private Task ExecuteStep(StepDescriptor step, IPipelineExecutionContext executionContext, CancellationToken cancellationToken, ExecuteStepDelegate @delegate, IPipelineBehavior[] behaviors)
{
var stepInstance = _factory(step.TypeInfo);
executionContext.CurrentStep = stepInstance;
Func <CancellationToken, Task> currentFunc = token => @delegate(stepInstance, executionContext, _namingStrategy, _unknownParameterBehavior, token);
for (var i = behaviors.Length - 1; i >= 0; i--)
{
var behavior = behaviors[i];
var previousFunc = currentFunc;
currentFunc = token => behavior.Handle(executionContext, cancellationToken, previousFunc);
}
return(currentFunc(cancellationToken));
}
internal static ExecuteStepDelegate CreateDelegate(this StepDescriptor step)
{
var arguments = new List <Expression>();
var executionContextParameter = Expression.Parameter(typeof(IPipelineExecutionContext));
var cancellationTokenParameter = Expression.Parameter(typeof(CancellationToken));
var namingStrategyParameter = Expression.Parameter(typeof(INamingStrategy));
var unknownParameterBehaviorParameter = Expression.Parameter(typeof(IUnknownParameterBehavior));
var instanceParameter = Expression.Parameter(typeof(object));
for (var i = 0; i < step.Parameters.Length; i++)
{
var(parameterName, parameterType) = step.Parameters[i];
if (parameterType == typeof(IPipelineExecutionContext))
{
arguments.Add(executionContextParameter);
}
else if (parameterType == typeof(CancellationToken))
{
arguments.Add(cancellationTokenParameter);
}
else
{
var allNames = Expression.Property(executionContextParameter, "Names");
var getParameterName = Expression.Call(namingStrategyParameter, "FindMatch", new Type[0], Expression.Constant(parameterName), allNames);
var body = Expression.Call(executionContextParameter, "Get", new[] { parameterType }, getParameterName);
var handleUnkownParameter = Expression.Call(unknownParameterBehaviorParameter, "Handle", new Type[] { parameterType }, Expression.Constant(parameterName));
var @catch = Expression.Catch(typeof(ArgumentException), handleUnkownParameter);
var @try = Expression.TryCatch(body, @catch);
arguments.Add(@try);
}
}
var methodCall = Expression.Call(Expression.Convert(instanceParameter, step.TypeInfo), step.Method, arguments);
if (!typeof(Task).IsAssignableFrom(step.Method.ReturnType))
{
var result = Expression.Constant(Task.CompletedTask);
var wrapper = Expression.Block(typeof(Task), methodCall, result);
return(Expression.Lambda <ExecuteStepDelegate>(wrapper, instanceParameter, executionContextParameter, namingStrategyParameter,
unknownParameterBehaviorParameter, cancellationTokenParameter).Compile());
}
return(Expression.Lambda <ExecuteStepDelegate>(methodCall, instanceParameter, executionContextParameter, namingStrategyParameter,
unknownParameterBehaviorParameter, cancellationTokenParameter).Compile());
}