Merge pull request #8660 from atom/as-null-bytes-paired-char

Avoid pairing null byte characters

spec/text-utils-spec.coffee

@@ -17,6 +17,9 @@ describe 'text utilities', ->
       expect(textUtils.hasPairedCharacter('\uFE0E\uFE0E')).toBe false
       expect(textUtils.hasPairedCharacter('\u0301\u0301')).toBe false
 
+      expect(textUtils.hasPairedCharacter('\0\u0301')).toBe false
+      expect(textUtils.hasPairedCharacter('\0\uFE0E')).toBe false
+
   describe '.isPairedCharacter(string, index)', ->
     it 'returns true when the index is the start of a high/low surrogate pair, variation sequence, or combined character', ->
       expect(textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 0)).toBe false
@@ -44,3 +47,6 @@ describe 'text utilities', ->
       expect(textUtils.isPairedCharacter('ae\u0301c', 2)).toBe false
       expect(textUtils.isPairedCharacter('ae\u0301c', 3)).toBe false
       expect(textUtils.isPairedCharacter('ae\u0301c', 4)).toBe false
+
+      expect(textUtils.isPairedCharacter('\0\u0301c', 0)).toBe false
+      expect(textUtils.isPairedCharacter('\0\uFE0E', 0)).toBe false

src/text-utils.coffee

@@ -30,6 +30,7 @@ isSurrogatePair = (charCodeA, charCodeB) ->
 #
 # Return a {Boolean}.
 isVariationSequence = (charCodeA, charCodeB) ->
+  return false if charCodeA is 0
   not isVariationSelector(charCodeA) and isVariationSelector(charCodeB)
 
 # Are the given character codes a combined character pair?
@@ -39,6 +40,7 @@ isVariationSequence = (charCodeA, charCodeB) ->
 #
 # Return a {Boolean}.
 isCombinedCharacter = (charCodeA, charCodeB) ->
+  return false if charCodeA is 0
   not isCombiningCharacter(charCodeA) and isCombiningCharacter(charCodeB)
 
 # Is the character at the given index the start of high/low surrogate pair