From 9368b1c33db290d7c80c93db5c867cdb7fcaf14d Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Mon, 11 Sep 2017 15:47:50 -0400
Subject: Implement collecting

---
 __tests__/dice.test.js   | 43 ++++++++++++++++++++++++++++++++++++++++++-
 __tests__/lexer.test.js  | 12 ++++++++++++
 __tests__/parser.test.js | 19 +++++++++++++++++++
 index.js                 |  2 ++
 src/dice.js              |  5 +++++
 src/lexer.js             |  2 ++
 src/parser.js            | 12 ++++++++++++
 7 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/__tests__/dice.test.js b/__tests__/dice.test.js
index 9c03a48..56572d2 100644
--- a/__tests__/dice.test.js
+++ b/__tests__/dice.test.js
@@ -19,7 +19,8 @@ const {
   againUnder,
   thresholdHigh,
   thresholdLow,
-  repeat
+  repeat,
+  collect
 } = require('../src/dice.js')
 
 const defaultNumberRolls = 500
@@ -817,3 +818,43 @@ describe('repeat', () => {
     })
   })
 })
+
+describe('collect', () => {
+  describe('[2d6]', () => {
+    const die = collect(d(constant(2), constant(6)))
+
+    testDie(die, {
+      diceCount: 1,
+      average: {
+        average: 7
+      },
+      variance: {
+        variance: 5.83
+      },
+      bounds: {
+        low: 2,
+        high: 12,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('[1d6 x 1d4]', () => {
+    const die =
+      collect(repeat(d(constant(1), constant(6)), d(constant(1), constant(4))))
+
+    testDie(die, {
+      diceCount: 1,
+      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 7124746..b2cb77e 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -171,6 +171,18 @@ describe('lex', () => {
         { type: 'constant', value: 4 }
       ])
     })
+
+    it('[2d8]+3', () => {
+      expect(lex('[2d8]+3')).toEqual([
+        { type: '[' },
+        { type: 'constant', value: 2 },
+        { type: 'd' },
+        { type: 'constant', value: 8 },
+        { type: ']' },
+        { type: 'plus' },
+        { type: 'constant', value: 3 }
+      ])
+    })
   })
 
   describe('lexes negatives', () => {
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index 3c9f6ec..cb89ad5 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -325,6 +325,25 @@ describe('parse', () => {
     })
   })
 
+  it('parses dice with collecting', () => {
+    expect(parse('[2d6] x 1d4')).toEqual({
+      type: 'repeat',
+      left: {
+        type: 'collect',
+        value: {
+          type: 'd',
+          left: { type: 'constant', value: 2 },
+          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 13e6378..db39fd1 100644
--- a/index.js
+++ b/index.js
@@ -43,6 +43,8 @@ const interpret = tree => {
     return D.bonusDivide(interpret(tree.left), interpret(tree.right))
   case 'repeat':
     return D.repeat(interpret(tree.left), interpret(tree.right))
+  case 'collect':
+    return D.collect(interpret(tree.value))
   }
 }
 
diff --git a/src/dice.js b/src/dice.js
index 0197f25..1e15937 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -222,6 +222,10 @@ const repeat = (die1, die2) => {
   }
 }
 
+const collect = die => {
+  return () => [() => roll(die)]
+}
+
 exports.pool = pool
 exports.roll = roll
 exports.constant = constant
@@ -244,3 +248,4 @@ exports.againUnder = againUnder
 exports.thresholdHigh = thresholdHigh
 exports.thresholdLow = thresholdLow
 exports.repeat = repeat
+exports.collect = collect
diff --git a/src/lexer.js b/src/lexer.js
index 6b75129..88bd188 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -26,6 +26,8 @@ newLexemeType('times', '\\*')
 newLexemeType('divide', '/')
 newLexemeType('(', '\\(')
 newLexemeType(')', '\\)')
+newLexemeType('[', '\\[')
+newLexemeType(']', '\\]')
 newLexemeType('E', 'E')
 newLexemeType('e', 'e')
 newLexemeType('K', 'K')
diff --git a/src/parser.js b/src/parser.js
index acae9ad..3cf6d55 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -44,6 +44,16 @@ newSymbol('constant', function() {
   return { type: 'constant', value: this.value }
 })
 
+const newBrackets = (openSymbol, closeSymbol, valueWrapper) => {
+  newSymbol(openSymbol, function(parser) {
+    const value = parser.expression(1)
+    parser.match(closeSymbol)
+    return valueWrapper(value)
+  })
+
+  newSymbol(closeSymbol)
+}
+
 newSymbol('(', function(parser) {
   const value = parser.expression(1)
   parser.match(')')
@@ -52,6 +62,8 @@ newSymbol('(', function(parser) {
 
 newSymbol(')')
 
+newBrackets('[', ']', value => ({ type: 'collect', value: value }))
+
 newDieOperation('d')
 newSymbol('d', (parser) => {
   return {
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