From be3415a7cb219fe0244e726ccd0f232485672ed6 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Wed, 19 Jul 2017 23:13:41 -0400
Subject: Lex and parse explosions

---
 __tests__/lexer.test.js  | 12 ++++++++++++
 __tests__/parser.test.js | 12 ++++++++++++
 index.js                 |  2 ++
 src/lexer.js             |  1 +
 src/parser.js            |  8 ++++++++
 5 files changed, 35 insertions(+)

diff --git a/__tests__/lexer.test.js b/__tests__/lexer.test.js
index b9260b8..3003fb9 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -124,4 +124,16 @@ describe('lex', () => {
       ])
     })
   })
+
+  describe('exploding dice', () => {
+    test('1E1d6', () => {
+      expect(lex('1E1d6')).toEqual([
+        { type: 'constant', value: 1 },
+        { type: 'E' },
+        { type: 'constant', value: 1 },
+        { type: 'd' },
+        { type: 'constant', value: 6 }
+      ])
+    })
+  })
 })
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index 47944d2..26febef 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -115,6 +115,18 @@ describe('parse', () => {
     })
   })
 
+  it('parses exploding dice', () => {
+    expect(parse('1E1d6')).toEqual({
+      type: 'E',
+      left: { type: 'constant', value: 1 },
+      right: {
+        type: 'd',
+        left: { type: 'constant', value: 1 },
+        right: { type: 'constant', value: 6 }
+      }
+    })
+  })
+
   describe('parsing parentheses', () => {
     test('(1d6)d6', () => {
       expect(parse('(1d6)d6')).toEqual({
diff --git a/index.js b/index.js
index 8cdfe1e..3b858a2 100644
--- a/index.js
+++ b/index.js
@@ -7,6 +7,8 @@ const interpret = tree => {
     return D.constant(tree.value)
   case 'd':
     return D.d(interpret(tree.left), interpret(tree.right))
+  case 'E':
+    return D.explode(interpret(tree.left), interpret(tree.right))
   case 'add':
     return D.add(interpret(tree.left), interpret(tree.right))
   case 'subtract':
diff --git a/src/lexer.js b/src/lexer.js
index 5e29e42..85579fb 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -24,6 +24,7 @@ newLexemeType('+', '\\+')
 newLexemeType('-', '-')
 newLexemeType('(', '\\(')
 newLexemeType(')', '\\)')
+newLexemeType('E', 'E')
 newSkippableLexeme('whitespace', '\\s+')
 
 const lex = (expressionString) => {
diff --git a/src/parser.js b/src/parser.js
index 3437f1a..9479abc 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -47,6 +47,14 @@ newSymbol('d', (parser) => {
   }
 })
 
+newSymbol('E', null, 30, (left, parser) => {
+  return {
+    type: 'E',
+    left: left,
+    right: parser.expression(29)
+  }
+})
+
 newSymbol('+', null, 20, (left, parser) => {
   return {
     type: 'add',
-- 
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