michael@0: // A map iterator can cope with removing the current entry.
michael@0: 
michael@0: function test(pairs) {
michael@0:     print(uneval(pairs));
michael@0:     var map = Map(pairs);
michael@0:     
michael@0:     var all_keys = '';
michael@0:     var false_keys = '';
michael@0:     for (let [k, v] of map) {
michael@0:         all_keys += k;
michael@0:         if (!v)
michael@0:             false_keys += k;
michael@0:     }
michael@0: 
michael@0:     var log = '';
michael@0:     for (let [k, remove] of map) {
michael@0:         log += k;
michael@0:         if (remove)
michael@0:             map.delete(k);
michael@0:     }
michael@0:     assertEq(log, all_keys);
michael@0: 
michael@0:     var remaining_keys = [k for ([k] of map)].join('');
michael@0:     assertEq(remaining_keys, false_keys);
michael@0: }
michael@0: 
michael@0: // removing the only entry
michael@0: test([['a', true]]);
michael@0: 
michael@0: // removing the first entry
michael@0: test([['a', true], ['b', false], ['c', false]]);
michael@0: 
michael@0: // removing a middle entry
michael@0: test([['a', false], ['b', true], ['c', false]]);
michael@0: 
michael@0: // removing the last entry
michael@0: test([['a', false], ['b', false], ['c', true]]);
michael@0: 
michael@0: // removing all entries
michael@0: test([['a', true], ['b', true], ['c', true]]);