CollectionExtensions.cs

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using System.Diagnostics.CodeAnalysis;
 
namespace System.Collections.Generic;
 
public static class CollectionExtensions
{
    public static TValue? GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key)
    {
        return dictionary.GetValueOrDefault(key, default(TValue));
    }
 
    public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dictionary, TKey key, TValue defaultValue)
    {
        if (dictionary == null)
        {
            throw new ArgumentNullException("dictionary");
        }
        if (!dictionary.TryGetValue(key, out TValue value))
        {
            return defaultValue;
        }
        return value;
    }
 
    public static bool TryAdd<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue value)
    {
        if (dictionary == null)
        {
            throw new ArgumentNullException("dictionary");
        }
        if (!dictionary.ContainsKey(key))
        {
            dictionary.Add(key, value);
            return true;
        }
        return false;
    }
 
    public static bool Remove<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, [MaybeNullWhen(false)] out TValue value)
    {
        if (dictionary == null)
        {
            throw new ArgumentNullException("dictionary");
        }
        if (dictionary.TryGetValue(key, out value))
        {
            dictionary.Remove(key);
            return true;
        }
        value = default(TValue);
        return false;
    }
}