public static ScoredConstructor GetBestConstructor(Type type, IEnumerable <Type> argumentTypes)
{
var context = new ConstructorDiscoveryContext(type, argumentTypes);
var scored = GetConstructorsByScore(context);
return(scored.Where(sc => sc.Score >= 0).OrderByDescending(sc => sc.Score).FirstOrDefault());
}
private static List <ScoredConstructor> GetConstructorsByScore(ConstructorDiscoveryContext context)
{
var constructors = context.TargetType.GetConstructors(BindingFlags.Public | BindingFlags.Instance);
var scoredList = new List <ScoredConstructor>();
foreach (var constructor in constructors)
{
ScoredConstructor scored = ScoreConstructor(constructor, context);
scoredList.Add(scored);
}
return(scoredList);
}
private static ScoredConstructor ScoreConstructor(ConstructorInfo constructor, ConstructorDiscoveryContext context)
{
if (constructor.IsPrivate)
{
return(ScoredConstructor.Unusable(constructor));
}
// parameters are the defined formal parameters of the constructor
// arguments are the values and object references provided by the caller
var parameters = constructor.GetParameters();
if (parameters.Length == 0)
{
return(ScoredConstructor.Parameterless(constructor));
}
int score = 0;
List <bool> usedArguments = context.ArgumentTypes.Select(t => false).ToList();
var argumentMap = new Dictionary <int, int>();
for (int paramIdx = 0; paramIdx < parameters.Length; paramIdx++)
{
var parameter = parameters[paramIdx];
int foundScore = -1;
var parameterType = parameter.ParameterType;
for (int argIdx = 0; argIdx < context.ArgumentTypes.Count; argIdx++)
{
if (usedArguments[argIdx])
{
continue;
}
var argType = context.ArgumentTypes[argIdx];
foundScore = ScoreTypeMatch(argType, parameterType);
if (foundScore >= 0)
{
usedArguments[argIdx] = true;
argumentMap.Add(paramIdx, argIdx);
score += foundScore;
break;
}
}
if (foundScore < 0)
{
return(ScoredConstructor.Unusable(constructor));
}
}
return(new ScoredConstructor(score, constructor, argumentMap));
}
