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

A minimalistic XPath 3.1 engine in JavaScript

import createAtomicValue from '../createAtomicValue';

const createIntegerValue = value => createAtomicValue(value, 'xs:integer');

/**
 * @param  {function(string):boolean}  instanceOf
 * @return {function (./AtomicValueDataType) : ({successful: boolean, value: ../AtomicValue}|{successful: boolean, error: !Error})}
 */
export default function castToInteger (instanceOf) {
	if (instanceOf('xs:boolean')) {
		return value => ({
			successful: true,
			value: createIntegerValue(value ? 1 : 0)
		});
	}
	if (instanceOf('xs:numeric')) {
		return value => {
			const integerValue = Math.trunc(value);
			if (!isFinite(integerValue) || isNaN(integerValue)) {
				return {
					successful: false,
					error: new Error(`FOCA0002: can not cast ${value} to xs:integer`)
				};

			}

			if (!Number.isSafeInteger(integerValue)) {
				return {
					successful: false,
					error: new Error(`FOAR0002: can not cast ${value} to xs:integer, it is out of bounds for JavaScript numbers.`)
				};
			}

			return {
				successful: true,
				value: createIntegerValue(integerValue)
			};
		};
	}
	if (instanceOf('xs:string') || instanceOf('xs:untypedAtomic')) {
		return value => {
			const integerValue = parseInt(value, 10);
			if (isNaN(integerValue)) {
				return {
					successful: false,
					error: new Error(`FORG0001: Cannot cast "${value}" to xs:integer.`)
				};
			}
			if (!Number.isSafeInteger(integerValue)) {
				return {
					successful: false,
					error: new Error(`FOCA0003: can not cast ${value} to xs:integer, it is out of bounds for JavaScript numbers.`)
				};
			}

			return {
				successful: true,
				value: createIntegerValue(integerValue)
			};
		};
	}
	return value => ({
		successful: false,
		error: new Error('XPTY0004: Casting not supported from given type to xs:integer or any of its derived types.')
	});
}