[CMake] version number parsing

[James Bigler]

James Bigler wrote:
> Is there an example I could look at to parse out the individual version 
> numbers, once I get this string?
> 
> STRING(REGEX MATCH "[0-9]+\\.[0-9]+\\.[0-9]+" version-string ${output})
> 
> I want to be able to get the three integers out of version-string.

I found some code in FindQt4.cmake:

STRING(REGEX REPLACE "^([0-9]+)\\.[0-9]+\\.[0-9]+" "\\1" req_qt_major_vers 
"${QT_MIN_VERSION}")
STRING(REGEX REPLACE "^[0-9]+\\.([0-9])+\\.[0-9]+" "\\1" req_qt_minor_vers 
"${QT_MIN_VERSION}")
STRING(REGEX REPLACE "^[0-9]+\\.[0-9]+\\.([0-9]+)" "\\1" req_qt_patch_vers 
"${QT_MIN_VERSION}")

According to the documentation, I believe the ()'s create groups that can be 
referenced by "\\1" or "\\2" and such.

James