Expose internal properties of map/set iterators via mirrors.

test/mjsunit/es6/mirror-iterators.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --expose-debug-as debug
 // Test the mirror object for collection iterators.
 
 function testIteratorMirror(iter, offset, expected, opt_limit) {
   while (offset-- > 0) iter.next();
 
   var mirror = debug.MakeMirror(iter);
   assertTrue(mirror.isIterator());
 
   var preview = mirror.preview(opt_limit);
   assertArrayEquals(expected, preview);
 
   // Check that iterator has not changed after taking preview.
   var values = [];
   for (var i of iter) {
     if (opt_limit && values.length >= opt_limit) break;
     values.push(i);
   }
   assertArrayEquals(expected, values);
 }
 
+function testIteratorInternalProperties(iter, offset, kind, index, has_more) {
+  while (offset-- > 0) iter.next();
+
+  var mirror = debug.MakeMirror(iter);
+  assertTrue(mirror.isIterator());
+
+  var properties = mirror.internalProperties();
+  assertEquals(3, properties.length);
+  assertEquals("[[IteratorHasMore]]", properties[0].name());
+  assertEquals(has_more, properties[0].value().value());
+  assertEquals("[[IteratorIndex]]", properties[1].name());
+  assertEquals(index, properties[1].value().value());
+  assertEquals("[[IteratorKind]]", properties[2].name());
+  assertEquals(kind, properties[2].value().value());
+}
+
 var o1 = { foo: 1 };
 var o2 = { foo: 2 };
 
 var map = new Map();
 map.set(41, 42);
 map.set(o1, o2);
 
 testIteratorMirror(map.keys(), 0, [41, o1]);
 testIteratorMirror(map.values(), 0, [42, o2]);
 testIteratorMirror(map.entries(), 0, [[41, 42], [o1, o2]]);
 
 testIteratorMirror(map.keys(), 1, [o1]);
 testIteratorMirror(map.values(), 1, [o2]);
 testIteratorMirror(map.entries(), 1, [[o1, o2]]);
 
 testIteratorMirror(map.keys(), 2, []);
 testIteratorMirror(map.values(), 2, []);
 testIteratorMirror(map.entries(), 2, []);
 
 // Test with maximum limit.
 testIteratorMirror(map.keys(), 0, [41], 1);
 testIteratorMirror(map.values(), 0, [42], 1);
 testIteratorMirror(map.entries(), 0, [[41, 42]], 1);
 
+testIteratorInternalProperties(map.keys(), 0, "keys", 0, true);
+testIteratorInternalProperties(map.values(), 1, "values", 1, true);
+testIteratorInternalProperties(map.entries(), 2, "entries", 2, false);
+testIteratorInternalProperties(map.keys(), 3, "keys", 2, false);
+
 var set = new Set();
 set.add(41);
 set.add(42);
 set.add(o1);
 set.add(o2);
 
 testIteratorMirror(set.keys(), 0, [41, 42, o1, o2]);
 testIteratorMirror(set.values(), 0, [41, 42, o1, o2]);
 testIteratorMirror(set.entries(), 0, [[41, 41], [42, 42], [o1, o1], [o2, o2]]);
 
 testIteratorMirror(set.keys(), 1, [42, o1, o2]);
 testIteratorMirror(set.values(), 1, [42, o1, o2]);
 testIteratorMirror(set.entries(), 1, [[42, 42], [o1, o1], [o2, o2]]);
 
 testIteratorMirror(set.keys(), 3, [o2]);
 testIteratorMirror(set.values(), 3, [o2]);
 testIteratorMirror(set.entries(), 3, [[o2, o2]]);
 
 testIteratorMirror(set.keys(), 5, []);
 testIteratorMirror(set.values(), 5, []);
 testIteratorMirror(set.entries(), 5, []);
 
 // Test with maximum limit.
 testIteratorMirror(set.keys(), 1, [42, o1], 2);
 testIteratorMirror(set.values(), 1, [42, o1], 2);
 testIteratorMirror(set.entries(), 1, [[42, 42], [o1, o1]], 2);
+
+testIteratorInternalProperties(set.keys(), 0, "values", 0, true);
+testIteratorInternalProperties(set.values(), 1, "values", 1, true);
+testIteratorInternalProperties(set.entries(), 2, "entries", 2, true);
+testIteratorInternalProperties(set.keys(), 3, "values", 3, true);
+testIteratorInternalProperties(set.values(), 4, "values", 4, false);
+testIteratorInternalProperties(set.entries(), 5, "entries", 4, false);