+bool VCS::makeRCSRevision(string const &version, string &revis) const
+{
+ string rev = revis;
+
+ if (isStrInt(rev)) {
+ int back = convert<int>(rev);
+ // if positive use as the last number in the whole revision string
+ if (back > 0) {
+ string base;
+ rsplit(version, base , '.' );
+ rev = base + "." + rev;
+ }
+ if (back == 0)
+ rev = version;
+ // we care about the last number from revision string
+ // in case of backward indexing
+ if (back < 0) {
+ string cur, base;
+ cur = rsplit(version, base , '.' );
+ if (!isStrInt(cur))
+ return false;
+ int want = convert<int>(cur) + back;
+ if (want <= 0)
+ return false;
+
+ rev = base + "." + convert<string>(want);
+ }
+ }
+
+ revis = rev;
+ return true;
+}
+
+