使用preg-split-DELIM-CAPTURE进行preg-split

我希望基于正则表达式拆分字符串,但我也有兴趣保留拆分的文本:

php > var_dump(preg_split("/(\^)/","category=Telecommunications &     CATV^ORcategory!=ORtest^caused_byISEMPTY^EQ"), null, PREG_SPLIT_DELIM_CAPTURE);
array(4) {
  [0]=> string(34) "category=Telecommunications & CATV"
  [1]=> string(18) "ORcategory!=ORtest"
  [2]=> string(16) "caused_byISEMPTY"
  [3]=> string(2) "EQ"
}
NULL
int(2)

我不明白的是为什么我没有得到一个数组,比如:

array(4) {
  [0]=> "category=Telecommunications & CATV"
  [1]=> "^"
  [2]=> "ORcategory!=ORtest"
  [3]=> "^"
  [4]=> "caused_byISEMPTY"
  [5]=> "^"
  [6]=> "EQ"
}

此外,我如何更改正则表达式以匹配“^”或“^”。我很难用一个lookbehind断言,比如:

$regexp = "/(?<=\^)OR|\^/";