implement findBetween method in StringHelper

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 2.3.1 under development
 
 - Enh #117: `WildcardPatters` uses memoization and accelerates ~2 times on repeated calls (@viktorprogger)
+- Enh #118: Added yii\helpers\BaseStringHelper::findBetween() to retrieve a substring that lies between two strings (salehhashemi1992)
 
 ## 2.3.0 October 23, 2023
 

README.md

@@ -63,6 +63,7 @@ Overall the helper has the following method groups.
 - startsWithIgnoringCase
 - endsWith
 - endsWithIgnoringCase
+- findBetween
 
 ### Truncation
 

src/StringHelper.php

@@ -619,6 +619,35 @@ public static function rtrim(string|array $string, string $pattern = self::DEFAU
         return preg_replace("#[$pattern]+$#uD", '', $string);
     }
 
+    /**
+     * Returns the portion of the string that lies between the first occurrence of the start string
+     * and the last occurrence of the end string after that.
+     *
+     * @param string $string The input string.
+     * @param string $start The string marking the start of the portion to extract.
+     * @param string $end The string marking the end of the portion to extract.
+     * @return string|null The portion of the string between the first occurrence of
+     * start and the last occurrence of end, or null if either start or end cannot be found.
+     */
+    public static function findBetween(string $string, string $start, string $end): ?string
+    {
+        $startPos = mb_strpos($string, $start);
+
+        if ($startPos === false) {
+            return null;
+        }
+
+        // Cut the string from the start position
+        $subString = mb_substr($string, $startPos + mb_strlen($start));
+        $endPos = mb_strrpos($subString, $end);
+
+        if ($endPos === false) {
+            return null;
+        }
+
+        return mb_substr($subString, 0, $endPos);
+    }
+
     /**
      * Ensure the input string is a valid UTF-8 string.
      *

tests/StringHelperTest.php

@@ -763,4 +763,30 @@ public function testInvalidTrimPattern(): void
 
         StringHelper::trim('string', "\xC3\x28");
     }
+
+    /**
+     * @dataProvider dataProviderFindBetween
+     */
+    public function testFindBetween(string $string, string $start, string $end, ?string $expectedResult): void
+    {
+        $this->assertSame($expectedResult, StringHelper::findBetween($string, $start, $end));
+    }
+
+    public function dataProviderFindBetween(): array
+    {
+        return [
+            ['hello world hello', ' hello', ' world', null],  // end before start
+            ['This is a sample string', ' is ', ' string', 'a sample'],  // normal case
+            ['startendstart', 'start', 'end', ''],  // end before start
+            ['startmiddleend', 'start', 'end', 'middle'],  // normal case
+            ['startend', 'start', 'end', ''],  // end immediately follows start
+            ['multiple start start end end', 'start ', ' end', 'start end'],  // multiple starts and ends
+            ['', 'start', 'end', null],  // empty string
+            ['no delimiters here', 'start', 'end', null],  // no start and end
+            ['start only', 'start', 'end', null], // start found but no end
+            ['end only', 'start', 'end', null], // end found but no start
+            ['spécial !@#$%^&*()', 'spé', '&*()', 'cial !@#$%^'],  // Special characters
+            ['من صالح هاشمی هستم', 'من ', ' هستم', 'صالح هاشمی'], // other languages
+        ];
+    }
 }