Add string literal parsing with escapes and related tests

YesNt.Interpreter/Statements/StringLiteralStatements.cs

@@ -0,0 +1,78 @@
+using System.Text;
+
+using YesNt.Interpreter.Attributes;
+using YesNt.Interpreter.Enums;
+using YesNt.Interpreter.Runtime;
+using YesNt.Interpreter.Utilities;
+
+namespace YesNt.Interpreter.Statements;
+
+internal class StringLiteralStatements : StatementRuntimeInformation
+{
+    [Statement("\"", SearchMode.Contains, SpaceAround.None, System.ConsoleColor.DarkYellow, Priority = Priority.PreProcessing, KeepStatementInArgs = true)]
+    public void ParseStringLiterals(string args)
+    {
+        if (!args.Contains('"'))
+        {
+            return;
+        }
+
+        StringBuilder output = new StringBuilder(args.Length);
+
+        for (int i = 0; i < args.Length; i++)
+        {
+            char current = args[i];
+            if (current != '"')
+            {
+                _ = output.Append(current);
+                continue;
+            }
+
+            StringBuilder literal = new StringBuilder();
+            bool closed = false;
+            i++;
+
+            for (; i < args.Length; i++)
+            {
+                char ch = args[i];
+                if (ch == '\\' && i + 1 < args.Length)
+                {
+                    i++;
+                    _ = literal.Append(ParseEscape(args[i]));
+                    continue;
+                }
+
+                if (ch == '"')
+                {
+                    closed = true;
+                    break;
+                }
+
+                _ = literal.Append(ch);
+            }
+
+            if (!closed)
+            {
+                RuntimeInfo.Exit("Invalid string literal", true);
+                return;
+            }
+
+            _ = output.Append(literal.ToString().ToSafeString());
+        }
+
+        RuntimeInfo.CurrentLine = output.ToString();
+    }
+
+    private static char ParseEscape(char escapeChar)
+    {
+        return escapeChar switch
+        {
+            'n' => '\n',
+            'r' => '\r',
+            't' => '\t',
+            '"' => '"',
+            '\\' => '\\',
+            _ => escapeChar
+        };
+    }
+}