[CMake] Regex Alternation

[Allen Barnett]

Hi: I was wondering how the alternation character, |, works in CMake
regular expressions. To match "this" or "that" in a longer string would
it be "(this|that)" or "(this)|(that)"? The CMake --help says | is
supported but header file kwsys/RegularExpression.hxx.in doesn't mention
it.
Thanks,
Allen
-- 
Allen Barnett
Transpire, Inc
E-Mail: allen at transpireinc.com