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 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 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. 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. 57 inline int FastD2I(double x) { 58 return static_cast<int32_t>(x); 59 } 60 61 inline unsigned int FastD2UI(double x); 62 63 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 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); 150 151 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
