1
2// Allowable floating-point values range
3// std::numeric_limits<double>::lowest() to std::numeric_limits<double>::max(),
4// so from -1.7976e308 all the way to 1.7975e308 in binary64. The lowest
5// non-zero normal values is std::numeric_limits<double>::min() or
6// about 2.225074e-308.
7static const double power_of_ten[] = {
8 1e-308, 1e-307, 1e-306, 1e-305, 1e-304, 1e-303, 1e-302, 1e-301, 1e-300,
9 1e-299, 1e-298, 1e-297, 1e-296, 1e-295, 1e-294, 1e-293, 1e-292, 1e-291,
10 1e-290, 1e-289, 1e-288, 1e-287, 1e-286, 1e-285, 1e-284, 1e-283, 1e-282,
11 1e-281, 1e-280, 1e-279, 1e-278, 1e-277, 1e-276, 1e-275, 1e-274, 1e-273,
12 1e-272, 1e-271, 1e-270, 1e-269, 1e-268, 1e-267, 1e-266, 1e-265, 1e-264,
13 1e-263, 1e-262, 1e-261, 1e-260, 1e-259, 1e-258, 1e-257, 1e-256, 1e-255,
14 1e-254, 1e-253, 1e-252, 1e-251, 1e-250, 1e-249, 1e-248, 1e-247, 1e-246,
15 1e-245, 1e-244, 1e-243, 1e-242, 1e-241, 1e-240, 1e-239, 1e-238, 1e-237,
16 1e-236, 1e-235, 1e-234, 1e-233, 1e-232, 1e-231, 1e-230, 1e-229, 1e-228,
17 1e-227, 1e-226, 1e-225, 1e-224, 1e-223, 1e-222, 1e-221, 1e-220, 1e-219,
18 1e-218, 1e-217, 1e-216, 1e-215, 1e-214, 1e-213, 1e-212, 1e-211, 1e-210,
19 1e-209, 1e-208, 1e-207, 1e-206, 1e-205, 1e-204, 1e-203, 1e-202, 1e-201,
20 1e-200, 1e-199, 1e-198, 1e-197, 1e-196, 1e-195, 1e-194, 1e-193, 1e-192,
21 1e-191, 1e-190, 1e-189, 1e-188, 1e-187, 1e-186, 1e-185, 1e-184, 1e-183,
22 1e-182, 1e-181, 1e-180, 1e-179, 1e-178, 1e-177, 1e-176, 1e-175, 1e-174,
23 1e-173, 1e-172, 1e-171, 1e-170, 1e-169, 1e-168, 1e-167, 1e-166, 1e-165,
24 1e-164, 1e-163, 1e-162, 1e-161, 1e-160, 1e-159, 1e-158, 1e-157, 1e-156,
25 1e-155, 1e-154, 1e-153, 1e-152, 1e-151, 1e-150, 1e-149, 1e-148, 1e-147,
26 1e-146, 1e-145, 1e-144, 1e-143, 1e-142, 1e-141, 1e-140, 1e-139, 1e-138,
27 1e-137, 1e-136, 1e-135, 1e-134, 1e-133, 1e-132, 1e-131, 1e-130, 1e-129,
28 1e-128, 1e-127, 1e-126, 1e-125, 1e-124, 1e-123, 1e-122, 1e-121, 1e-120,
29 1e-119, 1e-118, 1e-117, 1e-116, 1e-115, 1e-114, 1e-113, 1e-112, 1e-111,
30 1e-110, 1e-109, 1e-108, 1e-107, 1e-106, 1e-105, 1e-104, 1e-103, 1e-102,
31 1e-101, 1e-100, 1e-99, 1e-98, 1e-97, 1e-96, 1e-95, 1e-94, 1e-93,
32 1e-92, 1e-91, 1e-90, 1e-89, 1e-88, 1e-87, 1e-86, 1e-85, 1e-84,
33 1e-83, 1e-82, 1e-81, 1e-80, 1e-79, 1e-78, 1e-77, 1e-76, 1e-75,
34 1e-74, 1e-73, 1e-72, 1e-71, 1e-70, 1e-69, 1e-68, 1e-67, 1e-66,
35 1e-65, 1e-64, 1e-63, 1e-62, 1e-61, 1e-60, 1e-59, 1e-58, 1e-57,
36 1e-56, 1e-55, 1e-54, 1e-53, 1e-52, 1e-51, 1e-50, 1e-49, 1e-48,
37 1e-47, 1e-46, 1e-45, 1e-44, 1e-43, 1e-42, 1e-41, 1e-40, 1e-39,
38 1e-38, 1e-37, 1e-36, 1e-35, 1e-34, 1e-33, 1e-32, 1e-31, 1e-30,
39 1e-29, 1e-28, 1e-27, 1e-26, 1e-25, 1e-24, 1e-23, 1e-22, 1e-21,
40 1e-20, 1e-19, 1e-18, 1e-17, 1e-16, 1e-15, 1e-14, 1e-13, 1e-12,
41 1e-11, 1e-10, 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3,
42 1e-2, 1e-1, 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6,
43 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15,
44 1e16, 1e17, 1e18, 1e19, 1e20, 1e21, 1e22, 1e23, 1e24,
45 1e25, 1e26, 1e27, 1e28, 1e29, 1e30, 1e31, 1e32, 1e33,
46 1e34, 1e35, 1e36, 1e37, 1e38, 1e39, 1e40, 1e41, 1e42,
47 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49, 1e50, 1e51,
48 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59, 1e60,
49 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69,
50 1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78,
51 1e79, 1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87,
52 1e88, 1e89, 1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96,
53 1e97, 1e98, 1e99, 1e100, 1e101, 1e102, 1e103, 1e104, 1e105,
54 1e106, 1e107, 1e108, 1e109, 1e110, 1e111, 1e112, 1e113, 1e114,
55 1e115, 1e116, 1e117, 1e118, 1e119, 1e120, 1e121, 1e122, 1e123,
56 1e124, 1e125, 1e126, 1e127, 1e128, 1e129, 1e130, 1e131, 1e132,
57 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139, 1e140, 1e141,
58 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149, 1e150,
59 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
60 1e160, 1e161, 1e162, 1e163, 1e164, 1e165, 1e166, 1e167, 1e168,
61 1e169, 1e170, 1e171, 1e172, 1e173, 1e174, 1e175, 1e176, 1e177,
62 1e178, 1e179, 1e180, 1e181, 1e182, 1e183, 1e184, 1e185, 1e186,
63 1e187, 1e188, 1e189, 1e190, 1e191, 1e192, 1e193, 1e194, 1e195,
64 1e196, 1e197, 1e198, 1e199, 1e200, 1e201, 1e202, 1e203, 1e204,
65 1e205, 1e206, 1e207, 1e208, 1e209, 1e210, 1e211, 1e212, 1e213,
66 1e214, 1e215, 1e216, 1e217, 1e218, 1e219, 1e220, 1e221, 1e222,
67 1e223, 1e224, 1e225, 1e226, 1e227, 1e228, 1e229, 1e230, 1e231,
68 1e232, 1e233, 1e234, 1e235, 1e236, 1e237, 1e238, 1e239, 1e240,
69 1e241, 1e242, 1e243, 1e244, 1e245, 1e246, 1e247, 1e248, 1e249,
70 1e250, 1e251, 1e252, 1e253, 1e254, 1e255, 1e256, 1e257, 1e258,
71 1e259, 1e260, 1e261, 1e262, 1e263, 1e264, 1e265, 1e266, 1e267,
72 1e268, 1e269, 1e270, 1e271, 1e272, 1e273, 1e274, 1e275, 1e276,
73 1e277, 1e278, 1e279, 1e280, 1e281, 1e282, 1e283, 1e284, 1e285,
74 1e286, 1e287, 1e288, 1e289, 1e290, 1e291, 1e292, 1e293, 1e294,
75 1e295, 1e296, 1e297, 1e298, 1e299, 1e300, 1e301, 1e302, 1e303,
76 1e304, 1e305, 1e306, 1e307, 1e308};
77
78static inline bool is_integer(char c) {
79 return (c >= '0' && c <= '9');
80 // this gets compiled to (uint8_t)(c - '0') <= 9 on all decent compilers
81}
82
83// We need to check that the character following a zero is valid. This is
84// probably frequent and it is hard than it looks. We are building all of this
85// just to differentiate between 0x1 (invalid), 0,1 (valid) 0e1 (valid)...
86const bool structural_or_whitespace_or_exponent_or_decimal_negated[256] = {
87 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
88 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1,
89 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1,
90 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1,
91 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
92 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
93 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
94 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
95 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
96 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
97 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
98
99really_inline bool
100is_not_structural_or_whitespace_or_exponent_or_decimal(unsigned char c) {
101 return structural_or_whitespace_or_exponent_or_decimal_negated[c];
102}
103
104// check quickly whether the next 8 chars are made of digits
105// at a glance, it looks better than Mula's
106// http://0x80.pl/articles/swar-digits-validate.html
107static inline bool is_made_of_eight_digits_fast(const char *chars) {
108 uint64_t val;
109 // this can read up to 7 bytes beyond the buffer size, but we require
110 // SIMDJSON_PADDING of padding
111 static_assert(7 <= SIMDJSON_PADDING);
112 memcpy(&val, chars, 8);
113 // a branchy method might be faster:
114 // return (( val & 0xF0F0F0F0F0F0F0F0 ) == 0x3030303030303030)
115 // && (( (val + 0x0606060606060606) & 0xF0F0F0F0F0F0F0F0 ) ==
116 // 0x3030303030303030);
117 return (((val & 0xF0F0F0F0F0F0F0F0) |
118 (((val + 0x0606060606060606) & 0xF0F0F0F0F0F0F0F0) >> 4)) ==
119 0x3333333333333333);
120}
121
122
123//
124// This function computes base * 10 ^ (- negative_exponent ).
125// It is only even going to be used when negative_exponent is tiny.
126static double subnormal_power10(double base, int64_t negative_exponent) {
127 // avoid integer overflows in the pow expression, those values would
128 // become zero anyway.
129 if(negative_exponent < -1000) {
130 return 0;
131 }
132
133 // this is probably not going to be fast
134 return base * 1e-308 * pow(10, negative_exponent + 308);
135}
136
137// called by parse_number when we know that the output is a float,
138// but where there might be some integer overflow. The trick here is to
139// parse using floats from the start.
140// Do not call this function directly as it skips some of the checks from
141// parse_number
142//
143// This function will almost never be called!!!
144//
145// Note: a redesign could avoid this function entirely.
146//
147static never_inline bool parse_float(const uint8_t *const buf, ParsedJson &pj,
148 const uint32_t offset, bool found_minus) {
149 const char *p = reinterpret_cast<const char *>(buf + offset);
150 bool negative = false;
151 if (found_minus) {
152 ++p;
153 negative = true;
154 }
155 long double i;
156 if (*p == '0') { // 0 cannot be followed by an integer
157 ++p;
158 i = 0;
159 } else {
160 unsigned char digit = *p - '0';
161 i = digit;
162 p++;
163 while (is_integer(*p)) {
164 digit = *p - '0';
165 i = 10 * i + digit;
166 ++p;
167 }
168 }
169 if ('.' == *p) {
170 ++p;
171 int fractional_weight = 308;
172 if (is_integer(*p)) {
173 unsigned char digit = *p - '0';
174 ++p;
175
176 fractional_weight--;
177 i = i + digit * (fractional_weight >= 0 ? power_of_ten[fractional_weight]
178 : 0);
179 } else {
180#ifdef JSON_TEST_NUMBERS // for unit testing
181 found_invalid_number(buf + offset);
182#endif
183 return false;
184 }
185 while (is_integer(*p)) {
186 unsigned char digit = *p - '0';
187 ++p;
188 fractional_weight--;
189 i = i + digit * (fractional_weight >= 0 ? power_of_ten[fractional_weight]
190 : 0);
191 }
192 }
193 if (('e' == *p) || ('E' == *p)) {
194 ++p;
195 bool neg_exp = false;
196 if ('-' == *p) {
197 neg_exp = true;
198 ++p;
199 } else if ('+' == *p) {
200 ++p;
201 }
202 if (!is_integer(*p)) {
203#ifdef JSON_TEST_NUMBERS // for unit testing
204 found_invalid_number(buf + offset);
205#endif
206 return false;
207 }
208 unsigned char digit = *p - '0';
209 int64_t exp_number = digit; // exponential part
210 p++;
211 if (is_integer(*p)) {
212 digit = *p - '0';
213 exp_number = 10 * exp_number + digit;
214 ++p;
215 }
216 if (is_integer(*p)) {
217 digit = *p - '0';
218 exp_number = 10 * exp_number + digit;
219 ++p;
220 }
221 if (is_integer(*p)) {
222 digit = *p - '0';
223 exp_number = 10 * exp_number + digit;
224 ++p;
225 }
226 while (is_integer(*p)) {
227 if (exp_number > 0x100000000) { // we need to check for overflows
228// we refuse to parse this
229#ifdef JSON_TEST_NUMBERS // for unit testing
230 found_invalid_number(buf + offset);
231#endif
232 return false;
233 }
234 digit = *p - '0';
235 exp_number = 10 * exp_number + digit;
236 ++p;
237 }
238 if (unlikely(exp_number > 308)) {
239 // this path is unlikely
240 if (neg_exp) {
241 // We either have zero or a subnormal.
242 // We expect this to be uncommon so we go through a slow path.
243 i = subnormal_power10(i, -exp_number);
244 } else {
245// We know for sure that we have a number that is too large,
246// we refuse to parse this
247#ifdef JSON_TEST_NUMBERS // for unit testing
248 found_invalid_number(buf + offset);
249#endif
250 return false;
251 }
252 } else {
253 int exponent = (neg_exp ? -exp_number : exp_number);
254 // we have that exp_number is [0,308] so that
255 // exponent is [-308,308] so that
256 // 308 + exponent is in [0, 2 * 308]
257 i *= power_of_ten[308 + exponent];
258 }
259 }
260 if (is_not_structural_or_whitespace(*p)) {
261 return false;
262 }
263 // check that we can go from long double to double safely.
264 if(i > std::numeric_limits<double>::max()) {
265#ifdef JSON_TEST_NUMBERS // for unit testing
266 found_invalid_number(buf + offset);
267#endif
268 return false;
269 }
270 double d = negative ? -i : i;
271 pj.write_tape_double(d);
272#ifdef JSON_TEST_NUMBERS // for unit testing
273 found_float(d, buf + offset);
274#endif
275 return is_structural_or_whitespace(*p);
276}
277
278// called by parse_number when we know that the output is an integer,
279// but where there might be some integer overflow.
280// we want to catch overflows!
281// Do not call this function directly as it skips some of the checks from
282// parse_number
283//
284// This function will almost never be called!!!
285//
286static never_inline bool parse_large_integer(const uint8_t *const buf,
287 ParsedJson &pj,
288 const uint32_t offset,
289 bool found_minus) {
290 const char *p = reinterpret_cast<const char *>(buf + offset);
291
292 bool negative = false;
293 if (found_minus) {
294 ++p;
295 negative = true;
296 }
297 uint64_t i;
298 if (*p == '0') { // 0 cannot be followed by an integer
299 ++p;
300 i = 0;
301 } else {
302 unsigned char digit = *p - '0';
303 i = digit;
304 p++;
305 // the is_made_of_eight_digits_fast routine is unlikely to help here because
306 // we rarely see large integer parts like 123456789
307 while (is_integer(*p)) {
308 digit = *p - '0';
309 if (mul_overflow(i, 10, &i)) {
310#ifdef JSON_TEST_NUMBERS // for unit testing
311 found_invalid_number(buf + offset);
312#endif
313 return false; // overflow
314 }
315 if (add_overflow(i, digit, &i)) {
316#ifdef JSON_TEST_NUMBERS // for unit testing
317 found_invalid_number(buf + offset);
318#endif
319 return false; // overflow
320 }
321 ++p;
322 }
323 }
324 if (negative) {
325 if (i > 0x8000000000000000) {
326 // overflows!
327#ifdef JSON_TEST_NUMBERS // for unit testing
328 found_invalid_number(buf + offset);
329#endif
330 return false; // overflow
331 } else if (i == 0x8000000000000000) {
332 // In two's complement, we cannot represent 0x8000000000000000
333 // as a positive signed integer, but the negative version is
334 // possible.
335 constexpr int64_t signed_answer = INT64_MIN;
336 pj.write_tape_s64(signed_answer);
337#ifdef JSON_TEST_NUMBERS // for unit testing
338 found_integer(signed_answer, buf + offset);
339#endif
340 } else {
341 // we can negate safely
342 int64_t signed_answer = -static_cast<int64_t>(i);
343 pj.write_tape_s64(signed_answer);
344#ifdef JSON_TEST_NUMBERS // for unit testing
345 found_integer(signed_answer, buf + offset);
346#endif
347 }
348 } else {
349 // we have a positive integer, the contract is that
350 // we try to represent it as a signed integer and only
351 // fallback on unsigned integers if absolutely necessary.
352 if(i < 0x8000000000000000) {
353#ifdef JSON_TEST_NUMBERS // for unit testing
354 found_integer(i, buf + offset);
355#endif
356 pj.write_tape_s64(i);
357 } else {
358#ifdef JSON_TEST_NUMBERS // for unit testing
359 found_unsigned_integer(i, buf + offset);
360#endif
361 pj.write_tape_u64(i);
362 }
363 }
364 return is_structural_or_whitespace(*p);
365}
366
367// parse the number at buf + offset
368// define JSON_TEST_NUMBERS for unit testing
369//
370// It is assumed that the number is followed by a structural ({,},],[) character
371// or a white space character. If that is not the case (e.g., when the JSON
372// document is made of a single number), then it is necessary to copy the
373// content and append a space before calling this function.
374//
375// Our objective is accurate parsing (ULP of 0 or 1) at high speed.
376static really_inline bool parse_number(const uint8_t *const buf, ParsedJson &pj,
377 const uint32_t offset,
378 bool found_minus) {
379#ifdef SIMDJSON_SKIPNUMBERPARSING // for performance analysis, it is sometimes
380 // useful to skip parsing
381 pj.write_tape_s64(0); // always write zero
382 return true; // always succeeds
383#else
384 const char *p = reinterpret_cast<const char *>(buf + offset);
385 bool negative = false;
386 if (found_minus) {
387 ++p;
388 negative = true;
389 if (!is_integer(*p)) { // a negative sign must be followed by an integer
390#ifdef JSON_TEST_NUMBERS // for unit testing
391 found_invalid_number(buf + offset);
392#endif
393 return false;
394 }
395 }
396 const char *const start_digits = p;
397
398 uint64_t i; // an unsigned int avoids signed overflows (which are bad)
399 if (*p == '0') { // 0 cannot be followed by an integer
400 ++p;
401 if (is_not_structural_or_whitespace_or_exponent_or_decimal(*p)) {
402#ifdef JSON_TEST_NUMBERS // for unit testing
403 found_invalid_number(buf + offset);
404#endif
405 return false;
406 }
407 i = 0;
408 } else {
409 if (!(is_integer(*p))) { // must start with an integer
410#ifdef JSON_TEST_NUMBERS // for unit testing
411 found_invalid_number(buf + offset);
412#endif
413 return false;
414 }
415 unsigned char digit = *p - '0';
416 i = digit;
417 p++;
418 // the is_made_of_eight_digits_fast routine is unlikely to help here because
419 // we rarely see large integer parts like 123456789
420 while (is_integer(*p)) {
421 digit = *p - '0';
422 // a multiplication by 10 is cheaper than an arbitrary integer
423 // multiplication
424 i = 10 * i + digit; // might overflow, we will handle the overflow later
425 ++p;
426 }
427 }
428 int64_t exponent = 0;
429 bool is_float = false;
430 if ('.' == *p) {
431 is_float = true; // At this point we know that we have a float
432 // we continue with the fiction that we have an integer. If the
433 // floating point number is representable as x * 10^z for some integer
434 // z that fits in 53 bits, then we will be able to convert back the
435 // the integer into a float in a lossless manner.
436 ++p;
437 const char *const first_after_period = p;
438 if (is_integer(*p)) {
439 unsigned char digit = *p - '0';
440 ++p;
441 i = i * 10 + digit; // might overflow + multiplication by 10 is likely
442 // cheaper than arbitrary mult.
443 // we will handle the overflow later
444 } else {
445#ifdef JSON_TEST_NUMBERS // for unit testing
446 found_invalid_number(buf + offset);
447#endif
448 return false;
449 }
450#ifdef SWAR_NUMBER_PARSING
451 // this helps if we have lots of decimals!
452 // this turns out to be frequent enough.
453 if (is_made_of_eight_digits_fast(p)) {
454 i = i * 100000000 + parse_eight_digits_unrolled(p);
455 p += 8;
456 }
457#endif
458 while (is_integer(*p)) {
459 unsigned char digit = *p - '0';
460 ++p;
461 i = i * 10 + digit; // in rare cases, this will overflow, but that's ok
462 // because we have parse_highprecision_float later.
463 }
464 exponent = first_after_period - p;
465 }
466 int digit_count =
467 p - start_digits - 1; // used later to guard against overflows
468 int64_t exp_number = 0; // exponential part
469 if (('e' == *p) || ('E' == *p)) {
470 is_float = true;
471 ++p;
472 bool neg_exp = false;
473 if ('-' == *p) {
474 neg_exp = true;
475 ++p;
476 } else if ('+' == *p) {
477 ++p;
478 }
479 if (!is_integer(*p)) {
480#ifdef JSON_TEST_NUMBERS // for unit testing
481 found_invalid_number(buf + offset);
482#endif
483 return false;
484 }
485 unsigned char digit = *p - '0';
486 exp_number = digit;
487 p++;
488 if (is_integer(*p)) {
489 digit = *p - '0';
490 exp_number = 10 * exp_number + digit;
491 ++p;
492 }
493 if (is_integer(*p)) {
494 digit = *p - '0';
495 exp_number = 10 * exp_number + digit;
496 ++p;
497 }
498 while (is_integer(*p)) {
499 if (exp_number > 0x100000000) { // we need to check for overflows
500 // we refuse to parse this
501#ifdef JSON_TEST_NUMBERS // for unit testing
502 found_invalid_number(buf + offset);
503#endif
504 return false;
505 }
506 digit = *p - '0';
507 exp_number = 10 * exp_number + digit;
508 ++p;
509 }
510 exponent += (neg_exp ? -exp_number : exp_number);
511 }
512 if (is_float) {
513 uint64_t power_index = 308 + exponent;
514 if (unlikely((digit_count >= 19))) { // this is uncommon
515 // It is possible that the integer had an overflow.
516 // We have to handle the case where we have 0.0000somenumber.
517 const char *start = start_digits;
518 while ((*start == '0') || (*start == '.')) {
519 start++;
520 }
521 // we over-decrement by one when there is a '.'
522 digit_count -= (start - start_digits);
523 if (digit_count >= 19) {
524 // Ok, chances are good that we had an overflow!
525 // this is almost never going to get called!!!
526 // we start anew, going slowly!!!
527 return parse_float(buf, pj, offset, found_minus);
528 }
529 }
530 if (unlikely((power_index > 2 * 308))) { // this is uncommon!!!
531 // this is almost never going to get called!!!
532 // we start anew, going slowly!!!
533 return parse_float(buf, pj, offset, found_minus);
534 }
535 double factor = power_of_ten[power_index];
536 factor = negative ? -factor : factor;
537 double d = i * factor;
538 pj.write_tape_double(d);
539#ifdef JSON_TEST_NUMBERS // for unit testing
540 found_float(d, buf + offset);
541#endif
542 } else {
543 if (unlikely(digit_count >= 18)) { // this is uncommon!!!
544 // there is a good chance that we had an overflow, so we need
545 // need to recover: we parse the whole thing again.
546 return parse_large_integer(buf, pj, offset, found_minus);
547 }
548 i = negative ? 0 - i : i;
549 pj.write_tape_s64(i);
550#ifdef JSON_TEST_NUMBERS // for unit testing
551 found_integer(i, buf + offset);
552#endif
553 }
554 return is_structural_or_whitespace(*p);
555#endif // SIMDJSON_SKIPNUMBERPARSING
556}
557
558