public bool AddRange(SCG.IEnumerable <T> items)
{
// is Valid, not disposed
Requires(IsValid);
// Collection must be non-read-only
Requires(!IsReadOnly, CollectionMustBeNonReadOnly);
// Collection must be non-fixed-sized
Requires(!IsFixedSize, CollectionMustBeNonFixedSize);
// Argument must be non-null
Requires(items != null, ArgumentMustBeNonNull);
// All items must be non-null if collection disallows null values
Requires(AllowsNull || ForAll(items, item => item != null), ItemsMustBeNonNull);
// The collection becomes non-empty, if items are non-empty
Ensures(items.IsEmpty() || !IsEmpty);
// The collection will contain the items added
Ensures(ForAll(items, item => this.Contains(item, EqualityComparer)));
// If items were added, the count increases; otherwise it stays the same
Ensures(Result <bool>() ? Count > OldValue(Count) : Count == OldValue(Count));
// Empty enumerable returns false
Ensures(!items.IsEmpty() || !Result <bool>());
// Collection doesn't change if enumerator throws an exception
EnsuresOnThrow <Exception>(this.IsSameSequenceAs(OldValue(ToArray())));
// If result is false, the collection remains unchanged
Ensures(Result <bool>() || this.IsSameSequenceAs(OldValue(ToArray())));
// TODO: Make more exact check of added items - especially for sets
return(default(bool));
}
