/// <summary>
/// Adds additional <see cref="ICriteria{T}"/> to the fuzzy search list.
/// </summary>
/// <param name="methods">The list of methods to rank.</param>
/// <param name="finderContext">The <see cref="IMethodFinderContext"/> that describes the target method.</param>
protected override void Rank(IList <IFuzzyItem <TMethod> > methods, IMethodFinderContext finderContext)
{
var additionalArguments = finderContext.Arguments ?? new object[0];
var argumentTypes = (from argument in additionalArguments
let argumentType = argument == null ? typeof(object) : argument.GetType()
select argumentType).ToList();
var argumentCount = argumentTypes.Count;
foreach (var fuzzyItem in methods)
{
if (fuzzyItem.Confidence < 0)
{
continue;
}
// Check the constructor for any
// parameter types that might not exist
// in the container and eliminate the
// constructor as a candidate match if
// that parameter type cannot be found
var constructor = fuzzyItem.Item;
var parameters = constructor.GetParameters();
var parameterCount = parameters.Length;
var maxRelativeIndex = parameterCount - argumentCount;
CheckParameters(fuzzyItem, Container, maxRelativeIndex);
}
}
/// <summary>
/// Uses the <paramref name="container"/> to determine which member to use from
/// the <paramref name="concreteType">concrete type</paramref>.
/// </summary>
/// <param name="concreteType">The target type.</param>
/// <param name="container">The container that contains the member values that will be used to invoke the members.</param>
/// <param name="finderContext">The <see cref="IMethodFinderContext"/> that describes the target method.</param>
/// <returns>A member instance if a match is found; otherwise, it will return <c>null</c>.</returns>
public TMember ResolveFrom(Type concreteType, IServiceContainer container,
IMethodFinderContext finderContext)
{
IEnumerable <TMember> constructors = GetMembers(concreteType);
if (constructors == null)
{
return(null);
}
IMethodFinder <TMember> resolver = GetMethodFinder(container);
TMember bestMatch = resolver.GetBestMatch(constructors, finderContext);
// If all else fails, find the
// default constructor and use it as the
// best match by default
if (bestMatch == null)
{
TMember defaultResult = GetDefaultResult(concreteType);
bestMatch = defaultResult;
}
Debug.Assert(bestMatch != null);
return(bestMatch);
}
/// <summary>
/// Determines which method best matches the
/// services currently in the target container.
/// </summary>
/// <param name="items">The list of methods to search.</param>
/// <param name="finderContext">The <see cref="IMethodFinderContext"/> that describes the target method.</param>
/// <returns>Returns the method with the most resolvable parameters from the target <see cref="IServiceContainer"/> instance.</returns>
public T GetBestMatch(IEnumerable <T> items, IMethodFinderContext finderContext)
{
T bestMatch = null;
IList <IFuzzyItem <T> > fuzzyList = items.AsFuzzyList();
// Return the first item
// if there is no other alternative
if (fuzzyList.Count == 1)
{
return(fuzzyList[0].Item);
}
IEnumerable <object> additionalArguments = finderContext.Arguments;
List <Type> additionalArgumentTypes = (from argument in additionalArguments
let argumentType =
argument == null ? typeof(object) : argument.GetType()
select argumentType).ToList();
Rank(fuzzyList, finderContext);
// Match the generic parameter types
int genericParameterCount = finderContext.TypeArguments != null?finderContext.TypeArguments.Count() : 0;
Func <T, bool> matchGenericArgumentCount = method =>
{
Type[] genericArguments = method.IsGenericMethod
? method.GetGenericArguments
()
: new Type[0];
int currentParameterCount = genericArguments.Count();
return(genericParameterCount == currentParameterCount);
};
fuzzyList.AddCriteria(matchGenericArgumentCount, CriteriaType.Critical);
IEnumerable <IFuzzyItem <T> > candidates = fuzzyList.Where(fuzzy => fuzzy.Confidence > 0);
bestMatch = SelectBestMatch(candidates);
// If all else fails, find the method
// that matches only the additional arguments
if (bestMatch != null)
{
return(bestMatch);
}
return(GetNextBestMatch(fuzzyList, additionalArgumentTypes, bestMatch));
}
/// <summary>
/// Adds additional <see cref="ICriteria{T}"/> to the fuzzy search list.
/// </summary>
/// <param name="methods">The list of methods to rank.</param>
/// <param name="finderContext">The <see cref="IMethodFinderContext"/> that describes the target method.</param>
protected virtual void Rank(IList <IFuzzyItem <T> > methods, IMethodFinderContext finderContext)
{
}
public Option<TMethod> GetBestMatch(IEnumerable<TMethod> methods, IMethodFinderContext finderContext)
{
var methodName = finderContext.MethodName;
var candidateMethods = (methods ?? Enumerable.Empty<TMethod>());
// Match the method name
if (methodName.HasValue && !string.IsNullOrEmpty(methodName.ValueOrDefault()))
candidateMethods = candidateMethods.Where(m =>
_methodFinderStrategy.GetMethodName(m) == methodName.ValueOrFailure());
// Match the argument count
var argumentTypes = finderContext.ArgumentTypes.ToArray();
var argumentCount = argumentTypes.Count();
candidateMethods =
candidateMethods.Where(m => _methodFinderStrategy.GetParameterTypes(m).Count() == argumentCount);
// Find a compatible method signature
bool HasCompatibleParameters(TMethod method, int position, IReadOnlyList<Option<Type>> currentArgumentTypes)
{
var parameters = _methodFinderStrategy.GetParameterTypes(method).ToArray();
if (currentArgumentTypes.Count != parameters.Length)
return false;
var parameterType = parameters[position];
var argumentType = currentArgumentTypes[position];
if (!argumentType.HasValue)
return false;
var hasCompatibleParameterType =
parameterType.IsAssignableFrom(argumentType.ValueOrFailure());
return hasCompatibleParameterType;
}
// Exact parameter type matches will outweigh compatible method overloads
bool HasExactParameterTypes(TMethod method, int position, IReadOnlyList<Option<Type>> currentArguments)
{
var parameters = _methodFinderStrategy.GetParameterTypes(method).ToArray();
if (currentArguments.Count != parameters.Length)
return false;
var parameterType = parameters[position];
var argumentType = currentArguments[position];
return argumentType.HasValue && parameterType == argumentType.ValueOrFailure();
}
bool HasCompatibleReturnType(TMethod method, Type expectedReturnType)
{
var returnType = _methodFinderStrategy.GetReturnType(method);
return returnType.HasValue && expectedReturnType.IsAssignableFrom(returnType.ValueOrFailure());
}
var fuzzyList = candidateMethods.AsFuzzyList();
// Override the search results if there is only one match
// and that match has compatible parameters
var hasRequestedCompatibleMethodType = finderContext.ReturnType.HasValue;
if (fuzzyList.Count == 1)
{
var nextBestMatch = fuzzyList[0];
var hasCompatibleParameters = true;
for (var i = 0; i < argumentTypes.Length; i++)
{
hasCompatibleParameters &= HasCompatibleParameters(nextBestMatch.Item, i, argumentTypes);
}
// Match the return type if the caller requests a method return type match
if (hasRequestedCompatibleMethodType && hasCompatibleParameters)
return HasCompatibleReturnType(nextBestMatch.Item, finderContext.ReturnType.ValueOrFailure())
? Option.Some(nextBestMatch.Item)
: Option.None<TMethod>();
if (hasCompatibleParameters)
return Option.Some(nextBestMatch.Item);
}
// Otherwise, fall back to a weighted search against the other remaining methods
for (var i = 0; i < argumentTypes.Length; i++)
{
var currentIndex = i;
fuzzyList.AddCriteria(method => HasCompatibleParameters(method, currentIndex, argumentTypes),
CriteriaType.Critical);
fuzzyList.AddCriteria(method => HasExactParameterTypes(method, currentIndex, argumentTypes));
}
// Match the method return type
if (hasRequestedCompatibleMethodType)
fuzzyList.AddCriteria(
method => HasCompatibleReturnType(method, finderContext.ReturnType.ValueOrFailure()),
CriteriaType.Critical);
if (argumentTypes.Length == 0)
fuzzyList.AddCriteria(method => !_methodFinderStrategy.GetParameterTypes(method).Any());
var bestMatch = fuzzyList.BestMatch(_finderTolerance);
return bestMatch == null ? Option.None<TMethod>() : Option.Some(bestMatch?.Item);
}
public static bool HasMatchingMethods <TMethod>(this MethodBaseFinder <TMethod> finder,
IEnumerable <TMethod> methods, IMethodFinderContext context)
where TMethod : MethodBase
{
return(finder.GetBestMatch(methods, context).HasValue);
}