Support nested redirects with call constraints (#70)

docs/documentation/dependency_injection.md

@@ -111,15 +111,16 @@ After reset all resolved redirect proxies will be returned to their initial stat
 *Nested registrations* are used to redirect calls on types that are not directly resolved by the DI container such as instances created by factory services.
 
 E.g. if we have an `IBarFactory` factory service, resolved by the DI, that has factory methods that create `IBar` instances.
-A nested `IBar` registration off a parent `IBarFactory` registration can be declared as follows:
+A nested `IBar` redirect registration from the parent `IBarFactory` registration can be declared as follows:
 
 ```csharp
-var diverter = new Diverter()
+var diverter = new DiverterBuilder()
     .Register<IBarFactory>(x => x
-        .ThenRegister<IBar>());
+        .ThenRedirect<IBar>()) // Proxy redirect any IBar instances returned by IBarFactory
+    .Create();
 ```
 
-> Nested registrations on nested registration is supported.
+> Nested registrations of nested registrations can be chained to any depth.
 {: .note }
 
 This is installed into the existing `IServiceCollection` as usual:

src/DivertR/DiverterBuilder.cs

@@ -35,13 +35,13 @@ public DiverterBuilder(IRedirectSet redirectSet)
         public IRedirectSet RedirectSet { get; }
 
         /// <inheritdoc />
-        public IDiverterBuilder Register<TTarget>(Action<INestedRegisterBuilder>? nestedRegisterAction = null) where TTarget : class?
+        public IDiverterBuilder Register<TTarget>(Action<INestedRegisterBuilder<TTarget>>? nestedRegisterAction = null) where TTarget : class?
         {
-            return Register<TTarget>(null, nestedRegisterAction);
+            return Register(null, nestedRegisterAction);
         }
 
         /// <inheritdoc />
-        public IDiverterBuilder Register<TTarget>(string? name, Action<INestedRegisterBuilder>? nestedRegisterAction = null) where TTarget : class?
+        public IDiverterBuilder Register<TTarget>(string? name, Action<INestedRegisterBuilder<TTarget>>? nestedRegisterAction = null) where TTarget : class?
         {
             var redirect = RedirectSet.GetOrCreate<TTarget>(name);
 

src/DivertR/IDiverterBuilder.cs

@@ -23,7 +23,7 @@ public interface IDiverterBuilder
         /// <typeparam name="TTarget">The type to register.</typeparam>
         /// <returns>This <see cref="IDiverterBuilder"/> instance.</returns>
         /// <exception cref="DiverterException">Thrown if the <typeparamref name="TTarget"/> type with with default <see cref="RedirectId.Name" /> has already been registered.</exception>
-        IDiverterBuilder Register<TTarget>(Action<INestedRegisterBuilder>? nestedRegisterAction = null) where TTarget : class?;
+        IDiverterBuilder Register<TTarget>(Action<INestedRegisterBuilder<TTarget>>? nestedRegisterAction = null) where TTarget : class?;
 
         /// <summary>
         /// Register a type to redirect.
@@ -33,7 +33,7 @@ public interface IDiverterBuilder
         /// <typeparam name="TTarget">The type to register.</typeparam>
         /// <returns>This <see cref="IDiverterBuilder"/> instance.</returns>
         /// <exception cref="DiverterException">Thrown if the <typeparamref name="TTarget"/> type with matching <paramref name="name"/> has already been registered.</exception>
-        IDiverterBuilder Register<TTarget>(string? name, Action<INestedRegisterBuilder>? nestedRegisterAction = null) where TTarget : class?;
+        IDiverterBuilder Register<TTarget>(string? name, Action<INestedRegisterBuilder<TTarget>>? nestedRegisterAction = null) where TTarget : class?;
 
         /// <summary>
         /// Register a type to redirect.

src/DivertR/INestedRegisterBuilder.cs

@@ -1,44 +1,63 @@
 using System;
+using System.Linq.Expressions;
 
 namespace DivertR
 {
     /// <summary>
     /// A builder interface for providing nested register actions on parent registrations.
     /// Nested registrations can be used to intercept and redirect inner services created outside the dependency injection container e.g. from factories.
     /// </summary>
-    public interface INestedRegisterBuilder
+    public interface INestedRegisterBuilder<TTarget> where TTarget : class?
     {
         /// <summary>
-        /// Add a nested registration to redirect calls from the parent registration with return type <typeparamref name="TReturn"/>
-        /// by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
-        /// A corresponding <see cref="IRedirect{TReturn}"/> is created and added to the underlying <see cref="IRedirectSet"/>.
-        /// The returned instances are proxied by inserting a <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/> that is persistent, i.e. remains after reset.
+        /// Redirect calls from the parent registration with return type <typeparamref name="TReturn"/> by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
+        /// The returned instances are proxied by inserting a persistent <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/>.
         /// </summary>
+        /// <param name="registerAction">Optional nested register action.</param>
         /// <typeparam name="TReturn">The return type of calls to redirect.</typeparam>
-        /// <returns>This <see cref="INestedRegisterBuilder"/> instance.</returns>
+        /// <returns>This <see cref="INestedRegisterBuilder{TTarget}"/> instance.</returns>
         /// <exception cref="DiverterException">Thrown if a nested <see cref="IRedirect{TReturn}"/> has already been registered on the parent with matching <typeparamref name="TReturn"/> type and default <see cref="RedirectId.Name" />.</exception>
-        INestedRegisterBuilder ThenRegister<TReturn>(Action<INestedRegisterBuilder>? registerAction = null) where TReturn : class?;
+        INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?;
 
         /// <summary>
-        /// Add a nested registration to redirect calls from the parent registration with return type <typeparamref name="TReturn"/>
-        /// by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
-        /// A corresponding <see cref="IRedirect{TReturn}"/> is created and added to the underlying <see cref="IRedirectSet"/>.
-        /// The returned instances are proxied by inserting a <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/> that is persistent, i.e. remains after reset.
+        /// Redirect calls from the parent registration with return type <typeparamref name="TReturn"/> by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
+        /// The returned instances are proxied by inserting a persistent <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/>.
         /// </summary>
         /// <param name="name">Specify the <see cref="DivertR.RedirectId.Name" /> of the returned <see cref="IRedirect{TReturn}"/>.</param>
         /// <param name="registerAction">Optional nested register action.</param>
         /// <typeparam name="TReturn">The return type of calls to redirect.</typeparam>
-        /// <returns>This <see cref="INestedRegisterBuilder"/> instance.</returns>
+        /// <returns>This <see cref="INestedRegisterBuilder{TTarget}"/> instance.</returns>
         /// <exception cref="DiverterException">Thrown if a nested <see cref="IRedirect{TReturn}"/> has already been registered on the parent with matching <typeparamref name="TReturn"/> type and <paramref name="name"/>.</exception>
-        INestedRegisterBuilder ThenRegister<TReturn>(string? name, Action<INestedRegisterBuilder>? registerAction = null) where TReturn : class?;
+        INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(string? name, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?;
+
+        /// <summary>
+        /// Redirect calls matching a constraint from the parent registration by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
+        /// The returned instances are proxied by inserting a persistent <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/>.
+        /// </summary>
+        /// <param name="constraintExpression">The call constraint expression.</param>
+        /// <param name="registerAction">Optional nested register action.</param>
+        /// <typeparam name="TReturn">The return type of calls to redirect.</typeparam>
+        /// <returns>This <see cref="INestedRegisterBuilder{TTarget}"/> instance.</returns>
+        INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(Expression<Func<TTarget, TReturn>> constraintExpression, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?;
+
+        /// <summary>
+        /// Redirect calls matching a constraint from the parent registration by proxying instances returned from parent methods via an <see cref="IRedirect{TReturn}"/>.
+        /// The returned instances are proxied by inserting a persistent <see cref="IVia"/> on the <see cref="IRedirect{TReturn}"/>.
+        /// </summary>
+        /// <param name="name">Specify the <see cref="DivertR.RedirectId.Name" /> of the returned <see cref="IRedirect{TReturn}"/>.</param>
+        /// <param name="constraintExpression">The call constraint expression.</param>
+        /// <param name="registerAction">Optional nested register action.</param>
+        /// <typeparam name="TReturn">The return type of calls to redirect.</typeparam>
+        /// <returns>This <see cref="INestedRegisterBuilder{TTarget}"/> instance.</returns>
+        INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(string? name, Expression<Func<TTarget, TReturn>> constraintExpression, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?;
 
         /// <summary>
         /// Register a decorator on call returns of type <typeparamref name="TReturn"/> on the nested redirect.
         /// The decorator is applied by inserting a <see cref="IVia"/> on the nested redirect that is persistent, i.e. remains after reset.
         /// </summary>
         /// <param name="decorator">The decorator function.</param>
         /// <typeparam name="TReturn">The return type of calls to decorate.</typeparam>
-        /// <returns>This <see cref="INestedRegisterBuilder"/> instance.</returns>
-        INestedRegisterBuilder ThenDecorate<TReturn>(Func<TReturn, TReturn> decorator);
+        /// <returns>This <see cref="INestedRegisterBuilder{TTarget}"/> instance.</returns>
+        INestedRegisterBuilder<TTarget> ThenDecorate<TReturn>(Func<TReturn, TReturn> decorator);
     }
 }

src/DivertR/Internal/NestedRegisterBuilder.cs

@@ -1,9 +1,10 @@
 using System;
 using System.Collections.Concurrent;
+using System.Linq.Expressions;
 
 namespace DivertR.Internal
 {
-    internal class NestedRegisterBuilder<TTarget> : INestedRegisterBuilder where TTarget : class?
+    internal class NestedRegisterBuilder<TTarget> : INestedRegisterBuilder<TTarget> where TTarget : class?
     {
         private readonly IRedirect<TTarget> _redirect;
         private readonly ConcurrentDictionary<RedirectId, ConcurrentDictionary<RedirectId, IRedirect>> _registeredRedirects;
@@ -14,12 +15,12 @@ public NestedRegisterBuilder(IRedirect<TTarget> redirect, ConcurrentDictionary<R
             _registeredRedirects = registeredRedirects;
         }
 
-        public INestedRegisterBuilder ThenRegister<TReturn>(Action<INestedRegisterBuilder>? registerAction = null) where TReturn : class?
+        public INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?
         {
-            return ThenRegister<TReturn>(null, registerAction);
+            return ThenRedirect((string?) null, registerAction);
         }
 
-        public INestedRegisterBuilder ThenRegister<TReturn>(string? name, Action<INestedRegisterBuilder>? registerAction = null) where TReturn : class?
+        public INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(string? name, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?
         {
             var nestedRedirect = _redirect.RedirectSet.GetOrCreate<TReturn>(name);
 
@@ -39,7 +40,27 @@ public INestedRegisterBuilder ThenRegister<TReturn>(string? name, Action<INested
             return this;
         }
 
-        public INestedRegisterBuilder ThenDecorate<TReturn>(Func<TReturn, TReturn> decorator)
+        public INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(Expression<Func<TTarget, TReturn>> constraintExpression, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?
+        {
+            return ThenRedirect(null, constraintExpression, registerAction);
+        }
+
+        public INestedRegisterBuilder<TTarget> ThenRedirect<TReturn>(string? name, Expression<Func<TTarget, TReturn>> constraintExpression, Action<INestedRegisterBuilder<TReturn>>? registerAction = null) where TReturn : class?
+        {
+            var nestedRedirect = _redirect
+                .To(constraintExpression)
+                .ViaRedirect(name, opt =>
+                {
+                    opt.DisableSatisfyStrict();
+                    opt.Persist();
+                });
+
+            registerAction?.Invoke(new NestedRegisterBuilder<TReturn>(nestedRedirect, _registeredRedirects));
+
+            return this;
+        }
+
+        public INestedRegisterBuilder<TTarget> ThenDecorate<TReturn>(Func<TReturn, TReturn> decorator)
         {
             _redirect.ViaDecorator(decorator, opt =>
             {