Implement findBetween(), findBetweenFirst(), and findBetweenLast() Methods

CHANGELOG.md

@@ -1,8 +1,9 @@
 # Yii Strings Change Log
 
-## 2.3.2 under development
+## 2.4.0 under development
 
-- no changes in this release.
+- New #118: Add `findBetween()`, `findBetweenFirst()` and `findBetweenLast()` methods to `StringHelper` to retrieve
+  a substring that lies between two strings (@salehhashemi1992)
 
 ## 2.3.1 October 30, 2023
 

README.md

@@ -63,6 +63,9 @@ Overall the helper has the following method groups.
 - startsWithIgnoringCase
 - endsWith
 - endsWithIgnoringCase
+- findBetween
+- findBetweenFirst
+- findBetweenLast
 
 ### Truncation
 

src/StringHelper.php

@@ -49,9 +49,9 @@
      *
      * @return int The number of bytes in the given string.
      */
     public static function byteLength(string|null $input): int
     {
         return mb_strlen((string)$input, '8bit');
     }
 
     /**
@@ -619,6 +619,104 @@
         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|null $end The string marking the end of the portion to extract.
+     * If the `$end` string is not provided, it defaults to the value of the `$start` string.
+     * @return string|null The portion of the string between the first occurrence of
+     * `$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 $end = null): ?string
+    {
+        if ($end === null) {
+            $end = $start;
+        }
+
+        $startPos = mb_strpos($string, $start);
+
+        if ($startPos === false) {
+            return null;
+        }
+
+        $startPos += mb_strlen($start);
+        $endPos = mb_strrpos($string, $end, $startPos);
+
+        if ($endPos === false) {
+            return null;
+        }
+
+        return mb_substr($string, $startPos, $endPos - $startPos);
+    }
+
+    /**
+     * Returns the portion of the string between the initial occurrence of the '$start' string
+     * and the next occurrence of the '$end' string.
+     *
+     * @param string $string The input string.
+     * @param string $start The string marking the beginning of the segment to extract.
+     * @param string|null $end The string marking the termination of the segment.
+     * If the '$end' string is not provided, it defaults to the value of the '$start' string.
+     * @return string|null Extracted segment, or null if '$start' or '$end' is not present.
+     */
+    public static function findBetweenFirst(string $string, string $start, ?string $end = null): ?string
+    {
+        if ($end === null) {
+            $end = $start;
+        }
+
+        $startPos = mb_strpos($string, $start);
+
+        if ($startPos === false) {
+            return null;
+        }
+
+        $startPos += mb_strlen($start);
+        $endPos = mb_strpos($string, $end, $startPos);
+
+        if ($endPos === false) {
+            return null;
+        }
+
+        return mb_substr($string, $startPos, $endPos - $startPos);
+    }
+
+    /**
+     * Returns the portion of the string between the latest '$start' string
+     * and the subsequent '$end' string.
+     *
+     * @param string $string The input string.
+     * @param string $start The string marking the beginning of the segment to extract.
+     * @param string|null $end The string marking the termination of the segment.
+     * If the '$end' string is not provided, it defaults to the value of the '$start' string.
+     * @return string|null Extracted segment, or null if '$start' or '$end' is not present.
+     */
+    public static function findBetweenLast(string $string, string $start, ?string $end = null): ?string
+    {
+        if ($end === null) {
+            $end = $start;
+        }
+
+        $endPos = mb_strrpos($string, $end);
+
+        if ($endPos === false) {
+            return null;
+        }
+
+        $startPos = mb_strrpos(mb_substr($string, 0, $endPos), $start);
+
+        if ($startPos === false) {
+            return null;
+        }
+
+        $startPos += mb_strlen($start);
+
+        return mb_substr($string, $startPos, $endPos - $startPos);
+    }
+
     /**
      * Ensure the input string is a valid UTF-8 string.
      *

tests/StringHelperTest.php

@@ -763,4 +763,92 @@ 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, $end));
+    }
+
+    public function dataProviderFindBetween(): array
+    {
+        return [
+            ['hello world hello', ' hello', ' world', null],  // end before start
+            ['This is a sample string', ' is ', ' string', 'a sample'],  // normal case
+            ['startendstart', 'start', 'end', ''],  // end before start
+            ['startmiddleend', 'start', 'end', 'middle'],  // normal case
+            ['startend', 'start', 'end', ''],  // end immediately follows start
+            ['multiple start start end end', 'start ', ' end', 'start end'],  // multiple starts and ends
+            ['', 'start', 'end', null],  // empty string
+            ['no delimiters here', 'start', 'end', null],  // no start and end
+            ['start only', 'start', 'end', null], // start found but no end
+            ['end only', 'start', 'end', null], // end found but no start
+            ['a1a2a3a', 'a', 'a', '1a2a3'], // same start and end
+            ['a1a2a3a', 'a', null, '1a2a3'], // end is null
+            ['spécial !@#$%^&*()', 'spé', '&*()', 'cial !@#$%^'],  // Special characters
+            ['من صالح هاشمی هستم', 'من ', ' هستم', 'صالح هاشمی'], // other languages
+        ];
+    }
+
+    /**
+     * @dataProvider dataProviderFindBetweenFirst
+     */
+    public function testFindBetweenFirst(string $string, string $start, ?string $end, ?string $expectedResult): void
+    {
+        $this->assertSame($expectedResult, StringHelper::findBetweenFirst($string, $start, $end));
+    }
+
+    public function dataProviderFindBetweenFirst(): array
+    {
+        return [
+            ['[a][b][c]', '[', ']', 'a'], // normal case
+            ['[a]m[b]n[c]', '[', ']', 'a'], // normal case
+            ['hello world hello', ' hello', ' world', null],  // end before start
+            ['This is a sample string string', ' is ', ' string', 'a sample'],  // normal case
+            ['startendstartend', 'start', 'end', ''],  // end before start
+            ['startmiddleend', 'start', 'end', 'middle'],  // normal case
+            ['startend', 'start', 'end', ''],  // end immediately follows start
+            ['multiple start start end end', 'start ', ' end', 'start'],  // multiple starts and ends
+            ['', 'start', 'end', null],  // empty string
+            ['no delimiters here', 'start', 'end', null],  // no start and end
+            ['start only', 'start', 'end', null], // start found but no end
+            ['end only', 'start', 'end', null], // end found but no start
+            ['a1a2a3a', 'a', 'a', '1'], // same start and end
+            ['a1a2a3a', 'a', null, '1'], // end is null
+            ['spécial !@#$%^&*()', 'spé', '&*()', 'cial !@#$%^'],  // Special characters
+            ['من صالح هاشمی هستم هستم', 'من ', ' هستم', 'صالح هاشمی'], // other languages
+        ];
+    }
+
+    /**
+     * @dataProvider dataProviderFindBetweenLast
+     */
+    public function testFindBetweenLast(string $string, string $start, ?string $end, ?string $expectedResult): void
+    {
+        $this->assertSame($expectedResult, StringHelper::findBetweenLast($string, $start, $end));
+    }
+
+    public function dataProviderFindBetweenLast(): array
+    {
+        return [
+            ['[a][b][c]', '[', ']', 'c'], // normal case
+            ['[a]m[b]n[c]', '[', ']', 'c'], // normal case
+            ['hello world hello', ' hello', ' world', null],  // end before start
+            ['This is is a sample string string', ' is ', ' string', 'a sample string'],  // normal case
+            ['startendstartend', 'start', 'end', ''],  // end before start
+            ['startmiddleend', 'start', 'end', 'middle'],  // normal case
+            ['startend', 'start', 'end', ''],  // end immediately follows start
+            ['multiple start start end end', 'start ', ' end', 'end'],  // multiple starts and ends
+            ['', 'start', 'end', null],  // empty string
+            ['no delimiters here', 'start', 'end', null],  // no start and end
+            ['start only', 'start', 'end', null], // start found but no end
+            ['end only', 'start', 'end', null], // end found but no start
+            ['a1a2a3a', 'a', 'a', '3'], // same start and end
+            ['a1a2a3a', 'a', null, '3'], // end is null
+            ['spécial !@#$%^&*()', 'spé', '&*()', 'cial !@#$%^'],  // Special characters
+            ['من صالح هاشمی هستم هستم', 'من ', ' هستم', 'صالح هاشمی هستم'], // other languages
+        ];
+    }
 }