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