private function update_dash_spacing_regex( $parenthetical, $parenthetical_space, $interval, $interval_space ) {
		// Mandatory UTF-8 modifier.
		$this->parenthetical_dash_spacing = "/
			(?:
				\s
				({$parenthetical})
				\s
			)
		/xu";

		// Mandatory UTF-8 modifier.
		$this->interval_dash_spacing = "/
			(?:
				(?<=\S)             # lookbehind assertion
				({$interval})
				(?=\S)              # lookahead assertion
			)
		/xu";

		$this->em_dash_replacement            = "{$interval_space}\$1\$2{$interval_space}"; // is this correct?
		$this->parenthetical_dash_replacement = "{$parenthetical_space}\$1\$2{$parenthetical_space}";
		$this->interval_dash_replacement      = "{$interval_space}\$1\$2{$interval_space}";
	}
private function update_dash_spacing_regex( $parenthetical, $parenthetical_space, $interval, $interval_space ) {
		// Mandatory UTF-8 modifier.
		$this->parenthetical_dash_spacing = "/
			(?:
				\s
				({$parenthetical})
				\s
			)
		/xu";

		// Mandatory UTF-8 modifier.
		$this->interval_dash_spacing = "/
			(?:
				(?<=\S)             # lookbehind assertion
				({$interval})
				(?=\S)              # lookahead assertion
			)
		/xu";

		$this->em_dash_replacement            = "{$interval_space}\$1\$2{$interval_space}"; // is this correct?
		$this->parenthetical_dash_replacement = "{$parenthetical_space}\$1\$2{$parenthetical_space}";
		$this->interval_dash_replacement      = "{$interval_space}\$1\$2{$interval_space}";
	}
private function update_dash_spacing_regex ( $ parenthetical , $ parenthetical_space , $ interval , $ interval_space ) { // Mandatory UTF-8 modifier. $ this -> parenthetical_dash_spacing = "/
			(?:
				\s
				({$parenthetical})
				\s
			)
		/xu" ; // Mandatory UTF-8 modifier. $ this -> interval_dash_spacing = "/
			(?:
				(?<=\S)             # lookbehind assertion
				({$interval})
				(?=\S)              # lookahead assertion
			)
		/xu" ; $ this -> em_dash_replacement = "{$interval_space}\$1\$2{$interval_space}" ; // is this correct? $ this -> parenthetical_dash_replacement = "{$parenthetical_space}\$1\$2{$parenthetical_space}" ; $ this -> interval_dash_replacement = "{$interval_space}\$1\$2{$interval_space}" ; }
Update the dash spacing regular expression.

@param string $parenthetical       The dash character used for parenthetical dashes.
@param string $parenthetical_space The space character used around parenthetical dashes.
@param string $interval            The dash character used for interval dashes.
@param string $interval_space      The space character used around interval dashes.
Update the dash spacing regular expression .