reduce string allocations when rendering text

MLEM/Extensions/CharExtensions.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+
+namespace MLEM.Extensions {
+    /// <summary>
+    /// A set of extensions for dealing with <see cref="char"/>
+    /// </summary>
+    public static class CharExtensions {
+
+        private static readonly Dictionary<char, string> Cache = new Dictionary<char, string>();
+
+        /// <summary>
+        /// Returns the string representation of this character which will be stored and retrieved from a dictionary cache.
+        /// This method reduces string allocations, making it trade in processor efficiency for memory efficiency.
+        /// </summary>
+        /// <param name="c">The character to turn into a string</param>
+        /// <returns>A string representing the character</returns>
+        public static string ToCachedString(this char c) {
+            if (!Cache.TryGetValue(c, out var ret)) {
+                ret = c.ToString();
+                Cache.Add(c, ret);
+            }
+            return ret;
+        }
+
+    }
+}

MLEM/Font/GenericSpriteFont.cs

@@ -1,6 +1,8 @@
 using System.Text;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
+using MLEM.Extensions;
+using MLEM.Misc;
 
 namespace MLEM.Font {
     /// <inheritdoc/>
@@ -32,7 +34,7 @@ namespace MLEM.Font {
 
         /// <inheritdoc />
         protected override Vector2 MeasureChar(char c) {
-            return this.Font.MeasureString(c.ToString());
+            return this.Font.MeasureString(c.ToCachedString());
         }
 
         /// <inheritdoc/>

MLEM/Formatting/TokenizedString.cs

@@ -3,6 +3,7 @@ using System.Linq;
 using System.Text;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
+using MLEM.Extensions;
 using MLEM.Font;
 using MLEM.Formatting.Codes;
 using MLEM.Misc;
@@ -124,7 +125,7 @@ namespace MLEM.Formatting {
                     if (i == 0)
                         token.DrawSelf(time, batch, pos + innerOffset, font, color, scale, depth);
 
-                    var cString = c.ToString();
+                    var cString = c.ToCachedString();
                     token.DrawCharacter(time, batch, c, cString, i, pos + innerOffset, drawFont, drawColor, scale, depth);
                     innerOffset.X += font.MeasureString(cString).X * scale;
                 }