This repository was archived by the owner on Jun 25, 2023. It is now read-only.
Repository navigation
Expand file tree
/
Copy pathpystrtod.c
More file actions
1324 lines (1154 loc) · 40.7 KB
/
Copy pathpystrtod.c
File metadata and controls
1324 lines (1154 loc) · 40.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* -*- Mode: C; c-file-style: "python" -*- */
#include <Python.h>
#include "pycore_dtoa.h" // _Py_dg_strtod()
#include "pycore_pymath.h" // _PY_SHORT_FLOAT_REPR
#include <locale.h>
/* Case-insensitive string match used for nan and inf detection; t should be
lower-case. Returns 1 for a successful match, 0 otherwise. */
static int
case_insensitive_match(const char *s, const char *t)
{
while(*t && Py_TOLOWER(*s) == *t) {
s++;
t++;
}
return *t ? 0 : 1;
}
/* _Py_parse_inf_or_nan: Attempt to parse a string of the form "nan", "inf" or
"infinity", with an optional leading sign of "+" or "-". On success,
return the NaN or Infinity as a double and set *endptr to point just beyond
the successfully parsed portion of the string. On failure, return -1.0 and
set *endptr to point to the start of the string. */
#if _PY_SHORT_FLOAT_REPR == 1
double
_Py_parse_inf_or_nan(const char *p, char **endptr)
{
double retval;
const char *s;
int negate = 0;
s = p;
if (*s == '-') {
negate = 1;
s++;
}
else if (*s == '+') {
s++;
}
if (case_insensitive_match(s, "inf")) {
s += 3;
if (case_insensitive_match(s, "inity"))
s += 5;
retval = _Py_dg_infinity(negate);
}
else if (case_insensitive_match(s, "nan")) {
s += 3;
retval = _Py_dg_stdnan(negate);
}
else {
s = p;
retval = -1.0;
}
*endptr = (char *)s;
return retval;
}
#else
double
_Py_parse_inf_or_nan(const char *p, char **endptr)
{
double retval;
const char *s;
int negate = 0;
s = p;
if (*s == '-') {
negate = 1;
s++;
}
else if (*s == '+') {
s++;
}
if (case_insensitive_match(s, "inf")) {
s += 3;
if (case_insensitive_match(s, "inity"))
s += 5;
retval = negate ? -Py_HUGE_VAL : Py_HUGE_VAL;
}
else if (case_insensitive_match(s, "nan")) {
s += 3;
retval = negate ? -Py_NAN : Py_NAN;
}
else {
s = p;
retval = -1.0;
}
*endptr = (char *)s;
return retval;
}
#endif
/**
* _PyOS_ascii_strtod:
* @nptr: the string to convert to a numeric value.
* @endptr: if non-%NULL, it returns the character after
* the last character used in the conversion.
*
* Converts a string to a #gdouble value.
* This function behaves like the standard strtod() function
* does in the C locale. It does this without actually
* changing the current locale, since that would not be
* thread-safe.
*
* This function is typically used when reading configuration
* files or other non-user input that should be locale independent.
* To handle input from the user you should normally use the
* locale-sensitive system strtod() function.
*
* If the correct value would cause overflow, plus or minus %HUGE_VAL
* is returned (according to the sign of the value), and %ERANGE is
* stored in %errno. If the correct value would cause underflow,
* zero is returned and %ERANGE is stored in %errno.
* If memory allocation fails, %ENOMEM is stored in %errno.
*
* This function resets %errno before calling strtod() so that
* you can reliably detect overflow and underflow.
*
* Return value: the #gdouble value.
**/
#if _PY_SHORT_FLOAT_REPR == 1
static double
_PyOS_ascii_strtod(const char *nptr, char **endptr)
{
double result;
_Py_SET_53BIT_PRECISION_HEADER;
assert(nptr != NULL);
/* Set errno to zero, so that we can distinguish zero results
and underflows */
errno = 0;
_Py_SET_53BIT_PRECISION_START;
result = _Py_dg_strtod(nptr, endptr);
_Py_SET_53BIT_PRECISION_END;
if (*endptr == nptr)
/* string might represent an inf or nan */
result = _Py_parse_inf_or_nan(nptr, endptr);
return result;
}
#else
/*
Use system strtod; since strtod is locale aware, we may
have to first fix the decimal separator.
Note that unlike _Py_dg_strtod, the system strtod may not always give
correctly rounded results.
*/
static double
_PyOS_ascii_strtod(const char *nptr, char **endptr)
{
char *fail_pos;
double val;
struct lconv *locale_data;
const char *decimal_point;
size_t decimal_point_len;
const char *p, *decimal_point_pos;
const char *end = NULL; /* Silence gcc */
const char *digits_pos = NULL;
int negate = 0;
assert(nptr != NULL);
fail_pos = NULL;
locale_data = localeconv();
decimal_point = locale_data->decimal_point;
decimal_point_len = strlen(decimal_point);
assert(decimal_point_len != 0);
decimal_point_pos = NULL;
/* Parse infinities and nans */
val = _Py_parse_inf_or_nan(nptr, endptr);
if (*endptr != nptr)
return val;
/* Set errno to zero, so that we can distinguish zero results
and underflows */
errno = 0;
/* We process the optional sign manually, then pass the remainder to
the system strtod. This ensures that the result of an underflow
has the correct sign. (bug #1725) */
p = nptr;
/* Process leading sign, if present */
if (*p == '-') {
negate = 1;
p++;
}
else if (*p == '+') {
p++;
}
/* Some platform strtods accept hex floats; Python shouldn't (at the
moment), so we check explicitly for strings starting with '0x'. */
if (*p == '0' && (*(p+1) == 'x' || *(p+1) == 'X'))
goto invalid_string;
/* Check that what's left begins with a digit or decimal point */
if (!Py_ISDIGIT(*p) && *p != '.')
goto invalid_string;
digits_pos = p;
if (decimal_point[0] != '.' ||
decimal_point[1] != 0)
{
/* Look for a '.' in the input; if present, it'll need to be
swapped for the current locale's decimal point before we
call strtod. On the other hand, if we find the current
locale's decimal point then the input is invalid. */
while (Py_ISDIGIT(*p))
p++;
if (*p == '.')
{
decimal_point_pos = p++;
/* locate end of number */
while (Py_ISDIGIT(*p))
p++;
if (*p == 'e' || *p == 'E')
p++;
if (*p == '+' || *p == '-')
p++;
while (Py_ISDIGIT(*p))
p++;
end = p;
}
else if (strncmp(p, decimal_point, decimal_point_len) == 0)
/* Python bug #1417699 */
goto invalid_string;
/* For the other cases, we need not convert the decimal
point */
}
if (decimal_point_pos) {
char *copy, *c;
/* Create a copy of the input, with the '.' converted to the
locale-specific decimal point */
copy = (char *)PyMem_Malloc(end - digits_pos +
1 + decimal_point_len);
if (copy == NULL) {
*endptr = (char *)nptr;
errno = ENOMEM;
return val;
}
c = copy;
memcpy(c, digits_pos, decimal_point_pos - digits_pos);
c += decimal_point_pos - digits_pos;
memcpy(c, decimal_point, decimal_point_len);
c += decimal_point_len;
memcpy(c, decimal_point_pos + 1,
end - (decimal_point_pos + 1));
c += end - (decimal_point_pos + 1);
*c = 0;
val = strtod(copy, &fail_pos);
if (fail_pos)
{
if (fail_pos > decimal_point_pos)
fail_pos = (char *)digits_pos +
(fail_pos - copy) -
(decimal_point_len - 1);
else
fail_pos = (char *)digits_pos +
(fail_pos - copy);
}
PyMem_Free(copy);
}
else {
val = strtod(digits_pos, &fail_pos);
}
if (fail_pos == digits_pos)
goto invalid_string;
if (negate && fail_pos != nptr)
val = -val;
*endptr = fail_pos;
return val;
invalid_string:
*endptr = (char*)nptr;
errno = EINVAL;
return -1.0;
}
#endif
/* PyOS_string_to_double converts a null-terminated byte string s (interpreted
as a string of ASCII characters) to a float. The string should not have
leading or trailing whitespace. The conversion is independent of the
current locale.
If endptr is NULL, try to convert the whole string. Raise ValueError and
return -1.0 if the string is not a valid representation of a floating-point
number.
If endptr is non-NULL, try to convert as much of the string as possible.
If no initial segment of the string is the valid representation of a
floating-point number then *endptr is set to point to the beginning of the
string, -1.0 is returned and again ValueError is raised.
On overflow (e.g., when trying to convert '1e500' on an IEEE 754 machine),
if overflow_exception is NULL then +-Py_HUGE_VAL is returned, and no Python
exception is raised. Otherwise, overflow_exception should point to
a Python exception, this exception will be raised, -1.0 will be returned,
and *endptr will point just past the end of the converted value.
If any other failure occurs (for example lack of memory), -1.0 is returned
and the appropriate Python exception will have been set.
*/
double
PyOS_string_to_double(const char *s,
char **endptr,
PyObject *overflow_exception)
{
double x, result=-1.0;
char *fail_pos;
errno = 0;
x = _PyOS_ascii_strtod(s, &fail_pos);
if (errno == ENOMEM) {
PyErr_NoMemory();
fail_pos = (char *)s;
}
else if (!endptr && (fail_pos == s || *fail_pos != '\0'))
PyErr_Format(PyExc_ValueError,
"could not convert string to float: "
"'%.200s'", s);
else if (fail_pos == s)
PyErr_Format(PyExc_ValueError,
"could not convert string to float: "
"'%.200s'", s);
else if (errno == ERANGE && fabs(x) >= 1.0 && overflow_exception)
PyErr_Format(overflow_exception,
"value too large to convert to float: "
"'%.200s'", s);
else
result = x;
if (endptr != NULL)
*endptr = fail_pos;
return result;
}
/* Remove underscores that follow the underscore placement rule from
the string and then call the `innerfunc` function on the result.
It should return a new object or NULL on exception.
`what` is used for the error message emitted when underscores are detected
that don't follow the rule. `arg` is an opaque pointer passed to the inner
function.
This is used to implement underscore-agnostic conversion for floats
and complex numbers.
*/
PyObject *
_Py_string_to_number_with_underscores(
const char *s, Py_ssize_t orig_len, const char *what, PyObject *obj, void *arg,
PyObject *(*innerfunc)(const char *, Py_ssize_t, void *))
{
char prev;
const char *p, *last;
char *dup, *end;
PyObject *result;
assert(s[orig_len] == '\0');
if (strchr(s, '_') == NULL) {
return innerfunc(s, orig_len, arg);
}
dup = PyMem_Malloc(orig_len + 1);
if (dup == NULL) {
return PyErr_NoMemory();
}
end = dup;
prev = '\0';
last = s + orig_len;
for (p = s; *p; p++) {
if (*p == '_') {
/* Underscores are only allowed after digits. */
if (!(prev >= '0' && prev <= '9')) {
goto error;
}
}
else {
*end++ = *p;
/* Underscores are only allowed before digits. */
if (prev == '_' && !(*p >= '0' && *p <= '9')) {
goto error;
}
}
prev = *p;
}
/* Underscores are not allowed at the end. */
if (prev == '_') {
goto error;
}
/* No embedded NULs allowed. */
if (p != last) {
goto error;
}
*end = '\0';
result = innerfunc(dup, end - dup, arg);
PyMem_Free(dup);
return result;
error:
PyMem_Free(dup);
PyErr_Format(PyExc_ValueError,
"could not convert string to %s: "
"%R", what, obj);
return NULL;
}
#if _PY_SHORT_FLOAT_REPR == 0
/* Given a string that may have a decimal point in the current
locale, change it back to a dot. Since the string cannot get
longer, no need for a maximum buffer size parameter. */
Py_LOCAL_INLINE(void)
change_decimal_from_locale_to_dot(char* buffer)
{
struct lconv *locale_data = localeconv();
const char *decimal_point = locale_data->decimal_point;
if (decimal_point[0] != '.' || decimal_point[1] != 0) {
size_t decimal_point_len = strlen(decimal_point);
if (*buffer == '+' || *buffer == '-')
buffer++;
while (Py_ISDIGIT(*buffer))
buffer++;
if (strncmp(buffer, decimal_point, decimal_point_len) == 0) {
*buffer = '.';
buffer++;
if (decimal_point_len > 1) {
/* buffer needs to get smaller */
size_t rest_len = strlen(buffer +
(decimal_point_len - 1));
memmove(buffer,
buffer + (decimal_point_len - 1),
rest_len);
buffer[rest_len] = 0;
}
}
}
}
/* From the C99 standard, section 7.19.6:
The exponent always contains at least two digits, and only as many more digits
as necessary to represent the exponent.
*/
#define MIN_EXPONENT_DIGITS 2
/* Ensure that any exponent, if present, is at least MIN_EXPONENT_DIGITS
in length. */
Py_LOCAL_INLINE(void)
ensure_minimum_exponent_length(char* buffer, size_t buf_size)
{
char *p = strpbrk(buffer, "eE");
if (p && (*(p + 1) == '-' || *(p + 1) == '+')) {
char *start = p + 2;
int exponent_digit_cnt = 0;
int leading_zero_cnt = 0;
int in_leading_zeros = 1;
int significant_digit_cnt;
/* Skip over the exponent and the sign. */
p += 2;
/* Find the end of the exponent, keeping track of leading
zeros. */
while (*p && Py_ISDIGIT(*p)) {
if (in_leading_zeros && *p == '0')
++leading_zero_cnt;
if (*p != '0')
in_leading_zeros = 0;
++p;
++exponent_digit_cnt;
}
significant_digit_cnt = exponent_digit_cnt - leading_zero_cnt;
if (exponent_digit_cnt == MIN_EXPONENT_DIGITS) {
/* If there are 2 exactly digits, we're done,
regardless of what they contain */
}
else if (exponent_digit_cnt > MIN_EXPONENT_DIGITS) {
int extra_zeros_cnt;
/* There are more than 2 digits in the exponent. See
if we can delete some of the leading zeros */
if (significant_digit_cnt < MIN_EXPONENT_DIGITS)
significant_digit_cnt = MIN_EXPONENT_DIGITS;
extra_zeros_cnt = exponent_digit_cnt -
significant_digit_cnt;
/* Delete extra_zeros_cnt worth of characters from the
front of the exponent */
assert(extra_zeros_cnt >= 0);
/* Add one to significant_digit_cnt to copy the
trailing 0 byte, thus setting the length */
memmove(start,
start + extra_zeros_cnt,
significant_digit_cnt + 1);
}
else {
/* If there are fewer than 2 digits, add zeros
until there are 2, if there's enough room */
int zeros = MIN_EXPONENT_DIGITS - exponent_digit_cnt;
if (start + zeros + exponent_digit_cnt + 1
< buffer + buf_size) {
memmove(start + zeros, start,
exponent_digit_cnt + 1);
memset(start, '0', zeros);
}
}
}
}
/* Remove trailing zeros after the decimal point from a numeric string; also
remove the decimal point if all digits following it are zero. The numeric
string must end in '\0', and should not have any leading or trailing
whitespace. Assumes that the decimal point is '.'. */
Py_LOCAL_INLINE(void)
remove_trailing_zeros(char *buffer)
{
char *old_fraction_end, *new_fraction_end, *end, *p;
p = buffer;
if (*p == '-' || *p == '+')
/* Skip leading sign, if present */
++p;
while (Py_ISDIGIT(*p))
++p;
/* if there's no decimal point there's nothing to do */
if (*p++ != '.')
return;
/* scan any digits after the point */
while (Py_ISDIGIT(*p))
++p;
old_fraction_end = p;
/* scan up to ending '\0' */
while (*p != '\0')
p++;
/* +1 to make sure that we move the null byte as well */
end = p+1;
/* scan back from fraction_end, looking for removable zeros */
p = old_fraction_end;
while (*(p-1) == '0')
--p;
/* and remove point if we've got that far */
if (*(p-1) == '.')
--p;
new_fraction_end = p;
memmove(new_fraction_end, old_fraction_end, end-old_fraction_end);
}
/* Ensure that buffer has a decimal point in it. The decimal point will not
be in the current locale, it will always be '.'. Don't add a decimal point
if an exponent is present. Also, convert to exponential notation where
adding a '.0' would produce too many significant digits (see issue 5864).
Returns a pointer to the fixed buffer, or NULL on failure.
*/
Py_LOCAL_INLINE(char *)
ensure_decimal_point(char* buffer, size_t buf_size, int precision)
{
int digit_count, insert_count = 0, convert_to_exp = 0;
const char *chars_to_insert;
char *digits_start;
/* search for the first non-digit character */
char *p = buffer;
if (*p == '-' || *p == '+')
/* Skip leading sign, if present. I think this could only
ever be '-', but it can't hurt to check for both. */
++p;
digits_start = p;
while (*p && Py_ISDIGIT(*p))
++p;
digit_count = Py_SAFE_DOWNCAST(p - digits_start, Py_ssize_t, int);
if (*p == '.') {
if (Py_ISDIGIT(*(p+1))) {
/* Nothing to do, we already have a decimal
point and a digit after it */
}
else {
/* We have a decimal point, but no following
digit. Insert a zero after the decimal. */
/* can't ever get here via PyOS_double_to_string */
assert(precision == -1);
++p;
chars_to_insert = "0";
insert_count = 1;
}
}
else if (!(*p == 'e' || *p == 'E')) {
/* Don't add ".0" if we have an exponent. */
if (digit_count == precision) {
/* issue 5864: don't add a trailing .0 in the case
where the '%g'-formatted result already has as many
significant digits as were requested. Switch to
exponential notation instead. */
convert_to_exp = 1;
/* no exponent, no point, and we shouldn't land here
for infs and nans, so we must be at the end of the
string. */
assert(*p == '\0');
}
else {
assert(precision == -1 || digit_count < precision);
chars_to_insert = ".0";
insert_count = 2;
}
}
if (insert_count) {
size_t buf_len = strlen(buffer);
if (buf_len + insert_count + 1 >= buf_size) {
/* If there is not enough room in the buffer
for the additional text, just skip it. It's
not worth generating an error over. */
}
else {
memmove(p + insert_count, p,
buffer + strlen(buffer) - p + 1);
memcpy(p, chars_to_insert, insert_count);
}
}
if (convert_to_exp) {
int written;
size_t buf_avail;
p = digits_start;
/* insert decimal point */
assert(digit_count >= 1);
memmove(p+2, p+1, digit_count); /* safe, but overwrites nul */
p[1] = '.';
p += digit_count+1;
assert(p <= buf_size+buffer);
buf_avail = buf_size+buffer-p;
if (buf_avail == 0)
return NULL;
/* Add exponent. It's okay to use lower case 'e': we only
arrive here as a result of using the empty format code or
repr/str builtins and those never want an upper case 'E' */
written = PyOS_snprintf(p, buf_avail, "e%+.02d", digit_count-1);
if (!(0 <= written &&
written < Py_SAFE_DOWNCAST(buf_avail, size_t, int)))
/* output truncated, or something else bad happened */
return NULL;
remove_trailing_zeros(buffer);
}
return buffer;
}
/* see FORMATBUFLEN in unicodeobject.c */
#define FLOAT_FORMATBUFLEN 120
/**
* _PyOS_ascii_formatd:
* @buffer: A buffer to place the resulting string in
* @buf_size: The length of the buffer.
* @format: The printf()-style format to use for the
* code to use for converting.
* @d: The #gdouble to convert
* @precision: The precision to use when formatting.
*
* Converts a #gdouble to a string, using the '.' as
* decimal point. To format the number you pass in
* a printf()-style format string. Allowed conversion
* specifiers are 'e', 'E', 'f', 'F', 'g', 'G', and 'Z'.
*
* 'Z' is the same as 'g', except it always has a decimal and
* at least one digit after the decimal.
*
* Return value: The pointer to the buffer with the converted string.
* On failure returns NULL but does not set any Python exception.
**/
static char *
_PyOS_ascii_formatd(char *buffer,
size_t buf_size,
const char *format,
double d,
int precision)
{
char format_char;
size_t format_len = strlen(format);
/* Issue 2264: code 'Z' requires copying the format. 'Z' is 'g', but
also with at least one character past the decimal. */
char tmp_format[FLOAT_FORMATBUFLEN];
/* The last character in the format string must be the format char */
format_char = format[format_len - 1];
if (format[0] != '%')
return NULL;
/* I'm not sure why this test is here. It's ensuring that the format
string after the first character doesn't have a single quote, a
lowercase l, or a percent. This is the reverse of the commented-out
test about 10 lines ago. */
if (strpbrk(format + 1, "'l%"))
return NULL;
/* Also curious about this function is that it accepts format strings
like "%xg", which are invalid for floats. In general, the
interface to this function is not very good, but changing it is
difficult because it's a public API. */
if (!(format_char == 'e' || format_char == 'E' ||
format_char == 'f' || format_char == 'F' ||
format_char == 'g' || format_char == 'G' ||
format_char == 'Z'))
return NULL;
/* Map 'Z' format_char to 'g', by copying the format string and
replacing the final char with a 'g' */
if (format_char == 'Z') {
if (format_len + 1 >= sizeof(tmp_format)) {
/* The format won't fit in our copy. Error out. In
practice, this will never happen and will be
detected by returning NULL */
return NULL;
}
strcpy(tmp_format, format);
tmp_format[format_len - 1] = 'g';
format = tmp_format;
}
/* Have PyOS_snprintf do the hard work */
PyOS_snprintf(buffer, buf_size, format, d);
/* Do various fixups on the return string */
/* Get the current locale, and find the decimal point string.
Convert that string back to a dot. */
change_decimal_from_locale_to_dot(buffer);
/* If an exponent exists, ensure that the exponent is at least
MIN_EXPONENT_DIGITS digits, providing the buffer is large enough
for the extra zeros. Also, if there are more than
MIN_EXPONENT_DIGITS, remove as many zeros as possible until we get
back to MIN_EXPONENT_DIGITS */
ensure_minimum_exponent_length(buffer, buf_size);
/* If format_char is 'Z', make sure we have at least one character
after the decimal point (and make sure we have a decimal point);
also switch to exponential notation in some edge cases where the
extra character would produce more significant digits that we
really want. */
if (format_char == 'Z')
buffer = ensure_decimal_point(buffer, buf_size, precision);
return buffer;
}
/* The fallback code to use if _Py_dg_dtoa is not available. */
char * PyOS_double_to_string(double val,
char format_code,
int precision,
int flags,
int *type)
{
char format[32];
Py_ssize_t bufsize;
char *buf;
int t, exp;
int upper = 0;
/* Validate format_code, and map upper and lower case */
switch (format_code) {
case 'e': /* exponent */
case 'f': /* fixed */
case 'g': /* general */
break;
case 'E':
upper = 1;
format_code = 'e';
break;
case 'F':
upper = 1;
format_code = 'f';
break;
case 'G':
upper = 1;
format_code = 'g';
break;
case 'r': /* repr format */
/* Supplied precision is unused, must be 0. */
if (precision != 0) {
PyErr_BadInternalCall();
return NULL;
}
/* The repr() precision (17 significant decimal digits) is the
minimal number that is guaranteed to have enough precision
so that if the number is read back in the exact same binary
value is recreated. This is true for IEEE floating point
by design, and also happens to work for all other modern
hardware. */
precision = 17;
format_code = 'g';
break;
default:
PyErr_BadInternalCall();
return NULL;
}
/* Here's a quick-and-dirty calculation to figure out how big a buffer
we need. In general, for a finite float we need:
1 byte for each digit of the decimal significand, and
1 for a possible sign
1 for a possible decimal point
2 for a possible [eE][+-]
1 for each digit of the exponent; if we allow 19 digits
total then we're safe up to exponents of 2**63.
1 for the trailing nul byte
This gives a total of 24 + the number of digits in the significand,
and the number of digits in the significand is:
for 'g' format: at most precision, except possibly
when precision == 0, when it's 1.
for 'e' format: precision+1
for 'f' format: precision digits after the point, at least 1
before. To figure out how many digits appear before the point
we have to examine the size of the number. If fabs(val) < 1.0
then there will be only one digit before the point. If
fabs(val) >= 1.0, then there are at most
1+floor(log10(ceiling(fabs(val))))
digits before the point (where the 'ceiling' allows for the
possibility that the rounding rounds the integer part of val
up). A safe upper bound for the above quantity is
1+floor(exp/3), where exp is the unique integer such that 0.5
<= fabs(val)/2**exp < 1.0. This exp can be obtained from
frexp.
So we allow room for precision+1 digits for all formats, plus an
extra floor(exp/3) digits for 'f' format.
*/
if (Py_IS_NAN(val) || Py_IS_INFINITY(val))
/* 3 for 'inf'/'nan', 1 for sign, 1 for '\0' */
bufsize = 5;
else {
bufsize = 25 + precision;
if (format_code == 'f' && fabs(val) >= 1.0) {
frexp(val, &exp);
bufsize += exp/3;
}
}
buf = PyMem_Malloc(bufsize);
if (buf == NULL) {
PyErr_NoMemory();
return NULL;
}
/* Handle nan and inf. */
if (Py_IS_NAN(val)) {
strcpy(buf, "nan");
t = Py_DTST_NAN;
} else if (Py_IS_INFINITY(val)) {
if (copysign(1., val) == 1.)
strcpy(buf, "inf");
else
strcpy(buf, "-inf");
t = Py_DTST_INFINITE;
} else {
t = Py_DTST_FINITE;
if (flags & Py_DTSF_ADD_DOT_0)
format_code = 'Z';
PyOS_snprintf(format, sizeof(format), "%%%s.%i%c",
(flags & Py_DTSF_ALT ? "#" : ""), precision,
format_code);
_PyOS_ascii_formatd(buf, bufsize, format, val, precision);
if (flags & Py_DTSF_NO_NEG_0 && buf[0] == '-') {
char *buf2 = buf + 1;
while (*buf2 == '0' || *buf2 == '.') {
++buf2;
}
if (*buf2 == 0 || *buf2 == 'e') {
size_t len = buf2 - buf + strlen(buf2);
assert(buf[len] == 0);
memmove(buf, buf+1, len);
}
}
}
/* Add sign when requested. It's convenient (esp. when formatting
complex numbers) to include a sign even for inf and nan. */
if (flags & Py_DTSF_SIGN && buf[0] != '-') {
size_t len = strlen(buf);
/* the bufsize calculations above should ensure that we've got
space to add a sign */
assert((size_t)bufsize >= len+2);
memmove(buf+1, buf, len+1);
buf[0] = '+';
}
if (upper) {
/* Convert to upper case. */
char *p1;
for (p1 = buf; *p1; p1++)
*p1 = Py_TOUPPER(*p1);
}
if (type)
*type = t;
return buf;
}
#else // _PY_SHORT_FLOAT_REPR == 1
/* _Py_dg_dtoa is available. */
/* I'm using a lookup table here so that I don't have to invent a non-locale
specific way to convert to uppercase */
#define OFS_INF 0
#define OFS_NAN 1
#define OFS_E 2
/* The lengths of these are known to the code below, so don't change them */
static const char * const lc_float_strings[] = {
"inf",
"nan",
"e",
};
static const char * const uc_float_strings[] = {
"INF",
"NAN",
"E",
};
/* Convert a double d to a string, and return a PyMem_Malloc'd block of
memory contain the resulting string.
Arguments:
d is the double to be converted
format_code is one of 'e', 'f', 'g', 'r'. 'e', 'f' and 'g'
correspond to '%e', '%f' and '%g'; 'r' corresponds to repr.
mode is one of '0', '2' or '3', and is completely determined by
format_code: 'e' and 'g' use mode 2; 'f' mode 3, 'r' mode 0.
precision is the desired precision
always_add_sign is nonzero if a '+' sign should be included for positive
numbers
add_dot_0_if_integer is nonzero if integers in non-exponential form
should have ".0" added. Only applies to format codes 'r' and 'g'.
use_alt_formatting is nonzero if alternative formatting should be
used. Only applies to format codes 'e', 'f' and 'g'. For code 'g',
at most one of use_alt_formatting and add_dot_0_if_integer should
be nonzero.
type, if non-NULL, will be set to one of these constants to identify
the type of the 'd' argument:
Py_DTST_FINITE
Py_DTST_INFINITE
Py_DTST_NAN