fontoxpath/src/selectors/dataTypes/casting/castToBase64Binary.js

A minimalistic XPath 3.1 engine in JavaScript

import createAtomicValue from '../createAtomicValue';

const createBase64BinaryValue = value => createAtomicValue(value, 'xs:base64Binary');

function hexToString (hex) {
	let string = '';
	for (let i = 0; i < hex.length; i += 2) {
		string += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
	}
	return string;
}

/**
 * @param  {function(string):boolean}  instanceOf
 * @return {function (./AtomicValueDataType) : ({successful: boolean, value: ../AtomicValue}|{successful: boolean, error: !Error})}
 */
export default function castToBase64Binary (instanceOf) {
	if (instanceOf('xs:hexBinary')) {
		return value => ({
			successful: true,
			value: createBase64BinaryValue(btoa(hexToString(value)))
		});
	}
	if (instanceOf('xs:string') || instanceOf('xs:untypedAtomic')) {
		return value => ({
			successful: true,
			value: createBase64BinaryValue(value)
		});
	}
	return () => ({
		successful: false,
		error: new Error('XPTY0004: Casting not supported from given type to xs:base64Binary or any of its derived types.')
	});
}