fontoxpath/src/selectors/axes/ParentAxis.js

A minimalistic XPath 3.1 engine in JavaScript

import Selector from '../Selector';
import Sequence from '../dataTypes/Sequence';
import createNodeValue from '../dataTypes/createNodeValue';

/**
 * @extends {Selector}
 */
class ParentAxis extends Selector {
	/**
	 * @param  {!../tests/TestAbstractExpression}  parentSelector
	 */
	constructor (parentSelector) {
		super(parentSelector.specificity, {
			resultOrder: Selector.RESULT_ORDERINGS.REVERSE_SORTED,
			peer: true,
			subtree: true,
			canBeStaticallyEvaluated: false
		});

		this._parentSelector = parentSelector;
	}

	/**
	 * @param   {../DynamicContext}  dynamicContext
	 * @return  {Sequence}
	 */
	evaluate (dynamicContext) {
		if (dynamicContext.contextItem === null) {
			throw new Error('XPDY0002: context is absent, it needs to be present to use axes.');
		}

		const domFacade = dynamicContext.domFacade;

		const parentNode = domFacade.getParentNode(dynamicContext.contextItem.value);
		if (!parentNode) {
			return Sequence.empty();
		}
		const parentNodeValue = createNodeValue(parentNode);
		const nodeIsMatch = this._parentSelector.evaluateToBoolean(dynamicContext, parentNodeValue);
		if (!nodeIsMatch) {
			return Sequence.empty();
		}
		return Sequence.singleton(parentNodeValue);
	}
}

export default ParentAxis;