From da522e390d8a526ba9798b5683d8ae1f32a9b73e Mon Sep 17 00:00:00 2001
From: kpdecker <kpdecker@gmail.com>
Date: Wed, 26 Aug 2015 03:33:05 -0500
Subject: [PATCH] Special case handling of ignored terminals

Fixes #70
---
 src/diff/base.js  | 12 ++++++++++--
 test/diff/word.js |  8 ++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/diff/base.js b/src/diff/base.js
index 8d8e14c2..820979df 100644
--- a/src/diff/base.js
+++ b/src/diff/base.js
@@ -68,7 +68,7 @@ Diff.prototype = {
 
         // If we have hit the end of both strings, then we are done
         if (basePath.newPos + 1 >= newLen && oldPos + 1 >= oldLen) {
-          return done(buildValues(basePath.components, newString, oldString, self.useLongestToken));
+          return done(buildValues(self, basePath.components, newString, oldString, self.useLongestToken));
         } else {
           // Otherwise track this path as a potential candidate and continue.
           bestPath[diagonalPath] = basePath;
@@ -156,7 +156,7 @@ Diff.prototype = {
   }
 };
 
-function buildValues(components, newString, oldString, useLongestToken) {
+function buildValues(diff, components, newString, oldString, useLongestToken) {
   let componentPos = 0,
       componentLen = components.length,
       newPos = 0,
@@ -197,6 +197,14 @@ function buildValues(components, newString, oldString, useLongestToken) {
     }
   }
 
+  // Special case handle for when one terminal is ignored. For this case we merge the
+  // terminal into the prior string and drop the change.
+  let lastComponent = components[componentLen - 1];
+  if ((lastComponent.added || lastComponent.removed) && diff.equals('', lastComponent.value)) {
+    components[componentLen - 2].value += lastComponent.value;
+    components.pop();
+  }
+
   return components;
 }
 
diff --git a/test/diff/word.js b/test/diff/word.js
index 41e0de89..d8b6981e 100644
--- a/test/diff/word.js
+++ b/test/diff/word.js
@@ -77,6 +77,14 @@ describe('WordDiff', function() {
       expect(diffWords('', 'foo')).to.eql([{value: 'foo', count: 1, added: true, removed: undefined}]);
       expect(diffWords('', 'foo bar')).to.eql([{value: 'foo bar', count: 3, added: true, removed: undefined}]);
     });
+
+    it('should ignore whitespace', function() {
+      expect(diffWords('hase igel fuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs' }]);
+      expect(diffWords('hase igel fuchs', 'hase igel fuchs\n')).to.eql([{ count: 5, value: 'hase igel fuchs\n' }]);
+      expect(diffWords('hase igel fuchs\n', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs\n' }]);
+      expect(diffWords('hase igel fuchs', 'hase igel\nfuchs')).to.eql([{ count: 5, value: 'hase igel\nfuchs' }]);
+      expect(diffWords('hase igel\nfuchs', 'hase igel fuchs')).to.eql([{ count: 5, value: 'hase igel fuchs' }]);
+    });
   });
 
   describe('#diffWords - async', function() {