/// <summary>
/// Because the input <see cref="IDictionary{TKey, TValue}"/> is not an <see cref="IDistinctValuedDictionary{TKey, TValue}"/>, duplicate value handling must be specified.
/// </summary>
public static Dictionary <TValue, TKey> Invert <TKey, TValue>(this IDictionary <TKey, TValue> dictionary,
DuplicateValueHandling duplicateValueHandling = DuplicateValueHandling.Error)
{
var output = new Dictionary <TValue, TKey>();
foreach (var pair in dictionary)
{
var key = pair.Value;
var value = pair.Key;
if (output.ContainsKey(key))
{
var existing = output[key];
var chosen = duplicateValueHandling.Choose(existing, value);
output[key] = chosen;
}
else
{
output.Add(key, value);
}
}
return(output);
}
