cmSystemTools: Add strverscmp

Add support for natural string order by comparing non-numerical
character directly and numerical number by firstly collecting contiguous
digits.  The order is defined by the `strverscmp(3)` manual [1].

[1] http://man7.org/linux/man-pages/man3/strverscmp.3.html

Inspired-by: Pierluigi Taddei <pierluigi.taddei@gmail.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h
index 3c1a9f4..aecf40e 100644
--- a/Source/cmSystemTools.h
+++ b/Source/cmSystemTools.h
@@ -306,6 +306,16 @@ public:
                                       std::string const& rhs);
 
   /**
+   * Compare two ASCII strings using natural versioning order.
+   * Non-numerical characters are compared directly.
+   * Numerical characters are first globbed such that, e.g.
+   * `test000 < test01 < test0 < test1 < test10`.
+   * Return a value less than, equal to, or greater than zero if lhs
+   * precedes, equals, or succeeds rhs in the defined ordering.
+   */
+  static int strverscmp(std::string const& lhs, std::string const& rhs);
+
+  /**
    * Determine the file type based on the extension
    */
   static FileFormat GetFileFormat(const char* ext);