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 14namespace v8 { 15namespace internal { 16 17class 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. 26const int kMaxSignificantDigits = 772; 27 28 29inline 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 36inline 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. 45inline 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. 56inline int FastD2I(double x) { 57 return static_cast<int32_t>(x); 58} 59 60inline unsigned int FastD2UI(double x); 61 62 63inline 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 71inline 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. 80inline float DoubleToFloat32(double x); 81 82 83// This function should match the exact semantics of ECMA-262 9.4. 84inline double DoubleToInteger(double x); 85 86 87// This function should match the exact semantics of ECMA-262 9.5. 88inline int32_t DoubleToInt32(double x); 89 90 91// This function should match the exact semantics of ECMA-262 9.6. 92inline uint32_t DoubleToUint32(double x); 93 94 95// Enumeration for allowing octals and ignoring junk when converting 96// strings to numbers. 97enum 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 108double StringToDouble(UnicodeCache* unicode_cache, 109 Vector<const uint8_t> str, 110 int flags, 111 double empty_string_val = 0); 112double 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. 117double 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. 123double StringToInt(UnicodeCache* unicode_cache, 124 Vector<const uint8_t> vector, 125 int radix); 126 127 128double StringToInt(UnicodeCache* unicode_cache, 129 Vector<const uc16> vector, 130 int radix); 131 132const 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. 137const 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. 141const 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. 145char* DoubleToFixedCString(double value, int f); 146char* DoubleToExponentialCString(double value, int f); 147char* DoubleToPrecisionCString(double value, int f); 148char* DoubleToRadixCString(double value, int radix); 149 150static inline bool IsMinusZero(double value) { 151 return bit_cast<int64_t>(value) == bit_cast<int64_t>(-0.0); 152} 153 154// Returns true if value can be converted to a SMI, and returns the resulting 155// integer value of the SMI in |smi_int_value|. 156inline bool DoubleToSmiInteger(double value, int* smi_int_value); 157 158inline bool IsSmiDouble(double value); 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. 163inline bool IsInt32Double(double value); 164 165// UInteger32 is an integer that can be represented as an unsigned 32-bit 166// integer. It has to be in the range [0, 2^32 - 1]. 167// We also have to check for negative 0 as it is not a UInteger32. 168inline bool IsUint32Double(double value); 169 170// Convert from Number object to C integer. 171inline int32_t NumberToInt32(Object* number); 172inline uint32_t NumberToUint32(Object* number); 173inline int64_t NumberToInt64(Object* number); 174 175double StringToDouble(UnicodeCache* unicode_cache, Handle<String> string, 176 int flags, double empty_string_val = 0.0); 177 178inline bool TryNumberToSize(Object* number, size_t* result); 179 180// Converts a number into size_t. 181inline size_t NumberToSize(Object* number); 182 183// returns DoubleToString(StringToDouble(string)) == string 184bool IsSpecialIndex(UnicodeCache* unicode_cache, String* string); 185 186} // namespace internal 187} // namespace v8 188 189#endif // V8_CONVERSIONS_H_ 190