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      1 /*
      2  * Copyright (C) 2009 Apple Inc. All Rights Reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef DateInstanceCache_h
     27 #define DateInstanceCache_h
     28 
     29 #include <wtf/DateMath.h>
     30 #include <wtf/HashFunctions.h>
     31 #include <wtf/PassRefPtr.h>
     32 #include <wtf/RefCounted.h>
     33 
     34 namespace JSC {
     35 
     36     extern const double NaN;
     37 
     38     class DateInstanceData : public RefCounted<DateInstanceData> {
     39     public:
     40         static PassRefPtr<DateInstanceData> create() { return adoptRef(new DateInstanceData); }
     41 
     42         double m_gregorianDateTimeCachedForMS;
     43         GregorianDateTime m_cachedGregorianDateTime;
     44         double m_gregorianDateTimeUTCCachedForMS;
     45         GregorianDateTime m_cachedGregorianDateTimeUTC;
     46 
     47     private:
     48         DateInstanceData()
     49             : m_gregorianDateTimeCachedForMS(NaN)
     50             , m_gregorianDateTimeUTCCachedForMS(NaN)
     51         {
     52         }
     53     };
     54 
     55     class DateInstanceCache {
     56     public:
     57         DateInstanceCache()
     58         {
     59             reset();
     60         }
     61 
     62         void reset()
     63         {
     64             for (size_t i = 0; i < cacheSize; ++i)
     65                 m_cache[i].key = NaN;
     66         }
     67 
     68         DateInstanceData* add(double d)
     69         {
     70             CacheEntry& entry = lookup(d);
     71             if (d == entry.key)
     72                 return entry.value.get();
     73 
     74             entry.key = d;
     75             entry.value = DateInstanceData::create();
     76             return entry.value.get();
     77         }
     78 
     79     private:
     80         static const size_t cacheSize = 16;
     81 
     82         struct CacheEntry {
     83             double key;
     84             RefPtr<DateInstanceData> value;
     85         };
     86 
     87         CacheEntry& lookup(double d) { return m_cache[WTF::FloatHash<double>::hash(d) & (cacheSize - 1)]; }
     88 
     89         FixedArray<CacheEntry, cacheSize> m_cache;
     90     };
     91 
     92 } // namespace JSC
     93 
     94 #endif // DateInstanceCache_h
     95