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ConsoleApp2/Helpers/Extensions.String.cs

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+using System.Globalization;
+using System.Text;
+
+namespace ConsoleApp2.Helpers;
+
+public static class StringExtensions
+{
+    public static string Omit(this ReadOnlySpan<char> @this, int maxLength)
+    {
+        if (@this.Length > maxLength)
+            return @this[..maxLength].ToString() + "...";
+        return @this.ToString();
+    }
+
+    public static string Omit(this string @this, int maxLength) => Omit(@this.AsSpan(), maxLength);
+
+    public static string FromHex(ReadOnlySpan<char> hexString, Encoding? encoding = null)
+    {
+        encoding ??= Encoding.UTF8;
+
+        var realLength = 0;
+        for (var i = hexString.Length - 2; i >= 0; i -= 2)
+        {
+            var b = byte.Parse(hexString.Slice(i, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            if (b != 0) //not NULL character
+            {
+                realLength = i + 2;
+                break;
+            }
+        }
+
+        var bytes = new byte[realLength / 2];
+        for (var i = 0; i < bytes.Length; i++)
+        {
+            bytes[i] = byte.Parse(hexString.Slice(i * 2, 2), NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+        }
+
+        return encoding.GetString(bytes);
+    }
+    
+    public static bool CheckJsonHex(ReadOnlySpan<char> hexStr)
+    {
+        if (hexStr.Length < 2)
+            return false;
+        return FromHex(hexStr[..2]) is ['{'] or ['['];
+    }
+}