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