quiz-interactions/lib/util/formula.js

A React UI component Library for quiz interaction types.

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.formulaSyntaxError = exports.variablesFromItemBody = void 0;

var _uniq = _interopRequireDefault(require("lodash/uniq"));

var _util = require("../components/formula/common/util");

var _formatMessage = _interopRequireDefault(require("@instructure/quiz-i18n/lib/format-message"));

var variablesFromItemBody = function variablesFromItemBody(itemBody) {
  var body = itemBody || '';
  var matches = body.match(/`[A-Za-z]+`/g) || [];
  var matchesWithoutBackticks = matches.map(function (match) {
    return match.replace(/`/g, '');
  });
  return (0, _uniq.default)(matchesWithoutBackticks).sort();
};

exports.variablesFromItemBody = variablesFromItemBody;

var formulaSyntaxError = function formulaSyntaxError(variables, formula) {
  var substitutions = {};
  variables.forEach(function (varName) {
    return substitutions[varName] = 0;
  }); // eslint-disable-line no-return-assign

  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 = _util.mathjsLoadingWrapper.mathjs; // 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(formula);
    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;
    var match = message.match(/Undefined symbol ([A-Za-z]+)/);

    if (match) {
      return (0, _formatMessage.default)('Undefined symbol {symbol}', {
        symbol: match[1]
      });
    }

    match = message.match(/Unexpected end of expression/);

    if (match) {
      return (0, _formatMessage.default)('Unexpected end of expression');
    }

    match = message.match(/Unexpected operator ([^\s]+)/);

    if (match) {
      return (0, _formatMessage.default)('Unexpected operator {operator}', {
        operator: match[1]
      });
    }

    return (0, _formatMessage.default)('Invalid formula');
  }

  return null;
};

exports.formulaSyntaxError = formulaSyntaxError;