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#ifndef Decimal_h
32#define Decimal_h
33
34#include <stdint.h>
35#include <wtf/Assertions.h>
36#include <wtf/text/WTFString.h>
37
38namespace WebCore {
39
40namespace DecimalPrivate {
41class SpecialValueHandler;
42}
43
44// This class represents decimal base floating point number.
45//
46// FIXME: Once all C++ compiler support decimal type, we should replace this
47// class to compiler supported one. See below URI for current status of decimal
48// type for C++: // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1977.html
49class Decimal {
50    WTF_MAKE_FAST_ALLOCATED;
51public:
52    enum Sign {
53        Positive,
54        Negative,
55    };
56
57    // You should not use EncodedData other than unit testing.
58    class EncodedData {
59        // For accessing FormatClass.
60        friend class Decimal;
61        friend class DecimalPrivate::SpecialValueHandler;
62    public:
63        EncodedData(Sign, int exponent, uint64_t coefficient);
64
65        bool operator==(const EncodedData&) const;
66        bool operator!=(const EncodedData& another) const { return !operator==(another); }
67
68        uint64_t coefficient() const { return m_coefficient; }
69        int countDigits() const;
70        int exponent() const { return m_exponent; }
71        bool isFinite() const { return !isSpecial(); }
72        bool isInfinity() const { return m_formatClass == ClassInfinity; }
73        bool isNaN() const { return m_formatClass == ClassNaN; }
74        bool isSpecial() const { return m_formatClass == ClassInfinity || m_formatClass == ClassNaN; }
75        bool isZero() const { return m_formatClass == ClassZero; }
76        Sign sign() const { return m_sign; }
77        void setSign(Sign sign) { m_sign = sign; }
78
79    private:
80        enum FormatClass {
81            ClassInfinity,
82            ClassNormal,
83            ClassNaN,
84            ClassZero,
85        };
86
87        EncodedData(Sign, FormatClass);
88        FormatClass formatClass() const { return m_formatClass; }
89
90        uint64_t m_coefficient;
91        int16_t m_exponent;
92        FormatClass m_formatClass;
93        Sign m_sign;
94    };
95
96    Decimal(int32_t = 0);
97    Decimal(Sign, int exponent, uint64_t coefficient);
98    Decimal(const Decimal&);
99
100    Decimal& operator=(const Decimal&);
101    Decimal& operator+=(const Decimal&);
102    Decimal& operator-=(const Decimal&);
103    Decimal& operator*=(const Decimal&);
104    Decimal& operator/=(const Decimal&);
105
106    Decimal operator-() const;
107
108    bool operator==(const Decimal&) const;
109    bool operator!=(const Decimal&) const;
110    bool operator<(const Decimal&) const;
111    bool operator<=(const Decimal&) const;
112    bool operator>(const Decimal&) const;
113    bool operator>=(const Decimal&) const;
114
115    Decimal operator+(const Decimal&) const;
116    Decimal operator-(const Decimal&) const;
117    Decimal operator*(const Decimal&) const;
118    Decimal operator/(const Decimal&) const;
119
120    int exponent() const
121    {
122        ASSERT(isFinite());
123        return m_data.exponent();
124    }
125
126    bool isFinite() const { return m_data.isFinite(); }
127    bool isInfinity() const { return m_data.isInfinity(); }
128    bool isNaN() const { return m_data.isNaN(); }
129    bool isNegative() const { return sign() == Negative; }
130    bool isPositive() const { return sign() == Positive; }
131    bool isSpecial() const { return m_data.isSpecial(); }
132    bool isZero() const { return m_data.isZero(); }
133
134    Decimal abs() const;
135    Decimal ceiling() const;
136    Decimal floor() const;
137    Decimal remainder(const Decimal&) const;
138    Decimal round() const;
139
140    double toDouble() const;
141    // Note: toString method supports infinity and nan but fromString not.
142    String toString() const;
143
144    static Decimal fromDouble(double);
145    // fromString supports following syntax EBNF:
146    //  number ::= sign? digit+ ('.' digit*) (exponent-marker sign? digit+)?
147    //          | sign? '.' digit+ (exponent-marker sign? digit+)?
148    //  sign ::= '+' | '-'
149    //  exponent-marker ::= 'e' | 'E'
150    //  digit ::= '0' | '1' | ... | '9'
151    // Note: fromString doesn't support "infinity" and "nan".
152    static Decimal fromString(const String&);
153    static Decimal infinity(Sign);
154    static Decimal nan();
155    static Decimal zero(Sign);
156
157    // You should not use below methods. We expose them for unit testing.
158    explicit Decimal(const EncodedData&);
159    const EncodedData& value() const { return m_data; }
160
161private:
162    struct AlignedOperands {
163        uint64_t lhsCoefficient;
164        uint64_t rhsCoefficient;
165        int exponent;
166    };
167
168    Decimal(double);
169    Decimal compareTo(const Decimal&) const;
170
171    static AlignedOperands alignOperands(const Decimal& lhs, const Decimal& rhs);
172    static inline Sign invertSign(Sign sign) { return sign == Negative ? Positive : Negative; }
173
174    Sign sign() const { return m_data.sign(); }
175
176    EncodedData m_data;
177};
178
179} // namespace WebCore
180
181#endif // Decimal_h
182