Performance improvements and code cleanup

YesNt.Interpreter/Attributes/StatementAttribute.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 
 using YesNt.Interpreter.Enums;
 
@@ -60,6 +60,24 @@ public class StatementAttribute : Attribute
     /// </summary>
     public string Separator { get; set; }
 
+    /// <summary>
+    /// Gets or sets the name of the statement that marks the end of this block.
+    /// Used for block boundary caching (e.g., "while" has BlockPair = "end_while").
+    /// </summary>
+    public string BlockPair { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether this statement is the end of a block.
+    /// Used for block boundary caching (e.g., "end_while" has IsBlockEnd = true).
+    /// </summary>
+    public bool IsBlockEnd { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether this statement is an intermediate part of a block
+    /// (e.g., "else:" between "if" and "end_if").
+    /// </summary>
+    public bool IsBlockIntermediate { get; set; }
+
     /// <summary>
     /// Initializes a new <see cref="StatementAttribute"/> with a syntax-highlight color.
     /// </summary>

YesNt.Interpreter/Runtime/Line.cs

@@ -1,4 +1,6 @@
-namespace YesNt.Interpreter.Runtime;
+using System.Collections.Generic;
+
+namespace YesNt.Interpreter.Runtime;
 
 /// <summary>
 /// Represents a single source line together with its location metadata.

YesNt.Interpreter/Runtime/RuntimeInformation.cs

@@ -26,6 +26,8 @@ internal sealed class RuntimeInformation
 
     public Dictionary<string, string> GlobalVariables { get; set; } = [];
     public Dictionary<string, int> Functions { get; } = [];
+    public Dictionary<int, int> BlockBoundaries { get; } = [];
+    internal Action PreScanLinesAction { get; set; }
     public Stack<FunctionScope> FunctionCallStack { get; } = new();
     public Stack<string> InParametersStack { get; } = new();
     public Stack<string> OutParametersStack { get; set; } = new();
@@ -173,6 +175,7 @@ internal sealed class RuntimeInformation
         GlobalVariables.Clear();
         Labels.Clear();
         Functions.Clear();
+        BlockBoundaries.Clear();
         FunctionCallStack.Clear();
         InParametersStack.Clear();
         OutParametersStack.Clear();
@@ -187,8 +190,7 @@ internal sealed class RuntimeInformation
         IsInFunction = false;
         IsLocalSearch = false;
         LineNumber = 0;
-        TaskId = internalTaskId + 1;
+        TaskId = ++internalTaskId;
-        internalTaskId++;
     }
 
     private void ParentRuntimeInformation_OnExit(string exitMessage, bool stopAllTasks)

YesNt.Interpreter/Runtime/StatementHandler.cs

@@ -0,0 +1,9 @@
+using System;
+using YesNt.Interpreter.Attributes;
+
+namespace YesNt.Interpreter.Runtime;
+
+/// <summary>
+/// Pre-calculated statement handler information for faster matching.
+/// </summary>
+internal record StatementHandler(StatementAttribute Attribute, Action<string> Handler, string FullName);

YesNt.Interpreter/Runtime/StatementRuntimeInfo.cs

@@ -13,4 +13,12 @@ internal abstract class StatementRuntimeInformation
     /// Injected by the generated registry before any handler is invoked.
     /// </summary>
     public RuntimeInformation RuntimeInfo { get; set; }
+
+    /// <summary>
+    /// Trims surrounding whitespace and a trailing colon from a block or function name.
+    /// </summary>
+    protected static string NormalizeBlockName(string value)
+    {
+        return value.Trim().TrimEnd(':').Trim();
+    }
 }

YesNt.Interpreter/Runtime/YesNtInterpreter.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.IO;
@@ -13,20 +13,6 @@ namespace YesNt.Interpreter.Runtime;
 /// <summary>
 /// The main entry point for executing YesNt scripts.
 /// </summary>
-/// <example>
-/// Running a script file:
-/// <code>
-/// var interpreter = new YesNtInterpreter();
-/// interpreter.Execute("path/to/script.ynt");
-/// </code>
-/// Running script lines in memory with a custom statement:
-/// <code>
-/// var interpreter = new YesNtInterpreter();
-/// interpreter.AddStatement("log", SearchMode.StartOfLine, SpaceAround.End, args =>
-///     Console.WriteLine($"[LOG] {args}"));
-/// interpreter.Execute(new List&lt;string&gt; { "log hello world" });
-/// </code>
-/// </example>
 public class YesNtInterpreter
 {
     /// <summary>
@@ -43,6 +29,8 @@ public class YesNtInterpreter
 
     private readonly RuntimeInformation runtimeInfo = new RuntimeInformation();
     private Dictionary<StatementAttribute, Action<string>> statements;
+    private List<StatementHandler> statementHandlers;
+    private List<List<StatementHandler>> lineMatchingHandlers = [];
     private readonly List<KeyValuePair<StaticStatementAttribute, Action>> staticStatements;
     private readonly Dictionary<string, List<KeyValuePair<StatementAttribute, Action<string>>>> disabledStatements = [];
 
@@ -77,11 +65,28 @@ public class YesNtInterpreter
     public YesNtInterpreter()
     {
         GeneratedStatementRegistry.Register(runtimeInfo, out statements, out staticStatements);
+        UpdateStatementHandlers();
+        runtimeInfo.PreScanLinesAction = PreScanLines;
 
         runtimeInfo.OnDebugOutput += (s) => OnDebugOutput?.Invoke(s);
         runtimeInfo.OnLineExecuted += e => OnLineExecuted?.Invoke(e);
     }
 
+    private void UpdateStatementHandlers()
+    {
+        statementHandlers = statements.Select(s =>
+        {
+            string name = s.Key.SpaceAround switch
+            {
+                SpaceAround.StartEnd => $" {s.Key.Name.Trim()} ",
+                SpaceAround.Start => $" {s.Key.Name.Trim()}",
+                SpaceAround.End => $"{s.Key.Name.Trim()} ",
+                _ => s.Key.Name.Trim()
+            };
+            return new StatementHandler(s.Key, s.Value, name);
+        }).ToList();
+    }
+
     /// <summary>
     /// Registers a custom statement using a pre-built <see cref="StatementAttribute"/>.
     /// If a statement with the same attribute key (identical field values) already exists it will be replaced;
@@ -102,14 +107,16 @@ public class YesNtInterpreter
             .OrderBy(s => s.Key.Priority)
             .ThenByDescending(s => s.Key.Name.Length)
             .ToDictionary(x => x.Key, x => x.Value);
+        UpdateStatementHandlers();
+        PreScanLines();
     }
 
     /// <summary>
-    /// Registers a custom statement without a syntax-highlight color.
+    /// Registers a simple custom statement with default settings.
     /// </summary>
-    /// <param name="name">The keyword that identifies this statement in source code.</param>
+    /// <param name="name">The keyword to match.</param>
-    /// <param name="searchMode">Where in the line the keyword is matched.</param>
+    /// <param name="searchMode">Where in the line the keyword is searched for.</param>
-    /// <param name="spaceAround">Which sides of the keyword require a surrounding space.</param>
+    /// <param name="spaceAround">Which sides of the keyword must be padded with a space.</param>
     /// <param name="handler">The delegate invoked when the statement matches.</param>
     public void AddStatement(string name, SearchMode searchMode, SpaceAround spaceAround, Action<string> handler)
     {
@@ -117,12 +124,12 @@ public class YesNtInterpreter
     }
 
     /// <summary>
-    /// Registers a custom statement with a syntax-highlight color.
+    /// Registers a simple custom statement with a specific syntax-highlight color.
     /// </summary>
-    /// <param name="name">The keyword that identifies this statement in source code.</param>
+    /// <param name="name">The keyword to match.</param>
-    /// <param name="searchMode">Where in the line the keyword is matched.</param>
+    /// <param name="searchMode">Where in the line the keyword is searched for.</param>
-    /// <param name="spaceAround">Which sides of the keyword require a surrounding space.</param>
+    /// <param name="spaceAround">Which sides of the keyword must be padded with a space.</param>
-    /// <param name="consoleColor">The color used for syntax highlighting in the code editor.</param>
+    /// <param name="consoleColor">The color used for syntax highlighting.</param>
     /// <param name="handler">The delegate invoked when the statement matches.</param>
     public void AddStatement(string name, SearchMode searchMode, SpaceAround spaceAround, ConsoleColor consoleColor, Action<string> handler)
     {
@@ -130,10 +137,9 @@ public class YesNtInterpreter
     }
 
     /// <summary>
-    /// Permanently removes all built-in or custom statements that match <paramref name="name"/>.
+    /// Unregisters all handlers matching the specified keyword <paramref name="name"/>.
-    /// After removal, any script line that would have matched triggers an "Invalid statement" error.
     /// </summary>
-    /// <param name="name">The keyword of the statement(s) to remove.</param>
+    /// <param name="name">The keyword to remove.</param>
     public void RemoveStatement(string name)
     {
         foreach (StatementAttribute key in statements.Keys.Where(k => k.Name == name).ToList())
@@ -142,6 +148,8 @@ public class YesNtInterpreter
         }
 
         _ = disabledStatements.Remove(name);
+        UpdateStatementHandlers();
+        PreScanLines();
     }
 
     /// <summary>
@@ -171,6 +179,8 @@ public class YesNtInterpreter
         {
             statements[kv.Key] = _ => { };
         }
+        UpdateStatementHandlers();
+        PreScanLines();
     }
 
     /// <summary>
@@ -192,6 +202,8 @@ public class YesNtInterpreter
         }
 
         _ = disabledStatements.Remove(name);
+        UpdateStatementHandlers();
+        PreScanLines();
     }
 
     /// <summary>
@@ -236,9 +248,11 @@ public class YesNtInterpreter
 
         for (int i = 0; i < lines.Count; i++)
         {
-            runtimeInfo.Lines.Add(new Line(lines[i], Path.GetFileName("#Memory#"), i));
+            string content = lines[i].Trim().Replace("\r", string.Empty);
+            runtimeInfo.Lines.Add(new Line(content, Path.GetFileName("#Memory#"), i));
         }
 
+        PreScanLines();
         Execute();
     }
 
@@ -255,6 +269,7 @@ public class YesNtInterpreter
             runtimeInfo.Exit(ExitMessages.TerminatedByParentTask, parentRuntimeInformation.StopAllTasks);
             return;
         }
+        PreScanLines();
         Execute();
     }
 
@@ -267,20 +282,25 @@ public class YesNtInterpreter
                 break;
             }
 
-            runtimeInfo.CurrentLine = runtimeInfo.Lines[runtimeInfo.LineNumber].Content.Trim(' ').Replace("\r", string.Empty);
+            Line lineObj = runtimeInfo.Lines[runtimeInfo.LineNumber];
+            runtimeInfo.CurrentLine = lineObj.Content;
 
             if (string.IsNullOrWhiteSpace(runtimeInfo.CurrentLine) || runtimeInfo.CurrentLine.StartsWith('#'))
             {
                 continue;
             }
 
-            DebugEventArgs debugEventArgs = new DebugEventArgs()
+            DebugEventArgs debugEventArgs = null;
+            if (runtimeInfo.IsDebugMode)
+            {
+                debugEventArgs = new DebugEventArgs()
                 {
                     LineNumber = runtimeInfo.LineNumber + 1,
                     OriginalLine = runtimeInfo.CurrentLine.FromSafeString(),
                     IsTask = runtimeInfo.IsTask,
                     TaskId = runtimeInfo.TaskId
                 };
+            }
 
             foreach (KeyValuePair<StaticStatementAttribute, Action> staticStatement in staticStatements)
             {
@@ -296,9 +316,11 @@ public class YesNtInterpreter
             bool statementFound = false;
             bool notSearchingLabel = !runtimeInfo.IsSearching;
 
-            foreach (KeyValuePair<StatementAttribute, Action<string>> statement in statements)
+            List<StatementHandler> handlers = (runtimeInfo.LineNumber < lineMatchingHandlers.Count) ? lineMatchingHandlers[runtimeInfo.LineNumber] : [];
+
+            foreach (StatementHandler handler in handlers)
             {
-                StatementAttribute statementAttribute = statement.Key;
+                StatementAttribute statementAttribute = handler.Attribute;
 
                 if (!statementAttribute.ExecuteInSearchMode && runtimeInfo.IsSearching)
                 {
@@ -311,37 +333,31 @@ public class YesNtInterpreter
                     break;
                 }
 
-                string name = statementAttribute.SpaceAround switch
+                string name = handler.FullName;
-                {
-                    SpaceAround.StartEnd => $" {statementAttribute.Name.Trim()} ",
-                    SpaceAround.Start => $" {statementAttribute.Name.Trim()}",
-                    SpaceAround.End => $"{statementAttribute.Name.Trim()} ",
-                    _ => statementAttribute.Name.Trim()
-                };
 
-                if (statementAttribute.Separator is null || runtimeInfo.CurrentLine.Contains(statementAttribute.Separator))
+                if (statementAttribute.Separator is null || runtimeInfo.CurrentLine.Contains(statementAttribute.Separator, StringComparison.Ordinal))
                 {
-                    if (statementAttribute.SearchMode == SearchMode.StartOfLine && runtimeInfo.CurrentLine.StartsWith(name))
+                    if (statementAttribute.SearchMode == SearchMode.StartOfLine && runtimeInfo.CurrentLine.StartsWith(name, StringComparison.Ordinal))
                     {
                         string copyLine = statementAttribute.KeepStatementInArgs ? runtimeInfo.CurrentLine : runtimeInfo.CurrentLine[name.Length..];
-                        statement.Value.Invoke(copyLine);
+                        handler.Handler.Invoke(copyLine);
                         statementFound = true;
                     }
-                    else if (statementAttribute.SearchMode == SearchMode.Contains && runtimeInfo.CurrentLine.Contains(name))
+                    else if (statementAttribute.SearchMode == SearchMode.Contains && runtimeInfo.CurrentLine.Contains(name, StringComparison.Ordinal))
                     {
                         string copyLine = statementAttribute.KeepStatementInArgs ? runtimeInfo.CurrentLine : runtimeInfo.CurrentLine.Replace(name, string.Empty);
-                        statement.Value.Invoke(copyLine);
+                        handler.Handler.Invoke(copyLine);
                         statementFound = true;
                     }
-                    else if (statementAttribute.SearchMode == SearchMode.EndOfLine && runtimeInfo.CurrentLine.EndsWith(name))
+                    else if (statementAttribute.SearchMode == SearchMode.EndOfLine && runtimeInfo.CurrentLine.EndsWith(name, StringComparison.Ordinal))
                     {
                         string copyLine = statementAttribute.KeepStatementInArgs ? runtimeInfo.CurrentLine : runtimeInfo.CurrentLine[..^name.Length];
-                        statement.Value.Invoke(copyLine);
+                        handler.Handler.Invoke(copyLine);
                         statementFound = true;
                     }
-                    else if (statementAttribute.SearchMode == SearchMode.Exact && runtimeInfo.CurrentLine.Equals(name))
+                    else if (statementAttribute.SearchMode == SearchMode.Exact && runtimeInfo.CurrentLine.Equals(name, StringComparison.Ordinal))
                     {
-                        statement.Value.Invoke(runtimeInfo.CurrentLine);
+                        handler.Handler.Invoke(runtimeInfo.CurrentLine);
                         statementFound = true;
                     }
                 }
@@ -351,7 +367,7 @@ public class YesNtInterpreter
             {
                 runtimeInfo.Exit(ExitMessages.InvalidStatement, true);
             }
-            if (runtimeInfo.IsDebugMode && notSearchingLabel)
+            if (runtimeInfo.IsDebugMode && notSearchingLabel && debugEventArgs != null)
             {
                 debugEventArgs.CurrentLine = runtimeInfo.CurrentLine.FromSafeString();
                 runtimeInfo.LineExecuted(debugEventArgs);
@@ -402,9 +418,93 @@ public class YesNtInterpreter
 
         for (int i = 0; i < lines.Length; i++)
         {
-            runtimeInfo.Lines.Add(new Line(lines[i], Path.GetFileName(path), i));
+            string content = lines[i].Trim().Replace("\r", string.Empty);
+            runtimeInfo.Lines.Add(new Line(content, Path.GetFileName(path), i));
         }
 
+        PreScanLines();
         return true;
     }
+
+    internal void PreScanLines()
+    {
+        runtimeInfo.BlockBoundaries.Clear();
+        lineMatchingHandlers = new List<List<StatementHandler>>(runtimeInfo.Lines.Count);
+        
+        // Dictionary to track open blocks by their expected end statement name
+        var openBlocks = new Dictionary<string, Stack<int>>();
+
+        for (int i = 0; i < runtimeInfo.Lines.Count; i++)
+        {
+            string content = runtimeInfo.Lines[i].Content;
+            List<StatementHandler> matchingHandlers = [];
+
+            foreach (StatementHandler handler in statementHandlers)
+            {
+                if (IsPossibleMatch(content, handler))
+                {
+                    matchingHandlers.Add(handler);
+
+                    // Track block starts (skip intermediates — they are handled separately below)
+                    string blockPair = handler.Attribute.BlockPair;
+                    if (!string.IsNullOrEmpty(blockPair) && !handler.Attribute.IsBlockIntermediate)
+                    {
+                        if (!openBlocks.TryGetValue(blockPair, out var stack))
+                        {
+                            stack = new Stack<int>();
+                            openBlocks[blockPair] = stack;
+                        }
+                        stack.Push(i);
+                    }
+
+                    // Track block ends
+                    if (handler.Attribute.IsBlockEnd)
+                    {
+                        if (openBlocks.TryGetValue(handler.Attribute.Name, out var stack) && stack.Count > 0)
+                        {
+                            int startLine = stack.Pop();
+                            runtimeInfo.BlockBoundaries[startLine] = i;
+                            runtimeInfo.BlockBoundaries[i] = startLine;
+                        }
+                    }
+
+                    // Track block intermediates (e.g., else:): pop the opener, record boundary, push self
+                    if (handler.Attribute.IsBlockIntermediate)
+                    {
+                        string intermediatePair = handler.Attribute.BlockPair;
+                        if (!string.IsNullOrEmpty(intermediatePair))
+                        {
+                            if (!openBlocks.TryGetValue(intermediatePair, out var stack))
+                            {
+                                stack = new Stack<int>();
+                                openBlocks[intermediatePair] = stack;
+                            }
+                            if (stack.Count > 0)
+                            {
+                                int startLine = stack.Pop();
+                                runtimeInfo.BlockBoundaries[startLine] = i;
+                            }
+                            stack.Push(i);
+                        }
+                    }
+                }
+            }
+            lineMatchingHandlers.Add(matchingHandlers);
+        }
+    }
+
+    private static bool IsPossibleMatch(string content, StatementHandler handler)
+    {
+        StatementAttribute attr = handler.Attribute;
+        string fullName = handler.FullName;
+
+        return attr.SearchMode switch
+        {
+            SearchMode.Exact => content == fullName,
+            SearchMode.StartOfLine => content.StartsWith(fullName, StringComparison.Ordinal),
+            SearchMode.EndOfLine => content.EndsWith(fullName, StringComparison.Ordinal),
+            SearchMode.Contains => content.Contains(fullName, StringComparison.Ordinal),
+            _ => false
+        };
+    }
 }

YesNt.Interpreter/Statements/CodeFlowStatements.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 
 using YesNt.Interpreter.Attributes;
@@ -80,14 +80,7 @@ internal class CodeFlowStatements : StatementRuntimeInformation
             return;
         }
 
-        if (RuntimeInfo.Labels.ContainsKey(key))
-        {
         RuntimeInfo.Labels[key] = RuntimeInfo.LineNumber;
-        }
-        else
-        {
-            RuntimeInfo.Labels.Add(key, RuntimeInfo.LineNumber);
-        }
 
         if (!string.IsNullOrWhiteSpace(RuntimeInfo.SearchLabel) && RuntimeInfo.SearchLabel == key)
         {
@@ -153,7 +146,7 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         }
     }
 
-    [Statement("if", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":")]
+    [Statement("if", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":", BlockPair = "end_if")]
     public void IfBlock(string args)
     {
         args = args.Trim();
@@ -177,7 +170,7 @@ internal class CodeFlowStatements : StatementRuntimeInformation
             return;
         }
 
-        (int targetLine, _) = FindElseOrEndIf(RuntimeInfo.LineNumber);
+        int targetLine = FindBlockBoundary(RuntimeInfo.LineNumber);
         if (targetLine < 0)
         {
             RuntimeInfo.Exit(ExitMessages.NoMatchingEndIf, true);
@@ -187,10 +180,10 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         RuntimeInfo.LineNumber = targetLine;
     }
 
-    [Statement("else:", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    [Statement("else:", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green, IsBlockIntermediate = true, BlockPair = "end_if")]
     public void Else(string _)
     {
-        int targetLine = FindEndIf(RuntimeInfo.LineNumber);
+        int targetLine = FindBlockBoundary(RuntimeInfo.LineNumber);
         if (targetLine < 0)
         {
             RuntimeInfo.Exit(ExitMessages.NoMatchingEndIf, true);
@@ -200,12 +193,12 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         RuntimeInfo.LineNumber = targetLine;
     }
 
-    [Statement("end_if", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    [Statement("end_if", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green, IsBlockEnd = true)]
     public void EndIf(string _)
     {
     }
 
-    [Statement("while", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":")]
+    [Statement("while", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":", BlockPair = "end_while")]
     public void While(string args)
     {
         args = args.Trim();
@@ -229,7 +222,7 @@ internal class CodeFlowStatements : StatementRuntimeInformation
             return;
         }
 
-        int endWhileLine = FindEndWhile(RuntimeInfo.LineNumber);
+        int endWhileLine = FindBlockBoundary(RuntimeInfo.LineNumber);
         if (endWhileLine < 0)
         {
             RuntimeInfo.Exit(ExitMessages.NoMatchingEndWhile, true);
@@ -239,10 +232,10 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         RuntimeInfo.LineNumber = endWhileLine;
     }
 
-    [Statement("end_while", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    [Statement("end_while", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green, IsBlockEnd = true)]
     public void EndWhile(string _)
     {
-        int whileLine = FindWhile(RuntimeInfo.LineNumber);
+        int whileLine = FindBlockBoundary(RuntimeInfo.LineNumber);
         if (whileLine < 0)
         {
             RuntimeInfo.Exit(ExitMessages.NoMatchingWhile, true);
@@ -265,11 +258,8 @@ internal class CodeFlowStatements : StatementRuntimeInformation
 
             return;
         }
-        else
-        {
-            RuntimeInfo.IsInFunction = false;
-        }
 
+        RuntimeInfo.IsInFunction = false;
         RuntimeInfo.Exit(ExitMessages.PlannedTermination, false);
     }
 
@@ -286,11 +276,8 @@ internal class CodeFlowStatements : StatementRuntimeInformation
 
             return;
         }
-        else
-        {
-            RuntimeInfo.IsInFunction = false;
-        }
 
+        RuntimeInfo.IsInFunction = false;
         RuntimeInfo.Exit(ExitMessages.PlannedTerminationCancelingTasks, true);
     }
 
@@ -306,136 +293,8 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         RuntimeInfo.Exit(message, false);
     }
 
-    private static string NormalizeBlockName(string value)
+    private int FindBlockBoundary(int currentLine)
     {
-        return value.Trim().TrimEnd(':').Trim();
+        return RuntimeInfo.BlockBoundaries.TryGetValue(currentLine, out int cached) ? cached : -1;
-    }
-
-    private (int TargetLine, bool IsElse) FindElseOrEndIf(int currentLine)
-    {
-        int depth = 0;
-
-        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
-        {
-            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
-
-            if (IsIfStart(line))
-            {
-                depth++;
-                continue;
-            }
-
-            if (line == "end_if")
-            {
-                if (depth == 0)
-                {
-                    return (i, false);
-                }
-
-                depth--;
-                continue;
-            }
-
-            if (line == "else:" && depth == 0)
-            {
-                return (i, true);
-            }
-        }
-
-        return (-1, false);
-    }
-
-    private int FindEndIf(int currentLine)
-    {
-        int depth = 0;
-
-        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
-        {
-            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
-
-            if (IsIfStart(line))
-            {
-                depth++;
-                continue;
-            }
-
-            if (line == "end_if")
-            {
-                if (depth == 0)
-                {
-                    return i;
-                }
-
-                depth--;
-            }
-        }
-
-        return -1;
-    }
-
-    private static bool IsIfStart(string line)
-    {
-        return line.StartsWith("if ", StringComparison.Ordinal) && line.EndsWith(':');
-    }
-
-    private int FindEndWhile(int currentLine)
-    {
-        int depth = 0;
-
-        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
-        {
-            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
-
-            if (IsWhileStart(line))
-            {
-                depth++;
-                continue;
-            }
-
-            if (line == "end_while")
-            {
-                if (depth == 0)
-                {
-                    return i;
-                }
-
-                depth--;
-            }
-        }
-
-        return -1;
-    }
-
-    private int FindWhile(int currentLine)
-    {
-        int depth = 0;
-
-        for (int i = currentLine - 1; i >= 0; i--)
-        {
-            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
-
-            if (line == "end_while")
-            {
-                depth++;
-                continue;
-            }
-
-            if (IsWhileStart(line))
-            {
-                if (depth == 0)
-                {
-                    return i;
-                }
-
-                depth--;
-            }
-        }
-
-        return -1;
-    }
-
-    private static bool IsWhileStart(string line)
-    {
-        return line.StartsWith("while ", StringComparison.Ordinal) && line.EndsWith(':');
     }
 }

YesNt.Interpreter/Statements/FunctionStatements.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 
 using YesNt.Interpreter.Attributes;
@@ -33,14 +33,7 @@ internal class FunctionStatements : StatementRuntimeInformation
             return;
         }
 
-        if (RuntimeInfo.Functions.ContainsKey(key))
-        {
         RuntimeInfo.Functions[key] = RuntimeInfo.LineNumber;
-        }
-        else
-        {
-            RuntimeInfo.Functions.Add(key, RuntimeInfo.LineNumber);
-        }
 
         if (!string.IsNullOrWhiteSpace(RuntimeInfo.SearchFunction) && RuntimeInfo.SearchFunction == key)
         {
@@ -59,18 +52,7 @@ internal class FunctionStatements : StatementRuntimeInformation
     [Statement("%out", SearchMode.Contains, SpaceAround.None, ConsoleColor.Yellow, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetOutParameter(string args)
     {
-        while (args.Contains("%out"))
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessStackParameters(args, "%out", RuntimeInfo.OutParametersStack, RuntimeInfo, ExitMessages.NoOutArgumentInStack);
-        {
-            if (RuntimeInfo.OutParametersStack.Count == 0)
-            {
-                RuntimeInfo.Exit(ExitMessages.NoOutArgumentInStack, true);
-                return;
-            }
-
-            args = args.ReplaceFirstOccurrence("%out", RuntimeInfo.OutParametersStack.Pop());
-        }
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%has_out", SearchMode.Contains, SpaceAround.None, ConsoleColor.Yellow, KeepStatementInArgs = true, Priority = Priority.Highest)]
@@ -122,18 +104,7 @@ internal class FunctionStatements : StatementRuntimeInformation
             return;
         }
 
-        while (args.Contains("%in"))
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessStackParameters(args, "%in", RuntimeInfo.FunctionCallStack.Peek().Arguments, RuntimeInfo, ExitMessages.NoInArgumentInStack);
-        {
-            if (RuntimeInfo.FunctionCallStack.Peek().Arguments.Count == 0)
-            {
-                RuntimeInfo.Exit(ExitMessages.NoInArgumentInStack, true);
-                return;
-            }
-
-            args = args.ReplaceFirstOccurrence("%in", RuntimeInfo.FunctionCallStack.Peek().Arguments.Pop());
-        }
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%has_in", SearchMode.Contains, SpaceAround.None, ConsoleColor.Yellow, KeepStatementInArgs = true, Priority = Priority.Highest)]
@@ -181,10 +152,8 @@ internal class FunctionStatements : StatementRuntimeInformation
             }
             return;
         }
-        else
+
-        {
         RuntimeInfo.IsInFunction = false;
-        }
 
         if (RuntimeInfo.FunctionCallStack.Count > 0)
         {
@@ -204,9 +173,4 @@ internal class FunctionStatements : StatementRuntimeInformation
     {
         RuntimeInfo.FunctionCallStack.Clear();
     }
-
-    private static string NormalizeBlockName(string value)
-    {
-        return value.Trim().TrimEnd(':').Trim();
-    }
 }

YesNt.Interpreter/Statements/PredefinedVariableStatements.cs

@@ -1,4 +1,5 @@
-using System;
+using System;
+using System.Runtime.InteropServices;
 
 using YesNt.Interpreter.Attributes;
 using YesNt.Interpreter.Enums;
@@ -14,51 +15,36 @@ internal class PredefinedVariableStatements : StatementRuntimeInformation
     [Statement("%time", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetUnixTimestamp(string args)
     {
-        args = args.Replace("%time", DateTimeOffset.Now.ToUnixTimeSeconds().ToString());
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessSimplePlaceholders(args, "%time", DateTimeOffset.Now.ToUnixTimeSeconds().ToString()).TrimEnd();
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%os", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetOperatingSystem(string args)
     {
-        args = args.Replace("%os", Environment.OSVersion.Platform.ToString());
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessSimplePlaceholders(args, "%os", Environment.OSVersion.Platform.ToString()).TrimEnd();
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%cpu", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetProcessorArchitecture(string args)
     {
-        args = args.Replace("%cpu", System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture.ToString());
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessSimplePlaceholders(args, "%cpu", System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture.ToString()).TrimEnd();
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%is64", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetIsOperatingSystem64Bit(string args)
     {
-        args = args.Replace("%is64", $"{Environment.Is64BitOperatingSystem}");
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessSimplePlaceholders(args, "%is64", Environment.Is64BitOperatingSystem.ToString()).TrimEnd();
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%pi", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetPi(string args)
     {
-        args = args.Replace("%pi", Math.PI.ToString());
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessSimplePlaceholders(args, "%pi", Math.PI.ToString()).TrimEnd();
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 
     [Statement("%rand", SearchMode.Contains, SpaceAround.None, ConsoleColor.Blue, KeepStatementInArgs = true, Priority = Priority.Highest)]
     public void GetRandom(string args)
     {
-        while (args.Contains("%rand"))
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessDynamicPlaceholders(args, "%rand", () => random.Next(32767, int.MaxValue).ToString()).TrimEnd();
-        {
-            args = args.ReplaceFirstOccurrence("%rand", random.Next(32767, int.MaxValue).ToString());
-        }
-
-        RuntimeInfo.CurrentLine = args.TrimEnd();
     }
 }

YesNt.Interpreter/Statements/ProcessingStatements.cs

@@ -16,20 +16,7 @@ internal partial class ProcessingStatements : StatementRuntimeInformation
     [Statement("calc", SearchMode.EndOfLine, SpaceAround.Start, ConsoleColor.DarkYellow, Priority = Priority.High)]
     public void Calculate(string args)
     {
-        MatchCollection matches = CalculationRegex().Matches(args.FromSafeString());
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessCalculations(args.FromSafeString(), RuntimeInfo, CalculationRegex());
-
-        for (int i = 0; i < matches.Count; i++)
-        {
-            string res = Evaluator.Calculate(matches[i].Value);
-            if (res is null)
-            {
-                RuntimeInfo.Exit(ExitMessages.InvalidOperation, true);
-                return;
-            }
-            args = args.FromSafeString().Replace(matches[i].Value, res);
-        }
-
-        RuntimeInfo.CurrentLine = args;
     }
 
     [Statement("eval", SearchMode.EndOfLine, SpaceAround.Start, ConsoleColor.DarkYellow, Priority = Priority.VeryHigh)]
@@ -100,6 +87,7 @@ internal partial class ProcessingStatements : StatementRuntimeInformation
                 {
                     RuntimeInfo.Lines.Insert(RuntimeInfo.LineNumber + i, new Line(lines[i], Path.GetFileName(path), i));
                 }
+                RuntimeInfo.PreScanLinesAction?.Invoke();
                 RuntimeInfo.LineNumber--;
             }
             catch

YesNt.Interpreter/Statements/VariableStatements.cs

@@ -1,8 +1,10 @@
-using System.Text.RegularExpressions;
+using System;
+using System.Collections.Generic;
 
 using YesNt.Interpreter.Attributes;
 using YesNt.Interpreter.Enums;
 using YesNt.Interpreter.Runtime;
+using YesNt.Interpreter.Utilities;
 
 namespace YesNt.Interpreter.Statements;
 
@@ -11,32 +13,16 @@ internal partial class VariableStatements : StatementRuntimeInformation
     [Statement("var", SearchMode.StartOfLine, SpaceAround.End, System.ConsoleColor.DarkBlue, Priority = Priority.VeryLow, Separator = "=")]
     public void DefineVariable(string args)
     {
-        string[] parts = args.Split('=');
+        DefineVariableIn(RuntimeInfo.Variables, args);
-        if (parts.Length == 2)
-        {
-            string key = parts[0].Trim();
-            if (key.Contains(' '))
-            {
-                RuntimeInfo.Exit(ExitMessages.InvalidSyntax, true);
-            }
-
-            if (RuntimeInfo.Variables.ContainsKey(key))
-            {
-                RuntimeInfo.Variables[key] = parts[1].Trim();
-            }
-            else
-            {
-                RuntimeInfo.Variables.Add(key, parts[1].Trim());
-            }
-        }
-        else
-        {
-            RuntimeInfo.Exit(ExitMessages.InvalidSyntax, true);
-        }
     }
 
     [Statement("global", SearchMode.StartOfLine, SpaceAround.End, System.ConsoleColor.DarkBlue, Priority = Priority.VeryLow, Separator = "=")]
     public void DefineGlobalVariable(string args)
+    {
+        DefineVariableIn(RuntimeInfo.GlobalVariables, args);
+    }
+
+    private void DefineVariableIn(Dictionary<string, string> dict, string args)
     {
         string[] parts = args.Split('=');
         if (parts.Length == 2)
@@ -47,14 +33,7 @@ internal partial class VariableStatements : StatementRuntimeInformation
                 RuntimeInfo.Exit(ExitMessages.InvalidSyntax, true);
             }
 
-            if (RuntimeInfo.GlobalVariables.ContainsKey(key))
+            dict[key] = parts[1].Trim();
-            {
-                RuntimeInfo.GlobalVariables[key] = parts[1].Trim();
-            }
-            else
-            {
-                RuntimeInfo.GlobalVariables.Add(key, parts[1].Trim());
-            }
         }
         else
         {
@@ -84,38 +63,6 @@ internal partial class VariableStatements : StatementRuntimeInformation
     [Statement("${", SearchMode.Contains, SpaceAround.None, Priority = Priority.Highest, Separator = "}")]
     public void ReadVariable(string _)
     {
-        if (!RuntimeInfo.CurrentLine.Contains("${"))
+        RuntimeInfo.CurrentLine = TemplateProcessor.ProcessVariables(RuntimeInfo.CurrentLine, RuntimeInfo);
-        {
-            return;
-        }
-
-        MatchCollection matches = VariableStatementRegex().Matches(RuntimeInfo.CurrentLine);
-
-        if (matches.Count <= 0)
-        {
-            return;
-        }
-
-        for (int i = 0; i < matches.Count; i++)
-        {
-            string varName = matches[i].Groups[1].Value;
-            if (RuntimeInfo.Variables.TryGetValue(varName, out string value))
-            {
-                RuntimeInfo.CurrentLine = RuntimeInfo.CurrentLine.Replace(matches[i].Value, value);
-            }
-            else if (RuntimeInfo.GlobalVariables.TryGetValue(varName, out value))
-            {
-                RuntimeInfo.CurrentLine = RuntimeInfo.CurrentLine.Replace(matches[i].Value, value);
-            }
-            else if (!RuntimeInfo.IsSearching)
-            {
-                RuntimeInfo.Exit(ExitMessages.VariableNotFound(varName), true);
-                return;
     }
 }
-    }
-
-    [GeneratedRegex("\\$\\{([a-zA-Z0-9]+)\\}")]
-    private static partial Regex VariableStatementRegex();
-}
-

YesNt.Interpreter/Utilities/Evaluator.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Linq;
 using System.Text.RegularExpressions;
 
@@ -19,11 +19,13 @@ internal static partial class Evaluator
     /// </returns>
     public static bool? EvaluateCondition(string input)
     {
-        if (input.ToLower().FromSafeString().Trim() == "true")
+        input = input.FromSafeString();
+        string lower = input.ToLower().Trim();
+        if (lower == "true")
         {
             return true;
         }
-        else if (input.ToLower().FromSafeString().Trim() == "false")
+        else if (lower == "false")
         {
             return false;
         }
@@ -31,16 +33,16 @@ internal static partial class Evaluator
         string[] parts = input.Split("==");
         if (parts.Length == 2)
         {
-            string part1 = parts[0].FromSafeString().Trim();
+            string part1 = parts[0].Trim();
-            string part2 = parts[1].FromSafeString().Trim();
+            string part2 = parts[1].Trim();
             return part1 == part2;
         }
 
         parts = input.Split("!=");
         if (parts.Length == 2)
         {
-            string part1 = parts[0].FromSafeString().Trim();
+            string part1 = parts[0].Trim();
-            string part2 = parts[1].FromSafeString().Trim();
+            string part2 = parts[1].Trim();
             return part1 != part2;
         }
 
@@ -89,23 +91,26 @@ internal static partial class Evaluator
     /// <returns>The result as a culture-invariant numeric string, or <c>"NaN"</c> if evaluation failed.</returns>
     public static string Calculate(string input)
     {
+        input = input.FromSafeString();
         input = PlusPlusRegex().Replace(input, "+");
         input = MinusMinusRegex().Replace(input, "+");
         input = MinusPlusRegex().Replace(input, "-");
         input = PlusMinusRegex().Replace(input, "-");
 
-        string yes = Calculate(input, '+');
+        return CalculateInternal(input, '+');
-        return yes;
     }
 
-    private static string Calculate(string input, char op)
+    private static string CalculateInternal(string input, char op)
     {
-        if (input is null)
+        if (string.IsNullOrWhiteSpace(input))
         {
             return null;
         }
 
-        input = input.FromSafeString();
+        if (input.ToStandardizedNumber(out double quickNum))
+        {
+            return quickNum.ToString(System.Globalization.CultureInfo.InvariantCulture);
+        }
 
         MatchCollection matches = ParenthesesRegex().Matches(input);
         while (matches.Count > 0)
@@ -113,7 +118,7 @@ internal static partial class Evaluator
             for (int i = 0; i < matches.Count; i++)
             {
                 string calc = matches[i].Value.Substring(1, matches[i].Length - 2);
-                string ret = Calculate(calc);
+                string ret = CalculateInternal(calc, '+');
                 input = input.Replace(matches[i].Value, ret);
             }
             matches = ParenthesesRegex().Matches(input);
@@ -136,11 +141,11 @@ internal static partial class Evaluator
 
             part = op switch
             {
-                '+' => Calculate(part, '-'),
+                '+' => CalculateInternal(part, '-'),
-                '-' => Calculate(part, '*'),
+                '-' => CalculateInternal(part, '*'),
-                '*' => Calculate(part, '/'),
+                '*' => CalculateInternal(part, '/'),
-                '/' => Calculate(part, '%'),
+                '/' => CalculateInternal(part, '%'),
-                '%' => Calculate(part, '^'),
+                '%' => CalculateInternal(part, '^'),
                 _ => part
             };
 

YesNt.Interpreter/Utilities/FixedProcess.cs

@@ -19,7 +19,7 @@ internal delegate void UserCallBack(string data);
 /// <see cref="FixedProcess"/> flushes whatever is in the read buffer immediately, enabling real-time
 /// output forwarding for interactive child processes.
 /// </summary>
-public class FixedProcess : Process
+internal class FixedProcess : Process
 {
     public new event DataReceivedEventHandler OutputDataReceived;
 

YesNt.Interpreter/Utilities/StringExtensions.cs

@@ -64,13 +64,30 @@ public static class StringExtensions
     /// <returns>The safe-string encoded representation.</returns>
     public static string ToSafeString(this string input)
     {
-        StringBuilder output = new StringBuilder();
+        if (string.IsNullOrEmpty(input))
-        foreach (char c in input)
         {
-            _ = output.Append($"\v{c}\v");
+            return input;
         }
 
-        return ReplaceOnce(output.ToString(), ReplacementRules);
+        StringBuilder output = new StringBuilder(input.Length * 3);
+        foreach (char c in input)
+        {
+            string s = c.ToString();
+            if (ReplacementRules.TryGetValue(s, out string replacement))
+            {
+                _ = output.Append('\v');
+                _ = output.Append(replacement);
+                _ = output.Append('\v');
+            }
+            else
+            {
+                _ = output.Append('\v');
+                _ = output.Append(c);
+                _ = output.Append('\v');
+            }
+        }
+
+        return output.ToString();
     }
 
     /// <summary>
@@ -80,7 +97,35 @@ public static class StringExtensions
     /// <returns>The decoded plain string.</returns>
     public static string FromSafeString(this string input)
     {
-        return ReplaceOnce(input.Replace("\v", string.Empty), reverseReplacementRules);
+        if (string.IsNullOrEmpty(input) || (!input.Contains('\v') && !input.Contains('\x01')))
+        {
+            return input;
+        }
+
+        string stripped = input.Replace("\v", string.Empty);
+        if (!stripped.Contains('\x01'))
+        {
+            return stripped;
+        }
+
+        StringBuilder output = new StringBuilder(stripped.Length);
+        for (int i = 0; i < stripped.Length; i++)
+        {
+            if (stripped[i] == '\x01' && i + 4 < stripped.Length && stripped[i + 4] == '\x01')
+            {
+                string code = stripped.Substring(i, 5);
+                if (reverseReplacementRules.TryGetValue(code, out string value))
+                {
+                    _ = output.Append(value);
+                    i += 4;
+                    continue;
+                }
+            }
+
+            _ = output.Append(stripped[i]);
+        }
+
+        return output.ToString();
     }
 
     /// <summary>
@@ -92,7 +137,11 @@ public static class StringExtensions
     /// <returns><see langword="true"/> if parsing succeeded; otherwise <see langword="false"/>.</returns>
     public static bool ToStandardizedNumber(this string input, out double result)
     {
-        return double.TryParse(input.FromSafeString().Replace(',', '.'), NumberStyles.Any, CultureInfo.InvariantCulture, out result);
+        if (input.IndexOf(',') != -1)
+        {
+            input = input.Replace(',', '.');
+        }
+        return double.TryParse(input, NumberStyles.Any, CultureInfo.InvariantCulture, out result);
     }
 
     /// <summary>Replaces only the first occurrence of <paramref name="oldValue"/> in the string.</summary>
@@ -131,24 +180,4 @@ public static class StringExtensions
 
         return count;
     }
-
-    private static string ReplaceOnce(string input, Dictionary<string, string> replacementRules)
-    {
-        // \x01emp\x01/string.Empty is a special case, it is used to represent empty strings and won't work with the normal rules because an empty string always matches and causes an infinite loop 3 letter abbreviation
-        IEnumerable<KeyValuePair<string, string>> matches = replacementRules.Where(rule => rule.Key != string.Empty && input.Contains(rule.Key, StringComparison.Ordinal));
-        if (!matches.Any())
-        {
-            return input;
-        }
-
-        KeyValuePair<string, string> match = matches.First();
-        int startIndex = input.IndexOf(match.Key, StringComparison.Ordinal);
-        int endIndex = startIndex + match.Key.Length;
-
-        string before = ReplaceOnce(input[..startIndex], replacementRules);
-        string replaced = match.Value;
-        string after = ReplaceOnce(input[endIndex..], replacementRules);
-
-        return before + replaced + after;
-    }
 }

YesNt.Interpreter/Utilities/TemplateProcessor.cs

@@ -0,0 +1,167 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Text.RegularExpressions;
+using YesNt.Interpreter.Runtime;
+
+namespace YesNt.Interpreter.Utilities;
+
+/// <summary>
+/// Provides high-performance template substitution for variables and stack parameters.
+/// </summary>
+internal static class TemplateProcessor
+{
+    /// <summary>
+    /// Replaces all occurrences of ${variableName} with their current values.
+    /// </summary>
+    public static string ProcessVariables(string input, RuntimeInformation runtimeInfo)
+    {
+        if (string.IsNullOrEmpty(input)) return input;
+
+        int startIdx = input.IndexOf("${", StringComparison.Ordinal);
+        if (startIdx == -1) return input;
+
+        StringBuilder sb = new StringBuilder(input.Length);
+        int lastIdx = 0;
+
+        while (startIdx != -1)
+        {
+            sb.Append(input, lastIdx, startIdx - lastIdx);
+            int endIdx = input.IndexOf('}', startIdx + 2);
+            if (endIdx == -1)
+            {
+                sb.Append("${");
+                lastIdx = startIdx + 2;
+            }
+            else
+            {
+                string varName = input.Substring(startIdx + 2, endIdx - (startIdx + 2));
+                if (runtimeInfo.Variables.TryGetValue(varName, out string value))
+                {
+                    sb.Append(value);
+                }
+                else if (runtimeInfo.GlobalVariables.TryGetValue(varName, out value))
+                {
+                    sb.Append(value);
+                }
+                else if (!runtimeInfo.IsSearching)
+                {
+                    runtimeInfo.Exit(ExitMessages.VariableNotFound(varName), true);
+                    return input;
+                }
+                else
+                {
+                    sb.Append("${");
+                    sb.Append(varName);
+                    sb.Append('}');
+                }
+
+                lastIdx = endIdx + 1;
+            }
+
+            startIdx = input.IndexOf("${", lastIdx, StringComparison.Ordinal);
+        }
+
+        sb.Append(input, lastIdx, input.Length - lastIdx);
+        return sb.ToString();
+    }
+
+    /// <summary>
+    /// Replaces all occurrences of a placeholder (e.g., %in, %out) with values popped from a stack.
+    /// </summary>
+    public static string ProcessStackParameters(string input, string placeholder, Stack<string> stack, RuntimeInformation runtimeInfo, string emptyStackMessage)
+    {
+        if (string.IsNullOrEmpty(input)) return input;
+
+        int startIdx = input.IndexOf(placeholder, StringComparison.Ordinal);
+        if (startIdx == -1) return input;
+
+        StringBuilder sb = new StringBuilder(input.Length);
+        int lastIdx = 0;
+        int placeholderLen = placeholder.Length;
+
+        while (startIdx != -1)
+        {
+            sb.Append(input, lastIdx, startIdx - lastIdx);
+            if (stack.Count == 0)
+            {
+                runtimeInfo.Exit(emptyStackMessage, true);
+                return input;
+            }
+            sb.Append(stack.Pop());
+            lastIdx = startIdx + placeholderLen;
+            startIdx = input.IndexOf(placeholder, lastIdx, StringComparison.Ordinal);
+        }
+
+        sb.Append(input, lastIdx, input.Length - lastIdx);
+        return sb.ToString();
+    }
+
+    /// <summary>
+    /// Replaces all occurrences of a placeholder with a fixed value.
+    /// </summary>
+    public static string ProcessSimplePlaceholders(string input, string placeholder, string value)
+    {
+        if (string.IsNullOrEmpty(input)) return input;
+
+        return input.Replace(placeholder, value, StringComparison.Ordinal);
+    }
+
+    /// <summary>
+    /// Replaces all occurrences of a placeholder with values generated by a provider function.
+    /// </summary>
+    public static string ProcessDynamicPlaceholders(string input, string placeholder, Func<string> valueProvider)
+    {
+        if (string.IsNullOrEmpty(input)) return input;
+
+        int startIdx = input.IndexOf(placeholder, StringComparison.Ordinal);
+        if (startIdx == -1) return input;
+
+        StringBuilder sb = new StringBuilder(input.Length);
+        int lastIdx = 0;
+        int placeholderLen = placeholder.Length;
+
+        while (startIdx != -1)
+        {
+            sb.Append(input, lastIdx, startIdx - lastIdx);
+            sb.Append(valueProvider());
+            lastIdx = startIdx + placeholderLen;
+            startIdx = input.IndexOf(placeholder, lastIdx, StringComparison.Ordinal);
+        }
+
+        sb.Append(input, lastIdx, input.Length - lastIdx);
+        return sb.ToString();
+    }
+
+    /// <summary>
+    /// Replaces all occurrences of arithmetic expressions with their results.
+    /// </summary>
+    public static string ProcessCalculations(string input, RuntimeInformation runtimeInfo, Regex calculationRegex)
+    {
+        if (string.IsNullOrEmpty(input)) return input;
+
+        MatchCollection matches = calculationRegex.Matches(input);
+        if (matches.Count == 0) return input;
+
+        StringBuilder sb = new StringBuilder(input.Length);
+        int lastIdx = 0;
+
+        for (int i = 0; i < matches.Count; i++)
+        {
+            Match match = matches[i];
+            sb.Append(input, lastIdx, match.Index - lastIdx);
+            
+            string res = Evaluator.Calculate(match.Value);
+            if (res is null)
+            {
+                runtimeInfo.Exit(ExitMessages.InvalidOperation, true);
+                return input;
+            }
+            sb.Append(res);
+            lastIdx = match.Index + match.Length;
+        }
+
+        sb.Append(input, lastIdx, input.Length - lastIdx);
+        return sb.ToString();
+    }
+}