[inspector] introduced v8::debug::EntriesPreview for inspector

src/objects.cc

 // Copyright 2015 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.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 18604 matching lines @@
   Handle<ObjectHashTable> new_table =
       ObjectHashTable::Remove(table, key, &was_present, hash);
   weak_collection->set_table(*new_table);
   if (*table != *new_table) {
     // Zap the old table since we didn't record slots for its elements.
     table->FillWithHoles(0, table->length());
   }
   return was_present;
 }
 
+Handle<JSArray> JSWeakCollection::GetEntries(Handle<JSWeakCollection> holder,
+                                             int max_entries) {
+  Isolate* isolate = holder->GetIsolate();
+  Handle<ObjectHashTable> table(ObjectHashTable::cast(holder->table()));
+  if (max_entries == 0 || max_entries > table->NumberOfElements()) {
+    max_entries = table->NumberOfElements();
+  }
+  int values_per_entry = holder->IsJSWeakMap() ? 2 : 1;
+  Handle<FixedArray> entries =
+      isolate->factory()->NewFixedArray(max_entries * values_per_entry);
+  // Recompute max_values because GC could have removed elements from the table.
+  if (max_entries > table->NumberOfElements()) {
+    max_entries = table->NumberOfElements();
+  }
+
+  {
+    DisallowHeapAllocation no_gc;
+    int count = 0;
+    for (int i = 0;
+         count / values_per_entry < max_entries && i < table->Capacity(); i++) {
+      Handle<Object> key(table->KeyAt(i), isolate);
+      if (table->IsKey(isolate, *key)) {
+        entries->set(count++, *key);
+        if (values_per_entry > 1) {
+          Object* value = table->Lookup(key);
+          entries->set(count++, value);
+        }
+      }
+    }
+    DCHECK_EQ(max_entries * values_per_entry, count);
+  }
+  return isolate->factory()->NewJSArrayWithElements(entries);
+}
+
 // Check if there is a break point at this source position.
 bool DebugInfo::HasBreakPoint(int source_position) {
   // Get the break point info object for this code offset.
   Object* break_point_info = GetBreakPointInfo(source_position);
 
   // If there is no break point info object or no break points in the break
   // point info object there is no break point at this code offset.
   if (break_point_info->IsUndefined(GetIsolate())) return false;
   return BreakPointInfo::cast(break_point_info)->GetBreakPointCount() > 0;
 }
@@ skipping 1390 matching lines @@
       // depend on this.
       return DICTIONARY_ELEMENTS;
     }
     DCHECK_LE(kind, LAST_ELEMENTS_KIND);
     return kind;
   }
 }
 
 }  // namespace internal
 }  // namespace v8