@oat-sa/tao-item-runner-qti/src/scoring/processor/expressions/operators/roundTo.js

TAO QTI Item Runner modules

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; under version 2
 * of the License (non-upgradable).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (c) 2015-2019 (original work) Open Assessment Technlogies SA (under the project TAO-PRODUCT);
 *
 */

/**
 * The roundTo operator processor.
 * @see http://www.imsglobal.org/question/qtiv2p1/imsqti_infov2p1.html#element106470
 *
 * @author Bertrand Chevrier <bertrand@taotesting.com>
 */
import _ from 'lodash';
import errorHandler from 'taoQtiItem/scoring/processor/errorHandler';

/**
 * Process operands and returns roundTo result.
 * @type {OperatorProcessor}
 * @exports taoQtiItem/scoring/processor/expressions/operators/roundTo
 */
var roundToProcessor = {

    engines: {
        significantFigures: function(value, exp) {
            return decimalAdjust('round', value, exp);
        },
        decimalPlaces: function(value, exp) {
            return decimalAdjust('floor', value, exp);
        }
    },

    constraints: {
        minOperand: 1,
        maxOperand: 1,
        cardinality: ['single'],
        baseType: ['integer', 'float']
    },

    operands: [],

    /**
     * @returns {?ProcessingValue} a single boolean
     */
    process: function() {

        var roundingMode = _.isFunction(this.engines[this.expression.attributes.roundingMode]) ? this.engines[this.expression.attributes.roundingMode] : this.engines.significantFigures;
        var figures = this.preProcessor.parseValue(this.expression.attributes.figures, 'integerOrVariableRef');
        var result;
        var value;

        if (!this.preProcessor.isNumber(figures)) {
            errorHandler.throw('scoring', new Error('figures must be numeric'));
            return null;
        }

        if (figures <= 1 && roundingMode === this.engines.significantFigures) {
            errorHandler.throw('scoring', new Error('significantFigures must be numeric'));
            return null;
        }

        result = {
            cardinality: 'single',
            baseType: 'float'
        };

        //if at least one operand is null, then break and return null
        if (_.some(this.operands, _.isNull) === true) {
            return null;
        }

        value = this.preProcessor.parseVariable(this.operands[0]).value;

        if (!_.isFinite(value)) {
            result.value = value;
            return result;
        }

        result.value = roundingMode(value, figures);

        return result;
    }
};

/**
 * Decimal adjustment of a number.
 *
 * @param {String}  type  The type of adjustment.
 * @param {Number}  value The number.
 * @param {Integer} exp   The exponent (the 10 logarithm of the adjustment base).
 * @returns {Number} The adjusted value.
 * @private
 */
function decimalAdjust(type, value, exp) {

    // Shift
    value = value.toString().split('e');
    value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp)));
    // Shift back
    value = value.toString().split('e');
    return +(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp));
}

export default roundToProcessor;