From 1cc6b80cfd4875f289837421cdbe81e3dfcf0ed1 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Sat, 2 Sep 2017 00:47:46 -0400
Subject: Implement repeat

---
 __tests__/dice.test.js   | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 __tests__/lexer.test.js  | 12 ++++++++++++
 __tests__/parser.test.js | 16 ++++++++++++++++
 index.js                 |  2 ++
 src/dice.js              | 14 ++++++++++++++
 src/lexer.js             |  1 +
 src/parser.js            |  2 ++
 7 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/__tests__/dice.test.js b/__tests__/dice.test.js
index d397d4c..6a9ba46 100644
--- a/__tests__/dice.test.js
+++ b/__tests__/dice.test.js
@@ -16,7 +16,8 @@ const {
   againAbove,
   againUnder,
   thresholdHigh,
-  thresholdLow
+  thresholdLow,
+  repeat
 } = require('../src/dice.js')
 
 const defaultNumberRolls = 500
@@ -692,3 +693,45 @@ describe('threshold', () => {
     })
   })
 })
+
+describe('repeat', () => {
+  describe('1d6 x 2', () => {
+    const die = repeat(d(constant(1), constant(6)), constant(2))
+
+    testDie(die, {
+      diceCount: 2,
+      average: {
+        average: 7
+      },
+      variance: {
+        variance: 5.83
+      },
+      bounds: {
+        low: 2,
+        high: 12,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('1d6 x 1d4', () => {
+    const die = repeat(d(constant(1), constant(6)), d(constant(1), constant(4)))
+
+    testDie(die, {
+      variableDiceCount: {
+        min: 1,
+        max: 4
+      },
+      average: {
+        average: 8.75
+      },
+      bounds: {
+        low: 1,
+        high: 24,
+        expectLow: true,
+        expectHigh: false
+      }
+    })
+  })
+})
diff --git a/__tests__/lexer.test.js b/__tests__/lexer.test.js
index 0c615d5..6745715 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -284,4 +284,16 @@ describe('lex', () => {
       ])
     })
   })
+
+  describe('repeat', () => {
+    test('1d6 x 3', () => {
+      expect(lex('1d6 x 3')).toEqual([
+        { type: 'constant', value: 1 },
+        { type: 'd' },
+        { type: 'constant', value: 6 },
+        { type: ' x ' },
+        { type: 'constant', value: 3 }
+      ])
+    })
+  })
 })
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index bef11c5..d696b3e 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -285,6 +285,22 @@ describe('parse', () => {
     })
   })
 
+  it('parses dice with repeat', () => {
+    expect(parse('1d6 x 1d4')).toEqual({
+      type: 'repeat',
+      left: {
+        type: 'd',
+        left: { type: 'constant', value: 1 },
+        right: { type: 'constant', value: 6 }
+      },
+      right: {
+        type: 'd',
+        left: { type: 'constant', value: 1 },
+        right: { type: 'constant', value: 4 }
+      }
+    })
+  })
+
   describe('parsing parentheses', () => {
     test('(1d6)d6', () => {
       expect(parse('(1d6)d6')).toEqual({
diff --git a/index.js b/index.js
index 37883cc..cc768cb 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 'repeat':
+    return D.repeat(interpret(tree.left), interpret(tree.right))
   }
 }
 
diff --git a/src/dice.js b/src/dice.js
index d47455e..5a484b0 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -193,6 +193,19 @@ const thresholdLow = (die1, die2) => {
   return threshold(lessThanOrEqual, die1, die2)
 }
 
+const repeat = (die1, die2) => {
+  return () => {
+    const times = roll(die2)
+
+    let results = []
+    for (let i = 0; i < times; i++) {
+      results = results.concat(die1())
+    }
+
+    return results
+  }
+}
+
 exports.pool = pool
 exports.roll = roll
 exports.constant = constant
@@ -212,3 +225,4 @@ exports.againAbove = againAbove
 exports.againUnder = againUnder
 exports.thresholdHigh = thresholdHigh
 exports.thresholdLow = thresholdLow
+exports.repeat = repeat
diff --git a/src/lexer.js b/src/lexer.js
index 59fba16..248a9b2 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -32,6 +32,7 @@ newLexemeType('A', 'A')
 newLexemeType('a', 'a')
 newLexemeType('T', 'T')
 newLexemeType('t', 't')
+newLexemeType(' x ', ' x ')
 
 const lex = (expressionString) => {
   let lexemes = []
diff --git a/src/parser.js b/src/parser.js
index fd0fd59..b1f6ebb 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -82,6 +82,8 @@ newSymbol('minus', (parser) => {
   }
 })
 
+newInfix(' x ', 24, { type: 'repeat' })
+
 newSymbol('end', null, -1)
 
 const newParser = (tokens) => {
-- 
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