From 335d4a3d08c2669a1f23bd21c18a154b5b23cba3 Mon Sep 17 00:00:00 2001
From: Andrew El <laingas@gmail.com>
Date: Thu, 6 May 2021 21:48:52 -0400
Subject: [PATCH] add ReplaceAt method to Utf16ValueStringBuilder

---
 .../Scripts/ZString/Utf16ValueStringBuilder.cs   | 16 ++++++++++++++++
 src/ZString/Utf16ValueStringBuilder.cs           | 16 ++++++++++++++++
 tests/ZString.Tests/ReplaceTest.cs               | 13 +++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/src/ZString.Unity/Assets/Scripts/ZString/Utf16ValueStringBuilder.cs b/src/ZString.Unity/Assets/Scripts/ZString/Utf16ValueStringBuilder.cs
index b1d4419..63e634f 100644
--- a/src/ZString.Unity/Assets/Scripts/ZString/Utf16ValueStringBuilder.cs
+++ b/src/ZString.Unity/Assets/Scripts/ZString/Utf16ValueStringBuilder.cs
@@ -469,6 +469,22 @@ public void Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue, in
             buffer = newBuffer;
             index = newBufferIndex;
         }
+        
+        /// <summary>
+        /// Replaces the contents of a single position within the builder.
+        /// </summary>
+        /// <param name="newChar">The character to use at the position.</param>
+        /// <param name="replaceIndex">The index to replace.</param>
+        public void ReplaceAt(char newChar, int replaceIndex)
+        {
+            int currentLength = Length;
+            if ((uint)replaceIndex > (uint)currentLength)
+            {
+                ExceptionUtil.ThrowArgumentOutOfRangeException(nameof(replaceIndex));
+            }
+            
+            buffer[replaceIndex] = newChar;
+        }
 
         /// <summary>
         /// Removes a range of characters from this builder.
diff --git a/src/ZString/Utf16ValueStringBuilder.cs b/src/ZString/Utf16ValueStringBuilder.cs
index b1d4419..63e634f 100644
--- a/src/ZString/Utf16ValueStringBuilder.cs
+++ b/src/ZString/Utf16ValueStringBuilder.cs
@@ -469,6 +469,22 @@ public void Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue, in
             buffer = newBuffer;
             index = newBufferIndex;
         }
+        
+        /// <summary>
+        /// Replaces the contents of a single position within the builder.
+        /// </summary>
+        /// <param name="newChar">The character to use at the position.</param>
+        /// <param name="replaceIndex">The index to replace.</param>
+        public void ReplaceAt(char newChar, int replaceIndex)
+        {
+            int currentLength = Length;
+            if ((uint)replaceIndex > (uint)currentLength)
+            {
+                ExceptionUtil.ThrowArgumentOutOfRangeException(nameof(replaceIndex));
+            }
+            
+            buffer[replaceIndex] = newChar;
+        }
 
         /// <summary>
         /// Removes a range of characters from this builder.
diff --git a/tests/ZString.Tests/ReplaceTest.cs b/tests/ZString.Tests/ReplaceTest.cs
index 25f7f34..8b25eb1 100644
--- a/tests/ZString.Tests/ReplaceTest.cs
+++ b/tests/ZString.Tests/ReplaceTest.cs
@@ -7,6 +7,19 @@ namespace ZStringTests
 {
     public class ReplaceTest
     {
+        
+        [Fact]
+        public void ReplaceAtCharTest()
+        {
+            var s = new string(' ', 10);
+            using (var zsb = ZString.CreateStringBuilder())
+            {
+                zsb.Append(s);
+                zsb.ReplaceAt('-',2);
+                zsb.ToString().Should().Be(new StringBuilder(s) { [2] = '-'}.ToString());
+            }
+        }
+        
         [Fact]
         public void ReplaceCharTest()
         {