From cf2645fa040dde0476e7a6e5836371058cd716da Mon Sep 17 00:00:00 2001
From: Tonttu <15074459+TheTonttu@users.noreply.github.com>
Date: Sun, 16 Mar 2025 07:31:33 +0200
Subject: [PATCH] StringExtensions.ToString(IEnumerable<Rune>) use rented array
 as alternative buffer

---
 .../StringExtensions/ToStringEnumerable.cs    |  2 +-
 Terminal.Gui/Text/StringExtensions.cs         | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/Benchmarks/Text/StringExtensions/ToStringEnumerable.cs b/Benchmarks/Text/StringExtensions/ToStringEnumerable.cs
index 8d5d55f41..b44f33ad5 100644
--- a/Benchmarks/Text/StringExtensions/ToStringEnumerable.cs
+++ b/Benchmarks/Text/StringExtensions/ToStringEnumerable.cs
@@ -22,7 +22,7 @@ public class ToStringEnumerable
     }
 
     /// <summary>
-    /// Benchmark for current implementation with stackalloc char buffer and
+    /// Benchmark for current implementation with char buffer and
     /// fallback to rune chars appending to StringBuilder.
     /// </summary>
     /// <param name="runes"></param>
diff --git a/Terminal.Gui/Text/StringExtensions.cs b/Terminal.Gui/Text/StringExtensions.cs
index 3167bcf30..0dc1acdec 100644
--- a/Terminal.Gui/Text/StringExtensions.cs
+++ b/Terminal.Gui/Text/StringExtensions.cs
@@ -127,7 +127,7 @@ public static class StringExtensions
         const int maxCharsPerRune = 2;
         const int maxStackallocTextBufferSize = 1048; // ~2 kB
 
-        // Use stackalloc buffer if rune count is easily available and the count is reasonable.
+        // If rune count is easily available use stackalloc buffer or alternatively rented array.
         if (runes.TryGetNonEnumeratedCount (out int count))
         {
             if (count == 0)
@@ -135,10 +135,14 @@ public static class StringExtensions
                 return string.Empty;
             }
 
-            int maxRequiredTextBufferSize = count * maxCharsPerRune;
-            if (maxRequiredTextBufferSize <= maxStackallocTextBufferSize)
+            char[]? rentedBufferArray = null;
+            try
             {
-                Span<char> textBuffer = stackalloc char[maxRequiredTextBufferSize];
+                int maxRequiredTextBufferSize = count * maxCharsPerRune;
+                Span<char> textBuffer = maxRequiredTextBufferSize <= maxStackallocTextBufferSize
+                    ? stackalloc char[maxRequiredTextBufferSize]
+                    : (rentedBufferArray = ArrayPool<char>.Shared.Rent(maxRequiredTextBufferSize));
+
                 Span<char> remainingBuffer = textBuffer;
                 foreach (Rune rune in runes)
                 {
@@ -149,6 +153,13 @@ public static class StringExtensions
                 ReadOnlySpan<char> text = textBuffer[..^remainingBuffer.Length];
                 return text.ToString ();
             }
+            finally
+            {
+                if (rentedBufferArray != null)
+                {
+                    ArrayPool<char>.Shared.Return (rentedBufferArray);
+                }
+            }
         }
 
         // Fallback to StringBuilder append.