single space equals combine with replaces

If a single space equal operation is surrounded by replace
operations, then it is 'absorbed' into the replace operations.
i.e R,E,R becomes simply R.

Author: brendanjerwin

src/htmldiff.coffee

@@ -1,6 +1,6 @@
 is_end_of_tag = (char)-> char is '>'
 is_start_of_tag = (char)-> char is '<'
-is_whitespace = (char)-> /\s/.test char
+is_whitespace = (char)-> /^\s+$/.test char
 is_tag = (token)-> /^\s*<[^>]+>\s*$/.test token
 isnt_tag = (token)-> not is_tag token
 
@@ -200,7 +200,23 @@ calculate_operations = (before_tokens, after_tokens)->
     position_in_before = match.end_in_before + 1
     position_in_after = match.end_in_after + 1
 
-  return operations
+  post_processed = []
+  last_op = action: 'none'
+  is_single_whitespace = (op)->
+    return no unless op.action is 'equal'
+    return no unless op.end_in_before - op.start_in_before is 0
+    return /^\s$/.test before_tokens[op.start_in_before..op.end_in_before]
+
+  for op in operations
+    if ((is_single_whitespace op) and last_op.action is 'replace') or
+    (op.action is 'replace' and last_op.action is 'replace')
+      last_op.end_in_before = op.end_in_before
+      last_op.end_in_after = op.end_in_after
+    else
+      post_processed.push op
+      last_op = op
+
+  return post_processed
 
 consecutive_where = (start, content, predicate)->
   content = content[start..content.length]

test/calculate_operations.spec.coffee

@@ -32,7 +32,7 @@ describe 'calculate_operations', ->
           after = 'working on it'.split ' '
           @res = @cut before, after
 
-        it 'should result in 3 operation', ->
+        it 'should result in 3 operations', ->
           (expect @res.length).to.equal 3
 
         it 'should show an insert for "on"', ->
@@ -196,3 +196,42 @@ describe 'calculate_operations', ->
             end_in_before  : 5
             start_in_after : 4
             end_in_after   : undefined
+
+  describe 'Action Combination', ->
+    describe 'Absorb single-whitespace to make contiguous replace actions', ->
+      beforeEach ->
+        #There are a bunch of replaces, but, because whitespace is
+        #tokenized, they are broken up with equals. We want to combine
+        #them into a contiguous replace operation.
+        before = ['I', ' ', 'am', ' ', 'awesome']
+        after = ['You', ' ', 'are', ' ', 'great']
+        @res = @cut before, after
+
+      it 'should return 1 action', ->
+        (expect @res.length).to.equal 1
+
+      it 'should return the correct replace action', ->
+        (expect @res[0]).eql
+          action: 'replace'
+          start_in_before: 0
+          end_in_before: 4
+          start_in_after: 0
+          end_in_after: 4
+
+      describe 'but dont absorb non-single-whitespace tokens', ->
+        beforeEach ->
+          before = ['I', '  ', 'am', ' ', 'awesome']
+          after = ['You', '  ', 'are', ' ', 'great']
+          @res = @cut before, after
+
+        it 'should return 3 actions', ->
+          (expect @res.length).to.equal 3
+
+        it 'should have a replace first', ->
+          (expect @res[0].action).to.equal 'replace'
+
+        it 'should have an equal second', ->
+          (expect @res[1].action).to.equal 'equal'
+
+        it 'should have a replace last', ->
+          (expect @res[2].action).to.equal 'replace'

test/pain_games.spec.coffee

@@ -0,0 +1,11 @@
+describe 'Pain Games', ->
+  beforeEach ->
+    @cut = require '../src/htmldiff.coffee'
+
+  describe 'When an entire sentence is replaced', ->
+    beforeEach ->
+      @res = @cut 'this is what I had', 'and now we have a new one'
+
+    it 'should replace the whole chunk', ->
+      (expect @res).to.equal '<del>this is what I had</del>'\
+      + '<ins>and now we have a new one</ins>'