From e7383cc38bf2182e5ab95f30d639fe4a0317fd51 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Tue, 5 Sep 2017 22:43:38 -0400
Subject: Implement bonus division

---
 __tests__/dice.test.js   | 41 +++++++++++++++++++++++++++++++++++++++++
 __tests__/lexer.test.js  | 12 ++++++++++++
 __tests__/parser.test.js | 12 ++++++++++++
 index.js                 |  2 ++
 src/dice.js              |  9 +++++++++
 src/lexer.js             |  1 +
 src/parser.js            |  1 +
 7 files changed, 78 insertions(+)

diff --git a/__tests__/dice.test.js b/__tests__/dice.test.js
index 375c9ad..9c03a48 100644
--- a/__tests__/dice.test.js
+++ b/__tests__/dice.test.js
@@ -9,6 +9,7 @@ const {
   bonusAdd,
   bonusSubtract,
   bonusMultiply,
+  bonusDivide,
   negative,
   explodeAbove,
   explodeUnder,
@@ -503,6 +504,46 @@ describe('bonusMultiply', () => {
   })
 })
 
+describe('bonusDivide', () => {
+  describe('1d20/3', () => {
+    const die = bonusDivide(d(constant(1), constant(20)), constant(3))
+    testDie(die, {
+      diceCount: 1,
+      average: {
+        average: 3.15
+      },
+      variance: {
+        variance: 3.73
+      },
+      bounds: {
+        low: 0,
+        high: 6,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('3d4/2', () => {
+    const die = bonusDivide(d(constant(3), constant(4)), constant(2))
+    testDie(die, {
+      diceCount: 3,
+      average: {
+        average: 3
+      },
+      variance: {
+        variance: 1.5
+      },
+      bounds: {
+        low: 0,
+        high: 6,
+        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 31150bc..7124746 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -253,6 +253,18 @@ describe('lex', () => {
     })
   })
 
+  describe('bonusDivide', () => {
+    test('3d4/1', () => {
+      expect(lex('3d4/1')).toEqual([
+        { type: 'constant', value: 3 },
+        { type: 'd' },
+        { type: 'constant', value: 4 },
+        { type: 'divide' },
+        { 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 5580b4c..3c9f6ec 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -165,6 +165,18 @@ describe('parse', () => {
     })
   })
 
+  it('parses divisional bonuses', () => {
+    expect(parse('3d4/1')).toEqual({
+      type: 'bonusDivide',
+      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 4a0d942..13e6378 100644
--- a/index.js
+++ b/index.js
@@ -39,6 +39,8 @@ const interpret = tree => {
     return D.bonusSubtract(interpret(tree.left), interpret(tree.right))
   case 'bonusMultiply':
     return D.bonusMultiply(interpret(tree.left), interpret(tree.right))
+  case 'bonusDivide':
+    return D.bonusDivide(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 6351929..0197f25 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -81,6 +81,14 @@ const bonusMultiply = (die1, die2) => {
   }
 }
 
+const bonusDivide = (die1, die2) => {
+  return () => {
+    return die1().map(die => {
+      return () => Math.floor(die() / roll(die2))
+    })
+  }
+}
+
 const explode = (comparison, die1, die2) => {
   return () => {
     const explodeOn = roll(die1)
@@ -225,6 +233,7 @@ exports.divide = divide
 exports.bonusAdd = bonusAdd
 exports.bonusSubtract = bonusSubtract
 exports.bonusMultiply = bonusMultiply
+exports.bonusDivide = bonusDivide
 exports.negative = negative
 exports.explodeAbove = explodeAbove
 exports.explodeUnder = explodeUnder
diff --git a/src/lexer.js b/src/lexer.js
index e700f87..6b75129 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -23,6 +23,7 @@ newLexemeType('bigDivide', ' / ')
 newLexemeType('plus', '\\+')
 newLexemeType('minus', '-')
 newLexemeType('times', '\\*')
+newLexemeType('divide', '/')
 newLexemeType('(', '\\(')
 newLexemeType(')', '\\)')
 newLexemeType('E', 'E')
diff --git a/src/parser.js b/src/parser.js
index 54dc0ae..acae9ad 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -76,6 +76,7 @@ newInfix('bigDivide', 23, { type: 'divide' })
 newInfix('plus', 25, { type: 'bonusAdd' })
 newInfix('minus', 25, { type: 'bonusSubtract' })
 newInfix('times', 26, { type: 'bonusMultiply' })
+newInfix('divide', 26, { type: 'bonusDivide' })
 newSymbol('minus', (parser) => {
   return {
     type: 'negative',
-- 
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