/// <summary>Associates a key with a value in the dictionary, and gets the old value
/// if the key was already present.</summary>
/// <returns>The old value associated with the same key. If a new pair was added,
/// the result has no value.</returns>
public static Maybe <V> GetAndSet <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
if (dict.GetAndEdit(ref key, ref value, DictEditMode.AddOrReplace))
{
return(value);
}
return(new Maybe <V>());
}
/// <summary>Adds a new key/value pair if the key was not present, or gets the existing
/// value if the key was present.</summary>
/// <returns>The existing value. If a new pair was added, the result has no value.</returns>
/// <seealso cref="GetOrAdd{K, V}(IDictionaryEx{K, V}, K, V)"/>
public static Maybe <V> AddOrGetExisting <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
if (dict.GetAndEdit(ref key, ref value, DictEditMode.AddIfNotPresent))
{
return(value);
}
return(default(Maybe <V>));
}
/// <summary>Replaces an item in the map if the key was already present.
/// If the key was not already present, this method has no effect.</summary>
/// <returns>The old value if a value was replaced, or an empty value of <see cref="Maybe{V}"/> otherwise.</returns>
public static Maybe <V> SwapIfPresent <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
return(dict.GetAndEdit(ref key, ref value, DictEditMode.ReplaceIfPresent) ?
(Maybe <V>)value : default(Maybe <V>));
}
/// <summary>Replaces an item in the map if the key was already present.
/// If the key was not already present, this method has no effect.</summary>
/// <returns>True if a value existed and was replaced, false if not.</returns>
public static bool ReplaceIfPresent <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
return(dict.GetAndEdit(ref key, ref value, DictEditMode.ReplaceIfPresent));
}
/// <summary>Adds a key/value pair to the dictionary if the key is not already present,
/// and returns the existing or new value.</summary>
/// <returns>The existing value (if the key already existed) or the new value.</returns>
public static V GetOrAdd <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
dict.GetAndEdit(ref key, ref value, DictEditMode.AddIfNotPresent);
return(value);
}
public static bool TryAdd <K, V>(this IDictionaryEx <K, V> dict, K key, V value)
{
return(!dict.GetAndEdit(ref key, ref value, DictEditMode.AddIfNotPresent));
}
