Blazor API Review: Parameters (#12547)

* Blazor API Review: Parameters

Part of #11610

src/Components/Blazor/Build/test/BindRazorIntegrationTest.cs

@@ -68,7 +68,7 @@ namespace Test
 {
     public class MyComponent : ComponentBase, IComponent
     {
-        Task IComponent.SetParametersAsync(ParameterCollection parameters)
+        Task IComponent.SetParametersAsync(ParameterView parameters)
         {
             return Task.CompletedTask;
         }
@@ -142,7 +142,7 @@ namespace Test
 {
     public class MyComponent : ComponentBase, IComponent
     {
-        Task IComponent.SetParametersAsync(ParameterCollection parameters)
+        Task IComponent.SetParametersAsync(ParameterView parameters)
         {
             return Task.CompletedTask;
         }

src/Components/Blazor/Build/test/ComponentRenderingRazorIntegrationTest.cs

@@ -165,7 +165,7 @@ namespace Test
 {
     public class MyComponent : ComponentBase, IComponent
     {
-        Task IComponent.SetParametersAsync(ParameterCollection parameters)
+        Task IComponent.SetParametersAsync(ParameterView parameters)
         {
             return Task.CompletedTask;
         }

src/Components/Blazor/Build/test/DirectiveRazorIntegrationTest.cs

@@ -153,7 +153,7 @@ namespace Microsoft.AspNetCore.Blazor.Build.Test
             {
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 return Task.CompletedTask;
             }

src/Components/Blazor/Build/test/RazorIntegrationTestBase.cs

@@ -385,7 +385,7 @@ namespace Microsoft.AspNetCore.Blazor.Build.Test
         protected private RenderTreeFrame[] GetRenderTree(TestRenderer renderer, IComponent component)
         {
             renderer.AttachComponent(component);
-            var task = renderer.Dispatcher.InvokeAsync(() => component.SetParametersAsync(ParameterCollection.Empty));
+            var task = renderer.Dispatcher.InvokeAsync(() => component.SetParametersAsync(ParameterView.Empty));
             // we will have to change this method if we add a test that does actual async work.
             Assert.True(task.Status.HasFlag(TaskStatus.RanToCompletion) || task.Status.HasFlag(TaskStatus.Faulted));
             if (task.IsFaulted)

src/Components/Components/ref/Microsoft.AspNetCore.Components.netstandard2.0.cs

@@ -117,7 +117,7 @@ namespace Microsoft.AspNetCore.Components
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public T Value { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
         public void Attach(Microsoft.AspNetCore.Components.RenderHandle renderHandle) { }
-        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters) { throw null; }
+        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
     }
     public abstract partial class ComponentBase : Microsoft.AspNetCore.Components.IComponent, Microsoft.AspNetCore.Components.IHandleAfterRender, Microsoft.AspNetCore.Components.IHandleEvent
     {
@@ -134,7 +134,7 @@ namespace Microsoft.AspNetCore.Components
         protected virtual System.Threading.Tasks.Task OnInitializedAsync() { throw null; }
         protected virtual void OnParametersSet() { }
         protected virtual System.Threading.Tasks.Task OnParametersSetAsync() { throw null; }
-        public virtual System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters) { throw null; }
+        public virtual System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
         protected virtual bool ShouldRender() { throw null; }
         protected void StateHasChanged() { }
     }
@@ -238,7 +238,7 @@ namespace Microsoft.AspNetCore.Components
     public partial interface IComponent
     {
         void Attach(Microsoft.AspNetCore.Components.RenderHandle renderHandle);
-        System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters);
+        System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters);
     }
     public partial interface IComponentContext
     {
@@ -309,16 +309,7 @@ namespace Microsoft.AspNetCore.Components
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public System.Collections.Generic.IDictionary<string, object> PageParameters { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
         public void Attach(Microsoft.AspNetCore.Components.RenderHandle renderHandle) { }
-        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters) { throw null; }
+        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
-    }
-    [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
-    public readonly partial struct Parameter
-    {
-        private readonly object _dummy;
-        private readonly int _dummyPrimitive;
-        public bool Cascading { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public string Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public object Value { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Property, AllowMultiple=false, Inherited=true)]
     public sealed partial class ParameterAttribute : System.Attribute
@@ -327,29 +318,35 @@ namespace Microsoft.AspNetCore.Components
         public bool CaptureUnmatchedValues { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
     }
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
-    public readonly partial struct ParameterCollection
+    public readonly partial struct ParameterValue
     {
         private readonly object _dummy;
         private readonly int _dummyPrimitive;
-        public static Microsoft.AspNetCore.Components.ParameterCollection Empty { get { throw null; } }
+        public bool Cascading { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public static Microsoft.AspNetCore.Components.ParameterCollection FromDictionary(System.Collections.Generic.IDictionary<string, object> parameters) { throw null; }
+        public string Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public Microsoft.AspNetCore.Components.ParameterEnumerator GetEnumerator() { throw null; }
+        public object Value { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
-        public T GetValueOrDefault<T>(string parameterName) { throw null; }
-        public T GetValueOrDefault<T>(string parameterName, T defaultValue) { throw null; }
-        public System.Collections.Generic.IReadOnlyDictionary<string, object> ToDictionary() { throw null; }
-        public bool TryGetValue<T>(string parameterName, out T result) { throw null; }
-    }
-    public static partial class ParameterCollectionExtensions
-    {
-        public static void SetParameterProperties(this in Microsoft.AspNetCore.Components.ParameterCollection parameterCollection, object target) { }
     }
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
-    public partial struct ParameterEnumerator
+    public readonly partial struct ParameterView
     {
-        private object _dummy;
+        private readonly object _dummy;
-        private int _dummyPrimitive;
+        private readonly int _dummyPrimitive;
-        public Microsoft.AspNetCore.Components.Parameter Current { get { throw null; } }
+        public static Microsoft.AspNetCore.Components.ParameterView Empty { get { throw null; } }
-        public bool MoveNext() { throw null; }
+        public static Microsoft.AspNetCore.Components.ParameterView FromDictionary(System.Collections.Generic.IDictionary<string, object> parameters) { throw null; }
+        public Microsoft.AspNetCore.Components.ParameterView.Enumerator GetEnumerator() { throw null; }
+        public T GetValueOrDefault<T>(string parameterName) { throw null; }
+        public T GetValueOrDefault<T>(string parameterName, T defaultValue) { throw null; }
+        public void SetParameterProperties(object target) { }
+        public System.Collections.Generic.IReadOnlyDictionary<string, object> ToDictionary() { throw null; }
+        public bool TryGetValue<T>(string parameterName, out T result) { throw null; }
+        [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
+        public partial struct Enumerator
+        {
+            private object _dummy;
+            private int _dummyPrimitive;
+            public Microsoft.AspNetCore.Components.ParameterValue Current { get { throw null; } }
+            public bool MoveNext() { throw null; }
+        }
     }
     public delegate void RenderFragment(Microsoft.AspNetCore.Components.RenderTree.RenderTreeBuilder builder);
     public delegate Microsoft.AspNetCore.Components.RenderFragment RenderFragment<T>(T value);
@@ -502,8 +499,8 @@ namespace Microsoft.AspNetCore.Components.Rendering
         public override Microsoft.AspNetCore.Components.Dispatcher Dispatcher { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } }
         protected override void HandleException(System.Exception exception) { }
         [System.Diagnostics.DebuggerStepThroughAttribute]
-        public System.Threading.Tasks.Task<Microsoft.AspNetCore.Components.Rendering.ComponentRenderedText> RenderComponentAsync(System.Type componentType, Microsoft.AspNetCore.Components.ParameterCollection initialParameters) { throw null; }
+        public System.Threading.Tasks.Task<Microsoft.AspNetCore.Components.Rendering.ComponentRenderedText> RenderComponentAsync(System.Type componentType, Microsoft.AspNetCore.Components.ParameterView initialParameters) { throw null; }
-        public System.Threading.Tasks.Task<Microsoft.AspNetCore.Components.Rendering.ComponentRenderedText> RenderComponentAsync<TComponent>(Microsoft.AspNetCore.Components.ParameterCollection initialParameters) where TComponent : Microsoft.AspNetCore.Components.IComponent { throw null; }
+        public System.Threading.Tasks.Task<Microsoft.AspNetCore.Components.Rendering.ComponentRenderedText> RenderComponentAsync<TComponent>(Microsoft.AspNetCore.Components.ParameterView initialParameters) where TComponent : Microsoft.AspNetCore.Components.IComponent { throw null; }
         protected override System.Threading.Tasks.Task UpdateDisplayAsync(in Microsoft.AspNetCore.Components.Rendering.RenderBatch renderBatch) { throw null; }
     }
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
@@ -529,7 +526,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
         protected Microsoft.AspNetCore.Components.IComponent InstantiateComponent(System.Type componentType) { throw null; }
         protected System.Threading.Tasks.Task RenderRootComponentAsync(int componentId) { throw null; }
         [System.Diagnostics.DebuggerStepThroughAttribute]
-        protected System.Threading.Tasks.Task RenderRootComponentAsync(int componentId, Microsoft.AspNetCore.Components.ParameterCollection initialParameters) { throw null; }
+        protected System.Threading.Tasks.Task RenderRootComponentAsync(int componentId, Microsoft.AspNetCore.Components.ParameterView initialParameters) { throw null; }
         protected abstract System.Threading.Tasks.Task UpdateDisplayAsync(in Microsoft.AspNetCore.Components.Rendering.RenderBatch renderBatch);
     }
 }
@@ -663,6 +660,6 @@ namespace Microsoft.AspNetCore.Components.Routing
         public void Dispose() { }
         System.Threading.Tasks.Task Microsoft.AspNetCore.Components.IHandleAfterRender.OnAfterRenderAsync() { throw null; }
         protected virtual void Render(Microsoft.AspNetCore.Components.RenderTree.RenderTreeBuilder builder, System.Type handler, System.Collections.Generic.IDictionary<string, object> parameters) { }
-        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters) { throw null; }
+        public System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
     }
 }

src/Components/Components/src/CascadingParameterState.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.Components.Reflection;
 using Microsoft.AspNetCore.Components.Rendering;
 using System;
 using System.Collections.Concurrent;
@@ -89,7 +90,7 @@ namespace Microsoft.AspNetCore.Components
         private static ReflectedCascadingParameterInfo[] CreateReflectedCascadingParameterInfos(Type componentType)
         {
             List<ReflectedCascadingParameterInfo> result = null;
-            var candidateProps = ParameterCollectionExtensions.GetCandidateBindableProperties(componentType);
+            var candidateProps = ComponentProperties.GetCandidateBindableProperties(componentType);
             foreach (var prop in candidateProps)
             {
                 var attribute = prop.GetCustomAttribute<CascadingParameterAttribute>();

src/Components/Components/src/CascadingValue.cs

@@ -56,7 +56,7 @@ namespace Microsoft.AspNetCore.Components
         }
 
         /// <inheritdoc />
-        public Task SetParametersAsync(ParameterCollection parameters)
+        public Task SetParametersAsync(ParameterView parameters)
         {
             // Implementing the parameter binding manually, instead of just calling
             // parameters.SetParameterProperties(this), is just a very slight perf optimization
@@ -110,7 +110,7 @@ namespace Microsoft.AspNetCore.Components
             // because it serves no useful purpose to have a <CascadingValue> otherwise.
             if (!hasSuppliedValue)
             {
-                throw new ArgumentException($"Missing required parameter '{nameof(Value)}' for component '{nameof(Parameter)}'.");
+                throw new ArgumentException($"Missing required parameter '{nameof(Value)}' for component '{GetType().Name}'.");
             }
 
             // Rendering is most efficient when things are queued from rootmost to leafmost.

src/Components/Components/src/ComponentBase.cs

@@ -175,7 +175,7 @@ namespace Microsoft.AspNetCore.Components
         /// Method invoked to apply initial or updated parameters to the component.
         /// </summary>
         /// <param name="parameters">The parameters to apply.</param>
-        public virtual Task SetParametersAsync(ParameterCollection parameters)
+        public virtual Task SetParametersAsync(ParameterView parameters)
         {
             parameters.SetParameterProperties(this);
             if (!_initialized)

src/Components/Components/src/IComponent.cs

@@ -21,6 +21,6 @@ namespace Microsoft.AspNetCore.Components
         /// </summary>
         /// <param name="parameters">The parameters.</param>
         /// <returns>A <see cref="Task"/> that completes when the component has finished updating and rendering itself.</returns>
-        Task SetParametersAsync(ParameterCollection parameters);
+        Task SetParametersAsync(ParameterView parameters);
     }
 }

src/Components/Components/src/PageDisplay.cs

@@ -51,7 +51,7 @@ namespace Microsoft.AspNetCore.Components
         }
 
         /// <inheritdoc />
-        public Task SetParametersAsync(ParameterCollection parameters)
+        public Task SetParametersAsync(ParameterView parameters)
         {
             parameters.SetParameterProperties(this);
             Render();

src/Components/Components/src/ParameterEnumerator.cs

@@ -1,137 +0,0 @@
-// 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.Components.RenderTree;
-using System;
-using System.Collections.Generic;
-
-namespace Microsoft.AspNetCore.Components
-{
-    /// <summary>
-    /// An enumerator that iterates through a <see cref="ParameterCollection"/>.
-    /// </summary>
-    public struct ParameterEnumerator
-    {
-        private RenderTreeFrameParameterEnumerator _directParamsEnumerator;
-        private CascadingParameterEnumerator _cascadingParameterEnumerator;
-        private bool _isEnumeratingDirectParams;
-
-        internal ParameterEnumerator(RenderTreeFrame[] frames, int ownerIndex, IReadOnlyList<CascadingParameterState> cascadingParameters)
-        {
-            _directParamsEnumerator = new RenderTreeFrameParameterEnumerator(frames, ownerIndex);
-            _cascadingParameterEnumerator = new CascadingParameterEnumerator(cascadingParameters);
-            _isEnumeratingDirectParams = true;
-        }
-
-        /// <summary>
-        /// Gets the current value of the enumerator.
-        /// </summary>
-        public Parameter Current => _isEnumeratingDirectParams
-            ? _directParamsEnumerator.Current
-            : _cascadingParameterEnumerator.Current;
-
-        /// <summary>
-        /// Instructs the enumerator to move to the next value in the sequence.
-        /// </summary>
-        /// <returns>A flag to indicate whether or not there is a next value.</returns>
-        public bool MoveNext()
-        {
-            if (_isEnumeratingDirectParams)
-            {
-                if (_directParamsEnumerator.MoveNext())
-                {
-                    return true;
-                }
-                else
-                {
-                    _isEnumeratingDirectParams = false;
-                }
-            }
-
-            return _cascadingParameterEnumerator.MoveNext();
-        }
-
-        struct RenderTreeFrameParameterEnumerator
-        {
-            private readonly RenderTreeFrame[] _frames;
-            private readonly int _ownerIndex;
-            private readonly int _ownerDescendantsEndIndexExcl;
-            private int _currentIndex;
-            private Parameter _current;
-
-            internal RenderTreeFrameParameterEnumerator(RenderTreeFrame[] frames, int ownerIndex)
-            {
-                _frames = frames;
-                _ownerIndex = ownerIndex;
-                _ownerDescendantsEndIndexExcl = ownerIndex + _frames[ownerIndex].ElementSubtreeLength;
-                _currentIndex = ownerIndex;
-                _current = default;
-            }
-
-            public Parameter Current => _current;
-
-            public bool MoveNext()
-            {
-                // Stop iteration if you get to the end of the owner's descendants...
-                var nextIndex = _currentIndex + 1;
-                if (nextIndex == _ownerDescendantsEndIndexExcl)
-                {
-                    return false;
-                }
-
-                // ... or if you get to its first non-attribute descendant (because attributes
-                // are always before any other type of descendant)
-                if (_frames[nextIndex].FrameType != RenderTreeFrameType.Attribute)
-                {
-                    return false;
-                }
-
-                _currentIndex = nextIndex;
-
-                ref var frame = ref _frames[_currentIndex];
-                _current = new Parameter(frame.AttributeName, frame.AttributeValue, false);
-
-                return true;
-            }
-        }
-
-        struct CascadingParameterEnumerator
-        {
-            private readonly IReadOnlyList<CascadingParameterState> _cascadingParameters;
-            private int _currentIndex;
-            private Parameter _current;
-
-            public CascadingParameterEnumerator(IReadOnlyList<CascadingParameterState> cascadingParameters)
-            {
-                _cascadingParameters = cascadingParameters;
-                _currentIndex = -1;
-                _current = default;
-            }
-
-            public Parameter Current => _current;
-
-            public bool MoveNext()
-            {
-                // Bail out early if there are no cascading parameters
-                if (_cascadingParameters == null)
-                {
-                    return false;
-                }
-
-                var nextIndex = _currentIndex + 1;
-                if (nextIndex < _cascadingParameters.Count)
-                {
-                    _currentIndex = nextIndex;
-
-                    var state = _cascadingParameters[_currentIndex];
-                    _current = new Parameter(state.LocalValueName, state.ValueSupplier.CurrentValue, true);
-                    return true;
-                }
-                else
-                {
-                    return false;
-                }
-            }
-        }
-    }
-}

src/Components/Components/src/ParameterValue.cs

@@ -7,8 +7,15 @@ namespace Microsoft.AspNetCore.Components
     /// Represents a single parameter supplied to an <see cref="IComponent"/>
     /// by its parent in the render tree.
     /// </summary>
-    public readonly struct Parameter
+    public readonly struct ParameterValue
     {
+        internal ParameterValue(string name, object value, bool cascading)
+        {
+            Name = name;
+            Value = value;
+            Cascading = cascading;
+        }
+
         /// <summary>
         /// Gets the name of the parameter.
         /// </summary>
@@ -24,12 +31,5 @@ namespace Microsoft.AspNetCore.Components
         /// was supplied by a <see cref="CascadingValue{T}"/>.
         /// </summary>
         public bool Cascading { get; }
-
-        internal Parameter(string name, object value, bool cascading)
-        {
-            Name = name;
-            Value = value;
-            Cascading = cascading;
-        }
     }
 }

src/Components/Components/src/ParameterView.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using Microsoft.AspNetCore.Components.Reflection;
 using Microsoft.AspNetCore.Components.RenderTree;
 
 namespace Microsoft.AspNetCore.Components
@@ -11,27 +12,26 @@ namespace Microsoft.AspNetCore.Components
     /// Represents a collection of parameters supplied to an <see cref="IComponent"/>
     /// by its parent in the render tree.
     /// </summary>
-    public readonly struct ParameterCollection
+    public readonly struct ParameterView
     {
-        private const string GeneratedParameterCollectionElementName = "__ARTIFICIAL_PARAMETER_COLLECTION";
+        private const string GeneratedParameterViewElementName = "__ARTIFICIAL_PARAMETER_VIEW";
-        private static readonly RenderTreeFrame[] _emptyCollectionFrames = new RenderTreeFrame[]
+        private static readonly RenderTreeFrame[] _emptyFrames = new RenderTreeFrame[]
         {
             RenderTreeFrame.Element(0, string.Empty).WithComponentSubtreeLength(1)
         };
 
-        private static readonly ParameterCollection _emptyCollection
+        private static readonly ParameterView _empty = new ParameterView(_emptyFrames, 0, null);
-            = new ParameterCollection(_emptyCollectionFrames, 0, null);
 
         private readonly RenderTreeFrame[] _frames;
         private readonly int _ownerIndex;
         private readonly IReadOnlyList<CascadingParameterState> _cascadingParametersOrNull;
 
-        internal ParameterCollection(RenderTreeFrame[] frames, int ownerIndex)
+        internal ParameterView(RenderTreeFrame[] frames, int ownerIndex)
             : this(frames, ownerIndex, null)
         {
         }
 
-        private ParameterCollection(RenderTreeFrame[] frames, int ownerIndex, IReadOnlyList<CascadingParameterState> cascadingParametersOrNull)
+        private ParameterView(RenderTreeFrame[] frames, int ownerIndex, IReadOnlyList<CascadingParameterState> cascadingParametersOrNull)
         {
             _frames = frames;
             _ownerIndex = ownerIndex;
@@ -39,16 +39,16 @@ namespace Microsoft.AspNetCore.Components
         }
 
         /// <summary>
-        /// Gets an empty <see cref="ParameterCollection"/>.
+        /// Gets an empty <see cref="ParameterView"/>.
         /// </summary>
-        public static ParameterCollection Empty => _emptyCollection;
+        public static ParameterView Empty => _empty;
 
         /// <summary>
-        /// Returns an enumerator that iterates through the <see cref="ParameterCollection"/>.
+        /// Returns an enumerator that iterates through the <see cref="ParameterView"/>.
         /// </summary>
         /// <returns>The enumerator.</returns>
-        public ParameterEnumerator GetEnumerator()
+        public Enumerator GetEnumerator()
-            => new ParameterEnumerator(_frames, _ownerIndex, _cascadingParametersOrNull);
+            => new Enumerator(_frames, _ownerIndex, _cascadingParametersOrNull);
 
         /// <summary>
         /// Gets the value of the parameter with the specified name.
@@ -94,9 +94,9 @@ namespace Microsoft.AspNetCore.Components
             => TryGetValue<T>(parameterName, out T result) ? result : defaultValue;
 
         /// <summary>
-        /// Returns a dictionary populated with the contents of the <see cref="ParameterCollection"/>.
+        /// Returns a dictionary populated with the contents of the <see cref="ParameterView"/>.
         /// </summary>
-        /// <returns>A dictionary populated with the contents of the <see cref="ParameterCollection"/>.</returns>
+        /// <returns>A dictionary populated with the contents of the <see cref="ParameterView"/>.</returns>
         public IReadOnlyDictionary<string, object> ToDictionary()
         {
             var result = new Dictionary<string, object>();
@@ -107,13 +107,13 @@ namespace Microsoft.AspNetCore.Components
             return result;
         }
 
-        internal ParameterCollection WithCascadingParameters(IReadOnlyList<CascadingParameterState> cascadingParameters)
+        internal ParameterView WithCascadingParameters(IReadOnlyList<CascadingParameterState> cascadingParameters)
-            => new ParameterCollection(_frames, _ownerIndex, cascadingParameters);
+            => new ParameterView(_frames, _ownerIndex, cascadingParameters);
 
         // It's internal because there isn't a known use case for user code comparing
-        // ParameterCollection instances, and even if there was, it's unlikely it should
+        // ParameterView instances, and even if there was, it's unlikely it should
         // use these equality rules which are designed for their effect on rendering.
-        internal bool DefinitelyEquals(ParameterCollection oldParameters)
+        internal bool DefinitelyEquals(ParameterView oldParameters)
         {
             // In general we can't detect mutations on arbitrary objects. We can't trust
             // things like .Equals or .GetHashCode because they usually only tell us about
@@ -187,7 +187,7 @@ namespace Microsoft.AspNetCore.Components
             }
 
             // We need to prefix the captured frames with an "owner" frame that
-            // describes the length of the buffer so that ParameterCollection
+            // describes the length of the buffer so that ParameterView
             // knows how far to iterate through it.
             var owner = RenderTreeFrame.PlaceholderChildComponentWithSubtreeLength(1 + numEntries);
             builder.Append(owner);
@@ -199,14 +199,14 @@ namespace Microsoft.AspNetCore.Components
         }
 
         /// <summary>
-        /// Creates a new <see cref="ParameterCollection"/> from the given <see cref="IDictionary{TKey, TValue}"/>.
+        /// Creates a new <see cref="ParameterView"/> from the given <see cref="IDictionary{TKey, TValue}"/>.
         /// </summary>
         /// <param name="parameters">The <see cref="IDictionary{TKey, TValue}"/> with the parameters.</param>
-        /// <returns>A <see cref="ParameterCollection"/>.</returns>
+        /// <returns>A <see cref="ParameterView"/>.</returns>
-        public static ParameterCollection FromDictionary(IDictionary<string, object> parameters)
+        public static ParameterView FromDictionary(IDictionary<string, object> parameters)
         {
             var frames = new RenderTreeFrame[parameters.Count + 1];
-            frames[0] = RenderTreeFrame.Element(0, GeneratedParameterCollectionElementName)
+            frames[0] = RenderTreeFrame.Element(0, GeneratedParameterViewElementName)
                 .WithElementSubtreeLength(frames.Length);
 
             var i = 0;
@@ -215,7 +215,153 @@ namespace Microsoft.AspNetCore.Components
                 frames[++i] = RenderTreeFrame.Attribute(i, kvp.Key, kvp.Value);
             }
 
-            return new ParameterCollection(frames, 0);
+            return new ParameterView(frames, 0);
+        }
+
+        /// <summary>
+        /// For each parameter property on <paramref name="target"/>, updates its value to
+        /// match the corresponding entry in the <see cref="ParameterView"/>.
+        /// </summary>
+        /// <param name="target">An object that has a public writable property matching each parameter's name and type.</param>
+        public void SetParameterProperties(object target)
+        {
+            if (target is null)
+            {
+                throw new ArgumentNullException(nameof(target));
+            }
+
+            ComponentProperties.SetProperties(this, target);
+        }
+
+        /// <summary>
+        /// An enumerator that iterates through a <see cref="ParameterView"/>.
+        /// </summary>
+
+        // Note that this intentionally does not implement IEnumerator<>. This is the same pattern as Span<>.Enumerator
+        // it's valid to foreach over a type that doesn't implement IEnumerator<>.
+        public struct Enumerator
+        {
+            private RenderTreeFrameParameterEnumerator _directParamsEnumerator;
+            private CascadingParameterEnumerator _cascadingParameterEnumerator;
+            private bool _isEnumeratingDirectParams;
+
+            internal Enumerator(RenderTreeFrame[] frames, int ownerIndex, IReadOnlyList<CascadingParameterState> cascadingParameters)
+            {
+                _directParamsEnumerator = new RenderTreeFrameParameterEnumerator(frames, ownerIndex);
+                _cascadingParameterEnumerator = new CascadingParameterEnumerator(cascadingParameters);
+                _isEnumeratingDirectParams = true;
+            }
+
+            /// <summary>
+            /// Gets the current value of the enumerator.
+            /// </summary>
+            public ParameterValue Current => _isEnumeratingDirectParams
+                ? _directParamsEnumerator.Current
+                : _cascadingParameterEnumerator.Current;
+
+            /// <summary>
+            /// Instructs the enumerator to move to the next value in the sequence.
+            /// </summary>
+            /// <returns>A flag to indicate whether or not there is a next value.</returns>
+            public bool MoveNext()
+            {
+                if (_isEnumeratingDirectParams)
+                {
+                    if (_directParamsEnumerator.MoveNext())
+                    {
+                        return true;
+                    }
+                    else
+                    {
+                        _isEnumeratingDirectParams = false;
+                    }
+                }
+
+                return _cascadingParameterEnumerator.MoveNext();
+            }
+        }
+
+        private struct RenderTreeFrameParameterEnumerator
+        {
+            private readonly RenderTreeFrame[] _frames;
+            private readonly int _ownerIndex;
+            private readonly int _ownerDescendantsEndIndexExcl;
+            private int _currentIndex;
+            private ParameterValue _current;
+
+            internal RenderTreeFrameParameterEnumerator(RenderTreeFrame[] frames, int ownerIndex)
+            {
+                _frames = frames;
+                _ownerIndex = ownerIndex;
+                _ownerDescendantsEndIndexExcl = ownerIndex + _frames[ownerIndex].ElementSubtreeLength;
+                _currentIndex = ownerIndex;
+                _current = default;
+            }
+
+            public ParameterValue Current => _current;
+
+            public bool MoveNext()
+            {
+                // Stop iteration if you get to the end of the owner's descendants...
+                var nextIndex = _currentIndex + 1;
+                if (nextIndex == _ownerDescendantsEndIndexExcl)
+                {
+                    return false;
+                }
+
+                // ... or if you get to its first non-attribute descendant (because attributes
+                // are always before any other type of descendant)
+                if (_frames[nextIndex].FrameType != RenderTreeFrameType.Attribute)
+                {
+                    return false;
+                }
+
+                _currentIndex = nextIndex;
+
+                ref var frame = ref _frames[_currentIndex];
+                _current = new ParameterValue(frame.AttributeName, frame.AttributeValue, false);
+
+                return true;
+            }
+        }
+
+        private struct CascadingParameterEnumerator
+        {
+            private readonly IReadOnlyList<CascadingParameterState> _cascadingParameters;
+            private int _currentIndex;
+            private ParameterValue _current;
+
+            public CascadingParameterEnumerator(IReadOnlyList<CascadingParameterState> cascadingParameters)
+            {
+                _cascadingParameters = cascadingParameters;
+                _currentIndex = -1;
+                _current = default;
+            }
+
+            public ParameterValue Current => _current;
+
+            public bool MoveNext()
+            {
+                // Bail out early if there are no cascading parameters
+                if (_cascadingParameters == null)
+                {
+                    return false;
+                }
+
+                var nextIndex = _currentIndex + 1;
+                if (nextIndex < _cascadingParameters.Count)
+                {
+                    _currentIndex = nextIndex;
+
+                    var state = _cascadingParameters[_currentIndex];
+                    _current = new ParameterValue(state.LocalValueName, state.ValueSupplier.CurrentValue, true);
+                    return true;
+                }
+                else
+                {
+                    return false;
+                }
+            }
         }
     }
 }

src/Components/Components/src/Reflection/ComponentProperties.cs

@@ -7,29 +7,17 @@ using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
-using Microsoft.AspNetCore.Components.Reflection;
 
-namespace Microsoft.AspNetCore.Components
+namespace Microsoft.AspNetCore.Components.Reflection
 {
-    /// <summary>
+    internal static class ComponentProperties
-    /// Extension methods for the <see cref="ParameterCollection"/> type.
-    /// </summary>
-    public static class ParameterCollectionExtensions
     {
         private const BindingFlags _bindablePropertyFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.IgnoreCase;
 
         private readonly static ConcurrentDictionary<Type, WritersForType> _cachedWritersByType
             = new ConcurrentDictionary<Type, WritersForType>();
 
-        /// <summary>
+        public static void SetProperties(in ParameterView parameters, object target)
-        /// For each parameter property on <paramref name="target"/>, updates its value to
-        /// match the corresponding entry in the <see cref="ParameterCollection"/>.
-        /// </summary>
-        /// <param name="parameterCollection">The <see cref="ParameterCollection"/>.</param>
-        /// <param name="target">An object that has a public writable property matching each parameter's name and type.</param>
-        public static void SetParameterProperties(
-            in this ParameterCollection parameterCollection,
-            object target)
         {
             if (target == null)
             {
@@ -47,7 +35,7 @@ namespace Microsoft.AspNetCore.Components
             if (writers.CaptureUnmatchedValuesWriter == null)
             {
                 // Logic for components without a CaptureUnmatchedValues parameter
-                foreach (var parameter in parameterCollection)
+                foreach (var parameter in parameters)
                 {
                     var parameterName = parameter.Name;
                     if (!writers.WritersByName.TryGetValue(parameterName, out var writer))
@@ -65,7 +53,7 @@ namespace Microsoft.AspNetCore.Components
                 // Logic with components with a CaptureUnmatchedValues parameter
                 var isCaptureUnmatchedValuesParameterSetExplicitly = false;
                 Dictionary<string, object> unmatched = null;
-                foreach (var parameter in parameterCollection)
+                foreach (var parameter in parameters)
                 {
                     var parameterName = parameter.Name;
                     if (string.Equals(parameterName, writers.CaptureUnmatchedValuesPropertyName, StringComparison.OrdinalIgnoreCase))

src/Components/Components/src/RenderTree/RenderTreeDiffBuilder.cs

@@ -520,8 +520,8 @@ namespace Microsoft.AspNetCore.Components.RenderTree
             // comparisons it wants with the old values. Later we could choose to pass the
             // old parameter values if we wanted. By default, components always rerender
             // after any SetParameters call, which is safe but now always optimal for perf.
-            var oldParameters = new ParameterCollection(oldTree, oldComponentIndex);
+            var oldParameters = new ParameterView(oldTree, oldComponentIndex);
-            var newParameters = new ParameterCollection(newTree, newComponentIndex);
+            var newParameters = new ParameterView(newTree, newComponentIndex);
             if (!newParameters.DefinitelyEquals(oldParameters))
             {
                 componentState.SetDirectParameters(newParameters);
@@ -894,7 +894,7 @@ namespace Microsoft.AspNetCore.Components.RenderTree
             var childComponentState = frame.ComponentState;
 
             // Set initial parameters
-            var initialParameters = new ParameterCollection(frames, frameIndex);
+            var initialParameters = new ParameterView(frames, frameIndex);
             childComponentState.SetDirectParameters(initialParameters);
         }
 

src/Components/Components/src/Rendering/ComponentState.cs

@@ -105,7 +105,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             return Task.CompletedTask;
         }
 
-        public void SetDirectParameters(ParameterCollection parameters)
+        public void SetDirectParameters(ParameterView parameters)
         {
             // Note: We should be careful to ensure that the framework never calls
             // IComponent.SetParameters directly elsewhere. We should only call it
@@ -137,8 +137,8 @@ namespace Microsoft.AspNetCore.Components.Rendering
         public void NotifyCascadingValueChanged()
         {
             var directParams = _latestDirectParametersSnapshot != null
-                ? new ParameterCollection(_latestDirectParametersSnapshot.Buffer, 0)
+                ? new ParameterView(_latestDirectParametersSnapshot.Buffer, 0)
-                : ParameterCollection.Empty;
+                : ParameterView.Empty;
             var allParams = directParams.WithCascadingParameters(_cascadingParameters);
             var task = Component.SetParametersAsync(allParams);
             _renderer.AddToPendingTasks(task);

src/Components/Components/src/Rendering/HtmlRenderer.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Components.RenderTree;
@@ -49,9 +48,9 @@ namespace Microsoft.AspNetCore.Components.Rendering
         /// of the HTML produced by the component.
         /// </summary>
         /// <param name="componentType">The type of the <see cref="IComponent"/>.</param>
-        /// <param name="initialParameters">A <see cref="ParameterCollection"/> with the initial parameters to render the component.</param>
+        /// <param name="initialParameters">A <see cref="ParameterView"/> with the initial parameters to render the component.</param>
         /// <returns>A <see cref="Task"/> that on completion returns a sequence of <see cref="string"/> fragments that represent the HTML text of the component.</returns>
-        public async Task<ComponentRenderedText> RenderComponentAsync(Type componentType, ParameterCollection initialParameters)
+        public async Task<ComponentRenderedText> RenderComponentAsync(Type componentType, ParameterView initialParameters)
         {
             var (componentId, frames) = await CreateInitialRenderAsync(componentType, initialParameters);
 
@@ -66,9 +65,9 @@ namespace Microsoft.AspNetCore.Components.Rendering
         /// of the HTML produced by the component.
         /// </summary>
         /// <typeparam name="TComponent">The type of the <see cref="IComponent"/>.</typeparam>
-        /// <param name="initialParameters">A <see cref="ParameterCollection"/> with the initial parameters to render the component.</param>
+        /// <param name="initialParameters">A <see cref="ParameterView"/> with the initial parameters to render the component.</param>
         /// <returns>A <see cref="Task"/> that on completion returns a sequence of <see cref="string"/> fragments that represent the HTML text of the component.</returns>
-        public Task<ComponentRenderedText> RenderComponentAsync<TComponent>(ParameterCollection initialParameters) where TComponent : IComponent
+        public Task<ComponentRenderedText> RenderComponentAsync<TComponent>(ParameterView initialParameters) where TComponent : IComponent
         {
             return RenderComponentAsync(typeof(TComponent), initialParameters);
         }
@@ -224,7 +223,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             return position + maxElements;
         }
 
-        private async Task<(int, ArrayRange<RenderTreeFrame>)> CreateInitialRenderAsync(Type componentType, ParameterCollection initialParameters)
+        private async Task<(int, ArrayRange<RenderTreeFrame>)> CreateInitialRenderAsync(Type componentType, ParameterView initialParameters)
         {
             var component = InstantiateComponent(componentType);
             var componentId = AssignRootComponentId(component);

src/Components/Components/src/Rendering/Renderer.cs

@@ -109,7 +109,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
         /// </remarks>
         protected Task RenderRootComponentAsync(int componentId)
         {
-            return RenderRootComponentAsync(componentId, ParameterCollection.Empty);
+            return RenderRootComponentAsync(componentId, ParameterView.Empty);
         }
 
         /// <summary>
@@ -120,12 +120,12 @@ namespace Microsoft.AspNetCore.Components.Rendering
         /// this more than once.
         /// </summary>
         /// <param name="componentId">The ID returned by <see cref="AssignRootComponentId(IComponent)"/>.</param>
-        /// <param name="initialParameters">The <see cref="ParameterCollection"/>with the initial parameters to use for rendering.</param>
+        /// <param name="initialParameters">The <see cref="ParameterView"/>with the initial parameters to use for rendering.</param>
         /// <remarks>
         /// Rendering a root component is an asynchronous operation. Clients may choose to not await the returned task to
         /// start, but not wait for the entire render to complete.
         /// </remarks>
-        protected async Task RenderRootComponentAsync(int componentId, ParameterCollection initialParameters)
+        protected async Task RenderRootComponentAsync(int componentId, ParameterView initialParameters)
         {
             if (Interlocked.CompareExchange(ref _pendingTasks, new List<Task>(), null) != null)
             {

src/Components/Components/src/Routing/Router.cs

@@ -66,7 +66,7 @@ namespace Microsoft.AspNetCore.Components.Routing
         }
 
         /// <inheritdoc />
-        public Task SetParametersAsync(ParameterCollection parameters)
+        public Task SetParametersAsync(ParameterView parameters)
         {
             parameters.SetParameterProperties(this);
             Routes = RouteTableFactory.Create(AppAssembly);

src/Components/Components/test/CascadingParameterStateTest.cs

@@ -386,7 +386,7 @@ namespace Microsoft.AspNetCore.Components.Test
                 supplierParams.Add("Name", name);
             }
 
-            renderer.Dispatcher.InvokeAsync((Action)(() => supplier.SetParametersAsync(ParameterCollection.FromDictionary(supplierParams))));
+            renderer.Dispatcher.InvokeAsync((Action)(() => supplier.SetParametersAsync(ParameterView.FromDictionary(supplierParams))));
             return supplier;
         }
 
@@ -427,7 +427,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
 

src/Components/Components/test/CascadingParameterTest.cs

@@ -383,7 +383,7 @@ namespace Microsoft.AspNetCore.Components.Test
             [CascadingParameter] T CascadingParameter { get; set; }
             [Parameter] public string RegularParameter { get; set; }
 
-            public override async Task SetParametersAsync(ParameterCollection parameters)
+            public override async Task SetParametersAsync(ParameterView parameters)
             {
                 NumSetParametersCalls++;
                 await base.SetParametersAsync(parameters);

src/Components/Components/test/ComponentFactoryTest.cs

@@ -103,7 +103,7 @@ namespace Microsoft.AspNetCore.Components
                 throw new NotImplementedException();
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 throw new NotImplementedException();
             }
@@ -130,7 +130,7 @@ namespace Microsoft.AspNetCore.Components
                 throw new NotImplementedException();
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 throw new NotImplementedException();
             }
@@ -148,7 +148,7 @@ namespace Microsoft.AspNetCore.Components
                 throw new NotImplementedException();
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 throw new NotImplementedException();
             }

src/Components/Components/test/DependencyInjectionTest.cs

@@ -197,7 +197,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
     }

src/Components/Components/test/EventCallbackFactoryBinderExtensionsTest.cs

@@ -667,7 +667,7 @@ namespace Microsoft.AspNetCore.Components
                 throw new System.NotImplementedException();
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 throw new System.NotImplementedException();
             }

src/Components/Components/test/EventCallbackFactoryTest.cs

@@ -645,7 +645,7 @@ namespace Microsoft.AspNetCore.Components
                 throw new NotImplementedException();
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 throw new NotImplementedException();
             }

src/Components/Components/test/EventCallbackTest.cs

@@ -451,7 +451,7 @@ namespace Microsoft.AspNetCore.Components
 
             public void Attach(RenderHandle renderHandle) => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters) => throw new NotImplementedException();
+            public Task SetParametersAsync(ParameterView parameters) => throw new NotImplementedException();
         }
     }
 }

src/Components/Components/test/PageDisplayTest.cs

@@ -27,7 +27,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void DisplaysComponentInsideLayout()
         {
             // Arrange/Act
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(ComponentWithLayout) }
             })));
@@ -84,7 +84,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void DisplaysComponentInsideNestedLayout()
         {
             // Arrange/Act
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(ComponentWithNestedLayout) }
             })));
@@ -111,13 +111,13 @@ namespace Microsoft.AspNetCore.Components.Test
         public void CanChangeDisplayedPageWithSameLayout()
         {
             // Arrange
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(ComponentWithLayout) }
             })));
 
             // Act
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(DifferentComponentWithLayout) }
             })));
@@ -162,13 +162,13 @@ namespace Microsoft.AspNetCore.Components.Test
         public void CanChangeDisplayedPageWithDifferentLayout()
         {
             // Arrange
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(ComponentWithLayout) }
             })));
 
             // Act
-            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            _renderer.Dispatcher.InvokeAsync(() => _pageDisplayComponent.SetParametersAsync(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 { nameof(PageDisplay.Page), typeof(ComponentWithNestedLayout) }
             })));

src/Components/Components/test/ParameterViewTest.Assignment.cs

@@ -10,16 +10,16 @@ using Microsoft.AspNetCore.Components.RenderTree;
 using Microsoft.AspNetCore.Components.Test.Helpers;
 using Xunit;
 
-namespace Microsoft.AspNetCore.Components.Test
+namespace Microsoft.AspNetCore.Components
 {
-    public class ParameterCollectionAssignmentExtensionsTest
+    public partial class ParameterViewTest
     {
         [Fact]
         public void IncomingParameterMatchesAnnotatedPrivateProperty_SetsValue()
         {
             // Arrange
             var someObject = new object();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasInstanceProperties.IntProp), 123 },
                 { nameof(HasInstanceProperties.StringProp), "Hello" },
@@ -28,7 +28,7 @@ namespace Microsoft.AspNetCore.Components.Test
             var target = new HasInstanceProperties();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
@@ -40,14 +40,14 @@ namespace Microsoft.AspNetCore.Components.Test
         public void IncomingParameterMatchesDeclaredParameterCaseInsensitively_SetsValue()
         {
             // Arrange
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasInstanceProperties.IntProp).ToLowerInvariant(), 123 }
             }.Build();
             var target = new HasInstanceProperties();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
@@ -57,7 +57,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void IncomingParameterMatchesInheritedDeclaredParameter_SetsValue()
         {
             // Arrange
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasInheritedProperties.IntProp), 123 },
                 { nameof(HasInheritedProperties.DerivedClassIntProp), 456 },
@@ -65,7 +65,7 @@ namespace Microsoft.AspNetCore.Components.Test
             var target = new HasInheritedProperties();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(123, target.IntProp);
@@ -84,10 +84,10 @@ namespace Microsoft.AspNetCore.Components.Test
                 ObjectPropCurrentValue = existingObjectValue
             };
 
-            var parameterCollection = new ParameterCollectionBuilder().Build();
+            var parameters = new ParameterViewBuilder().Build();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(456, target.IntProp);
@@ -100,14 +100,14 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasPropertyWithoutParameterAttribute();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { "AnyOtherKey", 123 },
             }.Build();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.SetParameterProperties(target));
+                () => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -121,14 +121,14 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasPropertyWithoutParameterAttribute();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasPropertyWithoutParameterAttribute.IntProp), 123 },
             }.Build();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.SetParameterProperties(target));
+                () => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(default, target.IntProp);
@@ -144,13 +144,13 @@ namespace Microsoft.AspNetCore.Components.Test
             // Arrange
             var target = new HasCaptureUnmatchedValuesProperty();
             var value = new Dictionary<string, object>();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasCaptureUnmatchedValuesProperty.CaptureUnmatchedValues), value },
             }.Build();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Same(value, target.CaptureUnmatchedValues);
@@ -161,7 +161,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasCaptureUnmatchedValuesProperty();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasCaptureUnmatchedValuesProperty.StringProp), "hi" },
                 { "test1", 123 },
@@ -169,7 +169,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }.Build();
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal("hi", target.StringProp);
@@ -192,7 +192,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasCaptureUnmatchedValuesProperty();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasCaptureUnmatchedValuesProperty.CaptureUnmatchedValues), new Dictionary<string, object>() },
                 { "test1", 123 },
@@ -200,7 +200,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }.Build();
 
             // Act
-            var ex = Assert.Throws<InvalidOperationException>(() => parameterCollection.SetParameterProperties(target));
+            var ex = Assert.Throws<InvalidOperationException>(() => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -216,7 +216,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasCaptureUnmatchedValuesProperty();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { "test2", 456 },
                 { "test1", 123 },
@@ -224,7 +224,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }.Build();
 
             // Act
-            var ex = Assert.Throws<InvalidOperationException>(() => parameterCollection.SetParameterProperties(target));
+            var ex = Assert.Throws<InvalidOperationException>(() => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -240,10 +240,10 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasDupliateCaptureUnmatchedValuesProperty();
-            var parameterCollection = new ParameterCollectionBuilder().Build();
+            var parameters = new ParameterViewBuilder().Build();
 
             // Act
-            var ex = Assert.Throws<InvalidOperationException>(() => parameterCollection.SetParameterProperties(target));
+            var ex = Assert.Throws<InvalidOperationException>(() => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -261,10 +261,10 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasWrongTypeCaptureUnmatchedValuesProperty();
-            var parameterCollection = new ParameterCollectionBuilder().Build();
+            var parameters = new ParameterViewBuilder().Build();
 
             // Act
-            var ex = Assert.Throws<InvalidOperationException>(() => parameterCollection.SetParameterProperties(target));
+            var ex = Assert.Throws<InvalidOperationException>(() => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -279,7 +279,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var someObject = new object();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasInstanceProperties.IntProp), "string value" },
             }.Build();
@@ -287,7 +287,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.SetParameterProperties(target));
+                () => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -301,14 +301,14 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var target = new HasPropertyWhoseSetterThrows();
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasPropertyWhoseSetterThrows.StringProp), "anything" },
             }.Build();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => parameterCollection.SetParameterProperties(target));
+                () => parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -321,12 +321,12 @@ namespace Microsoft.AspNetCore.Components.Test
         public void DeclaredParametersVaryOnlyByCase_Throws()
         {
             // Arrange
-            var parameterCollection = new ParameterCollectionBuilder().Build();
+            var parameters = new ParameterViewBuilder().Build();
             var target = new HasParametersVaryingOnlyByCase();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(() =>
-                parameterCollection.SetParameterProperties(target));
+                parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -344,12 +344,12 @@ namespace Microsoft.AspNetCore.Components.Test
             // base class can legitimately depend on it for correct functioning.
 
             // Arrange
-            var parameterCollection = new ParameterCollectionBuilder().Build();
+            var parameters = new ParameterViewBuilder().Build();
             var target = new HasParameterClashingWithInherited();
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(() =>
-                parameterCollection.SetParameterProperties(target));
+                parameters.SetParameterProperties(target));
 
             // Assert
             Assert.Equal(
@@ -362,7 +362,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void SupplyingNullWritesDefaultForType()
         {
             // Arrange
-            var parameterCollection = new ParameterCollectionBuilder
+            var parameters = new ParameterViewBuilder
             {
                 { nameof(HasInstanceProperties.IntProp), null },
                 { nameof(HasInstanceProperties.StringProp), null },
@@ -370,7 +370,7 @@ namespace Microsoft.AspNetCore.Components.Test
             var target = new HasInstanceProperties { IntProp = 123, StringProp = "Hello" };
 
             // Act
-            parameterCollection.SetParameterProperties(target);
+            parameters.SetParameterProperties(target);
 
             // Assert
             Assert.Equal(0, target.IntProp);
@@ -446,7 +446,7 @@ namespace Microsoft.AspNetCore.Components.Test
             [Parameter(CaptureUnmatchedValues = true)] public KeyValuePair<string, object>[] CaptureUnmatchedValuesProp { get; set; }
         }
 
-        class ParameterCollectionBuilder : IEnumerable
+        class ParameterViewBuilder : IEnumerable
         {
             private readonly List<(string Name, object Value)> _keyValuePairs
                 = new List<(string, object)>();
@@ -457,7 +457,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public IEnumerator GetEnumerator()
                 => throw new NotImplementedException();
 
-            public ParameterCollection Build()
+            public ParameterView Build()
             {
                 var builder = new RenderTreeBuilder();
                 builder.OpenComponent<FakeComponent>(0);
@@ -466,17 +466,8 @@ namespace Microsoft.AspNetCore.Components.Test
                     builder.AddAttribute(1, kvp.Name, kvp.Value);
                 }
                 builder.CloseComponent();
-                return new ParameterCollection(builder.GetFrames().Array, ownerIndex: 0);
+                return new ParameterView(builder.GetFrames().Array, ownerIndex: 0);
             }
         }
-
-        class FakeComponent : IComponent
-        {
-            public void Attach(RenderHandle renderHandle)
-                => throw new NotImplementedException();
-
-            public Task SetParametersAsync(ParameterCollection parameters)
-                => throw new NotImplementedException();
-        }
     }
 }

src/Components/Components/test/ParameterViewTest.cs

@@ -8,9 +8,9 @@ using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.RenderTree;
 using Xunit;
 
-namespace Microsoft.AspNetCore.Components.Test
+namespace Microsoft.AspNetCore.Components
 {
-    public class ParameterCollectionTest
+    public partial class ParameterViewTest
     {
         [Fact]
         public void CanInitializeUsingComponentWithNoDescendants()
@@ -20,10 +20,10 @@ namespace Microsoft.AspNetCore.Components.Test
             {
                 RenderTreeFrame.ChildComponent(0, typeof(FakeComponent)).WithComponentSubtreeLength(1)
             };
-            var parameterCollection = new ParameterCollection(frames, 0);
+            var parameters = new ParameterView(frames, 0);
 
             // Assert
-            Assert.Empty(ToEnumerable(parameterCollection));
+            Assert.Empty(ToEnumerable(parameters));
         }
 
         [Fact]
@@ -34,10 +34,10 @@ namespace Microsoft.AspNetCore.Components.Test
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(1)
             };
-            var parameterCollection = new ParameterCollection(frames, 0);
+            var parameters = new ParameterView(frames, 0);
 
             // Assert
-            Assert.Empty(ToEnumerable(parameterCollection));
+            Assert.Empty(ToEnumerable(parameters));
         }
 
         [Fact]
@@ -52,14 +52,14 @@ namespace Microsoft.AspNetCore.Components.Test
                 RenderTreeFrame.Attribute(1, "attribute 1", attribute1Value),
                 RenderTreeFrame.Attribute(2, "attribute 2", attribute2Value),
                 // Although RenderTreeBuilder doesn't let you add orphaned attributes like this,
-                // still want to verify that ParameterCollection doesn't attempt to read past the
+                // still want to verify that parameters doesn't attempt to read past the
                 // end of the owner's descendants
                 RenderTreeFrame.Attribute(3, "orphaned attribute", "value")
             };
-            var parameterCollection = new ParameterCollection(frames, 0);
+            var parameters = new ParameterView(frames, 0);
 
             // Assert
-            Assert.Collection(ToEnumerable(parameterCollection),
+            Assert.Collection(ToEnumerable(parameters),
                 AssertParameter("attribute 1", attribute1Value, false),
                 AssertParameter("attribute 2", attribute2Value, false));
         }
@@ -78,10 +78,10 @@ namespace Microsoft.AspNetCore.Components.Test
                 RenderTreeFrame.Element(3, "child element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(4, "child attribute", "some value")
             };
-            var parameterCollection = new ParameterCollection(frames, 0);
+            var parameters = new ParameterView(frames, 0);
 
             // Assert
-            Assert.Collection(ToEnumerable(parameterCollection),
+            Assert.Collection(ToEnumerable(parameters),
                 AssertParameter("attribute 1", attribute1Value, false),
                 AssertParameter("attribute 2", attribute2Value, false));
         }
@@ -93,7 +93,7 @@ namespace Microsoft.AspNetCore.Components.Test
             var attribute1Value = new object();
             var attribute2Value = new object();
             var attribute3Value = new object();
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "attribute 1", attribute1Value)
@@ -104,7 +104,7 @@ namespace Microsoft.AspNetCore.Components.Test
             });
 
             // Assert
-            Assert.Collection(ToEnumerable(parameterCollection),
+            Assert.Collection(ToEnumerable(parameters),
                 AssertParameter("attribute 1", attribute1Value, false),
                 AssertParameter("attribute 2", attribute2Value, true),
                 AssertParameter("attribute 3", attribute3Value, true));
@@ -114,14 +114,14 @@ namespace Microsoft.AspNetCore.Components.Test
         public void CanTryGetNonExistingValue()
         {
             // Arrange
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "some other entry", new object())
             }, 0);
 
             // Act
-            var didFind = parameterCollection.TryGetValue<string>("nonexisting entry", out var value);
+            var didFind = parameters.TryGetValue<string>("nonexisting entry", out var value);
 
             // Assert
             Assert.False(didFind);
@@ -132,14 +132,14 @@ namespace Microsoft.AspNetCore.Components.Test
         public void CanTryGetExistingValueWithCorrectType()
         {
             // Arrange
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "my entry", "hello")
             }, 0);
 
             // Act
-            var didFind = parameterCollection.TryGetValue<string>("my entry", out var value);
+            var didFind = parameters.TryGetValue<string>("my entry", out var value);
 
             // Assert
             Assert.True(didFind);
@@ -151,7 +151,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var myEntryValue = new object();
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "my entry", myEntryValue),
@@ -159,7 +159,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }, 0);
 
             // Act
-            var result = parameterCollection.GetValueOrDefault<object>("my entry");
+            var result = parameters.GetValueOrDefault<object>("my entry");
 
             // Assert
             Assert.Same(myEntryValue, result);
@@ -170,7 +170,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var myEntryValue = new object();
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                 RenderTreeFrame.Attribute(1, "my entry", myEntryValue),
@@ -178,7 +178,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }, 0);
 
             // Act
-            var result = parameterCollection.GetValueOrDefault<object>("my entry");
+            var result = parameters.GetValueOrDefault<object>("my entry");
 
             // Assert: Picks first match
             Assert.Same(myEntryValue, result);
@@ -188,7 +188,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void CanGetValueOrDefault_WithNonExistingValue()
         {
             // Arrange
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "some other entry", new object())
@@ -198,7 +198,7 @@ namespace Microsoft.AspNetCore.Components.Test
             });
 
             // Act
-            var result = parameterCollection.GetValueOrDefault<DateTime>("nonexisting entry");
+            var result = parameters.GetValueOrDefault<DateTime>("nonexisting entry");
 
             // Assert
             Assert.Equal(default, result);
@@ -209,14 +209,14 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var explicitDefaultValue = new DateTime(2018, 3, 20);
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "some other entry", new object())
             }, 0);
 
             // Act
-            var result = parameterCollection.GetValueOrDefault("nonexisting entry", explicitDefaultValue);
+            var result = parameters.GetValueOrDefault("nonexisting entry", explicitDefaultValue);
 
             // Assert
             Assert.Equal(explicitDefaultValue, result);
@@ -226,7 +226,7 @@ namespace Microsoft.AspNetCore.Components.Test
         public void ThrowsIfTryGetExistingValueWithIncorrectType()
         {
             // Arrange
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "my entry", "hello")
@@ -235,7 +235,7 @@ namespace Microsoft.AspNetCore.Components.Test
             // Act/Assert
             Assert.Throws<InvalidCastException>(() =>
             {
-                parameterCollection.TryGetValue<bool>("my entry", out var value);
+                parameters.TryGetValue<bool>("my entry", out var value);
             });
         }
 
@@ -246,7 +246,7 @@ namespace Microsoft.AspNetCore.Components.Test
             var dictionary = new Dictionary<string, object>();
 
             // Act
-            var collection = ParameterCollection.FromDictionary(dictionary);
+            var collection = ParameterView.FromDictionary(dictionary);
 
             // Assert
             Assert.Empty(collection.ToDictionary());
@@ -263,7 +263,7 @@ namespace Microsoft.AspNetCore.Components.Test
             };
 
             // Act
-            var collection = ParameterCollection.FromDictionary(dictionary);
+            var collection = ParameterView.FromDictionary(dictionary);
 
             // Assert
             Assert.Equal(dictionary, collection.ToDictionary());
@@ -275,7 +275,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var entry2Value = new object();
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(3),
                 RenderTreeFrame.Attribute(0, "entry 1", "value 1"),
@@ -283,7 +283,7 @@ namespace Microsoft.AspNetCore.Components.Test
             }, 0);
 
             // Act
-            IReadOnlyDictionary<string, object> dict = parameterCollection.ToDictionary();
+            IReadOnlyDictionary<string, object> dict = parameters.ToDictionary();
 
             // Assert
             Assert.Collection(dict,
@@ -304,7 +304,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             // Arrange
             var myEntryValue = new object();
-            var parameterCollection = new ParameterCollection(new[]
+            var parameters = new ParameterView(new[]
             {
                 RenderTreeFrame.Element(0, "some element").WithElementSubtreeLength(2),
                 RenderTreeFrame.Attribute(1, "unrelated value", new object())
@@ -316,13 +316,13 @@ namespace Microsoft.AspNetCore.Components.Test
             });
 
             // Act
-            var result = parameterCollection.GetValueOrDefault<object>("my entry");
+            var result = parameters.GetValueOrDefault<object>("my entry");
 
             // Assert
             Assert.Same(myEntryValue, result);
         }
 
-        private Action<Parameter> AssertParameter(string expectedName, object expectedValue, bool expectedIsCascading)
+        private Action<ParameterValue> AssertParameter(string expectedName, object expectedValue, bool expectedIsCascading)
         {
             return parameter =>
             {
@@ -332,9 +332,9 @@ namespace Microsoft.AspNetCore.Components.Test
             };
         }
 
-        public IEnumerable<Parameter> ToEnumerable(ParameterCollection parameterCollection)
+        public IEnumerable<ParameterValue> ToEnumerable(ParameterView parameters)
         {
-            foreach (var item in parameterCollection)
+            foreach (var item in parameters)
             {
                 yield return item;
             }
@@ -345,7 +345,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
 

src/Components/Components/test/RenderTreeBuilderTest.cs

@@ -1803,7 +1803,7 @@ namespace Microsoft.AspNetCore.Components.Test
         {
             public void Attach(RenderHandle renderHandle) { }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
 

src/Components/Components/test/RenderTreeDiffBuilderTest.cs

@@ -2222,7 +2222,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public string NonParameterProperty { get; set; }
 
             public void Attach(RenderHandle renderHandle) { }
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 parameters.SetParameterProperties(this);
                 return Task.CompletedTask;
@@ -2235,7 +2235,7 @@ namespace Microsoft.AspNetCore.Components.Test
             {
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters) => Task.CompletedTask;
+            public Task SetParametersAsync(ParameterView parameters) => Task.CompletedTask;
         }
 
         private class CaptureSetParametersComponent : IComponent
@@ -2246,7 +2246,7 @@ namespace Microsoft.AspNetCore.Components.Test
             {
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 SetParametersCallCount++;
                 return Task.CompletedTask;
@@ -2260,14 +2260,14 @@ namespace Microsoft.AspNetCore.Components.Test
 
             public void Attach(RenderHandle renderHandle) { }
 
-            public Task SetParametersAsync(ParameterCollection parameters) => Task.CompletedTask;
+            public Task SetParametersAsync(ParameterView parameters) => Task.CompletedTask;
         }
 
         private class NonDisposableComponent : IComponent
         {
             public void Attach(RenderHandle renderHandle) { }
 
-            public Task SetParametersAsync(ParameterCollection parameters) => Task.CompletedTask;
+            public Task SetParametersAsync(ParameterView parameters) => Task.CompletedTask;
         }
 
         private static void AssertEdit(

src/Components/Components/test/RendererTest.cs

@@ -239,7 +239,7 @@ namespace Microsoft.AspNetCore.Components.Test
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
             var log = new ConcurrentQueue<(int id, NestedAsyncComponent.EventType @event)>();
-            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [EventActionsName] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -283,7 +283,7 @@ namespace Microsoft.AspNetCore.Components.Test
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
             var log = new ConcurrentQueue<(int id, NestedAsyncComponent.EventType @event)>();
-            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [EventActionsName] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -327,7 +327,7 @@ namespace Microsoft.AspNetCore.Components.Test
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
             var log = new ConcurrentQueue<(int id, NestedAsyncComponent.EventType @event)>();
-            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [EventActionsName] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -371,7 +371,7 @@ namespace Microsoft.AspNetCore.Components.Test
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
             var log = new ConcurrentQueue<(int id, NestedAsyncComponent.EventType @event)>();
-            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            await renderer.Dispatcher.InvokeAsync(() => renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [EventActionsName] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -2776,7 +2776,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var task = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var task = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -2809,7 +2809,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -2842,7 +2842,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -2876,7 +2876,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -2957,7 +2957,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3015,7 +3015,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3070,7 +3070,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3124,7 +3124,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3158,7 +3158,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var renderTask = renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3195,7 +3195,7 @@ namespace Microsoft.AspNetCore.Components.Test
 
             // Act/Assert
             var componentId = renderer.AssignRootComponentId(component);
-            await renderer.RenderRootComponentAsync(componentId, ParameterCollection.FromDictionary(new Dictionary<string, object>
+            await renderer.RenderRootComponentAsync(componentId, ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(NestedAsyncComponent.EventActions)] = new Dictionary<int, IList<NestedAsyncComponent.ExecutionAction>>
                 {
@@ -3428,7 +3428,7 @@ namespace Microsoft.AspNetCore.Components.Test
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 TriggerRender();
                 return Task.CompletedTask;
@@ -3497,7 +3497,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => RenderHandle = renderHandle;
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 parameters.SetParameterProperties(this);
                 return Task.CompletedTask;
@@ -3646,7 +3646,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => _renderHandle = renderHandle;
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 parameters.SetParameterProperties(this);
                 Render();
@@ -3677,7 +3677,7 @@ namespace Microsoft.AspNetCore.Components.Test
             public void Attach(RenderHandle renderHandle)
                 => _renderHandles.Add(renderHandle);
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 return Task.CompletedTask;
             }
@@ -3734,7 +3734,7 @@ namespace Microsoft.AspNetCore.Components.Test
                 return Task.CompletedTask;
             }
 
-            Task IComponent.SetParametersAsync(ParameterCollection parameters)
+            Task IComponent.SetParametersAsync(ParameterView parameters)
             {
                 TriggerRender();
                 return Task.CompletedTask;
@@ -3793,7 +3793,7 @@ namespace Microsoft.AspNetCore.Components.Test
                 _renderHandler = renderHandle;
             }
 
-            public async Task SetParametersAsync(ParameterCollection parameters)
+            public async Task SetParametersAsync(ParameterView parameters)
             {
                 int n;
                 while (Number > 0)
@@ -3842,7 +3842,7 @@ namespace Microsoft.AspNetCore.Components.Test
                 return task;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 return TriggerRenderAsync();
             }

src/Components/Components/test/Rendering/HtmlRendererTestBase.cs

@@ -32,7 +32,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -52,7 +52,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -72,7 +72,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -93,7 +93,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -116,7 +116,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -150,7 +150,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -172,7 +172,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -193,7 +193,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -214,7 +214,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -237,7 +237,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -267,7 +267,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -296,7 +296,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -326,7 +326,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -339,7 +339,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var expectedHtml = new[] {
                 "<", "p", ">", "<", "input", " ", "value", "=", "\"", "5", "\"", " />", "</", "p", ">" };
 
-            RenderFragment Content(ParameterCollection pc) => new RenderFragment((RenderTreeBuilder rtb) =>
+            RenderFragment Content(ParameterView pc) => new RenderFragment((RenderTreeBuilder rtb) =>
             {
                 rtb.OpenElement(0, "p");
                 rtb.OpenElement(1, "input");
@@ -350,7 +350,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             });
 
             var serviceProvider = new ServiceCollection()
-                .AddSingleton(new Func<ParameterCollection, RenderFragment>(Content))
+                .AddSingleton(new Func<ParameterView, RenderFragment>(Content))
                 .BuildServiceProvider();
 
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
@@ -358,7 +358,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
 
             // Act
             var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<ComponentWithParameters>(
-                new ParameterCollection(new[] {
+                new ParameterView(new[] {
                     RenderTreeFrame.Element(0,string.Empty),
                     RenderTreeFrame.Attribute(1,"update",change),
                     RenderTreeFrame.Attribute(2,"value",5)
@@ -388,7 +388,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -415,7 +415,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty)));
+            var result = GetResult(htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<TestComponent>(ParameterView.Empty)));
 
             // Assert
             Assert.Equal(expectedHtml, result);
@@ -445,9 +445,9 @@ namespace Microsoft.AspNetCore.Components.Rendering
             }
 
             [Inject]
-            Func<ParameterCollection, RenderFragment> CreateRenderFragment { get; set; }
+            Func<ParameterView, RenderFragment> CreateRenderFragment { get; set; }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 RenderHandle.Render(CreateRenderFragment(parameters));
                 return Task.CompletedTask;
@@ -465,7 +465,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = await htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<AsyncComponent>(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var result = await htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<AsyncComponent>(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 ["Value"] = 10
             })));
@@ -489,7 +489,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
             var htmlRenderer = GetHtmlRenderer(serviceProvider);
 
             // Act
-            var result = await htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<NestedAsyncComponent>(ParameterCollection.FromDictionary(new Dictionary<string, object>
+            var result = await htmlRenderer.Dispatcher.InvokeAsync(() => htmlRenderer.RenderComponentAsync<NestedAsyncComponent>(ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 ["Nested"] = false,
                 ["Value"] = 10
@@ -558,13 +558,13 @@ namespace Microsoft.AspNetCore.Components.Rendering
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 _renderHandle.Render(CreateRenderFragment(parameters));
                 return Task.CompletedTask;
             }
 
-            private RenderFragment CreateRenderFragment(ParameterCollection parameters)
+            private RenderFragment CreateRenderFragment(ParameterView parameters)
             {
                 return RenderFragment;
 
@@ -589,7 +589,7 @@ namespace Microsoft.AspNetCore.Components.Rendering
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 _renderHandle.Render(Fragment);
                 return Task.CompletedTask;

src/Components/Server/ref/Microsoft.AspNetCore.Components.Server.netcoreapp3.0.cs

@@ -41,7 +41,7 @@ namespace Microsoft.AspNetCore.Components.Server
         public ComponentPrerenderingContext() { }
         public System.Type ComponentType { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
         public Microsoft.AspNetCore.Http.HttpContext Context { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
-        public Microsoft.AspNetCore.Components.ParameterCollection Parameters { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
+        public Microsoft.AspNetCore.Components.ParameterView Parameters { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
     }
     public sealed partial class ComponentPrerenderResult
     {

src/Components/Server/src/Circuits/CircuitHost.cs

@@ -96,7 +96,7 @@ namespace Microsoft.AspNetCore.Components.Server.Circuits
 
         public IServiceProvider Services { get; }
 
-        public Task<ComponentRenderedText> PrerenderComponentAsync(Type componentType, ParameterCollection parameters)
+        public Task<ComponentRenderedText> PrerenderComponentAsync(Type componentType, ParameterView parameters)
         {
             return Renderer.Dispatcher.InvokeAsync(async () =>
             {

src/Components/Server/src/Prerendering/ComponentPrerenderingContext.cs

@@ -19,7 +19,7 @@ namespace Microsoft.AspNetCore.Components.Server
         /// <summary>
         /// Gets or sets the parameters for the component.
         /// </summary>
-        public ParameterCollection Parameters { get; set; }
+        public ParameterView Parameters { get; set; }
 
         /// <summary>
         /// Gets or sets the <see cref="HttpContext"/> in which the prerendering has been initiated.

src/Components/Server/test/Circuits/CircuitHostTest.cs

@@ -275,7 +275,7 @@ namespace Microsoft.AspNetCore.Components.Server.Circuits
             public bool DidCallDispose { get; private set; }
             public void Attach(RenderHandle renderHandle) { }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => Task.CompletedTask;
 
             public void Dispose()

src/Components/Server/test/Circuits/CircuitPrerendererTest.cs

@@ -55,7 +55,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
             var prerenderingContext = new ComponentPrerenderingContext
             {
                 ComponentType = typeof(UriDisplayComponent),
-                Parameters = ParameterCollection.Empty,
+                Parameters = ParameterView.Empty,
                 Context = httpContext
             };
 
@@ -109,7 +109,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
             var prerenderingContext = new ComponentPrerenderingContext
             {
                 ComponentType = typeof(UriDisplayComponent),
-                Parameters = ParameterCollection.Empty,
+                Parameters = ParameterView.Empty,
                 Context = httpContext
             };
 
@@ -145,7 +145,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
             var prerenderingContext = new ComponentPrerenderingContext
             {
                 ComponentType = typeof(UriDisplayComponent),
-                Parameters = ParameterCollection.Empty,
+                Parameters = ParameterView.Empty,
                 Context = httpContext
             };
 
@@ -170,7 +170,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
             var prerenderingContext = new ComponentPrerenderingContext
             {
                 ComponentType = typeof(ThrowExceptionComponent),
-                Parameters = ParameterCollection.Empty,
+                Parameters = ParameterView.Empty,
                 Context = httpContext
             };
 
@@ -227,7 +227,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 _renderHandle.Render(builder =>
                 {
@@ -246,7 +246,7 @@ namespace Microsoft.AspNetCore.Components.Server.Tests.Circuits
             public void Attach(RenderHandle renderHandle)
                 => throw new InvalidTimeZoneException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                  => Task.CompletedTask;
         }
     }

src/Components/Server/test/Circuits/RemoteRendererTest.cs

@@ -139,7 +139,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
 
             // This produces the initial batch (id = 2)
             var result = await renderer.RenderComponentAsync<AutoParameterTestComponent>(
-            ParameterCollection.FromDictionary(new Dictionary<string, object>
+            ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(AutoParameterTestComponent.Content)] = initialContent,
                 [nameof(AutoParameterTestComponent.Trigger)] = trigger
@@ -202,7 +202,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
 
             // This produces the initial batch (id = 2)
             var result = await renderer.RenderComponentAsync<AutoParameterTestComponent>(
-            ParameterCollection.FromDictionary(new Dictionary<string, object>
+            ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(AutoParameterTestComponent.Content)] = initialContent,
                 [nameof(AutoParameterTestComponent.Trigger)] = trigger
@@ -265,7 +265,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
 
             // This produces the initial batch (id = 2)
             var result = await renderer.RenderComponentAsync<AutoParameterTestComponent>(
-            ParameterCollection.FromDictionary(new Dictionary<string, object>
+            ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(AutoParameterTestComponent.Content)] = initialContent,
                 [nameof(AutoParameterTestComponent.Trigger)] = trigger
@@ -322,7 +322,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
 
             // This produces the initial batch (id = 2)
             var result = await renderer.RenderComponentAsync<AutoParameterTestComponent>(
-            ParameterCollection.FromDictionary(new Dictionary<string, object>
+            ParameterView.FromDictionary(new Dictionary<string, object>
             {
                 [nameof(AutoParameterTestComponent.Content)] = initialContent,
                 [nameof(AutoParameterTestComponent.Trigger)] = trigger
@@ -366,8 +366,8 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
                 new CircuitClientProxy());
 
             // Act
-            var first = await renderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty);
+            var first = await renderer.RenderComponentAsync<TestComponent>(ParameterView.Empty);
-            var second = await renderer.RenderComponentAsync<TestComponent>(ParameterCollection.Empty);
+            var second = await renderer.RenderComponentAsync<TestComponent>(ParameterView.Empty);
 
             // Assert
             Assert.Equal(0, first.ComponentId);
@@ -427,7 +427,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
                 return Task.CompletedTask;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 TriggerRender();
                 return Task.CompletedTask;
@@ -453,7 +453,7 @@ namespace Microsoft.AspNetCore.Components.Web.Rendering
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 Content = parameters.GetValueOrDefault<RenderFragment>(nameof(Content));
                 Trigger ??= parameters.GetValueOrDefault<Trigger>(nameof(Trigger));

src/Components/Server/test/Circuits/RenderBatchWriterTest.cs

@@ -374,7 +374,7 @@ namespace Microsoft.AspNetCore.Components.Server
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
 

src/Components/Shared/test/AutoRenderComponent.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Components.Test.Helpers
             _renderHandle = renderHandle;
         }
 
-        public virtual Task SetParametersAsync(ParameterCollection parameters)
+        public virtual Task SetParametersAsync(ParameterView parameters)
         {
             parameters.SetParameterProperties(this);
             TriggerRender();

src/Components/Shared/test/IComponentExtensions.cs

@@ -13,27 +13,7 @@ namespace Microsoft.AspNetCore.Components.Test.Helpers
             this IComponent component,
             Dictionary<string, object> parameters)
         {
-            component.SetParametersAsync(DictionaryToParameterCollection(parameters));
+            component.SetParametersAsync(ParameterView.FromDictionary(parameters));
-        }
-
-        private static ParameterCollection DictionaryToParameterCollection(
-            IDictionary<string, object> parameters)
-        {
-            var builder = new RenderTreeBuilder();
-            builder.OpenComponent<AbstractComponent>(0);
-            foreach (var pair in parameters)
-            {
-                builder.AddAttribute(0, pair.Key, pair.Value);
-            }
-            builder.CloseElement();
-
-            return new ParameterCollection(builder.GetFrames().Array, 0);
-        }
-
-        private abstract class AbstractComponent : IComponent
-        {
-            public abstract void Attach(RenderHandle renderHandle);
-            public abstract Task SetParametersAsync(ParameterCollection parameters);
         }
     }
 }

src/Components/Shared/test/TestRenderer.cs

@@ -48,16 +48,16 @@ namespace Microsoft.AspNetCore.Components.Test.Helpers
         public new int AssignRootComponentId(IComponent component)
             => base.AssignRootComponentId(component);
 
-        public void RenderRootComponent(int componentId, ParameterCollection? parameters = default)
+        public void RenderRootComponent(int componentId, ParameterView? parameters = default)
         {
-            var task = Dispatcher.InvokeAsync(() => base.RenderRootComponentAsync(componentId, parameters ?? ParameterCollection.Empty));
+            var task = Dispatcher.InvokeAsync(() => base.RenderRootComponentAsync(componentId, parameters ?? ParameterView.Empty));
             UnwrapTask(task);
         }
 
         public new Task RenderRootComponentAsync(int componentId)
             => Dispatcher.InvokeAsync(() => base.RenderRootComponentAsync(componentId));
 
-        public new Task RenderRootComponentAsync(int componentId, ParameterCollection parameters)
+        public new Task RenderRootComponentAsync(int componentId, ParameterView parameters)
             => Dispatcher.InvokeAsync(() => base.RenderRootComponentAsync(componentId, parameters));
 
         public Task DispatchEventAsync(ulong eventHandlerId, UIEventArgs args)

src/Components/Web/ref/Microsoft.AspNetCore.Components.Web.netstandard2.0.cs

@@ -317,7 +317,7 @@ namespace Microsoft.AspNetCore.Components.Forms
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public System.Linq.Expressions.Expression<System.Func<T>> ValueExpression { [System.Runtime.CompilerServices.CompilerGeneratedAttribute]get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute]set { } }
         protected virtual string FormatValueAsString(T value) { throw null; }
-        public override System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterCollection parameters) { throw null; }
+        public override System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
         protected abstract bool TryParseValueFromString(string value, out T result, out string validationErrorMessage);
     }
     public partial class InputCheckbox : Microsoft.AspNetCore.Components.Forms.InputBase<bool>

src/Components/Web/src/Forms/InputBase.cs

@@ -168,7 +168,7 @@ namespace Microsoft.AspNetCore.Components.Forms
 
 
         /// <inheritdoc />
-        public override Task SetParametersAsync(ParameterCollection parameters)
+        public override Task SetParametersAsync(ParameterView parameters)
         {
             parameters.SetParameterProperties(this);
 
@@ -206,7 +206,7 @@ namespace Microsoft.AspNetCore.Components.Forms
             }
 
             // For derived components, retain the usual lifecycle with OnInit/OnParametersSet/etc.
-            return base.SetParametersAsync(ParameterCollection.Empty);
+            return base.SetParametersAsync(ParameterView.Empty);
         }
     }
 }

src/Components/test/Ignitor.Test/RenderBatchReaderTest.cs

@@ -331,7 +331,7 @@ namespace Ignitor
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
 

src/Components/test/testassets/Ignitor/RenderBatchReader.cs

@@ -310,7 +310,7 @@ namespace Ignitor
             public void Attach(RenderHandle renderHandle)
                 => throw new NotImplementedException();
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
                 => throw new NotImplementedException();
         }
     }

src/Mvc/Mvc.Components.Prerendering/src/HtmlHelperComponentPrerenderingExtensions.cs

@@ -58,8 +58,8 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
             }
 
             var parametersCollection = parameters == null ?
-                ParameterCollection.Empty :
+                ParameterView.Empty :
-                ParameterCollection.FromDictionary(HtmlHelper.ObjectToDictionary(parameters));
+                ParameterView.FromDictionary(HtmlHelper.ObjectToDictionary(parameters));
 
             var result = await prerenderer.PrerenderComponentAsync(
                 new ComponentPrerenderingContext

src/Mvc/Mvc.Components.Prerendering/test/HtmlHelperComponentPrerenderingExtensionsTests.cs

@@ -277,7 +277,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 _renderHandle.Render(builder =>
                 {

src/Mvc/Mvc.ViewFeatures/src/HtmlHelperRazorComponentExtensions.cs

@@ -52,8 +52,8 @@ namespace Microsoft.AspNetCore.Mvc.Rendering
             var prerenderer = serviceProvider.GetRequiredService<StaticComponentRenderer>();
 
             var parametersCollection = parameters == null ?
-                ParameterCollection.Empty :
+                ParameterView.Empty :
-                ParameterCollection.FromDictionary(HtmlHelper.ObjectToDictionary(parameters));
+                ParameterView.FromDictionary(HtmlHelper.ObjectToDictionary(parameters));
 
             var result = await prerenderer.PrerenderComponentAsync(
                 parametersCollection,

src/Mvc/Mvc.ViewFeatures/src/RazorComponents/StaticComponentRenderer.cs

@@ -26,7 +26,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.RazorComponents
         }
 
         public async Task<IEnumerable<string>> PrerenderComponentAsync(
-            ParameterCollection parameters,
+            ParameterView parameters,
             HttpContext httpContext,
             Type componentType)
         {

src/Mvc/Mvc.ViewFeatures/test/HtmlHelperComponentExtensionsTests.cs

@@ -256,7 +256,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Test
                 _renderHandle = renderHandle;
             }
 
-            public Task SetParametersAsync(ParameterCollection parameters)
+            public Task SetParametersAsync(ParameterView parameters)
             {
                 _renderHandle.Render(builder =>
                 {