refactor: performance refactor for Utils

Signed-off-by: Alan Brault <alan.brault@visus.io>

Author: xaevik

src/Utils.php

@@ -23,26 +23,12 @@ private function __construct()
     {
     }
 
-    /**
-     * Converts a single hexadecimal character to its numeric value.
-     *
-     * @param string $char Single hex character (0-9, a-f, A-F).
-     *
-     * @return int Numeric value (0-15).
-     */
-    private static function parseHexCharacter(string $char): int
-    {
-        return match (true) {
-            $char >= '0' && $char <= '9' => ord($char) - 48,
-            $char >= 'a' && $char <= 'f' => ord($char) - 87,
-            $char >= 'A' && $char <= 'F' => ord($char) - 55,
-            default => 0,
-        };
-    }
-
     /**
      * Converts a hexadecimal string to large base representation.
      *
+     * Processes 8 hexadecimal characters at a time for improved performance,
+     * reducing loop iterations by 8x compared to single-character processing.
+     *
      * @param string $hexValue Hexadecimal string to convert.
      * @param int $base Large base for digit storage (100 million).
      *
@@ -51,13 +37,38 @@ private static function parseHexCharacter(string $char): int
     private static function convertHexToLargeBase(string $hexValue, int $base): array
     {
         $digits = [0];
+        $len = strlen($hexValue);
+
+        $remainder = $len % 8;
+        $i = 0;
+
+        if ($remainder > 0) {
+            $chunk = substr($hexValue, 0, $remainder);
+            $chunkValue = (int) hexdec($chunk);
+            $carry = $chunkValue;
+            $multiplier = 1 << $remainder * 4; // 16^remainder = 2^(remainder*4)
+
+            for ($j = 0, $jlen = count($digits); $j < $jlen; $j++) {
+                $current = $digits[$j] * $multiplier + $carry;
+                $digits[$j] = $current % $base;
+                $carry = intdiv($current, $base);
+            }
+
+            while ($carry > 0) {
+                $digits[] = $carry % $base;
+                $carry = intdiv($carry, $base);
+            }
+
+            $i = $remainder;
+        }
 
-        for ($i = 0, $len = strlen($hexValue); $i < $len; $i++) {
-            $hexDigit = self::parseHexCharacter($hexValue[$i]);
-            $carry = $hexDigit;
+        for (; $i < $len; $i += 8) {
+            $chunk = substr($hexValue, $i, 8);
+            $chunkValue = (int) hexdec($chunk);
+            $carry = $chunkValue;
 
             for ($j = 0, $jlen = count($digits); $j < $jlen; $j++) {
-                $current = $digits[$j] * 16 + $carry;
+                $current = $digits[$j] * 4294967296 + $carry; // 16^8 = 2^32 = 4294967296
                 $digits[$j] = $current % $base;
                 $carry = intdiv($current, $base);
             }
@@ -108,15 +119,17 @@ private static function convertLargeBaseToBase36(array $digits, int $base): stri
      * Converts a hexadecimal string to base36 encoding.
      *
      * This function performs arbitrary precision base conversion without requiring
-     * the GMP extension. It uses a large intermediate base (100 million) for efficient
-     * arithmetic operations on large numbers.
+     * the GMP extension. For small values (≤14 hex chars), it uses the native
+     * base_convert() function for optimal performance. For larger values, it uses
+     * a large intermediate base (100 million) for efficient arithmetic operations.
      *
      * Base36 encoding uses digits 0-9 and lowercase letters a-z (36 characters total),
      * producing shorter strings than hexadecimal while remaining URL-safe.
      *
      * Algorithm:
-     * 1. Convert hex string to internal representation using base 100M
-     * 2. Convert internal representation to base36 by repeated division
+     * 1. Fast path: Use base_convert() for small values (≤14 hex chars / 56 bits)
+     * 2. Large values: Convert hex string to internal representation using base 100M
+     * 3. Convert internal representation to base36 by repeated division
      *
      * @param string $hexValue Hexadecimal string to convert (case-insensitive).
      *
@@ -128,6 +141,10 @@ public static function hexToBase36(string $hexValue): string
             return '0';
         }
 
+        if (strlen($hexValue) <= 14) {
+            return base_convert($hexValue, 16, 36);
+        }
+
         $base = 100_000_000;
         $digits = self::convertHexToLargeBase($hexValue, $base);