private function update_smart_quotes_brackets( $primary_open, $primary_close, $secondary_open, $secondary_close ) {
		$brackets = [
			// Single quotes.
			"['"  => '[' . $secondary_open,
			"{'"  => '{' . $secondary_open,
			"('"  => '(' . $secondary_open,
			"']"  => $secondary_close . ']',
			"'}"  => $secondary_close . '}',
			"')"  => $secondary_close . ')',

			// Double quotes.
			'["'  => '[' . $primary_open,
			'{"'  => '{' . $primary_open,
			'("'  => '(' . $primary_open,
			'"]'  => $primary_close . ']',
			'"}'  => $primary_close . '}',
			'")'  => $primary_close . ')',

			// Quotes & quotes.
			"\"'" => $primary_open . $secondary_open,
			"'\"" => $secondary_close . $primary_close,
		];

		$this->brackets_matches      = \array_keys( $brackets );
		$this->brackets_replacements = \array_values( $brackets );
	}