1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #ifndef V8_CONVERSIONS_H_
6 #define V8_CONVERSIONS_H_
7
8 #include <limits>
9
10 #include "src/base/logging.h"
11 #include "src/utils.h"
12
13 namespace v8 {
14 namespace internal {
15
16 template <typename T>
17 class Handle;
18 class UnicodeCache;
19
20 // Maximum number of significant digits in decimal representation.
21 // The longest possible double in decimal representation is
22 // (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
23 // (768 digits). If we parse a number whose first digits are equal to a
24 // mean of 2 adjacent doubles (that could have up to 769 digits) the result
25 // must be rounded to the bigger one unless the tail consists of zeros, so
26 // we don't need to preserve all the digits.
27 const int kMaxSignificantDigits = 772;
28
29
isDigit(int x,int radix)30 inline bool isDigit(int x, int radix) {
31 return (x >= '0' && x <= '9' && x < '0' + radix)
32 || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
33 || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
34 }
35
36
isBinaryDigit(int x)37 inline bool isBinaryDigit(int x) {
38 return x == '0' || x == '1';
39 }
40
41
42 // The fast double-to-(unsigned-)int conversion routine does not guarantee
43 // rounding towards zero.
44 // If x is NaN, the result is INT_MIN. Otherwise the result is the argument x,
45 // clamped to [INT_MIN, INT_MAX] and then rounded to an integer.
FastD2IChecked(double x)46 inline int FastD2IChecked(double x) {
47 if (!(x >= INT_MIN)) return INT_MIN; // Negation to catch NaNs.
48 if (x > INT_MAX) return INT_MAX;
49 return static_cast<int>(x);
50 }
51
52
53 // The fast double-to-(unsigned-)int conversion routine does not guarantee
54 // rounding towards zero.
55 // The result is unspecified if x is infinite or NaN, or if the rounded
56 // integer value is outside the range of type int.
FastD2I(double x)57 inline int FastD2I(double x) {
58 return static_cast<int32_t>(x);
59 }
60
61 inline unsigned int FastD2UI(double x);
62
63
FastI2D(int x)64 inline double FastI2D(int x) {
65 // There is no rounding involved in converting an integer to a
66 // double, so this code should compile to a few instructions without
67 // any FPU pipeline stalls.
68 return static_cast<double>(x);
69 }
70
71
FastUI2D(unsigned x)72 inline double FastUI2D(unsigned x) {
73 // There is no rounding involved in converting an unsigned integer to a
74 // double, so this code should compile to a few instructions without
75 // any FPU pipeline stalls.
76 return static_cast<double>(x);
77 }
78
79
80 // This function should match the exact semantics of ECMA-262 20.2.2.17.
81 inline float DoubleToFloat32(double x);
82
83
84 // This function should match the exact semantics of ECMA-262 9.4.
85 inline double DoubleToInteger(double x);
86
87
88 // This function should match the exact semantics of ECMA-262 9.5.
89 inline int32_t DoubleToInt32(double x);
90
91
92 // This function should match the exact semantics of ECMA-262 9.6.
93 inline uint32_t DoubleToUint32(double x);
94
95
96 // Enumeration for allowing octals and ignoring junk when converting
97 // strings to numbers.
98 enum ConversionFlags {
99 NO_FLAGS = 0,
100 ALLOW_HEX = 1,
101 ALLOW_OCTAL = 2,
102 ALLOW_IMPLICIT_OCTAL = 4,
103 ALLOW_BINARY = 8,
104 ALLOW_TRAILING_JUNK = 16
105 };
106
107
108 // Converts a string into a double value according to ECMA-262 9.3.1
109 double StringToDouble(UnicodeCache* unicode_cache,
110 Vector<const uint8_t> str,
111 int flags,
112 double empty_string_val = 0);
113 double StringToDouble(UnicodeCache* unicode_cache,
114 Vector<const uc16> str,
115 int flags,
116 double empty_string_val = 0);
117 // This version expects a zero-terminated character array.
118 double StringToDouble(UnicodeCache* unicode_cache,
119 const char* str,
120 int flags,
121 double empty_string_val = 0);
122
123 // Converts a string into an integer.
124 double StringToInt(UnicodeCache* unicode_cache,
125 Vector<const uint8_t> vector,
126 int radix);
127
128
129 double StringToInt(UnicodeCache* unicode_cache,
130 Vector<const uc16> vector,
131 int radix);
132
133 const int kDoubleToCStringMinBufferSize = 100;
134
135 // Converts a double to a string value according to ECMA-262 9.8.1.
136 // The buffer should be large enough for any floating point number.
137 // 100 characters is enough.
138 const char* DoubleToCString(double value, Vector<char> buffer);
139
140 // Convert an int to a null-terminated string. The returned string is
141 // located inside the buffer, but not necessarily at the start.
142 const char* IntToCString(int n, Vector<char> buffer);
143
144 // Additional number to string conversions for the number type.
145 // The caller is responsible for calling free on the returned pointer.
146 char* DoubleToFixedCString(double value, int f);
147 char* DoubleToExponentialCString(double value, int f);
148 char* DoubleToPrecisionCString(double value, int f);
149 char* DoubleToRadixCString(double value, int radix);
150
IsMinusZero(double value)151 static inline bool IsMinusZero(double value) {
152 return bit_cast<int64_t>(value) == bit_cast<int64_t>(-0.0);
153 }
154
155 // Returns true if value can be converted to a SMI, and returns the resulting
156 // integer value of the SMI in |smi_int_value|.
157 inline bool DoubleToSmiInteger(double value, int* smi_int_value);
158
159 inline bool IsSmiDouble(double value);
160
161 // Integer32 is an integer that can be represented as a signed 32-bit
162 // integer. It has to be in the range [-2^31, 2^31 - 1].
163 // We also have to check for negative 0 as it is not an Integer32.
164 inline bool IsInt32Double(double value);
165
166 // UInteger32 is an integer that can be represented as an unsigned 32-bit
167 // integer. It has to be in the range [0, 2^32 - 1].
168 // We also have to check for negative 0 as it is not a UInteger32.
169 inline bool IsUint32Double(double value);
170
171 // Tries to convert |value| to a uint32, setting the result in |uint32_value|.
172 // If the output does not compare equal to the input, returns false and the
173 // value in |uint32_value| is left unspecified.
174 // Used for conversions such as in ECMA-262 15.4.2.2, which check "ToUint32(len)
175 // is equal to len".
176 inline bool DoubleToUint32IfEqualToSelf(double value, uint32_t* uint32_value);
177
178 // Convert from Number object to C integer.
179 inline uint32_t PositiveNumberToUint32(Object* number);
180 inline int32_t NumberToInt32(Object* number);
181 inline uint32_t NumberToUint32(Object* number);
182 inline int64_t NumberToInt64(Object* number);
183
184 double StringToDouble(UnicodeCache* unicode_cache, Handle<String> string,
185 int flags, double empty_string_val = 0.0);
186
187 inline bool TryNumberToSize(Object* number, size_t* result);
188
189 // Converts a number into size_t.
190 inline size_t NumberToSize(Object* number);
191
192 // returns DoubleToString(StringToDouble(string)) == string
193 bool IsSpecialIndex(UnicodeCache* unicode_cache, String* string);
194
195 } // namespace internal
196 } // namespace v8
197
198 #endif // V8_CONVERSIONS_H_
199