- // All symmetry trees are equal. They are not supposed to appear in
- // ordinary expressions anyway...
+ // For archiving purposes we need to have an ordering of symmetries.
+ const symmetry &othersymm = ex_to<symmetry>(other);
+
+ // Compare type.
+ if (type > othersymm.type)
+ return 1;
+ if (type < othersymm.type)
+ return -1;
+
+ // Compare the index set.
+ size_t this_size = indices.size();
+ size_t that_size = othersymm.indices.size();
+ if (this_size > that_size)
+ return 1;
+ if (this_size < that_size)
+ return -1;
+ auto end = indices.end();
+ for (auto i=indices.begin(),j=othersymm.indices.begin(); i!=end; ++i,++j) {
+ if(*i < *j)
+ return 1;
+ if(*i > *j)
+ return -1;
+ }
+
+ // Compare the children.
+ if (children.size() > othersymm.children.size())
+ return 1;
+ if (children.size() < othersymm.children.size())
+ return -1;
+ for (size_t i=0; i<children.size(); ++i) {
+ int cmpval = ex_to<symmetry>(children[i])
+ .compare_same_type(ex_to<symmetry>(othersymm.children[i]));
+ if (cmpval)
+ return cmpval;
+ }
+