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