@instructure/quiz-interactions/es/util/formula.js

A React UI component Library for quiz interaction types.

import uniq from 'lodash/uniq';
import { mathjsLoadingWrapper } from '../components/formula/common/util';
import { Decimal } from '@instructure/quiz-i18n';
import t from '@instructure/quiz-i18n/es/format-message';
export var variablesFromItemBody = function variablesFromItemBody(itemBody) {
  var body = itemBody || '';
  var matches = body.match(/`[A-Za-z]\w*`/g) || [];
  var matchesWithoutBackticks = matches.map(function (match) {
    return match.replace(/`/g, '');
  });
  return uniq(matchesWithoutBackticks).sort();
};
export var formulaSyntaxError = function formulaSyntaxError(variables, formula) {
  var substitutions = {};
  variables.forEach(function (varName) {
    return substitutions[varName] = 1;
  });
  try {
    // TODO: This will fail if nothing has called components/formula/Edit/util/loadMathJs() yet.
    // we should either change this function signature to return a promise and do
    // loadMathjs().then(mathjs => mathjs.eval...) or make sure it is always preloaded by
    // the time we get here.,
    var math = mathjsLoadingWrapper.mathjs;

    // This parses the formula detecting if the locale uses comma as separator
    var parsedFormula = parseFormulaDecimalSeparator(window.document.documentElement.lang || 'en-US', formula);

    // we replace function e() with the constant e
    // and function pi() with the constant pi
    // this is to match legacy canvas quizzes behavior which accepted both e/pi and e()/pi()
    var node = math.parse(parsedFormula);
    var transformed = node.transform(function (node, path, parent) {
      if (node.isFunctionNode && node.fn.isSymbolNode && node.fn.name === 'e') {
        return new math.expression.node.ConstantNode(Math.E);
      } else if (node.isFunctionNode && node.fn.isSymbolNode && node.fn.name === 'pi') {
        return new math.expression.node.ConstantNode(Math.PI);
      } else {
        return node;
      }
    });
    var compiled = transformed.compile();
    compiled.eval(substitutions);
  } catch (e) {
    var message = e.message;
    console.error('Formula Error: ' + e.message);
    var match = message.match(/Undefined symbol ([A-Za-z]+)/);
    if (match) {
      return t('Undefined symbol {symbol}', {
        symbol: match[1]
      });
    }
    match = message.match(/Unexpected end of expression/);
    if (match) {
      return t('Unexpected end of expression');
    }
    match = message.match(/Unexpected operator ([^\s]+)/);
    if (match) {
      return t('Unexpected operator {operator}', {
        operator: match[1]
      });
    }
    return t('Invalid formula');
  }
  return null;
};
export var parseFormulaDecimalSeparator = function parseFormulaDecimalSeparator(locale, formula) {
  var _Decimal$getDelimiter = Decimal.getDelimiters(locale),
    decimal = _Decimal$getDelimiter.decimal;
  if (decimal === '.') {
    return formula;
  }
  return formula.replace(/(\d+),(\d+)/g, '$1.$2');
};