runtime/NumericStrings.h

   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 NumericStrings_h
  27 #define NumericStrings_h
  28
  29 #include "UString.h"
  30 #include <wtf/HashFunctions.h>
  31
  32 namespace JSC {
  33
  34     class NumericStrings {
  35     public:
  36         UString add(double d)
  37         {
  38             CacheEntry<double>& entry = lookup(d);
  39             if (d == entry.key && !entry.value.isNull())
  40                 return entry.value;
  41             entry.key = d;
  42             entry.value = UString::from(d);
  43             return entry.value;
  44         }
  45
  46         UString add(int i)
  47         {
  48             if (static_cast<unsigned>(i) < cacheSize)
  49                 return lookupSmallString(static_cast<unsigned>(i));
  50             CacheEntry<int>& entry = lookup(i);
  51             if (i == entry.key && !entry.value.isNull())
  52                 return entry.value;
  53             entry.key = i;
  54             entry.value = UString::from(i);
  55             return entry.value;
  56         }
  57
  58         UString add(unsigned i)
  59         {
  60             if (i < cacheSize)
  61                 return lookupSmallString(static_cast<unsigned>(i));
  62             CacheEntry<unsigned>& entry = lookup(i);
  63             if (i == entry.key && !entry.value.isNull())
  64                 return entry.value;
  65             entry.key = i;
  66             entry.value = UString::from(i);
  67             return entry.value;
  68         }
  69     private:
  70         static const size_t cacheSize = 64;
  71
  72         template<typename T>
  73         struct CacheEntry {
  74             T key;
  75             UString value;
  76         };
  77
  78         CacheEntry<double>& lookup(double d) { return doubleCache[WTF::FloatHash<double>::hash(d) & (cacheSize - 1)]; }
  79         CacheEntry<int>& lookup(int i) { return intCache[WTF::IntHash<int>::hash(i) & (cacheSize - 1)]; }
  80         CacheEntry<unsigned>& lookup(unsigned i) { return unsignedCache[WTF::IntHash<unsigned>::hash(i) & (cacheSize - 1)]; }
  81         const UString& lookupSmallString(unsigned i)
  82         {
  83             ASSERT(i < cacheSize);
  84             if (smallIntCache[i].isNull())
  85                 smallIntCache[i] = UString::from(i);
  86             return smallIntCache[i];
  87         }
  88
  89         CacheEntry<double> doubleCache[cacheSize];
  90         CacheEntry<int> intCache[cacheSize];
  91         CacheEntry<unsigned> unsignedCache[cacheSize];
  92         UString smallIntCache[cacheSize];
  93     };
  94
  95 } // namespace JSC
  96
  97 #endif // NumericStrings_h