/// <summary>
/// Obtains the value for the specified key from a dictionary, or adds a new value to the dictionary where the key did not previously exist.
/// </summary>
/// <typeparam name="TKey">The type of key stored by the dictionary.</typeparam>
/// <typeparam name="TValue">The type of value stored by the dictionary.</typeparam>
/// <typeparam name="TArg">The type of argument supplied to the value factory.</typeparam>
/// <param name="location">The variable or field to atomically update if the specified <paramref name="key" /> is not in the dictionary.</param>
/// <param name="key">The key for the value to retrieve or add.</param>
/// <param name="valueFactory">The function to execute to obtain the value to insert into the dictionary if the key is not found.</param>
/// <param name="factoryArgument">The argument to pass to the value factory.</param>
/// <returns>The value obtained from the dictionary or <paramref name="valueFactory" /> if it was not present.</returns>
public static TValue GetOrAdd <TKey, TValue, TArg>(ref ImmutableHashMap <TKey, TValue> location, TKey key, Func <TKey, TArg, TValue> valueFactory, TArg factoryArgument)
{
//#### Contract.ThrowIfNull(valueFactory);
var map = Volatile.Read(ref location);
//#### Contract.ThrowIfNull(map);
// if the key exists return the value
if (map.TryGetValue(key, out var existingValue))
{
return(existingValue);
}
TValue newValue = valueFactory(key, factoryArgument);
do
{
var augmentedMap = map.Add(key, newValue);
// if location has not changed since "var map = Volatile.Read(ref location)"
var replacedMap = Interlocked.CompareExchange(ref location, augmentedMap, map);
if (replacedMap == map)
{
return(newValue);
}
map = replacedMap;
}
// ReSharper disable once PossibleNullReferenceException
while (!map.TryGetValue(key, out existingValue));
return(existingValue);
}
public ImmutableHashMap <TKey, TValue> WithComparers(IEqualityComparer <TKey> keyComparer,
IEqualityComparer <TValue> valueComparer)
{
if (keyComparer == null)
{
keyComparer = EqualityComparer <TKey> .Default;
}
if (valueComparer == null)
{
valueComparer = EqualityComparer <TValue> .Default;
}
if (_keyComparer == keyComparer)
{
if (_valueComparer == valueComparer)
{
return(this);
}
else
{
return(new ImmutableHashMap <TKey, TValue>(_root, _keyComparer, valueComparer));
}
}
else
{
var set = new ImmutableHashMap <TKey, TValue>(keyComparer, valueComparer);
set = set.AddRange(this, overwriteOnCollision: false, avoidToHashMap: true);
return(set);
}
}
private static bool TryCastToImmutableMap(IEnumerable <KeyValuePair <TKey, TValue> > sequence,
out ImmutableHashMap <TKey, TValue> other)
{
other = sequence as ImmutableHashMap <TKey, TValue>;
if (other != null)
{
return(true);
}
return(false);
}
public DebuggerProxy(ImmutableHashMap <TKey, TValue> map)
{
_map = map;
}