Add support for NumVariable expressions such as 2x fixes #6
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@ -18,8 +18,10 @@ console.log(Equation.solve('4 * lg(4) ^ 3')); // 32
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// equation
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let sphereArea = Equation.equation('4 * PI * r^2');
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console.log(sphereArea(5)); // 314.1592653589793
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let test = Equation.equation('2x + 6y');
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console.log(test(4, 3)).to.equal(8 + 18);
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```
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You can also register your own operators and constants.
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57
dist/index.js
vendored
57
dist/index.js
vendored
@ -70,14 +70,14 @@ var Equation = {
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*/
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equation: function equation(expression) {
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var stack = parseExpression(expression);
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console.log(stack);
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var variables = [];
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stack.forEach(function varCheck(a) {
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if (Array.isArray(a)) {
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return a.forEach(varCheck);
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}
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if (typeof a === 'string' && !_.isNumber(a) && !_operators2['default'][a] && a === a.toLowerCase()) {
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if (isVariable(a)) {
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// grouped variables like (y) need to have their parantheses removed
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variables.push(_.removeSymbols(a));
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}
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@ -88,15 +88,30 @@ var Equation = {
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args[_key] = arguments[_key];
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}
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expression = expression.replace(/[a-z]*/g, function (a) {
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stack.forEach(function varCheck(a, i, arr) {
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if (Array.isArray(a)) {
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return a.forEach(varCheck);
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}
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var index = variables.indexOf(a);
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if (index > -1) {
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return args[index] || 0;
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// grouped variables like (y) need to have their parantheses removed
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arr[i] = args[index];
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}
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return a;
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});
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return Equation.solve(expression);
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stack = sortStack(stack);
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stack = _.parseNumbers(stack);
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stack = solveStack(stack);
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// expression = expression.replace(/[a-z]*/g, a => {
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// let index = variables.indexOf(a);
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// if (index > -1) {
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// return args[index] || 0;
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// }
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// return a;
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// });
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return stack;
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};
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},
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@ -154,12 +169,15 @@ var MIN_PRECEDENCE = Math.min.apply(Math, _toConsumableArray(PRECEDENCES));
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var parseExpression = function parseExpression(expression) {
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var stream = new _ReadStream2['default'](expression),
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stack = [],
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record = '';
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record = '',
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cur = undefined,
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past = undefined;
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// Create an array of separated numbers & operators
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while (stream.next()) {
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var cur = stream.current(),
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cur = stream.current();
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past = stack.length - 1;
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if (cur === ' ') {
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continue;
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}
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@ -169,8 +187,14 @@ var parseExpression = function parseExpression(expression) {
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record += cur;
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} else if (record.length) {
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var beforeRecord = past - (record.length - 1);
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if (isVariable(record) && _.isNumber(stack[beforeRecord])) {
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stack.push('*');
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}
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stack.push(record, cur);
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record = '';
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// numbers and decimals
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} else if (_.isNumber(stack[past]) && (_.isNumber(cur) || cur === '.')) {
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stack[past] += cur;
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@ -199,6 +223,10 @@ var parseExpression = function parseExpression(expression) {
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}
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}
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if (record.length) {
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var beforeRecord = past - (record.length - 1);
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if (isVariable(record) && _.isNumber(stack[beforeRecord])) {
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stack.push('*');
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}
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stack.push(record);
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}
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@ -437,5 +465,16 @@ var fixFloat = function fixFloat(number) {
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return +number.toFixed(15);
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};
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/**
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* Recognizes variables such as x, y, z
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* @param {String} a
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* The string to check for
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* @return {Boolean}
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* true if variable, else false
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*/
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var isVariable = function isVariable(a) {
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return typeof a === 'string' && !_.isNumber(a) && !_operators2['default'][a] && a === a.toLowerCase();
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};
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exports.isVariable = isVariable;
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exports['default'] = Equation;
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module.exports = exports['default'];
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5
dist/tests/equation.js
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5
dist/tests/equation.js
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@ -30,6 +30,11 @@ describe('Equations', function () {
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_expect.expect(equation).to['throw']();
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});
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it('should work with NumVariable expressions like 2x', function () {
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var equation = _M2['default'].equation('2x + 6y');
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_expect.expect(equation(4, 3)).to.equal(8 + 18);
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});
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it('Test case', function () {
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var equation = _M2['default'].equation('2+x*(y+4)+z^2');
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_expect.expect(equation(2, 4, 3)).to.equal(27);
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56
lib/index.js
56
lib/index.js
@ -47,30 +47,44 @@ let Equation = {
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*/
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equation(expression) {
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let stack = parseExpression(expression);
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console.log(stack);
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let variables = [];
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stack.forEach(function varCheck(a) {
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if (Array.isArray(a)) {
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return a.forEach(varCheck);
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}
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if (typeof a === 'string' && !_.isNumber(a) &&
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!operators[a] && a === a.toLowerCase()) {
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if (isVariable(a)) {
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// grouped variables like (y) need to have their parantheses removed
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variables.push(_.removeSymbols(a));
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}
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});
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return function(...args) {
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expression = expression.replace(/[a-z]*/g, a => {
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stack.forEach(function varCheck(a, i, arr) {
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if (Array.isArray(a)) {
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return a.forEach(varCheck);
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}
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let index = variables.indexOf(a);
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if (index > -1) {
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return args[index] || 0;
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// grouped variables like (y) need to have their parantheses removed
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arr[i] = args[index];
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}
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return a;
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});
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return Equation.solve(expression);
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stack = sortStack(stack);
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stack = _.parseNumbers(stack);
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stack = solveStack(stack);
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// expression = expression.replace(/[a-z]*/g, a => {
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// let index = variables.indexOf(a);
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// if (index > -1) {
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// return args[index] || 0;
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// }
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// return a;
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// });
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return stack;
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};
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},
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@ -118,12 +132,14 @@ const MIN_PRECEDENCE = Math.min(...PRECEDENCES);
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const parseExpression = expression => {
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let stream = new ReadStream(expression),
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stack = [],
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record = '';
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record = '',
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cur, past;
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// Create an array of separated numbers & operators
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while (stream.next()) {
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const cur = stream.current(),
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cur = stream.current();
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past = stack.length - 1;
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if (cur === ' ') {
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continue;
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}
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@ -134,8 +150,14 @@ const parseExpression = expression => {
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record += cur;
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} else if (record.length) {
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let beforeRecord = past - (record.length - 1);
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if (isVariable(record) && _.isNumber(stack[beforeRecord])) {
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stack.push('*');
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}
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stack.push(record, cur);
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record = '';
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// numbers and decimals
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} else if (_.isNumber(stack[past]) &&
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(_.isNumber(cur) || cur === '.')) {
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@ -165,6 +187,10 @@ const parseExpression = expression => {
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}
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}
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if (record.length) {
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let beforeRecord = past - (record.length - 1);
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if (isVariable(record) && _.isNumber(stack[beforeRecord])) {
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stack.push('*');
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}
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stack.push(record);
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}
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@ -341,4 +367,16 @@ const fixFloat = number => {
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return +number.toFixed(15);
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};
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/**
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* Recognizes variables such as x, y, z
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* @param {String} a
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* The string to check for
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* @return {Boolean}
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* true if variable, else false
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*/
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export const isVariable = a => {
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return typeof a === 'string' && !_.isNumber(a) &&
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!operators[a] && a === a.toLowerCase();
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};
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export default Equation;
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@ -23,6 +23,11 @@ describe('Equations', () => {
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expect(equation).to.throw();
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});
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it('should work with NumVariable expressions like 2x', () => {
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let equation = M.equation('2x + 6y');
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expect(equation(4, 3)).to.equal(8 + 18);
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});
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it('Test case', () => {
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let equation = M.equation('2+x*(y+4)+z^2');
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expect(equation(2, 4, 3)).to.equal(27);
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