/// <summary>
/// Gets associate instance for specified parameters and result types.
/// All associate created instances are cached and returned on the same calls further.
/// </summary>
/// <typeparam name="TKey1">First type to try to provide the associate for.</typeparam>
/// <typeparam name="TKey2">Second type to try to provide the associate for.</typeparam>
/// <typeparam name="TAssociate">Type of result to provide the associate for.</typeparam>
/// <typeparam name="TResult">The type of result.</typeparam>
/// <returns>Associate instance, if found;
/// otherwise, <see langword="null"/>.</returns>
/// <exception cref="InvalidOperationException"><c>InvalidOperationException</c>.</exception>
protected TResult GetAssociate <TKey1, TKey2, TAssociate, TResult>()
where TAssociate : class
{
var key = new TypePair(typeof(TKey1), typeof(TResult));
return((TResult)cache.GetValue(key, _key => {
Type foundFor;
TAssociate associate1 = CreateAssociate <TKey1, TAssociate>(out foundFor);
TAssociate associate2 = CreateAssociate <TKey2, TAssociate>(out foundFor);
// Preferring non-null ;)
TAssociate associate;
if (associate1 == null)
{
associate = associate2;
}
else if (associate2 == null)
{
associate = associate1;
}
else
{
// Both are non-null; preferring one of two
associate = PreferAssociate <TKey1, TKey2, TAssociate>(associate1, associate2);
}
if (associate == null)
{
// Try to get complex associate (create it manually)
associate = CreateCustomAssociate <TKey1, TKey2, TAssociate>();
if (associate == null)
{
var stringBuilder = new StringBuilder();
for (int i = 0; i < TypeSuffixes.Length; i++)
{
if (i != 0)
{
stringBuilder.Append(", ");
}
stringBuilder.Append(TypeSuffixes[i]);
}
throw new InvalidOperationException(string.Format(
Strings.ExCantFindAssociate2, stringBuilder,
typeof(TAssociate).GetShortName(),
typeof(TKey1).GetShortName(),
typeof(TKey2).GetShortName()));
}
}
return ConvertAssociate <TKey1, TKey2, TAssociate, TResult>(associate);
}));
}
/// <inheritdoc/>
protected override TAssociate CreateCustomAssociate <TKey1, TKey2, TAssociate>()
{
Pair <Type> keyTypePair = new Pair <Type>(typeof(TKey1), typeof(TKey2));
if (InProgress.ContainsKey(keyTypePair))
{
throw new InvalidOperationException(Strings.ExRecursiveAssociateLookupDetected);
}
InProgress.Add(keyTypePair, true);
try {
TAssociate associate = base.CreateCustomAssociate <TKey1, TKey2, TAssociate>();
if (associate != null)
{
return(associate);
}
IAdvancedConverterFactory <TKey1> f1 = base.GetAssociate <TKey1, IAdvancedConverterFactory <TKey1>, IAdvancedConverterFactory <TKey1> >();
if (f1 != null)
{
associate = f1.CreateForwardConverter <TKey2>() as TAssociate;
if (associate != null)
{
return(associate);
}
}
IAdvancedConverterFactory <TKey2> f2 = base.GetAssociate <TKey2, IAdvancedConverterFactory <TKey2>, IAdvancedConverterFactory <TKey2> >();
if (f2 != null)
{
associate = f2.CreateBackwardConverter <TKey1>() as TAssociate;
if (associate != null)
{
return(associate);
}
}
return(null);
}
finally {
InProgress.Remove(keyTypePair);
}
}