WP_Rewrite::get_date_permastruct() WordPress Method

	public function get_date_permastruct() {
		if ( isset( $this->date_structure ) ) {
			return $this->date_structure;
		}

		if ( empty( $this->permalink_structure ) ) {
			$this->date_structure = '';
			return false;
		}

		// The date permalink must have year, month, and day separated by slashes.
		$endians = array( '%year%/%monthnum%/%day%', '%day%/%monthnum%/%year%', '%monthnum%/%day%/%year%' );

		$this->date_structure = '';
		$date_endian          = '';

		foreach ( $endians as $endian ) {
			if ( false !== strpos( $this->permalink_structure, $endian ) ) {
				$date_endian = $endian;
				break;
			}
		}

		if ( empty( $date_endian ) ) {
			$date_endian = '%year%/%monthnum%/%day%';
		}

		/*
		 * Do not allow the date tags and %post_id% to overlap in the permalink
		 * structure. If they do, move the date tags to $front/date/.
		 */
		$front = $this->front;
		preg_match_all( '/%.+?%/', $this->permalink_structure, $tokens );
		$tok_index = 1;
		foreach ( (array) $tokens[0] as $token ) {
			if ( '%post_id%' === $token && ( $tok_index <= 3 ) ) {
				$front = $front . 'date/';
				break;
			}
			$tok_index++;
		}

		$this->date_structure = $front . $date_endian;

		return $this->date_structure;
	}