Performance improvements and code cleanup

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();
+    }
+}