protected function boundaries()
	{
		if ( !is_null( $this->_boundaries ) )
			return $this->_boundaries;

		// we have defined the boundaries of two non-overlapping intervals,
		// so sorting puts both the intervals and their boundaries in order
		$this->_boundaries = [
			$this->model->getLeft(),
			$this->model->getRight(),
			$this->bound1(),
			$this->bound2()
		];
		sort( $this->_boundaries );

		return $this->_boundaries;
	}
protected function boundaries()
	{
		if ( !is_null( $this->_boundaries ) )
			return $this->_boundaries;

		// we have defined the boundaries of two non-overlapping intervals,
		// so sorting puts both the intervals and their boundaries in order
		$this->_boundaries = [
			$this->model->getLeft(),
			$this->model->getRight(),
			$this->bound1(),
			$this->bound2()
		];
		sort( $this->_boundaries );

		return $this->_boundaries;
	}
protected function boundaries ( ) { if ( ! is_null ( $ this -> _boundaries ) ) return $ this -> _boundaries ; // we have defined the boundaries of two non-overlapping intervals, // so sorting puts both the intervals and their boundaries in order $ this -> _boundaries = [ $ this -> model -> getLeft ( ) , $ this -> model -> getRight ( ) , $ this -> bound1 ( ) , $ this -> bound2 ( ) ] ; sort ( $ this -> _boundaries ) ; return $ this -> _boundaries ; }
Computes the boundaries array.

@return array
Computes the boundaries array .