Add another helper to strutils, to compare version strings.

simgear/misc/strutils.cxx

@@ -259,6 +259,26 @@ namespace simgear {
         return result;
     }
     
+    int compare_versions(const string& v1, const string& v2)
+    {
+        vector<string> v1parts(split(v1, "."));
+        vector<string> v2parts(split(v2, "."));
+
+        int lastPart = std::min(v1parts.size(), v2parts.size());
+        for (int part=0; part < lastPart; ++part) {
+            int part1 = to_int(v1parts[part]);
+            int part2 = to_int(v2parts[part]);
+
+            if (part1 != part2) {
+                return part1 - part2;
+            }
+        } // of parts iteration
+
+        // reached end - longer wins
+        return v1parts.size() - v2parts.size();
+    }
+    
+    
     } // end namespace strutils
     
 } // end namespace simgear

simgear/misc/strutils.hxx

@@ -127,6 +127,14 @@ namespace simgear {
      * convert a string representing a decimal number, to an int
      */
     int to_int(const std::string& s, int base = 10);
+    
+    /**
+     * Like strcmp(), but for dotted versions strings NN.NN.NN
+     * any number of terms are support.
+     * @return 0 if versions match, -ve number if v1 is lower, +ve if v1
+     * is greater
+     */
+    int compare_versions(const std::string& v1, const std::string& v2);
   } // end namespace strutils
 } // end namespace simgear
 

simgear/misc/strutils_test.cxx

@@ -53,6 +53,16 @@ int main (int ac, char ** av)
     COMPARE(to_int("0000000"), 0);
     COMPARE(to_int("-10000"), -10000);
     
+    VERIFY(compare_versions("1.0.12", "1.1") < 0);
+    VERIFY(compare_versions("1.1", "1.0.12") > 0);
+    VERIFY(compare_versions("10.6.7", "10.6.7") == 0);
+    VERIFY(compare_versions("2.0", "2.0.99") < 0);
+    VERIFY(compare_versions("99", "99") == 0);
+    VERIFY(compare_versions("99", "98") > 0);
+    
+// since we compare numerically, leasing zeros shouldn't matter
+    VERIFY(compare_versions("0.06.7", "0.6.07") == 0);
+    
     cout << "all tests passed successfully!" << endl;
     return 0;
 }