/// <summary>
/// Given a fully filled-out IObservedChange object, SetValueToProperty
/// will apply it to the specified object (i.e. it will ensure that
/// target.property == This.GetValue() and "replay" the observed change
/// onto another object)
/// </summary>
/// <param name="target">The target object to apply the change to.</param>
/// <param name="property">The target property to apply the change to.</param>
public static void SetValueToProperty <TSender, TValue, TTarget>(
this IObservedChange <TSender, TValue> This,
TTarget target,
Expression <Func <TTarget, TValue> > property)
{
Reflection.SetValueToPropertyChain(target, Reflection.ExpressionToPropertyNames(property), This.GetValue());
}
/// <summary>
/// WhenAny allows you to observe whenever one or more properties on an
/// object have changed, providing an initial value when the Observable
/// is set up, unlike ObservableForProperty(). Use this method in
/// constructors to set up bindings between properties that also need an
/// initial setup.
/// </summary>
public static IObservable <TRet> WhenAnyDynamic <TSender, TRet>(this TSender This,
string[] property1,
string[] property2,
string[] property3,
Func <IObservedChange <TSender, object>, IObservedChange <TSender, object>, IObservedChange <TSender, object>, TRet> selector)
{
var slot1 = new ObservedChange <TSender, object>()
{
Sender = This,
PropertyName = String.Join(".", property1),
};
object slot1Value = default(object); slot1.TryGetValue(out slot1Value); slot1.Value = slot1Value;
IObservedChange <TSender, object> islot1 = slot1;
var slot2 = new ObservedChange <TSender, object>()
{
Sender = This,
PropertyName = String.Join(".", property2),
};
object slot2Value = default(object); slot2.TryGetValue(out slot2Value); slot2.Value = slot2Value;
IObservedChange <TSender, object> islot2 = slot2;
var slot3 = new ObservedChange <TSender, object>()
{
Sender = This,
PropertyName = String.Join(".", property3),
};
object slot3Value = default(object); slot3.TryGetValue(out slot3Value); slot3.Value = slot3Value;
IObservedChange <TSender, object> islot3 = slot3;
return(Observable.Create <TRet>(subject => {
subject.OnNext(selector(islot1, islot2, islot3));
return Observable.Merge(This.ObservableForProperty(property1).Do(x => { lock (slot1) { islot1 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3)), This.ObservableForProperty(property2).Do(x => { lock (slot2) { islot2 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3)), This.ObservableForProperty(property3).Do(x => { lock (slot3) { islot3 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3))).Subscribe(subject);
}));
}
/// <summary>
/// Given a fully filled-out IObservedChange object, SetValueToProperty
/// will apply it to the specified object (i.e. it will ensure that
/// target.property == This.GetValue() and "replay" the observed change
/// onto another object)
/// </summary>
/// <param name="target">The target object to apply the change to.</param>
/// <param name="property">The target property to apply the change to.</param>
internal static void SetValueToProperty <TSender, TValue, TTarget>(
this IObservedChange <TSender, TValue> This,
TTarget target,
Expression <Func <TTarget, TValue> > property)
{
Reflection.TrySetValueToPropertyChain(target, Reflection.Rewrite(property.Body).GetExpressionChain(), This.GetValue());
}
private void OnDelegateChanging(IObservedChange <ViewModel, IUGCanvasViewDelegate> oldValues)
{
if (oldValues.Value is IDisposable disposable)
{
disposable.Dispose();
}
}
/// <summary>
/// Based on a list of Expressions get a IObservedChanged for the value
/// of the last property in the chain if possible.
/// The Expressions are property chains. Eg Property1.Property2.Property3
/// The method will make sure that each Expression can get a value along the way
/// and get each property until each expression is evaluated.
/// </summary>
/// <param name="changeValues">A IObservedChanged for the value.</param>
/// <param name="current">The object that starts the property chain.</param>
/// <param name="expressionChain">A list of expressions which will point towards a property or field.</param>
/// <returns>If the value was successfully retrieved or not.</returns>
public static bool TryGetAllValuesForPropertyChain(out IObservedChange <object, object>[] changeValues, object current, IEnumerable <Expression> expressionChain)
{
int currentIndex = 0;
var expressions = expressionChain.ToList();
changeValues = new IObservedChange <object, object> [expressions.Count()];
foreach (Expression expression in expressions.SkipLast(1))
{
if (current == null)
{
changeValues[currentIndex] = null;
return(false);
}
var sender = current;
current = GetValueFetcherOrThrow(expression.GetMemberInfo())(current, expression.GetArgumentsArray());
changeValues[currentIndex] = new ObservedChange <object, object>(sender, expression, current);
currentIndex++;
}
if (current == null)
{
changeValues[currentIndex] = null;
return(false);
}
Expression lastExpression = expressions.Last();
changeValues[currentIndex] = new ObservedChange <object, object>(current, lastExpression, GetValueFetcherOrThrow(lastExpression.GetMemberInfo())(current, lastExpression.GetArgumentsArray()));
return(true);
}
/// <summary>
/// WhenAny allows you to observe whenever one or more properties on an
/// object have changed, providing an initial value when the Observable
/// is set up, unlike ObservableForProperty(). Use this method in
/// constructors to set up bindings between properties that also need an
/// initial setup.
/// </summary>
public static IObservable <TRet> WhenAny <TSender, TRet, T1, T2>(this TSender This,
Expression <Func <TSender, T1> > property1,
Expression <Func <TSender, T2> > property2,
Func <IObservedChange <TSender, T1>, IObservedChange <TSender, T2>, TRet> selector)
where TSender : IReactiveNotifyPropertyChanged
{
var slot1 = new ObservedChange <TSender, T1>()
{
Sender = This,
PropertyName = String.Join(".", RxApp.expressionToPropertyNames(property1)),
};
T1 slot1Value = default(T1); slot1.TryGetValue(out slot1Value); slot1.Value = slot1Value;
IObservedChange <TSender, T1> islot1 = slot1;
var slot2 = new ObservedChange <TSender, T2>()
{
Sender = This,
PropertyName = String.Join(".", RxApp.expressionToPropertyNames(property2)),
};
T2 slot2Value = default(T2); slot2.TryGetValue(out slot2Value); slot2.Value = slot2Value;
IObservedChange <TSender, T2> islot2 = slot2;
return(Observable.Create <TRet>(subject => {
subject.OnNext(selector(islot1, islot2));
return Observable.Merge(
This.ObservableForProperty(property1).Do(x => { lock (slot1) { islot1 = x.fillInValue(); } }).Select(x => selector(islot1, islot2)),
This.ObservableForProperty(property2).Do(x => { lock (slot2) { islot2 = x.fillInValue(); } }).Select(x => selector(islot1, islot2))
).Subscribe(subject);
}));
}
/// <summary>
/// Returns the name of a property which has been changed.
/// </summary>
/// <typeparam name="TSender">The sender type.</typeparam>
/// <typeparam name="TValue">The value type.</typeparam>
/// <param name="item">The observed change.</param>
/// <returns>
/// The name of the property which has changed.
/// </returns>
public static string GetPropertyName <TSender, TValue>(this IObservedChange <TSender, TValue> item)
{
if (item is null)
{
throw new ArgumentNullException(nameof(item));
}
return(Reflection.ExpressionToPropertyNames(item.Expression));
}
/// <summary>
/// Returns the current value of a property given a notification that
/// it has changed.
/// </summary>
/// <returns>The current value of the property</returns>
public static TValue GetValue <TSender, TValue>(this IObservedChange <TSender, TValue> This)
{
TValue ret;
if (!This.TryGetValue(out ret))
{
throw new Exception(String.Format("One of the properties in the expression '{0}' was null", This.GetPropertyName()));
}
return(ret);
}
/// <summary>
/// Attempts to return the current value of a property given a
/// notification that it has changed. If any property in the
/// property expression is null, false is returned.
/// </summary>
/// <param name="changeValue">The value of the property
/// expression.</param>
/// <returns>True if the entire expression was able to be followed,
/// false otherwise</returns>
internal static bool TryGetValue <TSender, TValue>(this IObservedChange <TSender, TValue> This, out TValue changeValue)
{
if (!Equals(This.Value, default(TValue)))
{
changeValue = This.Value;
return(true);
}
return(Reflection.TryGetValueForPropertyChain(out changeValue, This.Sender, This.Expression.GetExpressionChain()));
}
/// <summary>
/// Returns the current value of a property given a notification that
/// it has changed.
/// </summary>
/// <typeparam name="TSender">The sender.</typeparam>
/// <typeparam name="TValue">The changed value.</typeparam>
/// <param name="item">
/// The <see cref="IObservedChange{TSender, TValue}"/> instance to get the value of.
/// </param>
/// <returns>
/// The current value of the property.
/// </returns>
public static TValue?GetValueOrDefault <TSender, TValue>(this IObservedChange <TSender, TValue> item)
{
if (item is null)
{
throw new ArgumentNullException(nameof(item));
}
if (!item.TryGetValue(out var returnValue))
{
return(default);
/// <summary>
/// Returns the current value of a property given a notification that
/// it has changed.
/// </summary>
/// <typeparam name="TSender">The sender.</typeparam>
/// <typeparam name="TValue">The changed value.</typeparam>
/// <param name="this">
/// The <see cref="IObservedChange{TSender, TValue}"/> instance to get the value of.
/// </param>
/// <returns>
/// The current value of the property.
/// </returns>
public static TValue GetValue <TSender, TValue>(this IObservedChange <TSender, TValue> @this)
{
TValue ret;
if ([email protected](out ret))
{
throw new Exception($"One of the properties in the expression '{@this.GetPropertyName()}' was null");
}
return(ret);
}
/// <summary>
/// Attempts to return the current value of a property given a
/// notification that it has changed. If any property in the
/// property expression is null, false is returned.
/// </summary>
/// <param name="changeValue">The value of the property
/// expression.</param>
/// <returns>True if the entire expression was able to be followed,
/// false otherwise</returns>
public static bool TryGetValue <TSender, TValue>(this IObservedChange <TSender, TValue> This, out TValue changeValue)
{
if (!Equals(This.Value, default(TValue)))
{
changeValue = This.Value;
return(true);
}
object current = This.Sender;
string fullPropName = This.PropertyName;
return(Reflection.TryGetValueForPropertyChain(out changeValue, current, fullPropName.Split('.')));
}
private static IObservedChange <object, object> ObservedChangeFor(
Expression expression, IObservedChange <object, object> sourceChange)
{
if (sourceChange.Value == null)
{
return(new ObservedChange <object, object>(sourceChange.Value, expression));
}
object value;
// expression is always a simple expression
Reflection.TryGetValueForPropertyChain(out value, sourceChange.Value, new[] { expression });
return(new ObservedChange <object, object>(sourceChange.Value, expression, value));
}
/// <summary>
/// Returns the current value of a property given a notification that
/// it has changed.
/// </summary>
/// <typeparam name="TSender">The sender.</typeparam>
/// <typeparam name="TValue">The changed value.</typeparam>
/// <param name="item">
/// The <see cref="IObservedChange{TSender, TValue}"/> instance to get the value of.
/// </param>
/// <returns>
/// The current value of the property.
/// </returns>
public static TValue GetValue <TSender, TValue>(this IObservedChange <TSender, TValue> item)
{
if (item is null)
{
throw new ArgumentNullException(nameof(item));
}
if (!item.TryGetValue(out var returnValue))
{
throw new Exception($"One of the properties in the expression '{item.GetPropertyName()}' was null");
}
return(returnValue);
}
/// <summary>
/// Attempts to return the current value of a property given a
/// notification that it has changed. If any property in the
/// property expression is null, false is returned.
/// </summary>
/// <typeparam name="TSender">The sender type.</typeparam>
/// <typeparam name="TValue">The value type.</typeparam>
/// <param name="item">
/// The <see cref="IObservedChange{TSender, TValue}"/> instance to get the value of.
/// </param>
/// <param name="changeValue">
/// The value of the property expression.
/// </param>
/// <returns>
/// True if the entire expression was able to be followed, false otherwise.
/// </returns>
internal static bool TryGetValue <TSender, TValue>(this IObservedChange <TSender, TValue> item, out TValue changeValue)
{
if (Equals(item.Sender, null))
{
throw new ArgumentNullException(nameof(item), "Sender of the item is null");
}
if (!Equals(item.Value, default(TValue)))
{
changeValue = item.Value;
return(true);
}
return(Reflection.TryGetValueForPropertyChain(out changeValue, item.Sender, item.Expression.GetExpressionChain()));
}
private void NavigateToEntriesListView(IObservedChange<EntriesListViewModel, PwCommon> obj)
{
if (obj.Value is PwGroup)
{
_navigationService.UriFor<EntriesListViewModel>().WithParam(vm => vm.GroupId, obj.Value.UUID).Navigate();
}
else if(obj.Value is PwEntry)
{
var entry = obj.Value as PwEntry;
_navigationService
.UriFor<AddOrEditEntryViewModel>()
.WithParam(vm => vm.EntryUuid, entry.UUID)
.WithParam(vm => vm.ParentGroupUuid, entry.ParentGroup.UUID)
.Navigate();
}
}
private void HandleStateChange(IObservedChange<CommandBase, CommandState> b)
{
CommandTraces.Add(new CommandTrace { DateTime = DateTime.Now, State = b.Value });
if (b.Value == CommandState.Successed)
{
SignalCommandFulfillment();
if (!ShouldExecuteForever)
{
CompleteCommand();
}
else
{
CurrentState = CommandState.Executing;
}
}
RegisterTimers(b.Value);
}
/// <summary>
/// WhenAny allows you to observe whenever one or more properties on an
/// object have changed, providing an initial value when the Observable
/// is set up, unlike ObservableForProperty(). Use this method in
/// constructors to set up bindings between properties that also need an
/// initial setup.
/// </summary>
public static IObservable <TRet> WhenAny <TSender, TRet, T1>(this TSender This,
Expression <Func <TSender, T1> > property1,
Func <IObservedChange <TSender, T1>, TRet> selector)
{
var slot1 = new ObservedChange <TSender, T1>()
{
Sender = This,
PropertyName = String.Join(".", Reflection.ExpressionToPropertyNames(property1)),
};
T1 slot1Value = default(T1); slot1.TryGetValue(out slot1Value); slot1.Value = slot1Value;
IObservedChange <TSender, T1> islot1 = slot1;
return(Observable.Create <TRet>(subject => {
subject.OnNext(selector(islot1));
return Observable.Merge(This.ObservableForProperty(property1).Do(x => { lock (slot1) { islot1 = x.fillInValue(); } }).Select(x => selector(islot1))).Subscribe(subject);
}));
}
private static IObservable <IObservedChange <object, object> > NestedObservedChanges(
Expression expression, IObservedChange <object, object> sourceChange, bool beforeChange)
{
// Make sure a change at a root node propagates events down
var kicker = ObservedChangeFor(expression, sourceChange);
// Handle null values in the chain
if (sourceChange.Value == null)
{
return(Observable.Return(kicker));
}
// Handle non null values in the chain
return
(NotifyForProperty(sourceChange.Value, expression, beforeChange)
.Select(x => new ObservedChange <object, object>(x.Sender, expression, x.GetValue()))
.StartWith(kicker));
}
/// <summary>
/// WhenAny allows you to observe whenever one or more properties on an
/// object have changed, providing an initial value when the Observable
/// is set up, unlike ObservableForProperty(). Use this method in
/// constructors to set up bindings between properties that also need an
/// initial setup.
/// </summary>
public static IObservable <TRet> WhenAny <TSender, TRet, T1, T2, T3, T4>(this TSender This,
Expression <Func <TSender, T1> > property1,
Expression <Func <TSender, T2> > property2,
Expression <Func <TSender, T3> > property3,
Expression <Func <TSender, T4> > property4,
Func <IObservedChange <TSender, T1>, IObservedChange <TSender, T2>, IObservedChange <TSender, T3>, IObservedChange <TSender, T4>, TRet> selector)
{
var slot1 = new ObservedChange <TSender, T1>()
{
Sender = This,
PropertyName = String.Join(".", Reflection.ExpressionToPropertyNames(property1)),
};
T1 slot1Value = default(T1); slot1.TryGetValue(out slot1Value); slot1.Value = slot1Value;
IObservedChange <TSender, T1> islot1 = slot1;
var slot2 = new ObservedChange <TSender, T2>()
{
Sender = This,
PropertyName = String.Join(".", Reflection.ExpressionToPropertyNames(property2)),
};
T2 slot2Value = default(T2); slot2.TryGetValue(out slot2Value); slot2.Value = slot2Value;
IObservedChange <TSender, T2> islot2 = slot2;
var slot3 = new ObservedChange <TSender, T3>()
{
Sender = This,
PropertyName = String.Join(".", Reflection.ExpressionToPropertyNames(property3)),
};
T3 slot3Value = default(T3); slot3.TryGetValue(out slot3Value); slot3.Value = slot3Value;
IObservedChange <TSender, T3> islot3 = slot3;
var slot4 = new ObservedChange <TSender, T4>()
{
Sender = This,
PropertyName = String.Join(".", Reflection.ExpressionToPropertyNames(property4)),
};
T4 slot4Value = default(T4); slot4.TryGetValue(out slot4Value); slot4.Value = slot4Value;
IObservedChange <TSender, T4> islot4 = slot4;
return(Observable.Create <TRet>(subject => {
subject.OnNext(selector(islot1, islot2, islot3, islot4));
return Observable.Merge(This.ObservableForProperty(property1).Do(x => { lock (slot1) { islot1 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3, islot4)), This.ObservableForProperty(property2).Do(x => { lock (slot2) { islot2 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3, islot4)), This.ObservableForProperty(property3).Do(x => { lock (slot3) { islot3 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3, islot4)), This.ObservableForProperty(property4).Do(x => { lock (slot4) { islot4 = x.fillInValue(); } }).Select(x => selector(islot1, islot2, islot3, islot4))).Subscribe(subject);
}));
}
/// <summary>
/// Given a fully filled-out IObservedChange object, SetValueToProperty
/// will apply it to the specified object (i.e. it will ensure that
/// target.property == This.GetValue() and "replay" the observed change
/// onto another object)
/// </summary>
/// <param name="target">The target object to apply the change to.</param>
/// <param name="property">The target property to apply the change to.</param>
public static void SetValueToProperty <TSender, TValue, TTarget>(
this IObservedChange <TSender, TValue> This,
TTarget target,
Expression <Func <TTarget, TValue> > property)
{
object current = target;
string[] propNames = RxApp.expressionToPropertyNames(property);
PropertyInfo pi;
foreach (var propName in propNames.SkipLast(1))
{
pi = RxApp.getPropertyInfoOrThrow(current.GetType(), propName);
current = pi.GetValue(current, null);
}
pi = RxApp.getPropertyInfoForProperty(current.GetType(), propNames.Last());
pi.SetValue(current, This.GetValue(), null);
}
public static bool TryGetAllValuesForPropertyChain(out IObservedChange <object, object>[] changeValues, object current, string[] propNames)
{
int currentIndex = 0;
changeValues = new IObservedChange <object, object> [propNames.Length];
foreach (var propName in propNames.SkipLast(1))
{
if (current == null)
{
changeValues[currentIndex] = null;
return(false);
}
var box = new ObservedChange <object, object> {
Sender = current, PropertyName = propName
};
current = GetValueFetcherOrThrow(current.GetType(), propName)(current);
box.Value = current;
changeValues[currentIndex] = box;
currentIndex++;
}
if (current == null)
{
changeValues[currentIndex] = null;
return(false);
}
changeValues[currentIndex] = new ObservedChange <object, object> {
Sender = current,
PropertyName = propNames.Last(),
Value = GetValueFetcherOrThrow(current.GetType(), propNames.Last())(current)
};
return(true);
}
/// <summary>
/// Attempts to return the current value of a property given a
/// notification that it has changed. If any property in the
/// property expression is null, false is returned.
/// </summary>
/// <param name="changeValue">The value of the property expression.</param>
/// <returns>True if the entire expression was able to be followed, false otherwise</returns>
public static bool TryGetValue <TSender, TValue>(this IObservedChange <TSender, TValue> This, out TValue changeValue)
{
if (!Equals(This.Value, default(TValue)))
{
changeValue = This.Value;
return(true);
}
object current = This.Sender;
string[] propNames = null;
lock (propStringToNameCache) { propNames = propStringToNameCache.Get(This.PropertyName); }
PropertyInfo pi;
foreach (var propName in propNames.SkipLast(1))
{
if (current == null)
{
changeValue = default(TValue);
return(false);
}
pi = RxApp.getPropertyInfoOrThrow(current.GetType(), propName);
current = pi.GetValue(current, null);
}
if (current == null)
{
changeValue = default(TValue);
return(false);
}
pi = RxApp.getPropertyInfoOrThrow(current.GetType(), propNames.Last());
changeValue = (TValue)pi.GetValue(current, null);
return(true);
}
private void NavigateToOpenDatabase(IObservedChange<DatabaseListViewModel, DatabaseItemViewModel> obj)
{
_cache.DatabaseName = obj.Value.DatabaseInfo.Info.DatabasePath;
_navService.UriFor<OpenDatabaseViewModel>()
.Navigate();
}
private void LiveLoginResultChanged(IObservedChange<SkydriveAccessViewModel, LiveLoginResult> obj)
{
OnLogin(obj.Value);
}
private void SetupCanSave(IObservedChange<AddOrEditGroupViewModel, string> obj)
{
CanSave = !string.IsNullOrWhiteSpace(obj.Value);
}
private void GetParentGroup(IObservedChange<AddOrEditGroupViewModel, string> obj)
{
ParentGroup = _databaseSource.PwDatabase.Tree.FindGroupByUuid(ParentGroupUuid);
}
/// <summary>
/// Returns the current value of a property given a notification that
/// it has changed.
/// </summary>
/// <returns>The current value of the property</returns>
public static string GetPropertyName <TSender, TValue>(this IObservedChange <TSender, TValue> This)
{
return(Reflection.ExpressionToPropertyNames(This.Expression));
}
private static bool CanExecuteLoginCommand(IObservedChange <MainViewModel, string> login, IObservedChange <MainViewModel, SecureString> password)
{
return(!string.IsNullOrEmpty(login.Value) && !string.IsNullOrEmpty(password.Value.ToInsecureString()));
}
static IObservedChange <object, object> observedChangeFor(string propertyName, IObservedChange <object, object> sourceChange)
{
var p = new ObservedChange <object, object>()
{
Sender = sourceChange.Value,
PropertyName = propertyName,
};
if (sourceChange.Value == null)
{
return(p);
}
return(p.fillInValue());
}
static IObservable <IObservedChange <object, object> > nestedObservedChanges(string propertyName, IObservedChange <object, object> sourceChange, bool beforeChange)
{
// Make sure a change at a root node propogates events down
var kicker = observedChangeFor(propertyName, sourceChange);
// Handle null values in the chain
if (sourceChange.Value == null)
{
return(Observable.Return(kicker));
}
// Handle non null values in the chain
return(notifyForProperty(sourceChange.Value, propertyName, beforeChange)
.Select(x => x.fillInValue())
.StartWith(kicker));
}
internal static IObservedChange <TSender, TValue> fillInValue <TSender, TValue>(this IObservedChange <TSender, TValue> This)
{
// XXX: This is an internal method because I'm unsafely upcasting,
// but in certain cases it's needed.
var ret = (ObservedChange <TSender, TValue>)This;
var val = default(TValue);
This.TryGetValue(out val);
ret.Value = val;
return(ret);
}
private void SkydriveItemSelected(IObservedChange<BrowseCloudFilesViewModel, ICloudItem> obj)
{
var value = obj.Value;
if (value.IsFolder)
{
NavigateToBrowseFolders(value);
}
else
{
_dialogService.ShowDialogBox(
"Download Confirmation",
string.Format("Are you sure you want to download {0}?", value.Name),
"yes",
"no",
async () => { await AttemptDownload(value); },
() => { SelectedSkyDriveItem = null; }
);
}
}
/// <summary>
/// Returns the name of a property which has been changed.
/// </summary>
/// <typeparam name="TSender">The sender type.</typeparam>
/// <typeparam name="TValue">The value type.</typeparam>
/// <param name="item">The observed change.</param>
/// <returns>
/// The name of the property which has changed.
/// </returns>
public static string GetPropertyName <TSender, TValue>(this IObservedChange <TSender, TValue> item) =>
item is null
? throw new ArgumentNullException(nameof(item))
static IObservedChange <object, object> observedChangeFor(Expression expression, IObservedChange <object, object> sourceChange)
{
var propertyName = expression.GetMemberInfo().Name;
if (sourceChange.Value == null)
{
return(new ObservedChange <object, object>(sourceChange.Value, expression));;
}
else
{
object value;
// expression is always a simple expression
Reflection.TryGetValueForPropertyChain(out value, sourceChange.Value, new[] { expression });
return(new ObservedChange <object, object>(sourceChange.Value, expression, value));
}
}