Prevent registration, resolving and constructor injection selection of structs

Fixes #25

source/poodinis/container.d

@@ -164,7 +164,7 @@ synchronized class DependencyContainer {
      *
      * See_Also: singleInstance, newInstance, existingInstance, RegistrationOption
      */
-    public Registration register(SuperType, ConcreteType : SuperType)(RegistrationOption options = RegistrationOption.none) {
+    public Registration register(SuperType, ConcreteType : SuperType)(RegistrationOption options = RegistrationOption.none) if (!is(ConcreteType == struct)) {
         TypeInfo registeredType = typeid(SuperType);
         TypeInfo_Class concreteType = typeid(ConcreteType);
 
@@ -262,7 +262,7 @@ synchronized class DependencyContainer {
      * ---
      * You need to use the resolve method which allows you to specify a qualifier.
      */
-    public RegistrationType resolve(RegistrationType)(ResolveOption resolveOptions = ResolveOption.none) {
+    public RegistrationType resolve(RegistrationType)(ResolveOption resolveOptions = ResolveOption.none) if (!is(RegistrationType == struct)) {
         return resolve!(RegistrationType, RegistrationType)(resolveOptions);
     }
 
@@ -292,7 +292,7 @@ synchronized class DependencyContainer {
      * container.resolve!(Animal, Dog);
      * ---
      */
-    public QualifierType resolve(RegistrationType, QualifierType : RegistrationType)(ResolveOption resolveOptions = ResolveOption.none) {
+    public QualifierType resolve(RegistrationType, QualifierType : RegistrationType)(ResolveOption resolveOptions = ResolveOption.none) if (!is(QualifierType == struct)) {
         TypeInfo resolveType = typeid(RegistrationType);
         TypeInfo qualifierType = typeid(QualifierType);
 

source/poodinis/factory.d

@@ -131,7 +131,7 @@ class ConstructorInjectingInstanceFactory(InstanceType) : InstanceFactory {
     private static bool parametersAreValid(Params...)() {
         bool isValid = true;
         foreach(param; Params) {
-            if (isBuiltinType!param) {
+            if (isBuiltinType!param || is(param == struct)) {
                 isValid = false;
                 break;
             }

test/poodinis/factorytest.d

@@ -124,6 +124,17 @@ version(unittest) {
         assert(instance.someOtherClassThen is container.resolve!SomeOtherClassThen);
     }
 
+    // Test injecting constructor of class with struct constructor parameters
+    unittest {
+        auto container = new shared DependencyContainer();
+        container.register!SomeOtherClassThen;
+
+        auto factory = new ConstructorInjectingInstanceFactory!ClassWithStructConstructor(container);
+        auto instance = cast(ClassWithStructConstructor) factory.getInstance();
+
+        assert(instance !is null);
+        assert(instance.someOtherClassThen is container.resolve!SomeOtherClassThen);
+    }
 
     // Test injecting constructor of class with empty constructor will skip injection
     unittest {

test/poodinis/testclasses.d

@@ -513,6 +513,17 @@ version(unittest) {
         }
     }
 
+    class ClassWithStructConstructor {
+        public SomeOtherClassThen someOtherClassThen;
+
+        this(Thing willNotBePicked) {
+        }
+
+        this(SomeOtherClassThen someOtherClassThen) {
+            this.someOtherClassThen = someOtherClassThen;
+        }
+    }
+
     class TestType {}
 
     class Dependency {}