parse-sizes-values.php

<?php

$sizes_values = array_filter(
	array_map(
		static function ( string $size ): string {
			$size        = trim( $size, " \t\f\r\n" );
			$lower_sizes = strtolower( $size );
			if ( 'auto' === $lower_sizes ) {
				// Normalize to lower-case.
				$size = $lower_sizes;
			}
			return $size;
		},
		explode( ',', $sizes )
	)
);
$has_auto = isset( $sizes_values[0] ) && 'auto' === $sizes_values[0];