michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: function referencesVia(from, edge, to) {
michael@0:     if (typeof findReferences !== 'function')
michael@0:         return true;
michael@0: 
michael@0:     edge = "edge: " + edge;
michael@0:     var edges = findReferences(to);
michael@0:     if (edge in edges && edges[edge].indexOf(from) != -1)
michael@0:         return true;
michael@0: 
michael@0:     // Be nice: make it easy to fix if the edge name has just changed.
michael@0:     var alternatives = [];
michael@0:     for (var e in edges) {
michael@0:         if (edges[e].indexOf(from) != -1)
michael@0:             alternatives.push(e);
michael@0:     }
michael@0:     if (alternatives.length == 0) {
michael@0:         print("referent not referred to by referrer after all");
michael@0:     } else {
michael@0:         print("referent is not referenced via: " + uneval(edge));
michael@0:         print("but it is referenced via:       " + uneval(alternatives));
michael@0:     }
michael@0:     print("all incoming edges, from any object:");
michael@0:     for (var e in edges)
michael@0:         print(e);
michael@0:     return false;
michael@0: }