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/checks.h" 11 #include "src/handles.h" 12 #include "src/objects.h" 13 #include "src/utils.h" 14 15 namespace v8 { 16 namespace internal { 17 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 // For NaN and values outside the int range, return INT_MIN or INT_MAX. 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 9.4. 80 inline double DoubleToInteger(double x); 81 82 83 // This function should match the exact semantics of ECMA-262 9.5. 84 inline int32_t DoubleToInt32(double x); 85 86 87 // This function should match the exact semantics of ECMA-262 9.6. 88 inline uint32_t DoubleToUint32(double x) { 89 return static_cast<uint32_t>(DoubleToInt32(x)); 90 } 91 92 93 // Enumeration for allowing octals and ignoring junk when converting 94 // strings to numbers. 95 enum ConversionFlags { 96 NO_FLAGS = 0, 97 ALLOW_HEX = 1, 98 ALLOW_OCTAL = 2, 99 ALLOW_IMPLICIT_OCTAL = 4, 100 ALLOW_BINARY = 8, 101 ALLOW_TRAILING_JUNK = 16 102 }; 103 104 105 // Converts a string into a double value according to ECMA-262 9.3.1 106 double StringToDouble(UnicodeCache* unicode_cache, 107 Vector<const uint8_t> str, 108 int flags, 109 double empty_string_val = 0); 110 double StringToDouble(UnicodeCache* unicode_cache, 111 Vector<const uc16> str, 112 int flags, 113 double empty_string_val = 0); 114 // This version expects a zero-terminated character array. 115 double StringToDouble(UnicodeCache* unicode_cache, 116 const char* str, 117 int flags, 118 double empty_string_val = 0); 119 120 // Converts a string into an integer. 121 double StringToInt(UnicodeCache* unicode_cache, 122 Vector<const uint8_t> vector, 123 int radix); 124 125 126 double StringToInt(UnicodeCache* unicode_cache, 127 Vector<const uc16> vector, 128 int radix); 129 130 const int kDoubleToCStringMinBufferSize = 100; 131 132 // Converts a double to a string value according to ECMA-262 9.8.1. 133 // The buffer should be large enough for any floating point number. 134 // 100 characters is enough. 135 const char* DoubleToCString(double value, Vector<char> buffer); 136 137 // Convert an int to a null-terminated string. The returned string is 138 // located inside the buffer, but not necessarily at the start. 139 const char* IntToCString(int n, Vector<char> buffer); 140 141 // Additional number to string conversions for the number type. 142 // The caller is responsible for calling free on the returned pointer. 143 char* DoubleToFixedCString(double value, int f); 144 char* DoubleToExponentialCString(double value, int f); 145 char* DoubleToPrecisionCString(double value, int f); 146 char* DoubleToRadixCString(double value, int radix); 147 148 149 static inline bool IsMinusZero(double value) { 150 static const DoubleRepresentation minus_zero(-0.0); 151 return DoubleRepresentation(value) == minus_zero; 152 } 153 154 155 // Integer32 is an integer that can be represented as a signed 32-bit 156 // integer. It has to be in the range [-2^31, 2^31 - 1]. 157 // We also have to check for negative 0 as it is not an Integer32. 158 static inline bool IsInt32Double(double value) { 159 return !IsMinusZero(value) && 160 value >= kMinInt && 161 value <= kMaxInt && 162 value == FastI2D(FastD2I(value)); 163 } 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 static inline bool IsUint32Double(double value) { 170 return !IsMinusZero(value) && 171 value >= 0 && 172 value <= kMaxUInt32 && 173 value == FastUI2D(FastD2UI(value)); 174 } 175 176 177 // Convert from Number object to C integer. 178 inline int32_t NumberToInt32(Object* number) { 179 if (number->IsSmi()) return Smi::cast(number)->value(); 180 return DoubleToInt32(number->Number()); 181 } 182 183 184 inline uint32_t NumberToUint32(Object* number) { 185 if (number->IsSmi()) return Smi::cast(number)->value(); 186 return DoubleToUint32(number->Number()); 187 } 188 189 190 double StringToDouble(UnicodeCache* unicode_cache, 191 String* string, 192 int flags, 193 double empty_string_val = 0.0); 194 195 196 inline bool TryNumberToSize(Isolate* isolate, 197 Object* number, size_t* result) { 198 SealHandleScope shs(isolate); 199 if (number->IsSmi()) { 200 int value = Smi::cast(number)->value(); 201 ASSERT(static_cast<unsigned>(Smi::kMaxValue) 202 <= std::numeric_limits<size_t>::max()); 203 if (value >= 0) { 204 *result = static_cast<size_t>(value); 205 return true; 206 } 207 return false; 208 } else { 209 ASSERT(number->IsHeapNumber()); 210 double value = HeapNumber::cast(number)->value(); 211 if (value >= 0 && 212 value <= std::numeric_limits<size_t>::max()) { 213 *result = static_cast<size_t>(value); 214 return true; 215 } else { 216 return false; 217 } 218 } 219 } 220 221 // Converts a number into size_t. 222 inline size_t NumberToSize(Isolate* isolate, 223 Object* number) { 224 size_t result = 0; 225 bool is_valid = TryNumberToSize(isolate, number, &result); 226 CHECK(is_valid); 227 return result; 228 } 229 230 } } // namespace v8::internal 231 232 #endif // V8_CONVERSIONS_H_ 233
