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