Implement multiplicative bonuses

7 files changed, 78 insertions, 0 deletions

diff --git a/__tests__/dice.test.js b/__tests__/dice.test.js
index 6a9ba46..375c9ad 100644
--- a/__tests__/dice.test.js
+++ b/__tests__/dice.test.js
@@ -8,6 +8,7 @@ const {
   divide,
   bonusAdd,
   bonusSubtract,
+  bonusMultiply,
   negative,
   explodeAbove,
   explodeUnder,
@@ -462,6 +463,46 @@ describe('bonusSubtract', () => {
   })
 })
 
+describe('bonusMultiply', () => {
+  describe('1d20*3', () => {
+    const die = bonusMultiply(d(constant(1), constant(20)), constant(3))
+    testDie(die, {
+      diceCount: 1,
+      average: {
+        average: 31.5
+      },
+      variance: {
+        variance: 299.25
+      },
+      bounds: {
+        low: 3,
+        high: 60,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('3d4*2', () => {
+    const die = bonusMultiply(d(constant(3), constant(4)), constant(2))
+    testDie(die, {
+      diceCount: 3,
+      average: {
+        average: 15
+      },
+      variance: {
+        variance: 15
+      },
+      bounds: {
+        low: 6,
+        high: 24,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+})
+
 describe('negative', () => {
   describeBasicDie(1, 6, defaultNumberRolls, true)
   describeBasicDie(0, 6, defaultNumberRolls, true)
diff --git a/__tests__/lexer.test.js b/__tests__/lexer.test.js
index 6745715..31150bc 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -241,6 +241,18 @@ describe('lex', () => {
     })
   })
 
+  describe('bonusMultiply', () => {
+    test('3d4*1', () => {
+      expect(lex('3d4*1')).toEqual([
+        { type: 'constant', value: 3 },
+        { type: 'd' },
+        { type: 'constant', value: 4 },
+        { type: 'times' },
+        { type: 'constant', value: 1 }
+      ])
+    })
+  })
+
   describe('again', () => {
     test('6A3d6', () => {
       expect(lex('6A3d6')).toEqual([
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index d696b3e..5580b4c 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -153,6 +153,18 @@ describe('parse', () => {
     })
   })
 
+  it('parses multiplicative bonuses', () => {
+    expect(parse('3d4*1')).toEqual({
+      type: 'bonusMultiply',
+      left: {
+        type: 'd',
+        left: { type: 'constant', value: 3 },
+        right: { type: 'constant', value: 4 }
+      },
+      right: { type: 'constant', value: 1 }
+    })
+  })
+
   test('bonus binds stronger than addition', () => {
     expect(parse('2d6 + 2d6+2d6')).toEqual({
       type: 'add',
diff --git a/index.js b/index.js
index cc768cb..4a0d942 100644
--- a/index.js
+++ b/index.js
@@ -37,6 +37,8 @@ const interpret = tree => {
     return D.bonusAdd(interpret(tree.left), interpret(tree.right))
   case 'bonusSubtract':
     return D.bonusSubtract(interpret(tree.left), interpret(tree.right))
+  case 'bonusMultiply':
+    return D.bonusMultiply(interpret(tree.left), interpret(tree.right))
   case 'repeat':
     return D.repeat(interpret(tree.left), interpret(tree.right))
   }
diff --git a/src/dice.js b/src/dice.js
index 5a484b0..6351929 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -73,6 +73,14 @@ const bonusSubtract = (die1, die2) => {
   }
 }
 
+const bonusMultiply = (die1, die2) => {
+  return () => {
+    return die1().map(die => {
+      return () => die() * roll(die2)
+    })
+  }
+}
+
 const explode = (comparison, die1, die2) => {
   return () => {
     const explodeOn = roll(die1)
@@ -216,6 +224,7 @@ exports.multiply = multiply
 exports.divide = divide
 exports.bonusAdd = bonusAdd
 exports.bonusSubtract = bonusSubtract
+exports.bonusMultiply = bonusMultiply
 exports.negative = negative
 exports.explodeAbove = explodeAbove
 exports.explodeUnder = explodeUnder
diff --git a/src/lexer.js b/src/lexer.js
index 248a9b2..e700f87 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -22,6 +22,7 @@ newLexemeType('bigTimes', ' \\* ')
 newLexemeType('bigDivide', ' / ')
 newLexemeType('plus', '\\+')
 newLexemeType('minus', '-')
+newLexemeType('times', '\\*')
 newLexemeType('(', '\\(')
 newLexemeType(')', '\\)')
 newLexemeType('E', 'E')
diff --git a/src/parser.js b/src/parser.js
index b1f6ebb..54dc0ae 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -75,6 +75,7 @@ newInfix('bigTimes', 23, { type: 'multiply' })
 newInfix('bigDivide', 23, { type: 'divide' })
 newInfix('plus', 25, { type: 'bonusAdd' })
 newInfix('minus', 25, { type: 'bonusSubtract' })
+newInfix('times', 26, { type: 'bonusMultiply' })
 newSymbol('minus', (parser) => {
   return {
     type: 'negative',