Merge pull request aalhour#103 from NdubuisiJr/master

Added CircularBuffer DataStructure.

Author: aalhour

DataStructures/Lists/CircularBuffer.cs

@@ -0,0 +1,241 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace DataStructures.Lists 
+{
+    public class CircularBuffer<T> : IEnumerable<T>, ICollection<T> where T : IComparable<T> 
+    {
+        private T[] _circularBuffer;
+        private int _end;
+        private int _start;
+        private static readonly int _defaultBufferLength = 10;
+
+        /// <summary>
+        /// Returns the length of the buffer
+        /// </summary>
+        public int Length 
+        {
+            get 
+            {
+                return _circularBuffer.Length - 1;
+            }
+        }
+
+        /// <summary>
+        ///  Checks if no element is inserted into the buffer
+        /// </summary>
+        public bool IsEmpty 
+        {
+            get 
+            {
+                return _count == 0;
+            }
+        }
+
+        /// <summary>
+        /// Checks if the buffer is filled up
+        /// </summary>
+        public bool IsFilledUp 
+        {
+            get 
+            {
+                return ((_end + 1) % _circularBuffer.Length == _start) && !_circularBuffer[_start].Equals(_circularBuffer[_end]);
+            }
+        }
+
+        /// <summary>
+        /// Controls whether data should be overridden when it is continously inserted without reading
+        /// </summary>
+        public bool CanOverride 
+        {
+            get;
+        }
+
+        /// <summary>
+        /// Initializes a circular buffer with initial length of 10
+        /// </summary>
+        public CircularBuffer(bool canOverride = true) : this(_defaultBufferLength, canOverride) 
+        {
+        }
+
+        /// <summary>
+        /// Initializes a circular buffer with given length
+        /// </summary>
+        /// <param name="length">The length of the buffer</param>
+        public CircularBuffer(int length, bool canOverride = true) 
+        {
+            if (length < 1) 
+            {
+                throw new ArgumentOutOfRangeException("length can not be zero or negative");
+            }
+            _circularBuffer = new T[length + 1];
+            _end = 0;
+            _start = 0;
+            CanOverride = canOverride;
+        }
+
+        /// <summary>
+        /// Writes value to the back of the buffer
+        /// </summary>
+        /// <param name="value">value to be added to the buffer</param>
+        public void Add(T value) 
+        {
+            if (CanOverride==false && IsFilledUp==true) 
+            {
+                throw new CircularBufferFullException($"Circular Buffer is filled up. {value} can not be inserted");
+            }
+            innerInsert(value);
+        }
+
+        // Inserts data into the buffer without checking if it is full
+        private void innerInsert(T value) 
+        {
+            _circularBuffer[_end] = value;
+            _end = (_end + 1) % _circularBuffer.Length;
+            if (_end == _start) 
+            {
+                _start = (_start + 1) % _circularBuffer.Length;
+            }
+
+            // Count should not be greater than the length of the buffer when overriding 
+            _count = _count < Length ? ++_count : _count;
+        }
+
+        /// <summary>
+        ///     Reads and removes the value in front of the buffer, and places the next value in front.
+        /// </summary>
+        public T Pop() 
+        {
+            var result = _circularBuffer[_start];
+            _circularBuffer[_start] = _circularBuffer[_end];
+            _start = (_start + 1) % _circularBuffer.Length;
+            //Count should not go below Zero when poping an empty buffer.
+            _count = _count > 0 ? --_count : _count;
+            return result;
+        }
+
+        #region IEnumerable Implementation
+        public IEnumerator<T> GetEnumerator() 
+        {
+            for (int i = _start; i < Count; i++) 
+            {
+                yield return _circularBuffer[i];
+            }
+        }
+
+        IEnumerator IEnumerable.GetEnumerator() 
+        {
+            return GetEnumerator();
+        }
+        #endregion
+
+        #region ICollection Implementation
+        private int _count;
+        /// <summary>
+        /// Returns the number of elements.
+        /// </summary>
+        public int Count 
+        {
+            get 
+            {
+                return _count;
+            }
+        }
+        /// <summary>
+        /// Checks whether this collection is readonly
+        /// </summary>
+        public bool IsReadOnly 
+        {
+            get 
+            {
+                return false;
+            }
+        }
+        /// <summary>
+        /// Clears this instance
+        /// </summary>
+        public void Clear() 
+        {
+            _count = 0;
+            _start = 0;
+            _end = 0;
+            _circularBuffer = new T[Length + 1];
+        }
+        /// <summary>
+        /// Checks whether the buffer contains an item
+        /// </summary>
+        public bool Contains(T item) 
+        {
+            return _circularBuffer.Contains(item);
+        }
+        /// <summary>
+        /// Copies this buffer to an array
+        /// </summary>
+        public void CopyTo(T[] array, int arrayIndex) 
+        {
+            if (array == null) 
+            {
+                throw new ArgumentNullException("array can not be null");
+            }
+
+            if (array.Length == 0 || arrayIndex >= array.Length || arrayIndex < 0) 
+            {
+                throw new IndexOutOfRangeException();
+            }
+
+            // Get enumerator
+            var enumarator = GetEnumerator();
+
+            // Copy elements if there is any in the buffer and if the index is within the valid range
+            while (arrayIndex < array.Length) 
+            {
+                if (enumarator.MoveNext()) 
+                {
+                    array[arrayIndex] = enumarator.Current;
+                    arrayIndex++;
+                }
+                else 
+                {
+                    break;
+                }
+            }
+        }
+        /// <summary>
+        /// Removes an item from the buffer
+        /// </summary>
+        public bool Remove(T item) 
+        {
+            if (!IsEmpty && Contains(item)) 
+            {
+               var sourceArray = _circularBuffer.Except(new T[] { item }).ToArray();
+                _circularBuffer = new T[Length + 1];
+                Array.Copy(sourceArray, _circularBuffer, sourceArray.Length);
+
+                if (!Equals(item,default(T))) 
+                {
+                    _end = sourceArray.Length - 1;
+                    _count = sourceArray.Length-1;
+                }
+                else 
+                {
+                    _end = sourceArray.Length;
+                    _count = sourceArray.Length;
+                }
+
+                return true;
+            }
+
+            return false;
+        }
+        #endregion
+    }
+
+    public class CircularBufferFullException : Exception 
+    {
+        public CircularBufferFullException(string message) : base(message) 
+        {
+        }
+    }
+}