mfbt/decimal/Decimal.h

   1 /*
   2  * Copyright (C) 2012 Google 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 are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 /**
  32  * Imported from:
  33  * http://src.chromium.org/viewvc/blink/trunk/Source/core/platform/Decimal.h
  34  * Check hg log for the svn rev of the last update from Blink core.
  35  */
  36
  37 #ifndef Decimal_h
  38 #define Decimal_h
  39
  40 #include "mozilla/Assertions.h"
  41 #include <stdint.h>
  42 #include "mozilla/Types.h"
  43
  44 #include <string>
  45
  46 #ifndef ASSERT
  47 #define DEFINED_ASSERT_FOR_DECIMAL_H 1
  48 #define ASSERT MOZ_ASSERT
  49 #endif
  50
  51 // To use WTF_MAKE_FAST_ALLOCATED we'd need:
  52 // http://src.chromium.org/viewvc/blink/trunk/Source/wtf/FastMalloc.h
  53 // Since we don't allocate Decimal objects, no need.
  54 #define WTF_MAKE_FAST_ALLOCATED \
  55   void ignore_this_dummy_method() = delete
  56
  57 namespace WebCore {
  58
  59 namespace DecimalPrivate {
  60 class SpecialValueHandler;
  61 }
  62
  63 // This class represents decimal base floating point number.
  64 //
  65 // FIXME: Once all C++ compiler support decimal type, we should replace this
  66 // class to compiler supported one. See below URI for current status of decimal
  67 // type for C++: // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1977.html
  68 class Decimal {
  69     WTF_MAKE_FAST_ALLOCATED;
  70 public:
  71     enum Sign {
  72         Positive,
  73         Negative,
  74     };
  75
  76     // You should not use EncodedData other than unit testing.
  77     class EncodedData {
  78         // For accessing FormatClass.
  79         friend class Decimal;
  80         friend class DecimalPrivate::SpecialValueHandler;
  81     public:
  82         EncodedData(Sign, int exponent, uint64_t coefficient);
  83
  84         bool operator==(const EncodedData&) const;
  85         bool operator!=(const EncodedData& another) const { return !operator==(another); }
  86
  87         uint64_t coefficient() const { return m_coefficient; }
  88         int countDigits() const;
  89         int exponent() const { return m_exponent; }
  90         bool isFinite() const { return !isSpecial(); }
  91         bool isInfinity() const { return m_formatClass == ClassInfinity; }
  92         bool isNaN() const { return m_formatClass == ClassNaN; }
  93         bool isSpecial() const { return m_formatClass == ClassInfinity || m_formatClass == ClassNaN; }
  94         bool isZero() const { return m_formatClass == ClassZero; }
  95         Sign sign() const { return m_sign; }
  96         void setSign(Sign sign) { m_sign = sign; }
  97
  98     private:
  99         enum FormatClass {
 100             ClassInfinity,
 101             ClassNormal,
 102             ClassNaN,
 103             ClassZero,
 104         };
 105
 106         EncodedData(Sign, FormatClass);
 107         FormatClass formatClass() const { return m_formatClass; }
 108
 109         uint64_t m_coefficient;
 110         int16_t m_exponent;
 111         FormatClass m_formatClass;
 112         Sign m_sign;
 113     };
 114
 115     MFBT_API explicit Decimal(int32_t = 0);
 116     MFBT_API Decimal(Sign, int exponent, uint64_t coefficient);
 117     MFBT_API Decimal(const Decimal&);
 118
 119     MFBT_API Decimal& operator=(const Decimal&);
 120     MFBT_API Decimal& operator+=(const Decimal&);
 121     MFBT_API Decimal& operator-=(const Decimal&);
 122     MFBT_API Decimal& operator*=(const Decimal&);
 123     MFBT_API Decimal& operator/=(const Decimal&);
 124
 125     MFBT_API Decimal operator-() const;
 126
 127     MFBT_API bool operator==(const Decimal&) const;
 128     MFBT_API bool operator!=(const Decimal&) const;
 129     MFBT_API bool operator<(const Decimal&) const;
 130     MFBT_API bool operator<=(const Decimal&) const;
 131     MFBT_API bool operator>(const Decimal&) const;
 132     MFBT_API bool operator>=(const Decimal&) const;
 133
 134     MFBT_API Decimal operator+(const Decimal&) const;
 135     MFBT_API Decimal operator-(const Decimal&) const;
 136     MFBT_API Decimal operator*(const Decimal&) const;
 137     MFBT_API Decimal operator/(const Decimal&) const;
 138
 139     int exponent() const
 140     {
 141         ASSERT(isFinite());
 142         return m_data.exponent();
 143     }
 144
 145     bool isFinite() const { return m_data.isFinite(); }
 146     bool isInfinity() const { return m_data.isInfinity(); }
 147     bool isNaN() const { return m_data.isNaN(); }
 148     bool isNegative() const { return sign() == Negative; }
 149     bool isPositive() const { return sign() == Positive; }
 150     bool isSpecial() const { return m_data.isSpecial(); }
 151     bool isZero() const { return m_data.isZero(); }
 152
 153     MFBT_API Decimal abs() const;
 154     MFBT_API Decimal ceiling() const;
 155     MFBT_API Decimal floor() const;
 156     MFBT_API Decimal remainder(const Decimal&) const;
 157     MFBT_API Decimal round() const;
 158
 159     MFBT_API double toDouble() const;
 160     // Note: toString method supports infinity and nan but fromString not.
 161     MFBT_API std::string toString() const;
 162     MFBT_API bool toString(char* strBuf, size_t bufLength) const;
 163
 164     static MFBT_API Decimal fromDouble(double);
 165     // fromString supports following syntax EBNF:
 166     //  number ::= sign? digit+ ('.' digit*) (exponent-marker sign? digit+)?
 167     //          | sign? '.' digit+ (exponent-marker sign? digit+)?
 168     //  sign ::= '+' | '-'
 169     //  exponent-marker ::= 'e' | 'E'
 170     //  digit ::= '0' | '1' | ... | '9'
 171     // Note: fromString doesn't support "infinity" and "nan".
 172     static MFBT_API Decimal fromString(const std::string& aValue);
 173     static MFBT_API Decimal infinity(Sign);
 174     static MFBT_API Decimal nan();
 175     static MFBT_API Decimal zero(Sign);
 176
 177     // You should not use below methods. We expose them for unit testing.
 178     MFBT_API explicit Decimal(const EncodedData&);
 179     const EncodedData& value() const { return m_data; }
 180
 181 private:
 182     struct AlignedOperands {
 183         uint64_t lhsCoefficient;
 184         uint64_t rhsCoefficient;
 185         int exponent;
 186     };
 187
 188     MFBT_API explicit Decimal(double);
 189     MFBT_API Decimal compareTo(const Decimal&) const;
 190
 191     static MFBT_API AlignedOperands alignOperands(const Decimal& lhs, const Decimal& rhs);
 192     static inline Sign invertSign(Sign sign) { return sign == Negative ? Positive : Negative; }
 193
 194     Sign sign() const { return m_data.sign(); }
 195
 196     EncodedData m_data;
 197 };
 198
 199 } // namespace WebCore
 200
 201 namespace mozilla {
 202   typedef WebCore::Decimal Decimal;
 203 }
 204
 205 #undef WTF_MAKE_FAST_ALLOCATED
 206
 207 #ifdef DEFINED_ASSERT_FOR_DECIMAL_H
 208 #undef DEFINED_ASSERT_FOR_DECIMAL_H
 209 #undef ASSERT
 210 #endif
 211
 212 #endif // Decimal_h
 213