JavaScriptCore/runtime/PropertyMapHashTable.h
changeset 0 4f2f89ce4247
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/JavaScriptCore/runtime/PropertyMapHashTable.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,90 @@
+/*
+ *  Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Library General Public License
+ *  along with this library; see the file COPYING.LIB.  If not, write to
+ *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ *  Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef PropertyMapHashTable_h
+#define PropertyMapHashTable_h
+
+#include "UString.h"
+#include <wtf/Vector.h>
+
+namespace JSC {
+
+    struct PropertyMapEntry {
+        UString::Rep* key;
+        unsigned offset;
+        unsigned attributes;
+        JSCell* specificValue;
+        unsigned index;
+
+        PropertyMapEntry(UString::Rep* key, unsigned attributes, JSCell* specificValue)
+            : key(key)
+            , offset(0)
+            , attributes(attributes)
+            , specificValue(specificValue)
+            , index(0)
+        {
+        }
+
+        PropertyMapEntry(UString::Rep* key, unsigned offset, unsigned attributes, JSCell* specificValue, unsigned index)
+            : key(key)
+            , offset(offset)
+            , attributes(attributes)
+            , specificValue(specificValue)
+            , index(index)
+        {
+        }
+    };
+
+    // lastIndexUsed is an ever-increasing index used to identify the order items
+    // were inserted into the property map. It's required that getEnumerablePropertyNames
+    // return the properties in the order they were added for compatibility with other
+    // browsers' JavaScript implementations.
+    struct PropertyMapHashTable {
+        unsigned sizeMask;
+        unsigned size;
+        unsigned keyCount;
+        unsigned deletedSentinelCount;
+        unsigned lastIndexUsed;
+        Vector<unsigned>* deletedOffsets;
+        unsigned entryIndices[1];
+
+        PropertyMapEntry* entries()
+        {
+            // The entries vector comes after the indices vector.
+            // The 0th item in the entries vector is not really used; it has to
+            // have a 0 in its key to allow the hash table lookup to handle deleted
+            // sentinels without any special-case code, but the other fields are unused.
+            return reinterpret_cast<PropertyMapEntry*>(&entryIndices[size]);
+        }
+
+        static size_t allocationSize(unsigned size)
+        {
+            // We never let a hash table get more than half full,
+            // So the number of indices we need is the size of the hash table.
+            // But the number of entries is half that (plus one for the deleted sentinel).
+            return sizeof(PropertyMapHashTable)
+                + (size - 1) * sizeof(unsigned)
+                + (1 + size / 2) * sizeof(PropertyMapEntry);
+        }
+    };
+
+} // namespace JSC
+
+#endif // PropertyMapHashTable_h