protected function computeBitfields()
	{
		if (empty($this->branches))
		{
			$this->allowChildBitfields = ["\0"];

			return;
		}
		foreach ($this->branches as $branch)
		{
			/**
			* @var string allowChild bitfield for current branch. Starts with the value associated
			*             with <div> in order to approximate a value if the whole branch uses the
			*             transparent content model
			*/
			$branchBitfield = $this->defaultBranchBitfield;

			foreach ($branch as $element)
			{
				if (!ElementInspector::isTransparent($element))
				{
					// If the element isn't transparent, we reset its bitfield
					$branchBitfield = "\0";
				}

				// allowChild rules are cumulative if transparent, and reset above otherwise
				$branchBitfield |= ElementInspector::getAllowChildBitfield($element);

				// denyDescendant rules are cumulative
				$this->denyDescendantBitfield |= ElementInspector::getDenyDescendantBitfield($element);
			}

			// Add this branch's bitfield to the list
			$this->allowChildBitfields[] = $branchBitfield;
		}
	}