js/src/jsnum.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef jsnum_h
   8 #define jsnum_h
   9
  10 #include "mozilla/FloatingPoint.h"
  11 #include "mozilla/Range.h"
  12 #include "mozilla/Utf8.h"
  13
  14 #include <limits>
  15
  16 #include "NamespaceImports.h"
  17
  18 #include "js/Conversions.h"
  19 #include "js/friend/ErrorMessages.h"  // JSMSG_*
  20
  21 #include "vm/StringType.h"
  22
  23 namespace js {
  24
  25 namespace frontend {
  26 class ParserAtomsTable;
  27 class TaggedParserAtomIndex;
  28 }  // namespace frontend
  29
  30 class GlobalObject;
  31 class StringBuffer;
  32
  33 [[nodiscard]] extern bool InitRuntimeNumberState(JSRuntime* rt);
  34
  35 // This is a no-op if built with JS_HAS_INTL_API.
  36 extern void FinishRuntimeNumberState(JSRuntime* rt);
  37
  38 /*
  39  * This function implements ToString() as specified by ECMA-262-5 section 9.8.1;
  40  * but note that it handles integers specially for performance.
  41  * See also js::NumberToCString().
  42  */
  43 template <AllowGC allowGC>
  44 extern JSString* NumberToString(JSContext* cx, double d);
  45
  46 extern JSString* NumberToStringPure(JSContext* cx, double d);
  47
  48 extern JSAtom* NumberToAtom(JSContext* cx, double d);
  49
  50 frontend::TaggedParserAtomIndex NumberToParserAtom(
  51     FrontendContext* fc, frontend::ParserAtomsTable& parserAtoms, double d);
  52
  53 template <AllowGC allowGC>
  54 extern JSLinearString* Int32ToString(JSContext* cx, int32_t i);
  55
  56 template <AllowGC allowGC>
  57 extern JSLinearString* Int32ToStringWithHeap(JSContext* cx, int32_t i,
  58                                              gc::Heap heap);
  59
  60 extern JSLinearString* Int32ToStringPure(JSContext* cx, int32_t i);
  61
  62 extern JSString* Int32ToStringWithBase(JSContext* cx, int32_t i, int32_t base);
  63
  64 extern JSAtom* Int32ToAtom(JSContext* cx, int32_t si);
  65
  66 frontend::TaggedParserAtomIndex Int32ToParserAtom(
  67     FrontendContext* fc, frontend::ParserAtomsTable& parserAtoms, int32_t si);
  68
  69 // ES6 15.7.3.12
  70 extern bool IsInteger(double d);
  71
  72 /*
  73  * Convert an integer or double (contained in the given value) to a string and
  74  * append to the given buffer.
  75  */
  76 [[nodiscard]] extern bool NumberValueToStringBuffer(const Value& v,
  77                                                     StringBuffer& sb);
  78
  79 extern JSLinearString* IndexToString(JSContext* cx, uint32_t index);
  80
  81 struct ToCStringBuf {
  82   char sbuf[JS::MaximumNumberToStringLength] = {};
  83 };
  84
  85 struct Int32ToCStringBuf {
  86   // The amount of space large enough to store the null-terminated result of
  87   // |ToString| on any int32.
  88   //
  89   // We use the same amount for uint32 (base 10 and base 16), even though uint32
  90   // only need 11 characters (base 10) resp. 9 characters (base 16) instead of
  91   // 12 characters for int32 in base 10.
  92   static constexpr size_t MaximumInt32ToStringLength =
  93       std::numeric_limits<int32_t>::digits10 +
  94       1 +  // account for the largest possible int32 value
  95       1 +  // sign for negative numbers
  96       1    // null character
  97       ;
  98
  99   char sbuf[MaximumInt32ToStringLength] = {};
 100 };
 101
 102 // Convert a number to a C string.  This function implements ToString() as
 103 // specified by ECMA-262-5 section 9.8.1.  It handles integral values cheaply.
 104 // Infallible: always returns a non-nullptr string.
 105 // The optional `length` out-param is set to the string length of the result.
 106 extern char* NumberToCString(ToCStringBuf* cbuf, double d,
 107                              size_t* length = nullptr);
 108
 109 extern char* Int32ToCString(Int32ToCStringBuf* cbuf, int32_t value,
 110                             size_t* length = nullptr);
 111
 112 extern char* Uint32ToCString(Int32ToCStringBuf* cbuf, uint32_t value,
 113                              size_t* length = nullptr);
 114
 115 // Like NumberToCString, but accepts only unsigned integers and uses base 16.
 116 // Infallible: always returns a non-nullptr string.
 117 // The optional `length` out-param is set to the string length of the result.
 118 extern char* Uint32ToHexCString(Int32ToCStringBuf* cbuf, uint32_t value,
 119                                 size_t* length = nullptr);
 120
 121 /*
 122  * The largest positive integer such that all positive integers less than it
 123  * may be precisely represented using the IEEE-754 double-precision format.
 124  */
 125 constexpr double DOUBLE_INTEGRAL_PRECISION_LIMIT = uint64_t(1) << 53;
 126
 127 /*
 128  * The smallest positive double such that all positive doubles larger or equal
 129  * than it have an exact decimal representation without exponential form.
 130  */
 131 constexpr double DOUBLE_DECIMAL_IN_SHORTEST_LOW = 1.0e-6;
 132
 133 /*
 134  * The largest positive double such that all positive doubles less than it
 135  * have an exact decimal representation without exponential form.
 136  */
 137 constexpr double DOUBLE_DECIMAL_IN_SHORTEST_HIGH = 1.0e21;
 138
 139 /*
 140  * Parse a decimal number encoded in |chars|.  The decimal number must be
 141  * sufficiently small that it will not overflow the integrally-precise range of
 142  * the double type -- that is, the number will be smaller than
 143  * DOUBLE_INTEGRAL_PRECISION_LIMIT
 144  */
 145 template <typename CharT>
 146 extern double ParseDecimalNumber(const mozilla::Range<const CharT> chars);
 147
 148 enum class IntegerSeparatorHandling : bool { None, SkipUnderscore };
 149
 150 /*
 151  * Compute the positive integer of the given base described immediately at the
 152  * start of the range [start, end) -- no whitespace-skipping, no magical
 153  * leading-"0" octal or leading-"0x" hex behavior, no "+"/"-" parsing, just
 154  * reading the digits of the integer.  Return the index one past the end of the
 155  * digits of the integer in *endp, and return the integer itself in *dp.  If
 156  * base is 10 or a power of two the returned integer is the closest possible
 157  * double; otherwise extremely large integers may be slightly inaccurate.
 158  *
 159  * The |separatorHandling| controls whether or not numeric separators can be
 160  * part of integer string. If the option is enabled, all '_' characters in the
 161  * string are ignored. Underscore characters must not appear directly next to
 162  * each other, e.g. '1__2' will lead to an assertion.
 163  *
 164  * If [start, end) does not begin with a number with the specified base,
 165  * *dp == 0 and *endp == start upon return.
 166  */
 167 template <typename CharT>
 168 [[nodiscard]] extern bool GetPrefixInteger(
 169     const CharT* start, const CharT* end, int base,
 170     IntegerSeparatorHandling separatorHandling, const CharT** endp, double* dp);
 171
 172 inline const char16_t* ToRawChars(const char16_t* units) { return units; }
 173
 174 inline const unsigned char* ToRawChars(const unsigned char* units) {
 175   return units;
 176 }
 177
 178 inline const unsigned char* ToRawChars(const mozilla::Utf8Unit* units) {
 179   return mozilla::Utf8AsUnsignedChars(units);
 180 }
 181
 182 /**
 183  * Like GetPrefixInteger, but [start, end) must all be digits in the given
 184  * base (and so this function doesn't take a useless outparam).
 185  */
 186 template <typename CharT>
 187 [[nodiscard]] extern bool GetFullInteger(
 188     const CharT* start, const CharT* end, int base,
 189     IntegerSeparatorHandling separatorHandling, double* dp) {
 190   decltype(ToRawChars(start)) realEnd;
 191   if (GetPrefixInteger(ToRawChars(start), ToRawChars(end), base,
 192                        separatorHandling, &realEnd, dp)) {
 193     MOZ_ASSERT(end == static_cast<const void*>(realEnd));
 194     return true;
 195   }
 196   return false;
 197 }
 198
 199 /*
 200  * This is like GetPrefixInteger, but only deals with base 10, always ignores
 201  * '_', and doesn't have an |endp| outparam. It should only be used when the
 202  * characters are known to match |DecimalIntegerLiteral|, cf. ES2020, 11.8.3
 203  * Numeric Literals.
 204  */
 205 template <typename CharT>
 206 [[nodiscard]] extern bool GetDecimalInteger(const CharT* start,
 207                                             const CharT* end, double* dp);
 208
 209 /*
 210  * This is like GetDecimalInteger, but also allows non-integer numbers. It
 211  * should only be used when the characters are known to match |DecimalLiteral|,
 212  * cf. ES2020, 11.8.3 Numeric Literals.
 213  */
 214 template <typename CharT>
 215 [[nodiscard]] extern bool GetDecimal(const CharT* start, const CharT* end,
 216                                      double* dp);
 217
 218 template <typename CharT>
 219 double CharsToNumber(const CharT* chars, size_t length);
 220
 221 [[nodiscard]] extern bool StringToNumber(JSContext* cx, JSString* str,
 222                                          double* result);
 223
 224 [[nodiscard]] extern bool StringToNumberPure(JSContext* cx, JSString* str,
 225                                              double* result);
 226
 227 // Infallible version of StringToNumber for linear strings.
 228 extern double LinearStringToNumber(JSLinearString* str);
 229
 230 // Parse the input string as if Number.parseInt had been called.
 231 extern bool NumberParseInt(JSContext* cx, JS::HandleString str, int32_t radix,
 232                            JS::MutableHandleValue result);
 233
 234 /* ES5 9.3 ToNumber, overwriting *vp with the appropriate number value. */
 235 [[nodiscard]] MOZ_ALWAYS_INLINE bool ToNumber(JSContext* cx,
 236                                               JS::MutableHandleValue vp) {
 237   if (vp.isNumber()) {
 238     return true;
 239   }
 240   double d;
 241   extern JS_PUBLIC_API bool ToNumberSlow(JSContext * cx, HandleValue v,
 242                                          double* dp);
 243   if (!ToNumberSlow(cx, vp, &d)) {
 244     return false;
 245   }
 246
 247   vp.setNumber(d);
 248   return true;
 249 }
 250
 251 bool ToNumericSlow(JSContext* cx, JS::MutableHandleValue vp);
 252
 253 // BigInt proposal section 3.1.6
 254 [[nodiscard]] MOZ_ALWAYS_INLINE bool ToNumeric(JSContext* cx,
 255                                                JS::MutableHandleValue vp) {
 256   if (vp.isNumeric()) {
 257     return true;
 258   }
 259   return ToNumericSlow(cx, vp);
 260 }
 261
 262 bool ToInt32OrBigIntSlow(JSContext* cx, JS::MutableHandleValue vp);
 263
 264 [[nodiscard]] MOZ_ALWAYS_INLINE bool ToInt32OrBigInt(
 265     JSContext* cx, JS::MutableHandleValue vp) {
 266   if (vp.isInt32()) {
 267     return true;
 268   }
 269   return ToInt32OrBigIntSlow(cx, vp);
 270 }
 271
 272 } /* namespace js */
 273
 274 /*
 275  * Similar to strtod except that it replaces overflows with infinities of the
 276  * correct sign, and underflows with zeros of the correct sign.  Guaranteed to
 277  * return the closest double number to the given input.
 278  *
 279  * Also allows inputs of the form [+|-]Infinity, which produce an infinity of
 280  * the appropriate sign.  The case of the "Infinity" string must match exactly.
 281  * If the string does not contain a number, set *dEnd to begin and return 0.0.
 282  */
 283 template <typename CharT>
 284 [[nodiscard]] extern double js_strtod(const CharT* begin, const CharT* end,
 285                                       const CharT** dEnd);
 286
 287 namespace js {
 288
 289 /**
 290  * Like js_strtod, but for when the number always constitutes the entire range
 291  * (and so |dEnd| would be a value already known).
 292  */
 293 template <typename CharT>
 294 [[nodiscard]] extern double FullStringToDouble(const CharT* begin,
 295                                                const CharT* end) {
 296   decltype(ToRawChars(begin)) realEnd;
 297   double d = js_strtod(ToRawChars(begin), ToRawChars(end), &realEnd);
 298   MOZ_ASSERT(end == static_cast<const void*>(realEnd));
 299   return d;
 300 }
 301
 302 [[nodiscard]] extern bool ThisNumberValueForToLocaleString(JSContext* cx,
 303                                                            unsigned argc,
 304                                                            Value* vp);
 305
 306 [[nodiscard]] extern bool num_valueOf(JSContext* cx, unsigned argc, Value* vp);
 307
 308 /*
 309  * Returns true if the given value is definitely an index: that is, the value
 310  * is a number that's an unsigned 32-bit integer.
 311  *
 312  * This method prioritizes common-case speed over accuracy in every case.  It
 313  * can produce false negatives (but not false positives): some values which are
 314  * indexes will be reported not to be indexes by this method.  Users must
 315  * consider this possibility when using this method.
 316  */
 317 static MOZ_ALWAYS_INLINE bool IsDefinitelyIndex(const Value& v,
 318                                                 uint32_t* indexp) {
 319   if (v.isInt32() && v.toInt32() >= 0) {
 320     *indexp = v.toInt32();
 321     return true;
 322   }
 323
 324   int32_t i;
 325   if (v.isDouble() && mozilla::NumberEqualsInt32(v.toDouble(), &i) && i >= 0) {
 326     *indexp = uint32_t(i);
 327     return true;
 328   }
 329
 330   if (v.isString() && v.toString()->hasIndexValue()) {
 331     *indexp = v.toString()->getIndexValue();
 332     return true;
 333   }
 334
 335   return false;
 336 }
 337
 338 // ES2020 draft rev 6b05bc56ba4e3c7a2b9922c4282d9eb844426d9b
 339 // 7.1.5 ToInteger ( argument )
 340 [[nodiscard]] static inline bool ToInteger(JSContext* cx, HandleValue v,
 341                                            double* dp) {
 342   if (v.isInt32()) {
 343     *dp = v.toInt32();
 344     return true;
 345   }
 346   if (v.isDouble()) {
 347     *dp = v.toDouble();
 348   } else if (v.isString() && v.toString()->hasIndexValue()) {
 349     *dp = v.toString()->getIndexValue();
 350     return true;
 351   } else {
 352     extern JS_PUBLIC_API bool ToNumberSlow(JSContext * cx, HandleValue v,
 353                                            double* dp);
 354     if (!ToNumberSlow(cx, v, dp)) {
 355       return false;
 356     }
 357   }
 358   *dp = JS::ToInteger(*dp);
 359   return true;
 360 }
 361
 362 /* ES2017 draft 7.1.17 ToIndex
 363  *
 364  * Return true and set |*index| to the integer value if |v| is a valid
 365  * integer index value. Otherwise report a RangeError and return false.
 366  *
 367  * The returned index will always be in the range 0 <= *index <= 2^53-1.
 368  */
 369 [[nodiscard]] extern bool ToIndexSlow(JSContext* cx, JS::HandleValue v,
 370                                       const unsigned errorNumber,
 371                                       uint64_t* index);
 372
 373 [[nodiscard]] static inline bool ToIndex(JSContext* cx, JS::HandleValue v,
 374                                          const unsigned errorNumber,
 375                                          uint64_t* index) {
 376   if (v.isInt32()) {
 377     int32_t i = v.toInt32();
 378     if (i >= 0) {
 379       *index = uint64_t(i);
 380       return true;
 381     }
 382   }
 383   return ToIndexSlow(cx, v, errorNumber, index);
 384 }
 385
 386 [[nodiscard]] static inline bool ToIndex(JSContext* cx, JS::HandleValue v,
 387                                          uint64_t* index) {
 388   return ToIndex(cx, v, JSMSG_BAD_INDEX, index);
 389 }
 390
 391 } /* namespace js */
 392
 393 #endif /* jsnum_h */