/// <summary>
/// Memoizer with two parameters, used to perform a lazy-cached evaluation. (see http://en.wikipedia.org/wiki/Memoization)
/// </summary>
/// <typeparam name="T">The return type to memoize</typeparam>
/// <param name="func">the function to evaluate</param>
/// <returns>A memoized value</returns>
public static Func <TArg1, TArg2, TResult> AsLockedMemoized <TArg1, TArg2, TResult>(this Func <TArg1, TArg2, TResult> func)
{
#if XAMARIN
// On Xamarin.iOS, the SynchronizedDictionary type costs a lot in terms of
// generic delegates, where trampolines are used a lot. As simple lock will not create that
// much contention for now.
var values = new Dictionary <CachedTuple <TArg1, TArg2>, TResult>(CachedTuple <TArg1, TArg2> .Comparer);
return((arg1, arg2) =>
{
var tuple = CachedTuple.Create(arg1, arg2);
lock (values)
{
return values.FindOrCreate(
tuple,
() => func(tuple.Item1, tuple.Item2)
);
}
});
#elif !HAS_NO_CONCURRENT_DICT
var values = new ConcurrentDictionary <CachedTuple <TArg1, TArg2>, TResult>(CachedTuple <TArg1, TArg2> .Comparer);
return((arg1, arg2) =>
{
var tuple = CachedTuple.Create(arg1, arg2);
return values.GetOrAdd(
tuple,
// Use the parameter to avoid closure heap allocation
k => func(k.Item1, k.Item2)
);
});
#else
var values = new SynchronizedDictionary <Tuple <TArg1, TArg2>, TResult>();
return((arg1, arg2) =>
{
TResult value = default(TResult);
var tuple = Tuple.Create(arg1, arg2);
values.Lock.Write(
v => v.TryGetValue(tuple, out value),
v => value = values[tuple] = func(arg1, arg2)
);
return value;
});
#endif
}
/// <summary>
/// Memoizer with four parameters, used to perform a lazy-cached evaluation. (see http://en.wikipedia.org/wiki/Memoization)
/// </summary>
/// <typeparam name="T">The return type to memoize</typeparam>
/// <param name="func">the function to evaluate</param>
/// <returns>A memoized value</returns>
public static Func <TArg1, TArg2, TArg3, TArg4, TResult> AsLockedMemoized <TArg1, TArg2, TArg3, TArg4, TResult>(this Func <TArg1, TArg2, TArg3, TArg4, TResult> func)
{
#if XAMARIN
var values = new Dictionary <CachedTuple <TArg1, TArg2, TArg3, TArg4>, TResult>(CachedTuple <TArg1, TArg2, TArg3, TArg4> .Comparer);
return((arg1, arg2, arg3, arg4) =>
{
var tuple = CachedTuple.Create(arg1, arg2, arg3, arg4);
lock (values)
{
return values.FindOrCreate(
tuple,
// Use the parameter to avoid closure heap allocation
() => func(tuple.Item1, tuple.Item2, tuple.Item3, tuple.Item4)
);
}
});
#elif !HAS_NO_CONCURRENT_DICT
var values = new ConcurrentDictionary <CachedTuple <TArg1, TArg2, TArg3, TArg4>, TResult>(CachedTuple <TArg1, TArg2, TArg3, TArg4> .Comparer);
return((arg1, arg2, arg3, arg4) =>
{
var tuple = CachedTuple.Create(arg1, arg2, arg3, arg4);
return values.GetOrAdd(
tuple,
// Use the parameter to avoid closure heap allocation
k => func(k.Item1, k.Item2, k.Item3, k.Item4)
);
});
#else
var values = new SynchronizedDictionary <Tuple <TArg1, TArg2, TArg3, TArg4>, TResult>();
return((arg1, arg2, arg3, arg4) =>
{
TResult value = default(TResult);
var tuple = new Tuple <TArg1, TArg2, TArg3, TArg4>(arg1, arg2, arg3, arg4);
values.Lock.Write(
v => v.TryGetValue(tuple, out value),
v => value = values[tuple] = func(arg1, arg2, arg3, arg4)
);
return value;
});
#endif
}
/// <summary>
/// Memoizer with two parameters, used to perform a lazy-cached evaluation. (see http://en.wikipedia.org/wiki/Memoization)
/// </summary>
/// <typeparam name="TParam1">The first parameter type to memoize</typeparam>
/// <typeparam name="TParam2">The second parameter type to memoize</typeparam>
/// <param name="func">the function to evaluate</param>
/// <returns>A memoized value</returns>
public static Func <TParam1, TParam2, TResult> AsMemoized <TParam1, TParam2, TResult>(this Func <TParam1, TParam2, TResult> func)
{
Dictionary <CachedTuple <TParam1, TParam2>, TResult> values = new Dictionary <CachedTuple <TParam1, TParam2>, TResult>(CachedTuple <TParam1, TParam2> .Comparer);
return((arg1, arg2) =>
{
var tuple = CachedTuple.Create(arg1, arg2);
TResult value;
if (!values.TryGetValue(tuple, out value))
{
value = values[tuple] = func(arg1, arg2);
}
return value;
});
}
public int GetHashCode(CachedTuple <T1, T2> obj)
{
return(obj._cachedHashCode);
}
public bool Equals(CachedTuple <T1, T2> x, CachedTuple <T1, T2> y)
{
return(InternalEquals(x, y));
}
