Merge pull request #1155 from alistairjevans/constructor-binder

Reflection Constructor Binding Refactor

src/Autofac/Autofac.csproj

@@ -98,10 +98,10 @@
       <AutoGen>True</AutoGen>
       <DependentUpon>ProvidedInstanceActivatorResources.resx</DependentUpon>
     </Compile>
-    <Compile Update="Core\Activators\Reflection\ConstructorParameterBindingResources.Designer.cs">
+    <Compile Update="Core\Activators\Reflection\BoundConstructorResources.Designer.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
-      <DependentUpon>ConstructorParameterBindingResources.resx</DependentUpon>
+      <DependentUpon>BoundConstructorResources.resx</DependentUpon>
     </Compile>
     <Compile Update="Core\Activators\Reflection\MatchingSignatureConstructorSelectorResources.Designer.cs">
       <DesignTime>True</DesignTime>
@@ -330,9 +330,9 @@
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>ProvidedInstanceActivatorResources.Designer.cs</LastGenOutput>
     </EmbeddedResource>
-    <EmbeddedResource Update="Core\Activators\Reflection\ConstructorParameterBindingResources.resx">
+    <EmbeddedResource Update="Core\Activators\Reflection\BoundConstructorResources.resx">
       <Generator>ResXFileCodeGenerator</Generator>
-      <LastGenOutput>ConstructorParameterBindingResources.Designer.cs</LastGenOutput>
+      <LastGenOutput>BoundConstructorResources.Designer.cs</LastGenOutput>
     </EmbeddedResource>
     <EmbeddedResource Update="Core\Activators\Reflection\MatchingSignatureConstructorSelectorResources.resx">
       <Generator>ResXFileCodeGenerator</Generator>

src/Autofac/Core/Activators/Reflection/BoundConstructor.cs

@@ -0,0 +1,159 @@
+// This software is part of the Autofac IoC container
+// Copyright © 2011 Autofac Contributors
+// https://autofac.org
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using System.Reflection;
+
+namespace Autofac.Core.Activators.Reflection
+{
+    /// <summary>
+    /// Represents the outcome of a single bind attempt by a <see cref="ConstructorBinder"/>.
+    /// </summary>
+    [SuppressMessage(
+        "Performance",
+        "CA1815:Override equals and operator equals on value types",
+        Justification = "Comparison of two BoundConstructor instances has no meaning.")]
+    public class BoundConstructor
+    {
+        private readonly Func<object?[], object>? _factory;
+        private readonly Func<object?>[]? _valueRetrievers;
+        private readonly ParameterInfo? _firstNonBindableParameter;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BoundConstructor"/> class for a successful bind.
+        /// </summary>
+        /// <param name="binder">The binder that generated this binding.</param>
+        /// <param name="factory">The instance factory.</param>
+        /// <param name="valueRetrievers">The set of value-retrieval functions.</param>
+        [SuppressMessage("Design", "CA1062:Validate arguments of public methods", Justification = "Validated in constructor.")]
+        public static BoundConstructor ForBindSuccess(ConstructorBinder binder, Func<object?[], object> factory, Func<object?>[] valueRetrievers)
+            => new BoundConstructor(binder, factory, valueRetrievers);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BoundConstructor"/> class, for an unsuccessful bind.
+        /// </summary>
+        /// <param name="binder">The binder that generated this binding.</param>
+        /// <param name="firstNonBindableParameter">The first parameter that prevented binding.</param>
+        public static BoundConstructor ForBindFailure(ConstructorBinder binder, ParameterInfo firstNonBindableParameter) =>
+            new BoundConstructor(binder, firstNonBindableParameter);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BoundConstructor"/> class for a successful bind.
+        /// </summary>
+        /// <param name="binder">The binder that generated this binding.</param>
+        /// <param name="factory">The instance factory.</param>
+        /// <param name="valueRetrievers">The set of value-retrieval functions.</param>
+        internal BoundConstructor(ConstructorBinder binder, Func<object?[], object> factory, Func<object?>[] valueRetrievers)
+        {
+            CanInstantiate = true;
+            Binder = binder;
+            _factory = factory ?? throw new ArgumentNullException(nameof(factory));
+            _valueRetrievers = valueRetrievers ?? throw new ArgumentNullException(nameof(valueRetrievers));
+            _firstNonBindableParameter = null;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BoundConstructor"/> class, for an unsuccessful bind.
+        /// </summary>
+        /// <param name="binder">The binder that generated this binding.</param>
+        /// <param name="firstNonBindableParameter">The first parameter that prevented binding.</param>
+        internal BoundConstructor(ConstructorBinder binder, ParameterInfo firstNonBindableParameter)
+        {
+            Binder = binder;
+            CanInstantiate = false;
+            _firstNonBindableParameter = firstNonBindableParameter ?? throw new ArgumentNullException(nameof(firstNonBindableParameter));
+            _factory = null;
+            _valueRetrievers = null;
+        }
+
+        /// <summary>
+        /// Gets the binder that created this binding.
+        /// </summary>
+        public ConstructorBinder Binder { get; }
+
+        /// <summary>
+        /// Gets the constructor on the target type. The actual constructor used
+        /// might differ, e.g. if using a dynamic proxy.
+        /// </summary>
+        public ConstructorInfo TargetConstructor => Binder.Constructor;
+
+        /// <summary>
+        /// Gets the total number of arguments for the bound constructor.
+        /// </summary>
+        public int ArgumentCount => Binder.ParameterCount;
+
+        /// <summary>
+        /// Gets a value indicating whether the binding is valid.
+        /// </summary>
+        public bool CanInstantiate { get; }
+
+        /// <summary>
+        /// Invoke the constructor with the parameter bindings.
+        /// </summary>
+        /// <returns>The constructed instance.</returns>
+        public object Instantiate()
+        {
+            if (!CanInstantiate)
+            {
+                throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, BoundConstructorResources.CannotInstantitate, this.Description));
+            }
+
+            var values = new object?[_valueRetrievers!.Length];
+            for (var i = 0; i < _valueRetrievers.Length; ++i)
+            {
+                values[i] = _valueRetrievers[i]();
+            }
+
+            try
+            {
+                return _factory!(values);
+            }
+            catch (TargetInvocationException ex)
+            {
+                throw new DependencyResolutionException(string.Format(CultureInfo.CurrentCulture, BoundConstructorResources.ExceptionDuringInstantiation, TargetConstructor, TargetConstructor.DeclaringType.Name), ex.InnerException);
+            }
+            catch (Exception ex)
+            {
+                throw new DependencyResolutionException(string.Format(CultureInfo.CurrentCulture, BoundConstructorResources.ExceptionDuringInstantiation, TargetConstructor, TargetConstructor.DeclaringType.Name), ex);
+            }
+        }
+
+        /// <summary>
+        /// Gets a description of the constructor parameter binding.
+        /// </summary>
+        public string Description => CanInstantiate
+            ? string.Format(CultureInfo.CurrentCulture, BoundConstructorResources.BoundConstructor, TargetConstructor)
+            : string.Format(CultureInfo.CurrentCulture, BoundConstructorResources.NonBindableConstructor, TargetConstructor, _firstNonBindableParameter);
+
+        /// <summary>Returns a System.String that represents the current System.Object.</summary>
+        /// <returns>A System.String that represents the current System.Object.</returns>
+        public override string ToString()
+        {
+            return Description;
+        }
+    }
+}