public override void PreBuildUp(IBuilderContext context)
{
Guard.ArgumentNotNull(context, "context");
DynamicBuildPlanGenerationContext buildContext =
(DynamicBuildPlanGenerationContext)context.Existing;
IConstructorSelectorPolicy selector =
context.Policies.Get <IConstructorSelectorPolicy>(context.BuildKey);
SelectedConstructor selectedCtor = selector.SelectConstructor(context);
// Method preamble - test if we have an existing object
// First off, set up jump - if there's an existing object, skip us entirely
Label existingObjectNotNull = buildContext.IL.DefineLabel();
buildContext.EmitLoadExisting();
buildContext.IL.Emit(OpCodes.Ldnull);
buildContext.IL.Emit(OpCodes.Ceq);
buildContext.IL.Emit(OpCodes.Brfalse, existingObjectNotNull);
// Verify we're not attempting to create an instance of an interface
buildContext.EmitLoadContext();
buildContext.IL.EmitCall(OpCodes.Call, throwForAttemptingToConstructInterface, null);
if (selectedCtor != null)
{
string signatureString = CreateSignatureString(selectedCtor.Constructor);
// Resolve parameters
ParameterInfo[] parameters = selectedCtor.Constructor.GetParameters();
int i = 0;
foreach (string parameterKey in selectedCtor.GetParameterKeys())
{
// Set the current operation
buildContext.IL.Emit(OpCodes.Ldstr, parameters[i].Name);
buildContext.IL.Emit(OpCodes.Ldstr, signatureString);
buildContext.EmitLoadContext();
buildContext.IL.EmitCall(OpCodes.Call, setCurrentOperationToResolvingParameter, null);
// Resolve the parameter
buildContext.EmitResolveDependency(parameters[i].ParameterType, parameterKey);
++i;
}
// Set the current operation
buildContext.IL.Emit(OpCodes.Ldstr, signatureString);
buildContext.EmitLoadContext();
buildContext.IL.EmitCall(OpCodes.Call, setCurrentOperationToInvokingConstructor, null);
// Call the constructor
buildContext.IL.Emit(OpCodes.Newobj, selectedCtor.Constructor);
// Store the existing object
buildContext.EmitStoreExisting();
// Clear the current operation
buildContext.EmitClearCurrentOperation();
}
else
{
// If we get here, object has no constructors. It's either
// an interface or a primitive (like int). In this case,
// verify that we have an Existing object, and if not,
// throw (via helper function).
buildContext.EmitLoadContext();
buildContext.IL.EmitCall(OpCodes.Call, throwForNullExistingObject, null);
}
buildContext.IL.MarkLabel(existingObjectNotNull);
}
private IEnumerable <Expression> CreateNewBuildupSequence(DynamicBuildPlanGenerationContext buildContext, SelectedConstructor selectedConstructor, string signature)
{
var parameterExpressions = this.BuildConstructionParameterExpressions(buildContext, selectedConstructor, signature);
var newItemExpression = Expression.Variable(selectedConstructor.Constructor.DeclaringType, "newItem");
yield return(Expression.Call(null,
SetCurrentOperationToInvokingConstructorMethod,
Expression.Constant(signature),
buildContext.ContextParameter));
yield return(Expression.Assign(
buildContext.GetExistingObjectExpression(),
Expression.Convert(
Expression.New(selectedConstructor.Constructor, parameterExpressions),
typeof(object))));
yield return(buildContext.GetClearCurrentOperationExpression());
}
private IEnumerable <Expression> BuildConstructionParameterExpressions(DynamicBuildPlanGenerationContext buildContext, SelectedConstructor selectedConstructor, string constructorSignature)
{
int i = 0;
var constructionParameters = selectedConstructor.Constructor.GetParameters();
foreach (IDependencyResolverPolicy parameterResolver in selectedConstructor.GetParameterResolvers())
{
yield return(buildContext.CreateParameterExpression(
parameterResolver,
constructionParameters[i].ParameterType,
Expression.Call(null,
SetCurrentOperationToResolvingParameterMethod,
Expression.Constant(constructionParameters[i].Name, typeof(string)),
Expression.Constant(constructorSignature),
buildContext.ContextParameter)));
i++;
}
}
private static bool IsInvalidConstructor(SelectedConstructor selectedConstructor)
{
return(selectedConstructor.Constructor.GetParameters().Any(pi => pi.ParameterType.IsByRef));
}
