From fe1bb829ba1feeb4d8f384afe0ed62669d82407f Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Wed, 23 Aug 2017 21:30:01 -0400
Subject: Lex and parse threshold

---
 __tests__/lexer.test.js  | 12 ++++++++++++
 __tests__/parser.test.js | 12 ++++++++++++
 index.js                 |  2 ++
 src/lexer.js             |  1 +
 src/parser.js            |  1 +
 5 files changed, 28 insertions(+)

diff --git a/__tests__/lexer.test.js b/__tests__/lexer.test.js
index 5ae84cc..21ae3b0 100644
--- a/__tests__/lexer.test.js
+++ b/__tests__/lexer.test.js
@@ -194,4 +194,16 @@ describe('lex', () => {
       ])
     })
   })
+
+  describe('threshold', () => {
+    test('8T3d10', () => {
+      expect(lex('8T3d10')).toEqual([
+        { type: 'constant', value: 8 },
+        { type: 'T' },
+        { type: 'constant', value: 3 },
+        { type: 'd' },
+        { type: 'constant', value: 10 }
+      ])
+    })
+  })
 })
diff --git a/__tests__/parser.test.js b/__tests__/parser.test.js
index 6bf5958..70ad98d 100644
--- a/__tests__/parser.test.js
+++ b/__tests__/parser.test.js
@@ -211,6 +211,18 @@ describe('parse', () => {
     })
   })
 
+  it('parases dice with threshold', () => {
+    expect(parse('7T4d8')).toEqual({
+      type: 'T',
+      left: { type: 'constant', value: 7 },
+      right: {
+        type: 'd',
+        left: { type: 'constant', value: 4 },
+        right: { type: 'constant', value: 8 }
+      }
+    })
+  })
+
   describe('parsing parentheses', () => {
     test('(1d6)d6', () => {
       expect(parse('(1d6)d6')).toEqual({
diff --git a/index.js b/index.js
index fa4a993..e117b7c 100644
--- a/index.js
+++ b/index.js
@@ -15,6 +15,8 @@ const interpret = tree => {
     return D.keepLow(interpret(tree.left), interpret(tree.right))
   case 'A':
     return D.again(interpret(tree.left), interpret(tree.right))
+  case 'T':
+    return D.threshold(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 a83ee2b..f316147 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -26,6 +26,7 @@ newLexemeType('E', 'E')
 newLexemeType('K', 'K')
 newLexemeType('k', 'k')
 newLexemeType('A', 'A')
+newLexemeType('T', 'T')
 
 const lex = (expressionString) => {
   let lexemes = []
diff --git a/src/parser.js b/src/parser.js
index 1b678e4..0201d05 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -64,6 +64,7 @@ newDieOperation('E')
 newDieOperation('K')
 newDieOperation('k')
 newDieOperation('A')
+newDieOperation('T')
 
 newInfix('bigPlus', 20, { type: 'add' })
 newInfix('bigMinus', 20, { type: 'subtract' })
-- 
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