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| 1 | +namespace AspnetRun.Core.Entities.Base |
| 2 | +{ |
| 3 | + public abstract class EntityBase<TId> : IEntityBase<TId> |
| 4 | + { |
| 5 | + public virtual TId Id { get; protected set; } |
| 6 | + |
| 7 | + int? _requestedHashCode; |
| 8 | + |
| 9 | + public bool IsTransient() |
| 10 | + { |
| 11 | + return Id.Equals(default(TId)); |
| 12 | + } |
| 13 | + |
| 14 | + public override bool Equals(object obj) |
| 15 | + { |
| 16 | + if (obj == null || !(obj is EntityBase<TId>)) |
| 17 | + return false; |
| 18 | + |
| 19 | + if (ReferenceEquals(this, obj)) |
| 20 | + return true; |
| 21 | + |
| 22 | + if (GetType() != obj.GetType()) |
| 23 | + return false; |
| 24 | + |
| 25 | + var item = (EntityBase<TId>)obj; |
| 26 | + |
| 27 | + if (item.IsTransient() || IsTransient()) |
| 28 | + return false; |
| 29 | + else |
| 30 | + return item == this; |
| 31 | + } |
| 32 | + |
| 33 | + public override int GetHashCode() |
| 34 | + { |
| 35 | + if (!IsTransient()) |
| 36 | + { |
| 37 | + if (!_requestedHashCode.HasValue) |
| 38 | + _requestedHashCode = Id.GetHashCode() ^ 31; // XOR for random distribution (http://blogs.msdn.com/b/ericlippert/archive/2011/02/28/guidelines-and-rules-for-gethashcode.aspx) |
| 39 | + |
| 40 | + return _requestedHashCode.Value; |
| 41 | + } |
| 42 | + else |
| 43 | + return base.GetHashCode(); |
| 44 | + } |
| 45 | + |
| 46 | + public static bool operator ==(EntityBase<TId> left, EntityBase<TId> right) |
| 47 | + { |
| 48 | + if (Equals(left, null)) |
| 49 | + return Equals(right, null) ? true : false; |
| 50 | + else |
| 51 | + return left.Equals(right); |
| 52 | + } |
| 53 | + |
| 54 | + public static bool operator !=(EntityBase<TId> left, EntityBase<TId> right) |
| 55 | + { |
| 56 | + return !(left == right); |
| 57 | + } |
| 58 | + } |
| 59 | +} |
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