From a24769d71cc0668271452b05f85347b5542d323d Mon Sep 17 00:00:00 2001
From: Ram Fattah <ramfattahrf@gmail.com>
Date: Tue, 11 Jul 2023 08:52:06 -0700
Subject: [PATCH] Use LRUCache in ExpressionParser for efficient memory usage

---
 libraries/AdaptiveExpressions/parser/ExpressionParser.cs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/libraries/AdaptiveExpressions/parser/ExpressionParser.cs b/libraries/AdaptiveExpressions/parser/ExpressionParser.cs
index c9113cd065..d7173b30ca 100644
--- a/libraries/AdaptiveExpressions/parser/ExpressionParser.cs
+++ b/libraries/AdaptiveExpressions/parser/ExpressionParser.cs
@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Data;
 using System.Globalization;
@@ -11,7 +10,6 @@
 using Antlr4.Runtime;
 using Antlr4.Runtime.Misc;
 using Antlr4.Runtime.Tree;
-using Newtonsoft.Json.Linq;
 
 namespace AdaptiveExpressions
 {
@@ -20,7 +18,7 @@ namespace AdaptiveExpressions
     /// </summary>
     public class ExpressionParser : IExpressionParser
     {
-        private static ConcurrentDictionary<string, IParseTree> expressionDict = new ConcurrentDictionary<string, IParseTree>();
+        private static LRUCache<string, IParseTree> expressionDict = new LRUCache<string, IParseTree>();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ExpressionParser"/> class.
@@ -64,7 +62,7 @@ public Expression Parse(string expression)
         /// <returns>A ParseTree.</returns>
         protected static IParseTree AntlrParse(string expression)
         {
-            if (expressionDict.TryGetValue(expression, out var expressionParseTree))
+            if (expressionDict.TryGet(expression, out var expressionParseTree))
             {
                 return expressionParseTree;
             }
@@ -78,7 +76,7 @@ protected static IParseTree AntlrParse(string expression)
             parser.AddErrorListener(ParserErrorListener.Instance);
             parser.BuildParseTree = true;
             var expressionContext = parser.file()?.expression();
-            expressionDict.TryAdd(expression, expressionContext);
+            expressionDict.Set(expression, expressionContext);
             return expressionContext;
         }