public static IChangeCollection <T> GetChanges <T>(T oldObject, T newObject, Expression <Func <T, object> > expression = null)
{
var a = GetValueOfExpressionFor(oldObject, expression);
var b = GetValueOfExpressionFor(newObject, expression);
var propertyPath = PropertyPathHelper.GetPropertyPath(expression);
using (var context = new ContextPair(a, b))
return(GetRecursiveChanges <ChangeCollection <T> >(context, propertyPath));
}
private static TCollection GetRecursiveChanges <TCollection>(ContextPair contextPair, string basePropertyPath) where TCollection : ChangeCollection, new()
{
var oldInstance = contextPair.OldInstanceContext.Instance;
var newInstance = contextPair.NewInstanceContext.Instance;
var type = GetTypeFromObjects(oldInstance, newInstance);
if (type == null)
{
return(new TCollection());
}
if (IsSimpleType(type))
{
var change = GetShallowChange(basePropertyPath, oldInstance, newInstance);
if (change == Change.Empty)
{
return(new TCollection());
}
var collection = new TCollection();
collection.Add(change);
return(collection);
}
var result = new TCollection();
ScanForChanges(contextPair, new ObjectPath()
{
OldInstance = oldInstance,
NewInstance = newInstance,
BasePropertyPath = null
}, result);
var objectPathQueue = contextPair.ObjectPathQueue;
while (objectPathQueue.Count > 0)
{
var objectPath = objectPathQueue.Dequeue();
var objectPathType = GetTypeFromObjects(
objectPath.OldInstance,
objectPath.NewInstance);
if (objectPathType == null)
{
continue;
}
ScanForChanges(contextPair, objectPath, result);
}
return(result);
}
public static IChangeCollection GetChanges(object oldObject, object newObject)
{
using (var context = new ContextPair(oldObject, newObject))
return(GetRecursiveChanges <ChangeCollection>(context, null));
}
private static void EnqueueObjectPathQueues(
ContextPair contextPair,
ObjectPath objectPath)
{
var oldInstance = objectPath.OldInstance;
var newInstance = objectPath.NewInstance;
var type = GetTypeFromObjects(oldInstance, newInstance);
if (type == null)
{
throw new InvalidOperationException("The type could not be determined.");
}
if (IsSimpleType(type))
{
throw new InvalidOperationException("This method can't be called with simple types.");
}
var seenObjectsOld = contextPair.OldInstanceContext.SeenObjects;
var seenObjectsNew = contextPair.NewInstanceContext.SeenObjects;
if (seenObjectsOld.Contains(objectPath.OldInstance) || seenObjectsNew.Contains(objectPath.NewInstance))
{
return;
}
if (objectPath.OldInstance != null)
{
seenObjectsOld.Add(objectPath.OldInstance);
}
if (objectPath.NewInstance != null)
{
seenObjectsNew.Add(objectPath.NewInstance);
}
var objectPathQueue = contextPair.ObjectPathQueue;
var properties = type.GetProperties();
foreach (var property in properties)
{
try
{
objectPathQueue.Enqueue(new ObjectPath()
{
OldInstance = oldInstance == null ? null : property.GetValue(oldInstance),
NewInstance = newInstance == null ? null : property.GetValue(newInstance),
Properties = property.PropertyType.GetProperties(),
BasePropertyPath = AddToPropertyPath(
objectPath.BasePropertyPath,
property.Name)
});
}
catch (Exception ex)
{
throw new Exception($"An error occured while comparing {AddToPropertyPath(objectPath.BasePropertyPath, property.Name)}.", ex);
}
}
}
private static void ScanForChanges(ContextPair contextPair, ObjectPath objectPath, ChangeCollection result)
{
var pathType = GetTypeFromObjects(
objectPath.OldInstance,
objectPath.NewInstance);
if (IsSimpleType(pathType))
{
var shallowChange = GetShallowChange(
objectPath.BasePropertyPath,
objectPath.OldInstance,
objectPath.NewInstance);
if (shallowChange != Change.Empty)
{
result.Add(shallowChange);
if (objectPath.ContainerChange != Change.Empty)
{
result.Add(objectPath.ContainerChange);
}
}
}
else if (IsEnumerableType(pathType))
{
Array itemsOldArray;
Array itemsNewArray;
if (pathType.IsArray)
{
itemsOldArray = (Array)objectPath.OldInstance;
itemsNewArray = (Array)objectPath.NewInstance;
}
else
{
var genericType = pathType
.GetInterfaces()
.Single(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IEnumerable <>))
.GetGenericArguments()
.Single();
var toArrayMethod = typeof(Enumerable)
.GetMethods()
.Single(x =>
x.Name == nameof(Enumerable.ToArray) &&
x.IsGenericMethod)
.MakeGenericMethod(genericType);
var emptyMethod = typeof(Array)
.GetMethods()
.Single(x =>
x.Name == nameof(Array.Empty) &&
x.IsGenericMethod)
.MakeGenericMethod(genericType);
itemsOldArray = objectPath.OldInstance == null
? (Array)emptyMethod.Invoke(null, Array.Empty <object>())
: (Array)toArrayMethod.Invoke(null, new[] { objectPath.OldInstance });
itemsNewArray = objectPath.NewInstance == null
? (Array)emptyMethod.Invoke(null, Array.Empty <object>())
: (Array)toArrayMethod.Invoke(null, new[] { objectPath.NewInstance });
}
var maxCount = Math.Max(itemsOldArray.Length, itemsNewArray.Length);
var newItemsOldArray = new object[maxCount];
var newItemsNewArray = new object[maxCount];
Array.Copy(itemsOldArray, newItemsOldArray, itemsOldArray.Length);
Array.Copy(itemsNewArray, newItemsNewArray, itemsNewArray.Length);
var shallowChange = GetShallowChange(
objectPath.BasePropertyPath ?? string.Empty,
objectPath.OldInstance,
objectPath.NewInstance);
for (var i = 0; i < maxCount; i++)
{
var itemOldInstance = newItemsOldArray[i];
var itemNewInstance = newItemsNewArray[i];
var itemType = GetTypeFromObjects(itemOldInstance, itemNewInstance);
if (itemType == null)
{
continue;
}
var arrayItemObjectPath = new ObjectPath()
{
BasePropertyPath = AddToPropertyPath(
objectPath.BasePropertyPath,
i.ToString()),
OldInstance = itemOldInstance,
NewInstance = itemNewInstance,
Properties = itemType.GetProperties(),
ContainerChange = shallowChange
};
contextPair.ObjectPathQueue.Enqueue(arrayItemObjectPath);
}
}
else
{
EnqueueObjectPathQueues(
contextPair,
objectPath);
}
}
private static void ScanForChanges(ContextPair contextPair, ObjectPath objectPath, ChangeCollection result)
{
var pathType = GetTypeFromObjects(
objectPath.OldInstance,
objectPath.NewInstance);
if (IsSimpleType(pathType))
{
var shallowChange = GetShallowChange(
objectPath.BasePropertyPath,
objectPath.OldInstance,
objectPath.NewInstance);
if (shallowChange == Change.Empty)
{
return;
}
result.Add(shallowChange);
if (objectPath.ParentChanges == null)
{
return;
}
foreach (var parentChange in objectPath.ParentChanges)
{
result.Add(parentChange);
}
}
else if (IsEnumerableType(pathType))
{
if (pathType == null)
{
throw new InvalidOperationException("Type was enumerable despite being null.");
}
Array?itemsOldArray;
Array?itemsNewArray;
if (pathType.IsArray)
{
itemsOldArray = (Array?)objectPath.OldInstance;
itemsNewArray = (Array?)objectPath.NewInstance;
}
else
{
var genericType = pathType
.GetInterfaces()
.Single(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IEnumerable <>))
.GetGenericArguments()
.Single();
var toArrayMethod = typeof(Enumerable)
.GetMethods()
.Single(x =>
x.Name == nameof(Enumerable.ToArray) &&
x.IsGenericMethod)
.MakeGenericMethod(genericType);
var emptyMethod = typeof(Array)
.GetMethods()
.Single(x =>
x.Name == nameof(Array.Empty) &&
x.IsGenericMethod)
.MakeGenericMethod(genericType);
itemsOldArray = objectPath.OldInstance == null
? (Array)emptyMethod.Invoke(null, Array.Empty <object>())
: (Array)toArrayMethod.Invoke(null, new[] { objectPath.OldInstance });
itemsNewArray = objectPath.NewInstance == null
? (Array)emptyMethod.Invoke(null, Array.Empty <object>())
: (Array)toArrayMethod.Invoke(null, new[] { objectPath.NewInstance });
}
var maxCount = Math.Max(
itemsOldArray?.Length ?? 0,
itemsNewArray?.Length ?? 0);
var newItemsOldArray = new object[maxCount];
var newItemsNewArray = new object[maxCount];
Array.Copy(itemsOldArray ?? Array.Empty <object>(), newItemsOldArray, itemsOldArray?.Length ?? 0);
Array.Copy(itemsNewArray ?? Array.Empty <object>(), newItemsNewArray, itemsNewArray?.Length ?? 0);
var shallowChange = new Change(
objectPath.BasePropertyPath ?? string.Empty,
objectPath.OldInstance,
objectPath.NewInstance);
var newParentChanges = new[]
{
shallowChange
};
var parentChanges = objectPath.ParentChanges == null ?
newParentChanges :
objectPath
.ParentChanges
.Union(newParentChanges)
.Distinct()
.ToArray();
for (var i = 0; i < maxCount; i++)
{
var itemOldInstance = newItemsOldArray[i];
var itemNewInstance = newItemsNewArray[i];
var itemType = GetTypeFromObjects(itemOldInstance, itemNewInstance);
if (itemType == null)
{
continue;
}
var arrayItemObjectPath = new ObjectPath()
{
BasePropertyPath = AddToPropertyPath(
objectPath.BasePropertyPath,
i.ToString()),
OldInstance = itemOldInstance,
NewInstance = itemNewInstance,
Properties = itemType.GetProperties(),
ParentChanges = parentChanges
};
contextPair.ObjectPathQueue.Enqueue(arrayItemObjectPath);
}
}
else
{
EnqueueObjectPathQueues(
contextPair,
objectPath);
}
}