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