parent.Children
+                .OfType<TagHelperDirectiveAttributeParameterIntermediateNode>()
+                .Where(p => p.TagHelper?.IsEventHandlerTagHelper() ?? false)
+                .GroupBy(p => p.AttributeName)
+                .Where(g => g.Count() > 1);
+
+            foreach (var duplicate in parameterDuplicates)
+            {
+                parent.Diagnostics.Add(ComponentDiagnosticFactory.CreateEventHandlerParameter_Duplicates(
+                    parent.Source,
+                    duplicate.Key,
+                    duplicate.ToArray()));
+                foreach (var property in duplicate)
+                {
+                    parent.Children.Remove(property);
+                }
+            }
         }
 
         private IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperDirectiveAttributeIntermediateNode node)
@@ -198,7 +239,7 @@ private IntermediateNode RewriteUsage(IntermediateNode parent, TagHelperDirectiv
             }
         }
 
-        private static IReadOnlyList<IntermediateToken> GetAttributeContent(TagHelperDirectiveAttributeIntermediateNode node)
+        private static IReadOnlyList<IntermediateToken> GetAttributeContent(IntermediateNode node)
         {
             var template = node.FindDescendantNodes<TemplateIntermediateNode>().FirstOrDefault();
             if (template != null)
@@ -222,5 +263,49 @@ private static IReadOnlyList<IntermediateToken> GetAttributeContent(TagHelperDir
                 return node.FindDescendantNodes<IntermediateToken>();
             }
         }
+
+        private IntermediateNode RewriteParameterUsage(IntermediateNode parent, TagHelperDirectiveAttributeParameterIntermediateNode node)
+        {
+            // Now rewrite the node to look like:
+            //
+            // builder.AddEventPreventDefaultAttribute(2, "onclick", true); // If minimized.
+            // or
+            // builder.AddEventPreventDefaultAttribute(2, "onclick", someBoolExpression); // If a bool expression is provided in the value.
+
+            string eventHandlerMethod;
+            if (node.BoundAttributeParameter.Name == "preventDefault")
+            {
+                eventHandlerMethod = ComponentsApi.RenderTreeBuilder.AddEventPreventDefaultAttribute;
+            }
+            else if (node.BoundAttributeParameter.Name == "stopPropagation")
+            {
+                eventHandlerMethod = ComponentsApi.RenderTreeBuilder.AddEventStopPropagationAttribute;
+            }
+            else
+            {
+                // Unsupported event handler attribute parameter. This can only happen if bound attribute descriptor
+                // is configured to expect a parameter other than 'preventDefault' and 'stopPropagation'.
+                return node;
+            }
+
+            var result = new ComponentAttributeIntermediateNode(node)
+            {
+                Annotations =
+                    {
+                        [ComponentMetadata.Common.OriginalAttributeName] = node.OriginalAttributeName,
+                        [ComponentMetadata.Common.AddAttributeMethodName] = eventHandlerMethod,
+                    },
+            };
+
+            result.Children.Clear();
+            if (node.AttributeStructure != AttributeStructure.Minimized)
+            {
+                var tokens = GetAttributeContent(node);
+                result.Children.Add(new CSharpExpressionIntermediateNode());
+                result.Children[0].Children.AddRange(tokens);
+            }
+
+            return result;
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentMetadata.cs

@@ -42,6 +42,8 @@ public static class Common
             public static readonly string OriginalAttributeName = "Common.OriginalAttributeName";
 
             public static readonly string DirectiveAttribute = "Common.DirectiveAttribute";
+
+            public static readonly string AddAttributeMethodName = "Common.AddAttributeMethodName";
         }
 
         public static class Bind

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentRuntimeNodeWriter.cs

@@ -509,10 +509,12 @@ public override void WriteComponentAttribute(CodeRenderingContext context, Compo
                 throw new ArgumentNullException(nameof(node));
             }
 
+            var addAttributeMethod = node.Annotations[ComponentMetadata.Common.AddAttributeMethodName] as string ?? ComponentsApi.RenderTreeBuilder.AddAttribute;
+
             // _builder.AddAttribute(1, "Foo", 42);
             context.CodeWriter.Write(_scopeStack.BuilderVarName);
             context.CodeWriter.Write(".");
-            context.CodeWriter.Write(ComponentsApi.RenderTreeBuilder.AddAttribute);
+            context.CodeWriter.Write(addAttributeMethod);
             context.CodeWriter.Write("(");
             context.CodeWriter.Write((_sourceSequence++).ToString());
             context.CodeWriter.Write(", ");

src/Microsoft.AspNetCore.Razor.Language/src/Components/ComponentsApi.cs

@@ -97,6 +97,10 @@ public static class RenderTreeBuilder
             public static readonly string SetKey = nameof(SetKey);
 
             public static readonly string SetUpdatesAttributeName = nameof(SetUpdatesAttributeName);
+
+            public static readonly string AddEventPreventDefaultAttribute = nameof(AddEventPreventDefaultAttribute);
+
+            public static readonly string AddEventStopPropagationAttribute = nameof(AddEventStopPropagationAttribute);
         }
 
         public static class RuntimeHelpers

src/Microsoft.AspNetCore.Razor.Language/src/Intermediate/ComponentAttributeIntermediateNode.cs

@@ -88,6 +88,32 @@ public ComponentAttributeIntermediateNode(TagHelperDirectiveAttributeIntermediat
             }
         }
 
+        public ComponentAttributeIntermediateNode(TagHelperDirectiveAttributeParameterIntermediateNode directiveAttributeParameterNode)
+        {
+            if (directiveAttributeParameterNode == null)
+            {
+                throw new ArgumentNullException(nameof(directiveAttributeParameterNode));
+            }
+
+            AttributeName = directiveAttributeParameterNode.AttributeNameWithoutParameter;
+            AttributeStructure = directiveAttributeParameterNode.AttributeStructure;
+            BoundAttribute = directiveAttributeParameterNode.BoundAttribute;
+            PropertyName = directiveAttributeParameterNode.BoundAttributeParameter.GetPropertyName();
+            Source = directiveAttributeParameterNode.Source;
+            TagHelper = directiveAttributeParameterNode.TagHelper;
+            TypeName = directiveAttributeParameterNode.BoundAttributeParameter.TypeName;
+
+            for (var i = 0; i < directiveAttributeParameterNode.Children.Count; i++)
+            {
+                Children.Add(directiveAttributeParameterNode.Children[i]);
+            }
+
+            for (var i = 0; i < directiveAttributeParameterNode.Diagnostics.Count; i++)
+            {
+                Diagnostics.Add(directiveAttributeParameterNode.Diagnostics[i]);
+            }
+        }
+
         public override IntermediateNodeCollection Children { get; } = new IntermediateNodeCollection();
 
         public string AttributeName { get; set; }

src/Microsoft.AspNetCore.Razor.Language/test/IntegrationTests/ComponentCodeGenerationTestBase.cs

@@ -2848,6 +2848,7 @@ public void EventHandler_OnElement_WithLambdaDelegate()
 
             // Act
             var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components.Web
 <input @onclick=""x => { }"" />");
 
             // Assert
@@ -2896,6 +2897,78 @@ void OnClick(MouseEventArgs e) {
             CompileToAssembly(generated);
         }
 
+        [Fact]
+        public void EventHandler_PreventDefault_StopPropagation_Minimized()
+        {
+            // Arrange
+
+            // Act
+            var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components.Web
+<input @onclick:preventDefault @onclick:stopPropagation />");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
+        [Fact]
+        public void EventHandler_PreventDefault_StopPropagation()
+        {
+            // Arrange
+
+            // Act
+            var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components.Web
+<input @onfocus:preventDefault=""true"" @onclick:stopPropagation=""Foo"" @onfocus:stopPropagation=""false"" />
+@code {
+    bool Foo { get; set; }
+}");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
+        [Fact]
+        public void EventHandler_WithDelegate_PreventDefault()
+        {
+            // Arrange
+
+            // Act
+            var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components.Web
+<input @onfocus=""OnFocus"" @onfocus:preventDefault=""ShouldPreventDefault()"" />
+@code {
+    void OnFocus(FocusEventArgs e) { }
+
+    bool ShouldPreventDefault() { return false; }
+}");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
+        [Fact]
+        public void EventHandler_PreventDefault_Duplicates()
+        {
+            // Arrange
+
+            // Act
+            var generated = CompileToCSharp(@"
+@using Microsoft.AspNetCore.Components.Web
+<input @onclick:preventDefault=""true"" @onclick:preventDefault />");
+
+            // Assert
+            AssertDocumentNodeMatchesBaseline(generated.CodeDocument);
+            AssertCSharpDocumentMatchesBaseline(generated.CodeDocument);
+            CompileToAssembly(generated);
+        }
+
         #endregion
 
         #region Generics

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToComponent_EventCallback_SpecifiesValueAndExpression/TestComponent.ir.txt

@@ -15,13 +15,13 @@ Document -
                 IntermediateToken -  - CSharp - #pragma warning restore 0414
             MethodDeclaration -  - protected override - void - BuildRenderTree
                 Component - (0:0,0 [41] x:\dir\subdir\Test\TestComponent.cshtml) - MyComponent
-                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - Value - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - Value - Value - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
-                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueChanged - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueChanged - ValueChanged - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.CreateInferredEventCallback(this, __value => ParentValue = __value, ParentValue)
-                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueExpression - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueExpression - ValueExpression - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - () => ParentValue
                 HtmlContent - (41:0,41 [2] x:\dir\subdir\Test\TestComponent.cshtml)

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToComponent_EventCallback_SpecifiesValueAndExpression_Generic/TestComponent.ir.txt

@@ -15,13 +15,13 @@ Document -
                 IntermediateToken -  - CSharp - #pragma warning restore 0414
             MethodDeclaration -  - protected override - void - BuildRenderTree
                 Component - (0:0,0 [45] x:\dir\subdir\Test\TestComponent.cshtml) - MyComponent
-                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParam - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParam - SomeParam - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
-                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParamChanged - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParamChanged - SomeParamChanged - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.CreateInferredEventCallback(this, __value => ParentValue = __value, ParentValue)
-                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParamExpression - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (30:0,30 [11] x:\dir\subdir\Test\TestComponent.cshtml) - SomeParamExpression - SomeParamExpression - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - () => ParentValue
                 HtmlContent - (45:0,45 [2] x:\dir\subdir\Test\TestComponent.cshtml)

src/Microsoft.AspNetCore.Razor.Language/test/TestFiles/IntegrationTests/ComponentDesignTimeCodeGenerationTest/BindToComponent_EventCallback_SpecifiesValue_WithMatchingProperties/TestComponent.ir.txt

@@ -15,10 +15,10 @@ Document -
                 IntermediateToken -  - CSharp - #pragma warning restore 0414
             MethodDeclaration -  - protected override - void - BuildRenderTree
                 Component - (0:0,0 [41] x:\dir\subdir\Test\TestComponent.cshtml) - MyComponent
-                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - Value - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - Value - Value - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - CSharp - ParentValue
-                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueChanged - AttributeStructure.DoubleQuotes
+                    ComponentAttribute - (26:0,26 [11] x:\dir\subdir\Test\TestComponent.cshtml) - ValueChanged - ValueChanged - AttributeStructure.DoubleQuotes
                         CSharpExpression - 
                             IntermediateToken -  - CSharp - Microsoft.AspNetCore.Components.CompilerServices.RuntimeHelpers.CreateInferredEventCallback(this, __value => ParentValue = __value, ParentValue)
                 HtmlContent - (41:0,41 [2] x:\dir\subdir\Test\TestComponent.cshtml)