/// <summary>
/// Creates new instance of the type defined by this node.
/// </summary>
/// <param name="context">Context to evaluate expressions against.</param>
/// <param name="evalContext">Current expression evaluation context.</param>
/// <returns>Node's value.</returns>
protected override object Get(object context, EvaluationContext evalContext)
{
var argValues = ResolveArguments(evalContext);
var namedArgValues = ResolveNamedArguments(evalContext);
if (_constructor == null)
{
lock (this)
{
if (_constructor == null)
{
_constructor = InitializeNode(argValues, namedArgValues);
}
}
}
var paramValues = (_isParamArray
? ReflectionUtils.PackageParamArray(argValues, _argumentCount, _paramArrayType)
: argValues);
var instance = _constructor.Invoke(paramValues);
if (namedArgValues != null)
{
SetNamedArguments(instance, namedArgValues);
}
return instance;
}
/// <summary>
/// Initializes this node by caching necessary constructor and property info.
/// </summary>
/// <param name="argValues"></param>
/// <param name="namedArgValues"></param>
private SafeConstructor InitializeNode(object[] argValues, IDictionary namedArgValues)
{
SafeConstructor ctor = null;
var objectType = GetObjectType(getText().Trim());
// cache constructor info
var ci = GetBestConstructor(objectType, argValues);
if (ci == null)
{
throw new ArgumentException(
String.Format("Constructor for the type [{0}] with a specified " +
"number and types of arguments does not exist.",
objectType.FullName));
}
var parameters = ci.GetParameters();
if (parameters.Length > 0)
{
var lastParameter = parameters[parameters.Length - 1];
_isParamArray = lastParameter.GetCustomAttributes(typeof (ParamArrayAttribute), false).Length > 0;
if (_isParamArray)
{
_paramArrayType = lastParameter.ParameterType.GetElementType();
_argumentCount = parameters.Length;
}
}
ctor = new SafeConstructor(ci);
// cache named args info
if (namedArgValues != null)
{
_namedArgs = new Hashtable(namedArgValues.Count);
foreach (string name in namedArgValues.Keys)
{
_namedArgs[name] = Expression.ParseProperty(name);
}
}
return ctor;
}
