Initial commit

Author: kael89

.gitignore

@@ -0,0 +1,4 @@
+coverage/
+dist/
+node_modules/
+yarn-error.log

.vscode/settings.json

@@ -0,0 +1,8 @@
+{
+    "cSpell.words": [
+        "BODMAS",
+        "beyondessential",
+        "unaries",
+        "unary"
+    ]
+}

README.md

@@ -0,0 +1,19 @@
+# @beyondessential/arithmetic
+
+Utility to evaluate [BODMAS](https://en.wikipedia.org/wiki/Order_of_operations) arithmetic formulas
+
+### Installation
+
+**Note:** Since this is a private repository, you will need to authenticate your connection to GitHub, for example via [ssh](https://docs.github.com/en/github/authenticating-to-github/connecting-to-github-with-ssh).
+
+```
+yarn add beyondessential/arithmetic
+```
+
+### Usage
+
+```js
+import { runArithmetic } from '@beyondessential/arithmetic';
+
+runArithmetic('(1 + 2) / 3');
+```

__tests__/arithmetic.test.js

@@ -0,0 +1,137 @@
+import { runArithmetic } from '../src/arithmetic';
+
+describe('Arithmetic', () => {
+  describe('basics', () => {
+    it('should perform an addition', () => {
+      const result = runArithmetic('1 + 2');
+      expect(result).toEqual(1 + 2);
+    });
+
+    it('should perform a subtraction', () => {
+      const result = runArithmetic('1 - 2');
+      expect(result).toEqual(1 - 2);
+    });
+
+    it('should handle double digits', () => {
+      const result = runArithmetic('10 - 20');
+      expect(result).toEqual(10 - 20);
+    });
+
+    it('should handle parentheses', () => {
+      const result = runArithmetic('(4 + (1 + 2) + (2 + 5) + 1)');
+      expect(result).toEqual(4 + (1 + 2) + (2 + 5) + 1);
+    });
+  });
+
+  describe('decimals', () => {
+    it('should handle adding decimals', () => {
+      const result = runArithmetic('5.5 - 1.9');
+      expect(result).toEqual(5.5 - 1.9);
+    });
+
+    it('should handle multiplying decimals', () => {
+      const result = runArithmetic('2.5352 * 102.99');
+      expect(result).toEqual(2.5352 * 102.99);
+    });
+  });
+
+  describe('multiplication', () => {
+    it('should handle a simple multiplication', () => {
+      const result = runArithmetic('5 * 3');
+      expect(result).toEqual(5 * 3);
+    });
+
+    it('should handle a bunch of operations', () => {
+      const result = runArithmetic('(4 + (1 * 2) / (2 + 5) - 1)');
+      expect(result).toEqual(4 + (1 * 2) / (2 + 5) - 1);
+    });
+
+    it('should handle putting x instead of *', () => {
+      const result = runArithmetic('5 x 3');
+      expect(result).toEqual(5 * 3);
+    });
+
+    it('should handle putting x in a more complicated expression', () => {
+      const result = runArithmetic('(4 + (1 x 2) / (2 + 5) - 1)');
+      expect(result).toEqual(4 + (1 * 2) / (2 + 5) - 1);
+    });
+  });
+
+  describe('unary minus (for eg, -1)', () => {
+    it('should handle multiplying by a negative', () => {
+      const result = runArithmetic('4 / - 2');
+      expect(result).toEqual(4 / -2);
+    });
+
+    it('should handle multiple negatives', () => {
+      const result = runArithmetic('4 * - 2 * - 2');
+      expect(result).toEqual(4 * -2 * -2);
+    });
+
+    it('should handle multiplying by a double negative', () => {
+      const result = runArithmetic('4 / - - 2');
+      expect(result).toEqual(4 / 2);
+    });
+
+    it('should handle negating a parenthesized expression', () => {
+      const result = runArithmetic('-(4 / 2)');
+      expect(result).toEqual(-(4 / 2));
+    });
+
+    it('should handle multiplying by a negative', () => {
+      const result = runArithmetic('3 * -(4 / 2)');
+      expect(result).toEqual(3 * -(4 / 2));
+    });
+
+    it('should handle varying whitespace', () => {
+      const result = runArithmetic('1+1 - - 5');
+      expect(result).toEqual(1 + 1 - -5);
+    });
+  });
+
+  describe('substituting values', () => {
+    const VALUES = {
+      fingers: 10,
+      eyes: 2,
+      pi: 3.14159,
+      sins: 7,
+      negative: -5,
+    };
+
+    it('should handle simple value substitution', () => {
+      const result = runArithmetic('fingers + eyes', VALUES);
+      expect(result).toEqual(10 + 2);
+    });
+
+    it('should handle negative value substitution', () => {
+      const result = runArithmetic('fingers + negative', VALUES);
+      expect(result).toEqual(10 - 5);
+    });
+
+    it('should handle a more complicated case', () => {
+      const result = runArithmetic('-eyes * (sins - pi * 3) / negative + (sins + 1)', VALUES);
+      expect(result).toEqual((-2 * (7 - 3.14159 * 3)) / -5 + (7 + 1));
+    });
+  });
+
+  describe('errors', () => {
+    it('should fail on an unexpected token', () => {
+      expect(() => runArithmetic('fail')).toThrow();
+      expect(() => runArithmetic('1 + fail')).toThrow();
+      expect(() => runArithmetic('4 + (1 * fail) / 2')).toThrow();
+    });
+
+    it('should fail on an unmatched parenthesis', () => {
+      expect(() => runArithmetic(')')).toThrow();
+      expect(() => runArithmetic('4 * (1 + 2')).toThrow();
+      expect(() => runArithmetic('4 * 1) + 2')).toThrow();
+      expect(() => runArithmetic('4 * 1 + 2)')).toThrow();
+    });
+
+    it('should fail if a substitution is not numeric', () => {
+      expect(() => runArithmetic('check + 1', { check: 'check' })).toThrow();
+      expect(() => runArithmetic('check + 1', { check: '+' })).toThrow();
+      expect(() => runArithmetic('check + 1', { check: '' })).toThrow();
+    });
+  });
+});

index.d.ts

@@ -0,0 +1 @@
+export function runArithmetic(formula: string): number;

package.json

@@ -0,0 +1,51 @@
+{
+  "name": "@beyondessential/arithmetic",
+  "private": true,
+  "version": "1.0.0",
+  "description": "Utility to evaluate BODMAS arithmetic formulas",
+  "main": "dist/index.js",
+  "files": [
+    "src",
+    "index.d.ts"
+  ],
+  "homepage": "https://github.com/beyondessential/arithmetic.git#readme",
+  "repository": "[email protected]:beyondessential/arithmetic.git",
+  "scripts": {
+    "build": "babel src --out-dir dist --ignore 'src/__tests__/**'",
+    "postinstall": "yarn build",
+    "test": "NODE_ENV=test jest",
+    "test:coverage": "yarn test --coverage",
+    "test:watch": "yarn test --watch"
+  },
+  "keywords": [],
+  "author": "Beyond Essential Systems Pty. Ltd.",
+  "license": "AGPL-3.0-only",
+  "devDependencies": {
+    "@babel/cli": "^7.10.5",
+    "@babel/core": "^7.11.1",
+    "@babel/preset-env": "^7.11.0",
+    "@beyondessential/eslint-config-beyondessential": "^2.5.0",
+    "babel-jest": "^26.3.0",
+    "eslint": "^7.7.0",
+    "jest": "^26.4.0",
+    "prettier": "^2.0.5"
+  },
+  "eslintConfig": {
+    "extends": "@beyondessential/eslint-config-beyondessential",
+    "overrides": [
+      {
+        "files": "**/__tests__/**",
+        "env": {
+          "jest": true
+        }
+      }
+    ]
+  },
+  "babel": {
+    "presets": [
+      [
+        "@babel/preset-env"
+      ]
+    ]
+  }
+}