General: Backport polyfills for str_ends_with() and str_starts_with() .

Merges [52040], [56016], and [56015] to 5.7 branch.

Props ocean90, SergeyBiryukov, desrosj, joemcgill, jorbin, mukesh27.


git-svn-id: https://develop.svn.wordpress.org/branches/5.7@57451 602fd350-edb4-49c9-b593-d223f7449a82

Author: joemcgill

src/wp-includes/compat.php

@@ -369,4 +369,50 @@ function is_countable( $var ) {
 	function is_iterable( $var ) {
 		return ( is_array( $var ) || $var instanceof Traversable );
 	}
+
+	if ( ! function_exists( 'str_starts_with' ) ) {
+		/**
+		 * Polyfill for `str_starts_with()` function added in PHP 8.0.
+		 *
+		 * Performs a case-sensitive check indicating if
+		 * the haystack begins with needle.
+		 *
+		 * @since 5.9.0
+		 *
+		 * @param string $haystack The string to search in.
+		 * @param string $needle   The substring to search for in the `$haystack`.
+		 * @return bool True if `$haystack` starts with `$needle`, otherwise false.
+		 */
+		function str_starts_with( $haystack, $needle ) {
+			if ( '' === $needle ) {
+				return true;
+			}
+
+			return 0 === strpos( $haystack, $needle );
+		}
+	}
+
+	if ( ! function_exists( 'str_ends_with' ) ) {
+		/**
+		 * Polyfill for `str_ends_with()` function added in PHP 8.0.
+		 *
+		 * Performs a case-sensitive check indicating if
+		 * the haystack ends with needle.
+		 *
+		 * @since 5.9.0
+		 *
+		 * @param string $haystack The string to search in.
+		 * @param string $needle   The substring to search for in the `$haystack`.
+		 * @return bool True if `$haystack` ends with `$needle`, otherwise false.
+		 */
+		function str_ends_with( $haystack, $needle ) {
+			if ( '' === $haystack ) {
+				return '' === $needle;
+			}
+
+			$len = strlen( $needle );
+
+			return substr( $haystack, -$len, $len ) === $needle;
+		}
+	}
 }