mirror of https://github.com/dahall/Vanara.git
145 lines
7.0 KiB
C#
145 lines
7.0 KiB
C#
using System;
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using System.Collections;
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using System.Collections.Generic;
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namespace Vanara.Collections
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{
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/// <summary>A sparse array based on a dictionary.</summary>
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public class SparseArray<T> : IList<T>
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{
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/// <summary>Base hash table</summary>
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protected readonly Dictionary<int, T> hashtable;
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/// <summary>Initializes a new instance of the <see cref="SparseArray{T}"/> class.</summary>
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public SparseArray()
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{
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hashtable = new Dictionary<int,T>();
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}
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/// <summary>Returns an enumerator that iterates through the collection.</summary>
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/// <returns>A <see cref="T:System.Collections.Generic.IEnumerator{T}"/> that can be used to iterate through the collection.</returns>
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public IEnumerator<T> GetEnumerator() => hashtable.Values.GetEnumerator();
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/// <summary>Determines whether the array contains the specified value.</summary>
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/// <param name="item">The value.</param>
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/// <returns><c>true</c> if the array contains the specified value; otherwise, <c>false</c>.</returns>
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public bool Contains(T item) => hashtable.ContainsValue(item);
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/// <summary>Removes all items from the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</summary>
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/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection{T}"/> is read-only.</exception>
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public void Clear()
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{
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hashtable.Clear();
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}
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/// <summary>Gets the index of the specified item, or returns -1 if item is not in the array.</summary>
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/// <param name="item">The item.</param>
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/// <returns></returns>
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public int IndexOf(T item)
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{
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foreach (var hash in hashtable)
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{
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if (hash.Value.Equals(item))
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return hash.Key;
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}
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return -1;
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}
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IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
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/// <summary>Inserts an item to the <see cref="T:System.Collections.Generic.IList{T}"/> at the specified index.</summary>
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/// <param name="index">The zero-based index at which <paramref name="item"/> should be inserted.</param>
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/// <param name="item">The object to insert into the <see cref="T:System.Collections.Generic.IList{T}"/>.</param>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="index"/> is not a valid index in the <see cref="T:System.Collections.Generic.IList{T}"/>.</exception>
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/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.IList{T}"/> is read-only.</exception>
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public void Insert(int index, T item)
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{
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if (hashtable.ContainsKey(index))
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hashtable[index] = item;
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else
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hashtable.Add(index, item);
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}
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/// <summary>Removes the <see cref="T:System.Collections.Generic.IList{T}"/> item at the specified index.</summary>
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/// <param name="index">The zero-based index of the item to remove.</param>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="index"/> is not a valid index in the <see cref="T:System.Collections.Generic.IList{T}"/>.</exception>
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/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.IList{T}"/> is read-only.</exception>
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public void RemoveAt(int index)
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{
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hashtable.Remove(index);
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}
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/// <summary>Gets or sets the element at the specified index.</summary>
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/// <param name="index">The index of the element.</param>
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/// <value>The element at the specified index.</value>
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public T this[int index]
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{
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get => hashtable.TryGetValue(index, out T ret) ? ret : default;
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set => Insert(index, value);
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}
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/// <summary>Adds an item to the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</summary>
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/// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</param>
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/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection{T}"/> is read-only.</exception>
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void ICollection<T>.Add(T item)
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{
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throw new NotSupportedException();
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}
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/// <summary>
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/// Copies the elements of the <see cref="T:System.Collections.Generic.ICollection{T}"/> to an <see cref="T:System.Array"/>, starting at a particular <see
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/// cref="T:System.Array"/> index.
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/// </summary>
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/// <param name="array">
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/// The one-dimensional <see cref="T:System.Array"/> that is the destination of the elements copied from <see
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/// cref="T:System.Collections.Generic.ICollection{T}"/>. The <see cref="T:System.Array"/> must have zero-based indexing.
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/// </param>
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/// <param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param>
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/// <exception cref="T:System.ArgumentNullException"><paramref name="array"/> is null.</exception>
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/// <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="arrayIndex"/> is less than 0.</exception>
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/// <exception cref="T:System.ArgumentException">
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/// <paramref name="array"/> is multidimensional.-or- <paramref name="arrayIndex"/> is equal to or greater than the length of <paramref
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/// name="array"/>.-or-The number of elements in the source <see cref="T:System.Collections.Generic.ICollection{T}"/> is greater than the available space
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/// from <paramref name="arrayIndex"/> to the end of the destination <paramref name="array"/>.-or-Type <c>T</c> cannot be cast automatically to the type
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/// of the destination <paramref name="array"/>.
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/// </exception>
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public void CopyTo(T[] array, int arrayIndex)
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{
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hashtable.Values.CopyTo(array, arrayIndex);
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}
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/// <summary>Gets the number of elements contained in the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</summary>
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/// <returns>The number of elements contained in the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</returns>
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public int Count => hashtable.Count;
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/// <summary>Gets a value indicating whether the <see cref="T:System.Collections.Generic.ICollection{T}"/> is read-only.</summary>
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/// <returns>true if the <see cref="T:System.Collections.Generic.ICollection{T}"/> is read-only; otherwise, false.</returns>
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public bool IsReadOnly => false;
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/// <summary>Removes the first occurrence of a specific object from the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</summary>
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/// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection{T}"/>.</param>
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/// <returns>
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/// true if <paramref name="item"/> was successfully removed from the <see cref="T:System.Collections.Generic.ICollection{T}"/>; otherwise, false. This
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/// method also returns false if <paramref name="item"/> is not found in the original <see cref="T:System.Collections.Generic.ICollection{T}"/>.
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/// </returns>
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/// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection{T}"/> is read-only.</exception>
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public bool Remove(T item)
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{
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var idx = IndexOf(item);
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if (idx == -1)
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return false;
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RemoveAt(idx);
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return true;
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}
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/// <summary>Collapses array into new, condensed array. Does not maintain indexes.</summary>
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/// <returns>An array of <typeparamref name="T"/></returns>
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public T[] ToArray()
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{
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var output = new T[hashtable.Values.Count];
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hashtable.Values.CopyTo(output, 0);
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return output;
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}
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}
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}
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