/// <summary>
/// Extracts generic type arguments from a constructed type that are necessary to close a generic type definition.
/// </summary>
/// <param name="genericTypeDefinition">A generic type definition.</param>
/// <param name="constructedType">A closed type from which may be obtained generic type arguments.</param>
/// <returns>The type argument necessary to construct the closed type.</returns>
internal static Rental <Type[]> ExtractGenericTypeArguments(Type genericTypeDefinition, Type constructedType)
{
Requires.NotNull(genericTypeDefinition, nameof(genericTypeDefinition));
Requires.NotNull(constructedType, nameof(constructedType));
var genericTypeDefinitionInfo = genericTypeDefinition.GetTypeInfo();
// The generic type arguments may be buried in the base type of the "constructedType" that we were given.
var constructedGenericType = constructedType;
while (constructedGenericType != null && (!constructedGenericType.GetTypeInfo().IsGenericType || !genericTypeDefinitionInfo.IsAssignableFrom(constructedGenericType.GetGenericTypeDefinition().GetTypeInfo())))
{
constructedGenericType = constructedGenericType.GetTypeInfo().BaseType;
}
Requires.Argument(constructedGenericType != null, "constructedType", Strings.NotClosedFormOfOther);
var result = ArrayRental <Type> .Get(genericTypeDefinitionInfo.GenericTypeParameters.Length);
for (int i = 0; i < result.Value.Length; i++)
{
result.Value[i] = constructedGenericType.GenericTypeArguments[i];
}
return(result);
}
/// <summary>
/// Creates a <see cref="Func{T}"/> delegate for a given <see cref="Func{Object}"/> delegate.
/// </summary>
/// <param name="func">The function that produces the T value typed as <see cref="object"/>.</param>
/// <param name="typeArg">The <c>T</c> type argument for the returned function's return type.</param>
/// <returns>An instance of <see cref="Func{T}"/>, typed as <see cref="Func{Object}"/>.</returns>
internal static Func <object> As(this Func <object> func, Type typeArg)
{
using (var args = ArrayRental <object> .Get(1))
{
args.Value[0] = func;
return((Func <object>)CastAsFuncMethodInfo.MakeGenericMethod(typeArg).Invoke(null, args.Value) !);
}
}
internal static ICollection <object> GetCollectionWrapper(Type itemType, object collectionObject)
{
Requires.NotNull(itemType, nameof(itemType));
Requires.NotNull(collectionObject, nameof(collectionObject));
var underlyingItemType = itemType.GetTypeInfo().UnderlyingSystemType;
if (underlyingItemType == typeof(object))
{
return((ICollection <object>)collectionObject);
}
// Most common .Net collections implement IList as well so for those
// cases we can optimize the wrapping instead of using reflection to create
// a generic type.
if (typeof(IList).GetTypeInfo().IsAssignableFrom(collectionObject.GetType().GetTypeInfo()))
{
return(new CollectionOfObjectList((IList)collectionObject));
}
Func <object, ICollection <object> > factory;
lock (CachedCollectionWrapperFactories)
{
CachedCollectionWrapperFactories.TryGetValue(underlyingItemType, out factory);
}
if (factory == null)
{
Type collectionType = typeof(CollectionOfObject <>).MakeGenericType(underlyingItemType);
#if RuntimeHandles
var ctor = (ConstructorInfo)MethodBase.GetMethodFromHandle(CollectionOfObjectCtor.MethodHandle, collectionType.TypeHandle);
#else
var ctor = typeof(CollectionOfObject <>).MakeGenericType(collectionType).GetConstructor(CollectionOfObjectCtorArgTypes);
#endif
factory = collection =>
{
using (var args = ArrayRental <object> .Get(1))
{
args.Value[0] = collection;
return((ICollection <object>)ctor.Invoke(args.Value));
}
};
lock (CachedCollectionWrapperFactories)
{
CachedCollectionWrapperFactories[underlyingItemType] = factory;
}
}
return(factory(collectionObject));
}
private ValueForImportSite GetValueForImportSite(RuntimePartLifecycleTracker importingPartTracker, RuntimeComposition.RuntimeImport import)
{
Requires.NotNull(import, nameof(import));
Func <Func <object?>, object, object>?lazyFactory = import.LazyFactory;
var exports = import.SatisfyingExports;
if (import.Cardinality == ImportCardinality.ZeroOrMore)
{
if (import.ImportingSiteType.IsArray || (import.ImportingSiteType.GetTypeInfo().IsGenericType&& import.ImportingSiteType.GetGenericTypeDefinition().IsEquivalentTo(typeof(IEnumerable <>))))
{
Array array = Array.CreateInstance(import.ImportingSiteTypeWithoutCollection, exports.Count);
using (var intArray = ArrayRental <int> .Get(1))
{
int i = 0;
foreach (var export in exports)
{
intArray.Value[0] = i++;
var exportedValue = this.GetValueForImportElement(importingPartTracker, import, export, lazyFactory);
this.ThrowIfExportedValueIsNotAssignableToImport(import, export, exportedValue);
array.SetValue(exportedValue, intArray.Value);
}
}
return(new ValueForImportSite(array));
}
else
{
object? collectionObject = null;
MemberInfo?importingMember = import.ImportingMember;
if (importingMember != null)
{
Assumes.NotNull(importingPartTracker.Value);
collectionObject = GetImportingMember(importingPartTracker.Value, importingMember);
}
bool preexistingInstance = collectionObject != null;
if (!preexistingInstance)
{
if (PartDiscovery.IsImportManyCollectionTypeCreateable(import.ImportingSiteType, import.ImportingSiteTypeWithoutCollection))
{
using (var typeArgs = ArrayRental <Type> .Get(1))
{
typeArgs.Value[0] = import.ImportingSiteTypeWithoutCollection;
Type listType = typeof(List <>).MakeGenericType(typeArgs.Value);
if (import.ImportingSiteType.GetTypeInfo().IsAssignableFrom(listType.GetTypeInfo()))
{
collectionObject = Activator.CreateInstance(listType) !;
}
else
{
collectionObject = Activator.CreateInstance(import.ImportingSiteType) !;
}
}
Assumes.NotNull(importingPartTracker.Value);
Assumes.NotNull(importingMember);
SetImportingMember(importingPartTracker.Value, importingMember, collectionObject);
}
else
{
throw new CompositionFailedException(
string.Format(
CultureInfo.CurrentCulture,
Strings.UnableToInstantiateCustomImportCollectionType,
import.ImportingSiteType.FullName,
$"{import.DeclaringTypeRef.FullName}.{import.ImportingMemberRef?.Name}"));
}
}
var collectionAccessor = CollectionServices.GetCollectionWrapper(import.ImportingSiteTypeWithoutCollection, collectionObject !);
if (preexistingInstance)
{
collectionAccessor.Clear();
}
foreach (var export in exports)
{
var exportedValue = this.GetValueForImportElement(importingPartTracker, import, export, lazyFactory);
this.ThrowIfExportedValueIsNotAssignableToImport(import, export, exportedValue);
collectionAccessor.Add(exportedValue);
}
return(default(ValueForImportSite)); // signal caller should not set value again.
}
}
else
{
var export = exports.FirstOrDefault();
if (export == null)
{
return(new ValueForImportSite(null));
}
var exportedValue = this.GetValueForImportElement(importingPartTracker, import, export, lazyFactory);
this.ThrowIfExportedValueIsNotAssignableToImport(import, export, exportedValue);
return(new ValueForImportSite(exportedValue));
}
}