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      1 /*
      2  * Copyright (C) 2010 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 DecimalNumber_h
     27 #define DecimalNumber_h
     28 
     29 #include <math.h>
     30 #include <wtf/dtoa.h>
     31 #include <wtf/MathExtras.h>
     32 #include <wtf/text/WTFString.h>
     33 
     34 namespace WTF {
     35 
     36 enum RoundingSignificantFiguresType { RoundingSignificantFigures };
     37 enum RoundingDecimalPlacesType { RoundingDecimalPlaces };
     38 
     39 class DecimalNumber {
     40 public:
     41     DecimalNumber(double d)
     42     {
     43         ASSERT(!isnan(d) && !isinf(d));
     44         dtoa(m_significand, d, m_sign, m_exponent, m_precision);
     45 
     46         ASSERT(m_precision);
     47         // Zero should always have exponent 0.
     48         ASSERT(m_significand[0] != '0' || !m_exponent);
     49         // No values other than zero should have a leading zero.
     50         ASSERT(m_significand[0] != '0' || m_precision == 1);
     51         // No values other than zero should have trailing zeros.
     52         ASSERT(m_significand[0] == '0' || m_significand[m_precision - 1] != '0');
     53     }
     54 
     55     DecimalNumber(double d, RoundingSignificantFiguresType, unsigned significantFigures)
     56     {
     57         ASSERT(!isnan(d) && !isinf(d));
     58         dtoaRoundSF(m_significand, d, significantFigures, m_sign, m_exponent, m_precision);
     59 
     60         ASSERT(significantFigures && significantFigures <= sizeof(DtoaBuffer));
     61         while (m_precision < significantFigures)
     62             m_significand[m_precision++] = '0';
     63 
     64         ASSERT(m_precision);
     65         // Zero should always have exponent 0.
     66         ASSERT(m_significand[0] != '0' || !m_exponent);
     67     }
     68 
     69     DecimalNumber(double d, RoundingDecimalPlacesType, unsigned decimalPlaces)
     70     {
     71         ASSERT(!isnan(d) && !isinf(d));
     72         dtoaRoundDP(m_significand, d, decimalPlaces, m_sign, m_exponent, m_precision);
     73 
     74         unsigned significantFigures = 1 + m_exponent + decimalPlaces;
     75         ASSERT(significantFigures && significantFigures <= sizeof(DtoaBuffer));
     76         while (m_precision < significantFigures)
     77             m_significand[m_precision++] = '0';
     78 
     79         ASSERT(m_precision);
     80         // Zero should always have exponent 0.
     81         ASSERT(m_significand[0] != '0' || !m_exponent);
     82     }
     83 
     84     unsigned bufferLengthForStringDecimal() const;
     85     unsigned bufferLengthForStringExponential() const;
     86 
     87     unsigned toStringDecimal(UChar* buffer, unsigned bufferLength) const;
     88     unsigned toStringExponential(UChar* buffer, unsigned bufferLength) const;
     89 
     90     bool sign() const { return m_sign; }
     91     int exponent() const { return m_exponent; }
     92     const char* significand() const { return m_significand; } // significand contains precision characters, is not null-terminated.
     93     unsigned precision() const { return m_precision; }
     94 
     95 private:
     96     bool m_sign;
     97     int m_exponent;
     98     DtoaBuffer m_significand;
     99     unsigned m_precision;
    100 };
    101 
    102 } // namespace WTF
    103 
    104 using WTF::DecimalNumber;
    105 using WTF::RoundingSignificantFigures;
    106 using WTF::RoundingDecimalPlaces;
    107 
    108 #endif // DecimalNumber_h
    109