Merge pull request #9 from airjp73/unary-operators

Unary operators

Author: airjp73

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@airjp73/dice-notation",
-  "version": "1.1.1",
+  "version": "1.2.0",
   "description": "A js library for parsing dice notation",
   "module": "dist/module/index.js",
   "main": "dist/main/index.js",

package.json

@@ -10,14 +10,31 @@ describe('roll', () => {
     ['1d12 * 2d4 / 2', 1, 48, 200],
     ['1d4 + 1d4 + 1d4 + 1d4', 4, 16, 24],
     ['1d4 * (1d4 + 2)', 3, 24, 30],
+    ['1d2', 1, 2, 10],
 
     // Constants to truly verify operator precedence
     ['2 + 3 * (4 + 2)', 20, 20, 1],
+    ['2*2', 4, 4, 1],
     ['4*4 + 4 / 2 -10', 8, 8, 1],
     ['(2 + 2) * (3 * (3 - 1)) - (3 + 1)', 20, 20, 1],
-
-    // TODO: Support negatives?
     ['64 * (0-3) - 4008 / 5 + (0-328)', -1321.6, -1321.6, 1],
+    ['2', 2, 2, 1],
+
+    // Support for unary operators
+    ['2 + -2', 0, 0, 1],
+    ['-2 + 2', 0, 0, 1],
+    ['+2 + 2', 4, 4, 1],
+    ['-2 + -2', -4, -4, 1],
+    ['2 * -2', -4, -4, 1],
+    ['-2 * -2', 4, 4, 1],
+    ['+2 / -2', -1, -1, 1],
+    ['------2', 2, 2, 1],
+    ['2 + ------2', 4, 4, 1],
+    ['++++++2 + ------2', 4, 4, 1],
+    ['-1d6 + -2d4', -14, -3, 20],
+    ['+1d6 + +2d4', 3, 14, 20],
+    ['+1d6 - +2d4', -7, 4, 20],
+    ['-(1d6 + -6) - +(4 + 5)', -9, -4, 20],
   ];
 
   it.each(cases)('should correctly roll %s', (notation, min, max, repeats) => {
@@ -27,6 +44,15 @@ describe('roll', () => {
       expect(result).toBeGreaterThanOrEqual(min);
     }
   });
+
+  const errorCases: [string, string][] = [
+    ['2 + *3', "Operator '*' may not be used as a unary operator"],
+    ['2 + /3', "Operator '/' may not be used as a unary operator"],
+  ];
+
+  it.each(errorCases)('should correctly error on %s', (notation, error) => {
+    expect(() => roll(notation)).toThrowError(error);
+  });
 });
 
 describe('rollDice', () => {

src/__test__/roll.test.ts

@@ -17,6 +17,20 @@ function doMath(val1: number, operator: Operator, val2: number): number {
   }
 }
 
+function calculateUnaryOperation(operator: Operator, val: number): number {
+  switch (operator) {
+    case '*':
+    case '/':
+      throw new Error(
+        `Operator '${operator}' may not be used as a unary operator`
+      );
+    case '+':
+      return +val;
+    case '-':
+      return -val;
+  }
+}
+
 const isOperator = (stackItem: ValueOrOperatorString): stackItem is Operator =>
   typeof stackItem === 'string';
 const isValue = (stackItem: ValueOrOperatorString): stackItem is number =>
@@ -53,9 +67,19 @@ function calculateFinalResult(tokens: Token[], values: RollTotal[]): number {
       let total = popValue();
 
       while (stack.length) {
-        const operator = popOperator();
-        const value = popValue();
-        total = doMath(value, operator, total);
+        let operator = popOperator();
+
+        while (isOperator(peekTop())) {
+          total = calculateUnaryOperation(operator, total);
+          operator = popOperator();
+        }
+
+        if (isNil(peekTop())) {
+          total = calculateUnaryOperation(operator, total);
+        } else {
+          const value = popValue();
+          total = doMath(value, operator, total);
+        }
       }
 
       stack.push(total);