Added Sigma operator – support for more complex operators 🌟

Fix README.md links pointing to Equation.js instead of Equation
Bump version to 1.3.0

dist/index.js

@@ -107,6 +107,13 @@ var Equation = {
     };
   },
 
+  // 2x + 5x * x  => 7x^2
+  simplify: function simplify(expression) {
+    var stack = parseExpression(expression);
+
+    console.log(stack);
+  },
+
   registerOperator: function registerOperator(key, options) {
     _operators2['default'][key] = options;
   },
@@ -127,7 +134,13 @@ var solveStack = (function (_solveStack) {
 
   return solveStack;
 })(function (stack) {
-  if (stack.some(Array.isArray)) {
+  // if an operator takes an expression argument, we should not dive into it
+  // and solve the expression inside
+  var hasExpressionArgument = stack.some(function (a) {
+    return _operators2['default'][a] && _operators2['default'][a].hasExpression;
+  });
+
+  if (!hasExpressionArgument && stack.some(Array.isArray)) {
     stack = stack.map(function (group) {
       if (!Array.isArray(group)) {
         return group;
@@ -159,6 +172,12 @@ var MIN_PRECEDENCE = Math.min.apply(Math, _toConsumableArray(PRECEDENCES));
   *         The parsed array
   */
 var parseExpression = function parseExpression(expression) {
+  // function arguments can be separated using comma,
+  // but we parse as groups, so this is the solution to getting comma to work
+  // sigma(0, 4, 2@) becomes sigma(0)(4)(2@) so every argument is parsed
+  // separately
+  expression = expression.replace(/,/g, ')(');
+
   var stream = new _ReadStream2['default'](expression),
       stack = [],
       record = '',
@@ -238,19 +257,19 @@ var parseExpression = function parseExpression(expression) {
   */
 var parseGroups = function parseGroups(stack) {
   // Parantheses become inner arrays which will then be processed first
-  var sub = 0;
+  var depth = 0;
   return stack.reduce(function (a, b) {
     if (b.indexOf('(') > -1) {
       if (b.length > 1) {
-        _.dive(a, sub).push(b.replace('(', ''), []);
+        _.dive(a, depth).push(b.replace('(', ''), []);
       } else {
-        _.dive(a, sub).push([]);
+        _.dive(a, depth).push([]);
       }
-      sub++;
+      depth++;
     } else if (b === ')') {
-      sub--;
+      depth--;
     } else {
-      _.dive(a, sub).push(b);
+      _.dive(a, depth).push(b);
     }
     return a;
   }, []);

dist/operators.js

@@ -1,8 +1,15 @@
 'use strict';
 
+var _interopRequireWildcard = function (obj) { return obj && obj.__esModule ? obj : { 'default': obj }; };
+
 Object.defineProperty(exports, '__esModule', {
   value: true
 });
+
+var _Equation = require('equation');
+
+var _Equation2 = _interopRequireWildcard(_Equation);
+
 /*
  * Operators and Functions
  * fn: function used to evaluate value
@@ -11,6 +18,11 @@ Object.defineProperty(exports, '__esModule', {
  *         e.g: factorial is 01, add is 010, like 2!, 2+2
  * precedence: determines which operators should be evaluated first
  *             the lower the value, the higher the precedence
+ * hasExpression: determines if any of the operator arguments are an expression
+ *                This way, arguments will not be solved by equation and instead
+ *                you have to call solve on each argument yourself.
+ *                You get the arguments as parsed arrays sigma(0, 5, 2@) becomes
+ *                sigma(0, 5, [2, '*', '@']). See sigma operator for reference
  */
 exports['default'] = {
   '^': {
@@ -119,6 +131,23 @@ exports['default'] = {
     fn: Math.floor,
     format: '10',
     precedence: -1
+  },
+  sigma: {
+    fn: function fn(from, to, expression) {
+      var expr = expression.join('').replace(/,/g, '');
+      var regex = new RegExp(ITERATOR_SIGN, 'g');
+
+      var sum = 0;
+      for (var i = from; i <= to; i++) {
+        sum += _Equation2['default'].solve(expr.replace(regex, i));
+      }
+      return sum;
+    },
+    format: '1000',
+    hasExpression: true,
+    precedence: -1
   }
 };
+
+var ITERATOR_SIGN = '@';
 module.exports = exports['default'];

dist/tests/solve.js

@@ -92,7 +92,25 @@ describe('Constats', function () {
     _expect.expect(_M2['default'].solve('sin(PI/2)')).to.equal(1);
   });
 
-  it('should work for functions as constants', function () {
+  it('should work for functions as constants - retry on fail', function () {
     _expect.expect(_M2['default'].solve('RAND')).to.not.equal(_M2['default'].solve('RAND'));
   });
+});
+
+describe('Sigma', function () {
+  it('should work with simple expressions', function () {
+    _expect.expect(_M2['default'].solve('sigma(0, 5, @)')).to.equal(15);
+  });
+
+  it('should work with more complex expressions', function () {
+    _expect.expect(_M2['default'].solve('sigma(0, 2, 2@+5)')).to.equal(21);
+  });
+
+  it('should work without an iterator sign', function () {
+    _expect.expect(_M2['default'].solve('sigma(0, 2, 5*2)')).to.equal(30);
+  });
+
+  it('should work with negative start / end points', function () {
+    _expect.expect(_M2['default'].solve('sigma(-5, -2, @)')).to.equal(-14);
+  });
 });