Add ability to resolve type which has multiple registrations by qualifier

source/poodinis/dependency.d

@@ -53,9 +53,12 @@ class DependencyContainer {
 			writeln(format("DEBUG: Register type %s (as %s)", concreteType.toString(), registeredType.toString()));
 		}
 		
-		auto existingRegistration = getRegistration(registeredType, concreteType);
-		if (existingRegistration) {
-			return existingRegistration;
+		auto existingCandidates = registeredType in registrations;
+		if (existingCandidates) {
+			auto existingRegistration = getRegistration(*existingCandidates, concreteType);
+			if (existingRegistration) {
+				return existingRegistration;
+			}
 		}
 		
 		Registration newRegistration = new Registration(registeredType, concreteType);
@@ -64,13 +67,11 @@ class DependencyContainer {
 		return newRegistration;
 	}
 	
-	private Registration getRegistration(TypeInfo registeredType, TypeInfo_Class concreteType) {
-		auto existingCandidates = registeredType in registrations;
-		if (existingCandidates) {
-			foreach(existingRegistration ; *existingCandidates) {
-				if (existingRegistration.instantiatableType == concreteType) {
-					return existingRegistration;
-				}
+	private Registration getRegistration(Registration[] candidates, TypeInfo concreteType) {
+		foreach(existingRegistration ; candidates) {
+			writeln("DEBUG: Test type " ~ existingRegistration.instantiatableType.toString() ~ " with " ~ concreteType.toString());
+			if (existingRegistration.instantiatableType == concreteType) {
+				return existingRegistration;
 			}
 		}
 		
@@ -78,9 +79,15 @@ class DependencyContainer {
 	}
 	
 	public RegistrationType resolve(RegistrationType)() {
+		return resolve!(RegistrationType, RegistrationType)();
+	}
+	
+	public RegistrationType resolve(RegistrationType, QualifierType : RegistrationType)() {
 		TypeInfo resolveType = typeid(RegistrationType);
+		TypeInfo qualifierType = typeid(QualifierType);
+		
 		debug {
-			writeln("DEBUG: Resolving type " ~ resolveType.toString());
+			writeln("DEBUG: Resolving type " ~ resolveType.toString() ~ " with qualifier " ~ qualifierType.toString());
 		}
 		
 		auto candidates = resolveType in registrations;
@@ -88,8 +95,7 @@ class DependencyContainer {
 			throw new ResolveException("Type not registered.", resolveType);
 		}
 		
-		auto registration = (*candidates)[0];
-		
+		Registration registration = getQualifiedRegistration(resolveType, qualifierType, *candidates);
 		RegistrationType instance = cast(RegistrationType) registration.getInstance();
 		
 		if (!autowireStack.canFind(registration)) {
@@ -101,6 +107,19 @@ class DependencyContainer {
 		return instance;
 	}
 	
+	private Registration getQualifiedRegistration(TypeInfo resolveType, TypeInfo qualifierType, Registration[] candidates) {
+		if (resolveType == qualifierType) {
+			if (candidates.length > 1) {
+				string candidateList = candidates.toConcreteTypeListString();
+				throw new ResolveException("Multiple qualified candidates available: " ~ candidateList ~ ". Please specify qualifier.", resolveType);
+			}
+			
+			return candidates[0];
+		}
+		
+		return getRegistration(candidates, qualifierType);
+	}
+	
 	public void clearAllRegistrations() {
 		registrations.destroy();
 	}

source/poodinis/registration.d

@@ -119,3 +119,14 @@ public Registration existingInstance(Registration registration, Object instance)
 	registration.registationScope = new ExistingInstanceScope(instance);
 	return registration;
 }
+
+public string toConcreteTypeListString(Registration[] registrations) {
+	auto concreteTypeListString = "";
+	foreach (registration ; registrations) {
+		if (!concreteTypeListString.length) {
+			concreteTypeListString ~= ", ";
+		}
+		concreteTypeListString ~= registration.instantiatableType.toString();
+	}
+	return concreteTypeListString;
+}

test/poodinis/dependencytest.d

@@ -172,7 +172,7 @@ version(unittest) {
 		auto autowiredInstance = container.resolve!AutowiredClass;
 		assert(componentInstance.autowiredClass is autowiredInstance, "Member is not autowired upon resolving");
 	}
-
+	
 	// Test circular autowiring
 	unittest {
 		auto container = new DependencyContainer();
@@ -290,4 +290,30 @@ version(unittest) {
 		
 		assert(firstRegistration is secondRegistration, "First registration is not the same as the second of equal types");
 	}
+	
+	// Test resolve registration with multiple qualifiers
+	unittest {
+		auto container = new DependencyContainer();
+		container.register!(Color, Blue);
+		container.register!(Color, Red);
+		try {
+			container.resolve!Color;
+		} catch (ResolveException e) {
+			return;
+		}
+		assert(false);
+	}
+	
+	// Test resolve registration with multiple qualifiers using a qualifier
+	unittest {
+		auto container = new DependencyContainer();
+		container.register!(Color, Blue);
+		container.register!(Color, Red);
+		auto blueInstance = container.resolve!(Color, Blue);
+		auto redInstance = container.resolve!(Color, Red);
+		
+		assert(blueInstance !is redInstance, "Resolving type with multiple, different registrations yielded the same instance");
+		assert(blueInstance !is null, "Resolved blue instance to null");
+		assert(redInstance !is null, "Resolved red instance to null");
+	}
 }