Use Buffer.traverseRegexMatchesInRange to implement substitution

src/atom/command-interpreter/substitution.coffee

@@ -5,40 +5,9 @@ class Substitution extends Command
   global: false
 
   constructor: (@findText, @replaceText, @options) ->
-    @findRegex = new RegExp(@findText, 'mg')
-    @global = 'g' in @options
+    @findRegex = new RegExp(@findText, options.join(''))
 
   execute: (editor) ->
-    selectedText = editor.getSelectedText()
-    selectionStartIndex = editor.buffer.characterIndexForPosition(editor.getSelection().getBufferRange().start)
-
-    buffer = editor.buffer
-    range = editor.getSelection().getBufferRange()
-    startIndex = buffer.characterIndexForPosition(range.start)
-    endIndex = buffer.characterIndexForPosition(range.end)
-
-    @replace(editor, buffer.getText(), startIndex, endIndex)
-
-  replace: (editor, text, startIndex, endIndex, lengthDelta=0) ->
-    @findRegex.lastIndex = startIndex
-    return unless match = @findRegex.exec(text)
-
-    matchLength = match[0].length
-    matchStartIndex = match.index
-    matchEndIndex = match.index + matchLength
-
-    return if matchEndIndex > endIndex
-
-    buffer = editor.buffer
-    startPosition = buffer.positionForCharacterIndex(matchStartIndex + lengthDelta)
-    endPosition = buffer.positionForCharacterIndex(matchEndIndex + lengthDelta)
-
-    buffer.change([startPosition, endPosition], @replaceText)
-
-    if matchLength is 0
-      matchStartIndex++
-      matchEndIndex++
-
-    if @global
-      @replace(editor, text, matchEndIndex, endIndex, lengthDelta + @replaceText.length - matchLength)
+    editor.buffer.traverseRegexMatchesInRange @findRegex, editor.getSelection().getBufferRange(), =>
+      @replaceText