private void BuildBinding(Expression <Func <TTargetMember> > bindTarget, Expression <Func <TSourceMember> > bindSource, Func <TSourceMember, TTargetMember> valueConverter, bool applyLeft)
{
_targetReference = bindTarget.Body as MemberExpression;
_sourceReference = bindSource.Body as MemberExpression;
if (_targetReference == null)
{
throw new ArgumentException($"{nameof(bindTarget)} is expected to contain a MemberExpression, instead it got {bindTarget.Body.NodeType}.");
}
if (_sourceReference == null)
{
throw new ArgumentException($"{nameof(bindSource)} is expected to contain a MemberExpression, instead it got {bindSource.Body.NodeType}.");
}
_targetInstance = ExpressionHelper.EvaluateExpression(_targetReference.Expression);
_sourceInstance = ExpressionHelper.EvaluateExpression(_sourceReference.Expression) as INotifyPropertyChanged;
if (bindTarget == null)
{
throw new ArgumentException($"{nameof(bindTarget)} must be the member of an instance.");
}
if (_sourceInstance == null)
{
throw new ArgumentException($"{nameof(bindSource)} must be the member of an instance that implements {nameof(INotifyPropertyChanged)}.");
}
_targetProperty = BindManager.GetBindEndpoint(_targetInstance).GetMemberAsTarget(_targetReference.Member, this);
_sourceProperty = BindManager.GetBindEndpoint(_sourceInstance).GetMemberAsSource(_sourceReference.Member, this);
if (valueConverter == null)
{
// Default just directly applies the value of bindSource to bindTarget
ApplyToTargetCall = Expression.Lambda <Action>(Expression.Assign(_targetReference, _sourceReference)).Compile();
}
else
{
// Converter was provided so we package it into an Action to call later
Action <TTargetMember> setTargetAction = ExpressionHelper.MakeAssignmentAction <TTargetMember>(_targetProperty.SetMethod, _targetInstance);
Func <TSourceMember> getSourceFunction = ExpressionHelper.MakeGetFunc <TSourceMember>(_sourceProperty.GetMethod, _sourceInstance);
ApplyToTargetCall = () => setTargetAction.Invoke(valueConverter(getSourceFunction()));
}
_sourceInstance.PropertyChanged += (sender, e) => {
if (_sourceProperty.Name == e.PropertyName && this.Enabled)
{
Run();
}
};
_enabled = true;
if (applyLeft)
{
Run();
}
}
/// <summary>
/// Gets a list of all bindings where a member of this instance is the target of the bind.
/// </summary>
public static IReadOnlyCollection <Binding> GetTargetedBindings(this INotifyPropertyChanged instance)
{
return(BindManager.GetBindEndpoint(instance).CachedMembers.SelectMany(d => d.Value.TargetBindings).ToList <Binding>().AsReadOnly());
}
