From aa17f293057039374f52d1741012ee3942658759 Mon Sep 17 00:00:00 2001
From: Chris Cameron <chris.cameron@wedoresi.com>
Date: Fri, 13 Sep 2019 16:35:38 -0400
Subject: [PATCH] feat: Adding BinarySearch extension method for ILists

---
 ICD.Common.Utils/Extensions/ListExtensions.cs | 58 +++++++++++++++----
 1 file changed, 46 insertions(+), 12 deletions(-)

diff --git a/ICD.Common.Utils/Extensions/ListExtensions.cs b/ICD.Common.Utils/Extensions/ListExtensions.cs
index 04d32b1..b7d8298 100644
--- a/ICD.Common.Utils/Extensions/ListExtensions.cs
+++ b/ICD.Common.Utils/Extensions/ListExtensions.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using ICD.Common.Properties;
 using ICD.Common.Utils.Comparers;
 
@@ -18,7 +17,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="extends"></param>
 		/// <param name="items"></param>
 		[PublicAPI]
-		public static void AddSorted<T>(this List<T> extends, IEnumerable<T> items)
+		public static void AddSorted<T>(this IList<T> extends, IEnumerable<T> items)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -37,7 +36,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="items"></param>
 		/// <param name="comparer"></param>
 		[PublicAPI]
-		public static void AddSorted<T>(this List<T> extends, IEnumerable<T> items, IComparer<T> comparer)
+		public static void AddSorted<T>(this IList<T> extends, IEnumerable<T> items, IComparer<T> comparer)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -60,7 +59,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="items"></param>
 		/// <param name="predicate"></param>
 		[PublicAPI]
-		public static void AddSorted<T, TProp>(this List<T> extends, IEnumerable<T> items, Func<T, TProp> predicate)
+		public static void AddSorted<T, TProp>(this IList<T> extends, IEnumerable<T> items, Func<T, TProp> predicate)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -82,7 +81,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="extends"></param>
 		/// <param name="item"></param>
 		[PublicAPI]
-		public static int AddSorted<T>(this List<T> extends, T item)
+		public static int AddSorted<T>(this IList<T> extends, T item)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -98,7 +97,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="item"></param>
 		/// <param name="comparer"></param>
 		[PublicAPI]
-		public static int AddSorted<T>(this List<T> extends, T item, IComparer<T> comparer)
+		public static int AddSorted<T>(this IList<T> extends, T item, IComparer<T> comparer)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -124,7 +123,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="item"></param>
 		/// <param name="predicate"></param>
 		[PublicAPI]
-		public static int AddSorted<T, TProp>(this List<T> extends, T item, Func<T, TProp> predicate)
+		public static int AddSorted<T, TProp>(this IList<T> extends, T item, Func<T, TProp> predicate)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -143,7 +142,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="extends"></param>
 		/// <param name="totalLength"></param>
 		[PublicAPI]
-		public static void PadRight<T>(this List<T> extends, int totalLength)
+		public static void PadRight<T>(this IList<T> extends, int totalLength)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -162,7 +161,7 @@ namespace ICD.Common.Utils.Extensions
 		/// <param name="totalLength"></param>
 		/// <param name="item"></param>
 		[PublicAPI]
-		public static void PadRight<T>(this List<T> extends, int totalLength, T item)
+		public static void PadRight<T>(this IList<T> extends, int totalLength, T item)
 		{
 			if (extends == null)
 				throw new ArgumentNullException("extends");
@@ -171,10 +170,45 @@ namespace ICD.Common.Utils.Extensions
 				throw new ArgumentOutOfRangeException("totalLength", "totalLength must be greater or equal to 0");
 
 			int pad = totalLength - extends.Count;
-			if (pad <= 0)
-				return;
+			for (int index = 0; index < pad; index++)
+				extends.Add(item);
+		}
 
-			extends.AddRange(Enumerable.Repeat(item, pad));
+		/// <summary>
+		/// Returns the index of the item in the list.
+		/// </summary>
+		/// <typeparam name="T"></typeparam>
+		/// <param name="extends"></param>
+		/// <param name="item"></param>
+		/// <param name="comparer"></param>
+		/// <returns></returns>
+		[PublicAPI]
+		public static int BinarySearch<T>(this IList<T> extends, T item, IComparer<T> comparer)
+		{
+			if (extends == null)
+				throw new ArgumentNullException("extends");
+
+			if (comparer == null)
+				throw new ArgumentNullException("comparer");
+
+			int lo = 0;
+			int hi = extends.Count - 1;
+
+			while (lo <= hi)
+			{
+				int i = lo + ((hi - lo) >> 1);
+				int order = comparer.Compare(extends[i], item);
+
+				if (order == 0)
+					return i;
+
+				if (order < 0)
+					lo = i + 1;
+				else
+					hi = i - 1;
+			}
+
+			return ~lo;
 		}
 	}
 }