readonlycollectionbase.cs

C#写的类似于STL的集合类,首先是C#编写,可以用于.net变程.

            IEqualityComparer<T> equalityComparer = EqualityComparer<T>.Default;
            foreach (T i in this) {
                if (equalityComparer.Equals(i, item))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// Copies all the items in the collection into an array. Implemented by
        /// using the enumerator returned from GetEnumerator to get all the items
        /// and copy them to the provided array.
        /// </summary>
        /// <param name="array">Array to copy to.</param>
        /// <param name="arrayIndex">Starting index in <paramref name="array"/> to copy to.</param>
        public virtual void CopyTo(T[] array, int arrayIndex)
        {
            int count = this.Count;

            if (count == 0)
                return;

            if (array == null)
                throw new ArgumentNullException("array");
            if (count < 0)
                throw new ArgumentOutOfRangeException("count", count, Strings.ArgMustNotBeNegative);
            if (arrayIndex < 0)
                throw new ArgumentOutOfRangeException("arrayIndex", arrayIndex, Strings.ArgMustNotBeNegative);
            if (arrayIndex >= array.Length || count > array.Length - arrayIndex)
                throw new ArgumentException("arrayIndex", Strings.ArrayTooSmall);

            int index = arrayIndex, i = 0;
            foreach (T item in (ICollection<T>)this) {
                if (i >= count)
                    break;

                array[index] = item;
                ++index;
                ++i;
            }
        }

        /// <summary>
        /// Creates an array of the correct size, and copies all the items in the 
        /// collection into the array, by calling CopyTo.
        /// </summary>
        /// <returns>An array containing all the elements in the collection, in order.</returns>
        public virtual T[] ToArray()
        {
            int count = this.Count;

            T[] array = new T[count];
            CopyTo(array, 0);
            return array;
        }

        /// <summary>
        /// Must be overridden to provide the number of items in the collection.
        /// </summary>
        /// <value>The number of items in the collection.</value>
        public abstract int Count { get; }

        /// <summary>
        /// Indicates whether the collection is read-only. Returns the value
        /// of readOnly that was provided to the constructor.
        /// </summary>
        /// <value>Always true.</value>
        bool ICollection<T>.IsReadOnly
        {
            get { return true; }
        }

        #endregion

        #region IEnumerable<T> Members

        /// <summary>
        /// Must be overridden to enumerate all the members of the collection.
        /// </summary>
        /// <returns>A generic IEnumerator&lt;T&gt; that can be used
        /// to enumerate all the items in the collection.</returns>
        public abstract IEnumerator<T> GetEnumerator();

        #endregion

        #region ICollection Members

        /// <summary>
        /// Copies all the items in the collection into an array. Implemented by
        /// using the enumerator returned from GetEnumerator to get all the items
        /// and copy them to the provided array.
        /// </summary>
        /// <param name="array">Array to copy to.</param>
        /// <param name="index">Starting index in <paramref name="array"/> to copy to.</param>
        void ICollection.CopyTo(Array array, int index)
        {
            int count = this.Count;

            if (count == 0)
                return;

            if (array == null)
                throw new ArgumentNullException("array");
            if (count < 0)
                throw new ArgumentOutOfRangeException("count", count, Strings.ArgMustNotBeNegative);
            if (index < 0)
                throw new ArgumentOutOfRangeException("index", index, Strings.ArgMustNotBeNegative);
            if (index >= array.Length || count > array.Length - index)
                throw new ArgumentException("index", Strings.ArrayTooSmall);

            int i = 0;
            foreach (object o in (ICollection)this) {
                if (i >= count)
                    break;

                array.SetValue(o, index);
                ++index;
                ++i;
            }
        }

        /// <summary>
        /// Indicates whether the collection is synchronized.
        /// </summary>
        /// <value>Always returns false, indicating that the collection is not synchronized.</value>
        bool ICollection.IsSynchronized
        {
            get { return false; }
        }

        /// <summary>
        /// Indicates the synchronization object for this collection.
        /// </summary>
        /// <value>Always returns this.</value>
        object ICollection.SyncRoot
        {
            get { return this; }
        }

        #endregion

        #region IEnumerable Members

        /// <summary>
        /// Provides an IEnumerator that can be used to iterate all the members of the
        /// collection. This implementation uses the IEnumerator&lt;T&gt; that was overridden
        /// by the derived classes to enumerate the members of the collection.
        /// </summary>
        /// <returns>An IEnumerator that can be used to iterate the collection.</returns>
        IEnumerator IEnumerable.GetEnumerator()
        {
            foreach (T item in this) {
                yield return item;
            }
        }

        #endregion

        /// <summary>
        /// Display the contents of the collection in the debugger. This is intentionally private, it is called
        /// only from the debugger due to the presence of the DebuggerDisplay attribute. It is similar
        /// format to ToString(), but is limited to 250-300 characters or so, so as not to overload the debugger.
        /// </summary>
        /// <returns>The string representation of the items in the collection, similar in format to ToString().</returns>
        internal string DebuggerDisplayString()
        {
            const int MAXLENGTH = 250;

            System.Text.StringBuilder builder = new System.Text.StringBuilder();

            builder.Append('{');

            // Call ToString on each item and put it in.
            bool firstItem = true;
            foreach (T item in this) {
                if (builder.Length >= MAXLENGTH) {
                    builder.Append(",...");
                    break;
                }

                if (!firstItem)
                    builder.Append(',');

                if (item == null)
                    builder.Append("null");
                else
                    builder.Append(item.ToString());

                firstItem = false;
            }

            builder.Append('}');
            return builder.ToString();
        }
    }
}