/// <summary>
/// Returns the dependencies for the given type. For
/// ConstructorExpressionGenerator, dependencies are
/// the constructor parameters
/// </summary>
/// <param name="type">
/// The type.
/// </param>
/// <returns>
/// An <see cref="IEnumerable{Expression}"/> representing the type's dependencies
/// </returns>
protected override IEnumerable<Expression> CreateDependencyExpressions(Type type)
{
return this.GetParametersForConstructor(type).Select(parameter =>
{
var eventArgs = new ExpressionGeneratingEventArgs(parameter.ParameterType);
this.OnExpressionGenerating(eventArgs);
if (eventArgs.Expression == null)
{
throw new DependencyResolutionException(eventArgs.DependencyType);
}
return eventArgs.Expression;
});
}
/// <summary>
/// Raises the <see cref="DependencyExpressionGenerating"/> event.
/// </summary>
/// <param name="args">
/// The event args for this event.
/// </param>
protected virtual void OnExpressionGenerating(ExpressionGeneratingEventArgs args)
{
var handler = this.DependencyExpressionGenerating;
handler(this, args);
}
/// <summary>
/// The default type resolution handler.
/// </summary>
/// <param name="sender">
/// The sender. This is the <see cref="ExpressionGenerator"/> that is currently building
/// an expression for a requested type.
/// </param>
/// <param name="args">
/// The args. The <see cref="ExpressionGeneratingEventArgs.DependencyType"/> property contains the type that
/// needs to be resolved.
/// </param>
public void ResolveDependencyExpression(object sender, ExpressionGeneratingEventArgs args)
{
if (this.IsRegistered(args.DependencyType))
{
args.Expression = this.GetRegistration(args.DependencyType).Expression;
}
// Not setting args.Expression will cause a DependencyResolution error
}