/*----------------------------------------------------------------------------------------*/
/// <summary>
/// Searches through the list of candidate bindings to find the default binding and one or
/// more conditional bindings that match the current context.
/// </summary>
/// <param name="context">The context in which the binding is being resolved.</param>
/// <param name="candidates">The available candidate bindings.</param>
/// <returns>A structure containing the matching bindings.</returns>
protected virtual BindingMatchCollection GetMatchingBindings(IContext context, IEnumerable <IBinding> candidates)
{
var matches = new BindingMatchCollection();
candidates.Each(candidate =>
{
if (candidate.IsDefault)
{
matches.DefaultBinding = candidate;
}
else if (candidate.Matches(context))
{
matches.ConditionalBindings.Add(candidate);
}
});
return(matches);
}
/*----------------------------------------------------------------------------------------*/
/// <summary>
/// Determines which binding should be used for the specified service in the specified context.
/// </summary>
/// <param name="service">The service type that is being activated.</param>
/// <param name="context">The context in which the binding is being resolved.</param>
/// <returns>The selected binding.</returns>
public IBinding SelectBinding(Type service, IContext context)
{
Ensure.ArgumentNotNull(context, "context");
Ensure.NotDisposed(this);
if (Logger.IsDebugEnabled)
{
Logger.Debug("Resolving binding for {0}", Format.Context(context));
}
ICollection <IBinding> bindings = Kernel.Components.BindingRegistry.GetBindings(service);
if (bindings == null)
{
// If no bindings were available, return null immediately.
if (Logger.IsDebugEnabled)
{
Logger.Debug("No candidate bindings available for service {0}", Format.Type(service));
}
return(null);
}
if (Logger.IsDebugEnabled)
{
Logger.Debug("{0} candidate binding{1} available for service {2}",
bindings.Count, (bindings.Count == 1 ? "" : "s"), Format.Type(service));
}
BindingMatchCollection matches = GetMatchingBindings(context, bindings);
if (Logger.IsDebugEnabled)
{
Logger.Debug("{0} default binding and {1} conditional binding{2} match the current context",
(matches.HasDefaultBinding ? "One" : "No"),
matches.ConditionalBindings.Count,
(matches.ConditionalBindings.Count == 1 ? "" : "s"));
}
if (!matches.HasConditionalBindings)
{
if (!matches.HasDefaultBinding)
{
if (Logger.IsDebugEnabled)
{
Logger.Debug("No conditional bindings matched, and no default binding is available.");
}
return(null);
}
else
{
if (Logger.IsDebugEnabled)
{
Logger.Debug("No conditional bindings matched, falling back on default binding.");
}
return(matches.DefaultBinding);
}
}
if (matches.ConditionalBindings.Count == 1)
{
if (Logger.IsDebugEnabled)
{
Logger.Debug("Using the single matching conditional binding");
}
return(matches.ConditionalBindings[0]);
}
if (matches.HasDefaultBinding)
{
if (Logger.IsDebugEnabled)
{
Logger.Debug("Multiple conditional bindings matched, falling back on default binding");
}
return(matches.DefaultBinding);
}
else
{
// More than one conditional binding matched, and there is no default binding, so fail.
throw new ActivationException(ExceptionFormatter.MultipleConditionalBindingsMatch(context, matches.ConditionalBindings));
}
}
/*----------------------------------------------------------------------------------------*/
/// <summary>
/// Searches through the list of candidate bindings to find the default binding and one or
/// more conditional bindings that match the current context.
/// </summary>
/// <param name="context">The context in which the binding is being resolved.</param>
/// <param name="candidates">The available candidate bindings.</param>
/// <returns>A structure containing the matching bindings.</returns>
protected virtual BindingMatchCollection GetMatchingBindings(IContext context, IEnumerable<IBinding> candidates)
{
var matches = new BindingMatchCollection();
candidates.Each(candidate =>
{
if (candidate.IsDefault)
matches.DefaultBinding = candidate;
else if (candidate.Matches(context))
matches.ConditionalBindings.Add(candidate);
});
return matches;
}