1// Copyright 2011 the V8 project authors. All rights reserved.
2// Redistribution and use in source and binary forms, with or without
3// modification, are permitted provided that the following conditions are
4// met:
5//
6//     * Redistributions of source code must retain the above copyright
7//       notice, this list of conditions and the following disclaimer.
8//     * Redistributions in binary form must reproduce the above
9//       copyright notice, this list of conditions and the following
10//       disclaimer in the documentation and/or other materials provided
11//       with the distribution.
12//     * Neither the name of Google Inc. nor the names of its
13//       contributors may be used to endorse or promote products derived
14//       from this software without specific prior written permission.
15//
16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27
28#include <stdarg.h>
29#include <limits.h>
30
31#include "v8.h"
32
33#include "conversions-inl.h"
34#include "dtoa.h"
35#include "factory.h"
36#include "scanner-base.h"
37#include "strtod.h"
38
39namespace v8 {
40namespace internal {
41
42namespace {
43
44// C++-style iterator adaptor for StringInputBuffer
45// (unlike C++ iterators the end-marker has different type).
46class StringInputBufferIterator {
47 public:
48  class EndMarker {};
49
50  explicit StringInputBufferIterator(StringInputBuffer* buffer);
51
52  int operator*() const;
53  void operator++();
54  bool operator==(EndMarker const&) const { return end_; }
55  bool operator!=(EndMarker const& m) const { return !end_; }
56
57 private:
58  StringInputBuffer* const buffer_;
59  int current_;
60  bool end_;
61};
62
63
64StringInputBufferIterator::StringInputBufferIterator(
65    StringInputBuffer* buffer) : buffer_(buffer) {
66  ++(*this);
67}
68
69int StringInputBufferIterator::operator*() const {
70  return current_;
71}
72
73
74void StringInputBufferIterator::operator++() {
75  end_ = !buffer_->has_more();
76  if (!end_) {
77    current_ = buffer_->GetNext();
78  }
79}
80}
81
82
83template <class Iterator, class EndMark>
84static bool SubStringEquals(Iterator* current,
85                            EndMark end,
86                            const char* substring) {
87  ASSERT(**current == *substring);
88  for (substring++; *substring != '\0'; substring++) {
89    ++*current;
90    if (*current == end || **current != *substring) return false;
91  }
92  ++*current;
93  return true;
94}
95
96
97// Maximum number of significant digits in decimal representation.
98// The longest possible double in decimal representation is
99// (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
100// (768 digits). If we parse a number whose first digits are equal to a
101// mean of 2 adjacent doubles (that could have up to 769 digits) the result
102// must be rounded to the bigger one unless the tail consists of zeros, so
103// we don't need to preserve all the digits.
104const int kMaxSignificantDigits = 772;
105
106
107static const double JUNK_STRING_VALUE = OS::nan_value();
108
109
110// Returns true if a nonspace found and false if the end has reached.
111template <class Iterator, class EndMark>
112static inline bool AdvanceToNonspace(UnicodeCache* unicode_cache,
113                                     Iterator* current,
114                                     EndMark end) {
115  while (*current != end) {
116    if (!unicode_cache->IsWhiteSpace(**current)) return true;
117    ++*current;
118  }
119  return false;
120}
121
122
123static bool isDigit(int x, int radix) {
124  return (x >= '0' && x <= '9' && x < '0' + radix)
125      || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
126      || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
127}
128
129
130static double SignedZero(bool negative) {
131  return negative ? -0.0 : 0.0;
132}
133
134
135// Parsing integers with radix 2, 4, 8, 16, 32. Assumes current != end.
136template <int radix_log_2, class Iterator, class EndMark>
137static double InternalStringToIntDouble(UnicodeCache* unicode_cache,
138                                        Iterator current,
139                                        EndMark end,
140                                        bool negative,
141                                        bool allow_trailing_junk) {
142  ASSERT(current != end);
143
144  // Skip leading 0s.
145  while (*current == '0') {
146    ++current;
147    if (current == end) return SignedZero(negative);
148  }
149
150  int64_t number = 0;
151  int exponent = 0;
152  const int radix = (1 << radix_log_2);
153
154  do {
155    int digit;
156    if (*current >= '0' && *current <= '9' && *current < '0' + radix) {
157      digit = static_cast<char>(*current) - '0';
158    } else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) {
159      digit = static_cast<char>(*current) - 'a' + 10;
160    } else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) {
161      digit = static_cast<char>(*current) - 'A' + 10;
162    } else {
163      if (allow_trailing_junk ||
164          !AdvanceToNonspace(unicode_cache, &current, end)) {
165        break;
166      } else {
167        return JUNK_STRING_VALUE;
168      }
169    }
170
171    number = number * radix + digit;
172    int overflow = static_cast<int>(number >> 53);
173    if (overflow != 0) {
174      // Overflow occurred. Need to determine which direction to round the
175      // result.
176      int overflow_bits_count = 1;
177      while (overflow > 1) {
178        overflow_bits_count++;
179        overflow >>= 1;
180      }
181
182      int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
183      int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
184      number >>= overflow_bits_count;
185      exponent = overflow_bits_count;
186
187      bool zero_tail = true;
188      while (true) {
189        ++current;
190        if (current == end || !isDigit(*current, radix)) break;
191        zero_tail = zero_tail && *current == '0';
192        exponent += radix_log_2;
193      }
194
195      if (!allow_trailing_junk &&
196          AdvanceToNonspace(unicode_cache, &current, end)) {
197        return JUNK_STRING_VALUE;
198      }
199
200      int middle_value = (1 << (overflow_bits_count - 1));
201      if (dropped_bits > middle_value) {
202        number++;  // Rounding up.
203      } else if (dropped_bits == middle_value) {
204        // Rounding to even to consistency with decimals: half-way case rounds
205        // up if significant part is odd and down otherwise.
206        if ((number & 1) != 0 || !zero_tail) {
207          number++;  // Rounding up.
208        }
209      }
210
211      // Rounding up may cause overflow.
212      if ((number & ((int64_t)1 << 53)) != 0) {
213        exponent++;
214        number >>= 1;
215      }
216      break;
217    }
218    ++current;
219  } while (current != end);
220
221  ASSERT(number < ((int64_t)1 << 53));
222  ASSERT(static_cast<int64_t>(static_cast<double>(number)) == number);
223
224  if (exponent == 0) {
225    if (negative) {
226      if (number == 0) return -0.0;
227      number = -number;
228    }
229    return static_cast<double>(number);
230  }
231
232  ASSERT(number != 0);
233  // The double could be constructed faster from number (mantissa), exponent
234  // and sign. Assuming it's a rare case more simple code is used.
235  return static_cast<double>(negative ? -number : number) * pow(2.0, exponent);
236}
237
238
239template <class Iterator, class EndMark>
240static double InternalStringToInt(UnicodeCache* unicode_cache,
241                                  Iterator current,
242                                  EndMark end,
243                                  int radix) {
244  const bool allow_trailing_junk = true;
245  const double empty_string_val = JUNK_STRING_VALUE;
246
247  if (!AdvanceToNonspace(unicode_cache, &current, end)) {
248    return empty_string_val;
249  }
250
251  bool negative = false;
252  bool leading_zero = false;
253
254  if (*current == '+') {
255    // Ignore leading sign; skip following spaces.
256    ++current;
257    if (!AdvanceToNonspace(unicode_cache, &current, end)) {
258      return JUNK_STRING_VALUE;
259    }
260  } else if (*current == '-') {
261    ++current;
262    if (!AdvanceToNonspace(unicode_cache, &current, end)) {
263      return JUNK_STRING_VALUE;
264    }
265    negative = true;
266  }
267
268  if (radix == 0) {
269    // Radix detection.
270    if (*current == '0') {
271      ++current;
272      if (current == end) return SignedZero(negative);
273      if (*current == 'x' || *current == 'X') {
274        radix = 16;
275        ++current;
276        if (current == end) return JUNK_STRING_VALUE;
277      } else {
278        radix = 8;
279        leading_zero = true;
280      }
281    } else {
282      radix = 10;
283    }
284  } else if (radix == 16) {
285    if (*current == '0') {
286      // Allow "0x" prefix.
287      ++current;
288      if (current == end) return SignedZero(negative);
289      if (*current == 'x' || *current == 'X') {
290        ++current;
291        if (current == end) return JUNK_STRING_VALUE;
292      } else {
293        leading_zero = true;
294      }
295    }
296  }
297
298  if (radix < 2 || radix > 36) return JUNK_STRING_VALUE;
299
300  // Skip leading zeros.
301  while (*current == '0') {
302    leading_zero = true;
303    ++current;
304    if (current == end) return SignedZero(negative);
305  }
306
307  if (!leading_zero && !isDigit(*current, radix)) {
308    return JUNK_STRING_VALUE;
309  }
310
311  if (IsPowerOf2(radix)) {
312    switch (radix) {
313      case 2:
314        return InternalStringToIntDouble<1>(
315            unicode_cache, current, end, negative, allow_trailing_junk);
316      case 4:
317        return InternalStringToIntDouble<2>(
318            unicode_cache, current, end, negative, allow_trailing_junk);
319      case 8:
320        return InternalStringToIntDouble<3>(
321            unicode_cache, current, end, negative, allow_trailing_junk);
322
323      case 16:
324        return InternalStringToIntDouble<4>(
325            unicode_cache, current, end, negative, allow_trailing_junk);
326
327      case 32:
328        return InternalStringToIntDouble<5>(
329            unicode_cache, current, end, negative, allow_trailing_junk);
330      default:
331        UNREACHABLE();
332    }
333  }
334
335  if (radix == 10) {
336    // Parsing with strtod.
337    const int kMaxSignificantDigits = 309;  // Doubles are less than 1.8e308.
338    // The buffer may contain up to kMaxSignificantDigits + 1 digits and a zero
339    // end.
340    const int kBufferSize = kMaxSignificantDigits + 2;
341    char buffer[kBufferSize];
342    int buffer_pos = 0;
343    while (*current >= '0' && *current <= '9') {
344      if (buffer_pos <= kMaxSignificantDigits) {
345        // If the number has more than kMaxSignificantDigits it will be parsed
346        // as infinity.
347        ASSERT(buffer_pos < kBufferSize);
348        buffer[buffer_pos++] = static_cast<char>(*current);
349      }
350      ++current;
351      if (current == end) break;
352    }
353
354    if (!allow_trailing_junk &&
355        AdvanceToNonspace(unicode_cache, &current, end)) {
356      return JUNK_STRING_VALUE;
357    }
358
359    ASSERT(buffer_pos < kBufferSize);
360    buffer[buffer_pos] = '\0';
361    Vector<const char> buffer_vector(buffer, buffer_pos);
362    return negative ? -Strtod(buffer_vector, 0) : Strtod(buffer_vector, 0);
363  }
364
365  // The following code causes accumulating rounding error for numbers greater
366  // than ~2^56. It's explicitly allowed in the spec: "if R is not 2, 4, 8, 10,
367  // 16, or 32, then mathInt may be an implementation-dependent approximation to
368  // the mathematical integer value" (15.1.2.2).
369
370  int lim_0 = '0' + (radix < 10 ? radix : 10);
371  int lim_a = 'a' + (radix - 10);
372  int lim_A = 'A' + (radix - 10);
373
374  // NOTE: The code for computing the value may seem a bit complex at
375  // first glance. It is structured to use 32-bit multiply-and-add
376  // loops as long as possible to avoid loosing precision.
377
378  double v = 0.0;
379  bool done = false;
380  do {
381    // Parse the longest part of the string starting at index j
382    // possible while keeping the multiplier, and thus the part
383    // itself, within 32 bits.
384    unsigned int part = 0, multiplier = 1;
385    while (true) {
386      int d;
387      if (*current >= '0' && *current < lim_0) {
388        d = *current - '0';
389      } else if (*current >= 'a' && *current < lim_a) {
390        d = *current - 'a' + 10;
391      } else if (*current >= 'A' && *current < lim_A) {
392        d = *current - 'A' + 10;
393      } else {
394        done = true;
395        break;
396      }
397
398      // Update the value of the part as long as the multiplier fits
399      // in 32 bits. When we can't guarantee that the next iteration
400      // will not overflow the multiplier, we stop parsing the part
401      // by leaving the loop.
402      const unsigned int kMaximumMultiplier = 0xffffffffU / 36;
403      uint32_t m = multiplier * radix;
404      if (m > kMaximumMultiplier) break;
405      part = part * radix + d;
406      multiplier = m;
407      ASSERT(multiplier > part);
408
409      ++current;
410      if (current == end) {
411        done = true;
412        break;
413      }
414    }
415
416    // Update the value and skip the part in the string.
417    v = v * multiplier + part;
418  } while (!done);
419
420  if (!allow_trailing_junk &&
421      AdvanceToNonspace(unicode_cache, &current, end)) {
422    return JUNK_STRING_VALUE;
423  }
424
425  return negative ? -v : v;
426}
427
428
429// Converts a string to a double value. Assumes the Iterator supports
430// the following operations:
431// 1. current == end (other ops are not allowed), current != end.
432// 2. *current - gets the current character in the sequence.
433// 3. ++current (advances the position).
434template <class Iterator, class EndMark>
435static double InternalStringToDouble(UnicodeCache* unicode_cache,
436                                     Iterator current,
437                                     EndMark end,
438                                     int flags,
439                                     double empty_string_val) {
440  // To make sure that iterator dereferencing is valid the following
441  // convention is used:
442  // 1. Each '++current' statement is followed by check for equality to 'end'.
443  // 2. If AdvanceToNonspace returned false then current == end.
444  // 3. If 'current' becomes be equal to 'end' the function returns or goes to
445  // 'parsing_done'.
446  // 4. 'current' is not dereferenced after the 'parsing_done' label.
447  // 5. Code before 'parsing_done' may rely on 'current != end'.
448  if (!AdvanceToNonspace(unicode_cache, &current, end)) {
449    return empty_string_val;
450  }
451
452  const bool allow_trailing_junk = (flags & ALLOW_TRAILING_JUNK) != 0;
453
454  // The longest form of simplified number is: "-<significant digits>'.1eXXX\0".
455  const int kBufferSize = kMaxSignificantDigits + 10;
456  char buffer[kBufferSize];  // NOLINT: size is known at compile time.
457  int buffer_pos = 0;
458
459  // Exponent will be adjusted if insignificant digits of the integer part
460  // or insignificant leading zeros of the fractional part are dropped.
461  int exponent = 0;
462  int significant_digits = 0;
463  int insignificant_digits = 0;
464  bool nonzero_digit_dropped = false;
465  bool fractional_part = false;
466
467  bool negative = false;
468
469  if (*current == '+') {
470    // Ignore leading sign.
471    ++current;
472    if (current == end) return JUNK_STRING_VALUE;
473  } else if (*current == '-') {
474    ++current;
475    if (current == end) return JUNK_STRING_VALUE;
476    negative = true;
477  }
478
479  static const char kInfinitySymbol[] = "Infinity";
480  if (*current == kInfinitySymbol[0]) {
481    if (!SubStringEquals(&current, end, kInfinitySymbol)) {
482      return JUNK_STRING_VALUE;
483    }
484
485    if (!allow_trailing_junk &&
486        AdvanceToNonspace(unicode_cache, &current, end)) {
487      return JUNK_STRING_VALUE;
488    }
489
490    ASSERT(buffer_pos == 0);
491    return negative ? -V8_INFINITY : V8_INFINITY;
492  }
493
494  bool leading_zero = false;
495  if (*current == '0') {
496    ++current;
497    if (current == end) return SignedZero(negative);
498
499    leading_zero = true;
500
501    // It could be hexadecimal value.
502    if ((flags & ALLOW_HEX) && (*current == 'x' || *current == 'X')) {
503      ++current;
504      if (current == end || !isDigit(*current, 16)) {
505        return JUNK_STRING_VALUE;  // "0x".
506      }
507
508      return InternalStringToIntDouble<4>(unicode_cache,
509                                          current,
510                                          end,
511                                          negative,
512                                          allow_trailing_junk);
513    }
514
515    // Ignore leading zeros in the integer part.
516    while (*current == '0') {
517      ++current;
518      if (current == end) return SignedZero(negative);
519    }
520  }
521
522  bool octal = leading_zero && (flags & ALLOW_OCTALS) != 0;
523
524  // Copy significant digits of the integer part (if any) to the buffer.
525  while (*current >= '0' && *current <= '9') {
526    if (significant_digits < kMaxSignificantDigits) {
527      ASSERT(buffer_pos < kBufferSize);
528      buffer[buffer_pos++] = static_cast<char>(*current);
529      significant_digits++;
530      // Will later check if it's an octal in the buffer.
531    } else {
532      insignificant_digits++;  // Move the digit into the exponential part.
533      nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
534    }
535    octal = octal && *current < '8';
536    ++current;
537    if (current == end) goto parsing_done;
538  }
539
540  if (significant_digits == 0) {
541    octal = false;
542  }
543
544  if (*current == '.') {
545    if (octal && !allow_trailing_junk) return JUNK_STRING_VALUE;
546    if (octal) goto parsing_done;
547
548    ++current;
549    if (current == end) {
550      if (significant_digits == 0 && !leading_zero) {
551        return JUNK_STRING_VALUE;
552      } else {
553        goto parsing_done;
554      }
555    }
556
557    if (significant_digits == 0) {
558      // octal = false;
559      // Integer part consists of 0 or is absent. Significant digits start after
560      // leading zeros (if any).
561      while (*current == '0') {
562        ++current;
563        if (current == end) return SignedZero(negative);
564        exponent--;  // Move this 0 into the exponent.
565      }
566    }
567
568    // We don't emit a '.', but adjust the exponent instead.
569    fractional_part = true;
570
571    // There is a fractional part.
572    while (*current >= '0' && *current <= '9') {
573      if (significant_digits < kMaxSignificantDigits) {
574        ASSERT(buffer_pos < kBufferSize);
575        buffer[buffer_pos++] = static_cast<char>(*current);
576        significant_digits++;
577        exponent--;
578      } else {
579        // Ignore insignificant digits in the fractional part.
580        nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
581      }
582      ++current;
583      if (current == end) goto parsing_done;
584    }
585  }
586
587  if (!leading_zero && exponent == 0 && significant_digits == 0) {
588    // If leading_zeros is true then the string contains zeros.
589    // If exponent < 0 then string was [+-]\.0*...
590    // If significant_digits != 0 the string is not equal to 0.
591    // Otherwise there are no digits in the string.
592    return JUNK_STRING_VALUE;
593  }
594
595  // Parse exponential part.
596  if (*current == 'e' || *current == 'E') {
597    if (octal) return JUNK_STRING_VALUE;
598    ++current;
599    if (current == end) {
600      if (allow_trailing_junk) {
601        goto parsing_done;
602      } else {
603        return JUNK_STRING_VALUE;
604      }
605    }
606    char sign = '+';
607    if (*current == '+' || *current == '-') {
608      sign = static_cast<char>(*current);
609      ++current;
610      if (current == end) {
611        if (allow_trailing_junk) {
612          goto parsing_done;
613        } else {
614          return JUNK_STRING_VALUE;
615        }
616      }
617    }
618
619    if (current == end || *current < '0' || *current > '9') {
620      if (allow_trailing_junk) {
621        goto parsing_done;
622      } else {
623        return JUNK_STRING_VALUE;
624      }
625    }
626
627    const int max_exponent = INT_MAX / 2;
628    ASSERT(-max_exponent / 2 <= exponent && exponent <= max_exponent / 2);
629    int num = 0;
630    do {
631      // Check overflow.
632      int digit = *current - '0';
633      if (num >= max_exponent / 10
634          && !(num == max_exponent / 10 && digit <= max_exponent % 10)) {
635        num = max_exponent;
636      } else {
637        num = num * 10 + digit;
638      }
639      ++current;
640    } while (current != end && *current >= '0' && *current <= '9');
641
642    exponent += (sign == '-' ? -num : num);
643  }
644
645  if (!allow_trailing_junk &&
646      AdvanceToNonspace(unicode_cache, &current, end)) {
647    return JUNK_STRING_VALUE;
648  }
649
650  parsing_done:
651  exponent += insignificant_digits;
652
653  if (octal) {
654    return InternalStringToIntDouble<3>(unicode_cache,
655                                        buffer,
656                                        buffer + buffer_pos,
657                                        negative,
658                                        allow_trailing_junk);
659  }
660
661  if (nonzero_digit_dropped) {
662    buffer[buffer_pos++] = '1';
663    exponent--;
664  }
665
666  ASSERT(buffer_pos < kBufferSize);
667  buffer[buffer_pos] = '\0';
668
669  double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
670  return negative ? -converted : converted;
671}
672
673
674double StringToDouble(UnicodeCache* unicode_cache,
675                      String* str, int flags, double empty_string_val) {
676  StringShape shape(str);
677  if (shape.IsSequentialAscii()) {
678    const char* begin = SeqAsciiString::cast(str)->GetChars();
679    const char* end = begin + str->length();
680    return InternalStringToDouble(unicode_cache, begin, end, flags,
681                                  empty_string_val);
682  } else if (shape.IsSequentialTwoByte()) {
683    const uc16* begin = SeqTwoByteString::cast(str)->GetChars();
684    const uc16* end = begin + str->length();
685    return InternalStringToDouble(unicode_cache, begin, end, flags,
686                                  empty_string_val);
687  } else {
688    StringInputBuffer buffer(str);
689    return InternalStringToDouble(unicode_cache,
690                                  StringInputBufferIterator(&buffer),
691                                  StringInputBufferIterator::EndMarker(),
692                                  flags,
693                                  empty_string_val);
694  }
695}
696
697
698double StringToInt(UnicodeCache* unicode_cache,
699                   String* str,
700                   int radix) {
701  StringShape shape(str);
702  if (shape.IsSequentialAscii()) {
703    const char* begin = SeqAsciiString::cast(str)->GetChars();
704    const char* end = begin + str->length();
705    return InternalStringToInt(unicode_cache, begin, end, radix);
706  } else if (shape.IsSequentialTwoByte()) {
707    const uc16* begin = SeqTwoByteString::cast(str)->GetChars();
708    const uc16* end = begin + str->length();
709    return InternalStringToInt(unicode_cache, begin, end, radix);
710  } else {
711    StringInputBuffer buffer(str);
712    return InternalStringToInt(unicode_cache,
713                               StringInputBufferIterator(&buffer),
714                               StringInputBufferIterator::EndMarker(),
715                               radix);
716  }
717}
718
719
720double StringToDouble(UnicodeCache* unicode_cache,
721                      const char* str, int flags, double empty_string_val) {
722  const char* end = str + StrLength(str);
723  return InternalStringToDouble(unicode_cache, str, end, flags,
724                                empty_string_val);
725}
726
727
728double StringToDouble(UnicodeCache* unicode_cache,
729                      Vector<const char> str,
730                      int flags,
731                      double empty_string_val) {
732  const char* end = str.start() + str.length();
733  return InternalStringToDouble(unicode_cache, str.start(), end, flags,
734                                empty_string_val);
735}
736
737
738const char* DoubleToCString(double v, Vector<char> buffer) {
739  switch (fpclassify(v)) {
740    case FP_NAN: return "NaN";
741    case FP_INFINITE: return (v < 0.0 ? "-Infinity" : "Infinity");
742    case FP_ZERO: return "0";
743    default: {
744      StringBuilder builder(buffer.start(), buffer.length());
745      int decimal_point;
746      int sign;
747      const int kV8DtoaBufferCapacity = kBase10MaximalLength + 1;
748      char decimal_rep[kV8DtoaBufferCapacity];
749      int length;
750
751      DoubleToAscii(v, DTOA_SHORTEST, 0,
752                    Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
753                    &sign, &length, &decimal_point);
754
755      if (sign) builder.AddCharacter('-');
756
757      if (length <= decimal_point && decimal_point <= 21) {
758        // ECMA-262 section 9.8.1 step 6.
759        builder.AddString(decimal_rep);
760        builder.AddPadding('0', decimal_point - length);
761
762      } else if (0 < decimal_point && decimal_point <= 21) {
763        // ECMA-262 section 9.8.1 step 7.
764        builder.AddSubstring(decimal_rep, decimal_point);
765        builder.AddCharacter('.');
766        builder.AddString(decimal_rep + decimal_point);
767
768      } else if (decimal_point <= 0 && decimal_point > -6) {
769        // ECMA-262 section 9.8.1 step 8.
770        builder.AddString("0.");
771        builder.AddPadding('0', -decimal_point);
772        builder.AddString(decimal_rep);
773
774      } else {
775        // ECMA-262 section 9.8.1 step 9 and 10 combined.
776        builder.AddCharacter(decimal_rep[0]);
777        if (length != 1) {
778          builder.AddCharacter('.');
779          builder.AddString(decimal_rep + 1);
780        }
781        builder.AddCharacter('e');
782        builder.AddCharacter((decimal_point >= 0) ? '+' : '-');
783        int exponent = decimal_point - 1;
784        if (exponent < 0) exponent = -exponent;
785        builder.AddFormatted("%d", exponent);
786      }
787    return builder.Finalize();
788    }
789  }
790}
791
792
793const char* IntToCString(int n, Vector<char> buffer) {
794  bool negative = false;
795  if (n < 0) {
796    // We must not negate the most negative int.
797    if (n == kMinInt) return DoubleToCString(n, buffer);
798    negative = true;
799    n = -n;
800  }
801  // Build the string backwards from the least significant digit.
802  int i = buffer.length();
803  buffer[--i] = '\0';
804  do {
805    buffer[--i] = '0' + (n % 10);
806    n /= 10;
807  } while (n);
808  if (negative) buffer[--i] = '-';
809  return buffer.start() + i;
810}
811
812
813char* DoubleToFixedCString(double value, int f) {
814  const int kMaxDigitsBeforePoint = 21;
815  const double kFirstNonFixed = 1e21;
816  const int kMaxDigitsAfterPoint = 20;
817  ASSERT(f >= 0);
818  ASSERT(f <= kMaxDigitsAfterPoint);
819
820  bool negative = false;
821  double abs_value = value;
822  if (value < 0) {
823    abs_value = -value;
824    negative = true;
825  }
826
827  // If abs_value has more than kMaxDigitsBeforePoint digits before the point
828  // use the non-fixed conversion routine.
829  if (abs_value >= kFirstNonFixed) {
830    char arr[100];
831    Vector<char> buffer(arr, ARRAY_SIZE(arr));
832    return StrDup(DoubleToCString(value, buffer));
833  }
834
835  // Find a sufficiently precise decimal representation of n.
836  int decimal_point;
837  int sign;
838  // Add space for the '\0' byte.
839  const int kDecimalRepCapacity =
840      kMaxDigitsBeforePoint + kMaxDigitsAfterPoint + 1;
841  char decimal_rep[kDecimalRepCapacity];
842  int decimal_rep_length;
843  DoubleToAscii(value, DTOA_FIXED, f,
844                Vector<char>(decimal_rep, kDecimalRepCapacity),
845                &sign, &decimal_rep_length, &decimal_point);
846
847  // Create a representation that is padded with zeros if needed.
848  int zero_prefix_length = 0;
849  int zero_postfix_length = 0;
850
851  if (decimal_point <= 0) {
852    zero_prefix_length = -decimal_point + 1;
853    decimal_point = 1;
854  }
855
856  if (zero_prefix_length + decimal_rep_length < decimal_point + f) {
857    zero_postfix_length = decimal_point + f - decimal_rep_length -
858                          zero_prefix_length;
859  }
860
861  unsigned rep_length =
862      zero_prefix_length + decimal_rep_length + zero_postfix_length;
863  StringBuilder rep_builder(rep_length + 1);
864  rep_builder.AddPadding('0', zero_prefix_length);
865  rep_builder.AddString(decimal_rep);
866  rep_builder.AddPadding('0', zero_postfix_length);
867  char* rep = rep_builder.Finalize();
868
869  // Create the result string by appending a minus and putting in a
870  // decimal point if needed.
871  unsigned result_size = decimal_point + f + 2;
872  StringBuilder builder(result_size + 1);
873  if (negative) builder.AddCharacter('-');
874  builder.AddSubstring(rep, decimal_point);
875  if (f > 0) {
876    builder.AddCharacter('.');
877    builder.AddSubstring(rep + decimal_point, f);
878  }
879  DeleteArray(rep);
880  return builder.Finalize();
881}
882
883
884static char* CreateExponentialRepresentation(char* decimal_rep,
885                                             int exponent,
886                                             bool negative,
887                                             int significant_digits) {
888  bool negative_exponent = false;
889  if (exponent < 0) {
890    negative_exponent = true;
891    exponent = -exponent;
892  }
893
894  // Leave room in the result for appending a minus, for a period, the
895  // letter 'e', a minus or a plus depending on the exponent, and a
896  // three digit exponent.
897  unsigned result_size = significant_digits + 7;
898  StringBuilder builder(result_size + 1);
899
900  if (negative) builder.AddCharacter('-');
901  builder.AddCharacter(decimal_rep[0]);
902  if (significant_digits != 1) {
903    builder.AddCharacter('.');
904    builder.AddString(decimal_rep + 1);
905    int rep_length = StrLength(decimal_rep);
906    builder.AddPadding('0', significant_digits - rep_length);
907  }
908
909  builder.AddCharacter('e');
910  builder.AddCharacter(negative_exponent ? '-' : '+');
911  builder.AddFormatted("%d", exponent);
912  return builder.Finalize();
913}
914
915
916
917char* DoubleToExponentialCString(double value, int f) {
918  const int kMaxDigitsAfterPoint = 20;
919  // f might be -1 to signal that f was undefined in JavaScript.
920  ASSERT(f >= -1 && f <= kMaxDigitsAfterPoint);
921
922  bool negative = false;
923  if (value < 0) {
924    value = -value;
925    negative = true;
926  }
927
928  // Find a sufficiently precise decimal representation of n.
929  int decimal_point;
930  int sign;
931  // f corresponds to the digits after the point. There is always one digit
932  // before the point. The number of requested_digits equals hence f + 1.
933  // And we have to add one character for the null-terminator.
934  const int kV8DtoaBufferCapacity = kMaxDigitsAfterPoint + 1 + 1;
935  // Make sure that the buffer is big enough, even if we fall back to the
936  // shortest representation (which happens when f equals -1).
937  ASSERT(kBase10MaximalLength <= kMaxDigitsAfterPoint + 1);
938  char decimal_rep[kV8DtoaBufferCapacity];
939  int decimal_rep_length;
940
941  if (f == -1) {
942    DoubleToAscii(value, DTOA_SHORTEST, 0,
943                  Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
944                  &sign, &decimal_rep_length, &decimal_point);
945    f = decimal_rep_length - 1;
946  } else {
947    DoubleToAscii(value, DTOA_PRECISION, f + 1,
948                  Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
949                  &sign, &decimal_rep_length, &decimal_point);
950  }
951  ASSERT(decimal_rep_length > 0);
952  ASSERT(decimal_rep_length <= f + 1);
953
954  int exponent = decimal_point - 1;
955  char* result =
956      CreateExponentialRepresentation(decimal_rep, exponent, negative, f+1);
957
958  return result;
959}
960
961
962char* DoubleToPrecisionCString(double value, int p) {
963  const int kMinimalDigits = 1;
964  const int kMaximalDigits = 21;
965  ASSERT(p >= kMinimalDigits && p <= kMaximalDigits);
966  USE(kMinimalDigits);
967
968  bool negative = false;
969  if (value < 0) {
970    value = -value;
971    negative = true;
972  }
973
974  // Find a sufficiently precise decimal representation of n.
975  int decimal_point;
976  int sign;
977  // Add one for the terminating null character.
978  const int kV8DtoaBufferCapacity = kMaximalDigits + 1;
979  char decimal_rep[kV8DtoaBufferCapacity];
980  int decimal_rep_length;
981
982  DoubleToAscii(value, DTOA_PRECISION, p,
983                Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
984                &sign, &decimal_rep_length, &decimal_point);
985  ASSERT(decimal_rep_length <= p);
986
987  int exponent = decimal_point - 1;
988
989  char* result = NULL;
990
991  if (exponent < -6 || exponent >= p) {
992    result =
993        CreateExponentialRepresentation(decimal_rep, exponent, negative, p);
994  } else {
995    // Use fixed notation.
996    //
997    // Leave room in the result for appending a minus, a period and in
998    // the case where decimal_point is not positive for a zero in
999    // front of the period.
1000    unsigned result_size = (decimal_point <= 0)
1001        ? -decimal_point + p + 3
1002        : p + 2;
1003    StringBuilder builder(result_size + 1);
1004    if (negative) builder.AddCharacter('-');
1005    if (decimal_point <= 0) {
1006      builder.AddString("0.");
1007      builder.AddPadding('0', -decimal_point);
1008      builder.AddString(decimal_rep);
1009      builder.AddPadding('0', p - decimal_rep_length);
1010    } else {
1011      const int m = Min(decimal_rep_length, decimal_point);
1012      builder.AddSubstring(decimal_rep, m);
1013      builder.AddPadding('0', decimal_point - decimal_rep_length);
1014      if (decimal_point < p) {
1015        builder.AddCharacter('.');
1016        const int extra = negative ? 2 : 1;
1017        if (decimal_rep_length > decimal_point) {
1018          const int len = StrLength(decimal_rep + decimal_point);
1019          const int n = Min(len, p - (builder.position() - extra));
1020          builder.AddSubstring(decimal_rep + decimal_point, n);
1021        }
1022        builder.AddPadding('0', extra + (p - builder.position()));
1023      }
1024    }
1025    result = builder.Finalize();
1026  }
1027
1028  return result;
1029}
1030
1031
1032char* DoubleToRadixCString(double value, int radix) {
1033  ASSERT(radix >= 2 && radix <= 36);
1034
1035  // Character array used for conversion.
1036  static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyz";
1037
1038  // Buffer for the integer part of the result. 1024 chars is enough
1039  // for max integer value in radix 2.  We need room for a sign too.
1040  static const int kBufferSize = 1100;
1041  char integer_buffer[kBufferSize];
1042  integer_buffer[kBufferSize - 1] = '\0';
1043
1044  // Buffer for the decimal part of the result.  We only generate up
1045  // to kBufferSize - 1 chars for the decimal part.
1046  char decimal_buffer[kBufferSize];
1047  decimal_buffer[kBufferSize - 1] = '\0';
1048
1049  // Make sure the value is positive.
1050  bool is_negative = value < 0.0;
1051  if (is_negative) value = -value;
1052
1053  // Get the integer part and the decimal part.
1054  double integer_part = floor(value);
1055  double decimal_part = value - integer_part;
1056
1057  // Convert the integer part starting from the back.  Always generate
1058  // at least one digit.
1059  int integer_pos = kBufferSize - 2;
1060  do {
1061    integer_buffer[integer_pos--] =
1062        chars[static_cast<int>(modulo(integer_part, radix))];
1063    integer_part /= radix;
1064  } while (integer_part >= 1.0);
1065  // Sanity check.
1066  ASSERT(integer_pos > 0);
1067  // Add sign if needed.
1068  if (is_negative) integer_buffer[integer_pos--] = '-';
1069
1070  // Convert the decimal part.  Repeatedly multiply by the radix to
1071  // generate the next char.  Never generate more than kBufferSize - 1
1072  // chars.
1073  //
1074  // TODO(1093998): We will often generate a full decimal_buffer of
1075  // chars because hitting zero will often not happen.  The right
1076  // solution would be to continue until the string representation can
1077  // be read back and yield the original value.  To implement this
1078  // efficiently, we probably have to modify dtoa.
1079  int decimal_pos = 0;
1080  while ((decimal_part > 0.0) && (decimal_pos < kBufferSize - 1)) {
1081    decimal_part *= radix;
1082    decimal_buffer[decimal_pos++] =
1083        chars[static_cast<int>(floor(decimal_part))];
1084    decimal_part -= floor(decimal_part);
1085  }
1086  decimal_buffer[decimal_pos] = '\0';
1087
1088  // Compute the result size.
1089  int integer_part_size = kBufferSize - 2 - integer_pos;
1090  // Make room for zero termination.
1091  unsigned result_size = integer_part_size + decimal_pos;
1092  // If the number has a decimal part, leave room for the period.
1093  if (decimal_pos > 0) result_size++;
1094  // Allocate result and fill in the parts.
1095  StringBuilder builder(result_size + 1);
1096  builder.AddSubstring(integer_buffer + integer_pos + 1, integer_part_size);
1097  if (decimal_pos > 0) builder.AddCharacter('.');
1098  builder.AddSubstring(decimal_buffer, decimal_pos);
1099  return builder.Finalize();
1100}
1101
1102
1103static Mutex* dtoa_lock_one = OS::CreateMutex();
1104static Mutex* dtoa_lock_zero = OS::CreateMutex();
1105
1106
1107} }  // namespace v8::internal
1108
1109
1110extern "C" {
1111void ACQUIRE_DTOA_LOCK(int n) {
1112  ASSERT(n == 0 || n == 1);
1113  (n == 0 ? v8::internal::dtoa_lock_zero : v8::internal::dtoa_lock_one)->Lock();
1114}
1115
1116
1117void FREE_DTOA_LOCK(int n) {
1118  ASSERT(n == 0 || n == 1);
1119  (n == 0 ? v8::internal::dtoa_lock_zero : v8::internal::dtoa_lock_one)->
1120      Unlock();
1121}
1122}
1123