1/*
2 * Copyright © 2019  Ebrahim Byagowi
3 *
4 *  This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 */
25
26#ifndef HB_NUMBER_PARSER_HH
27#define HB_NUMBER_PARSER_HH
28
29#include "hb.hh"
30
31#include <float.h>
32
33%%{
34
35machine double_parser;
36alphtype unsigned char;
37write data;
38
39action see_neg { neg = true; }
40action see_exp_neg { exp_neg = true; }
41
42action add_int  {
43	value = value * 10. + (fc - '0');
44}
45action add_frac {
46	if (likely (frac <= MAX_FRACT / 10))
47	{
48	  frac = frac * 10. + (fc - '0');
49	  ++frac_count;
50	}
51}
52action add_exp  {
53	if (likely (exp * 10 + (fc - '0') <= MAX_EXP))
54	  exp = exp * 10 + (fc - '0');
55	else
56	  exp_overflow = true;
57}
58
59num = [0-9]+;
60
61main := (
62	(
63		(('+'|'-'@see_neg)? num @add_int) ('.' num @add_frac)?
64		|
65		(('+'|'-'@see_neg)? '.' num @add_frac)
66	)
67	(('e'|'E') (('+'|'-'@see_exp_neg)? num @add_exp))?
68);
69
70}%%
71
72/* Works only for n < 512 */
73static inline double
74_pow10 (unsigned int exponent)
75{
76  static const double _powers_of_10[] =
77  {
78    1.0e+256,
79    1.0e+128,
80    1.0e+64,
81    1.0e+32,
82    1.0e+16,
83    1.0e+8,
84    10000.,
85    100.,
86    10.
87  };
88  unsigned int mask = 1 << (ARRAY_LENGTH (_powers_of_10) - 1);
89  double result = 1;
90  for (const double *power = _powers_of_10; mask; ++power, mask >>= 1)
91    if (exponent & mask) result *= *power;
92  return result;
93}
94
95static inline double
96strtod_rl (const char *buf, char **end_ptr)
97{
98  const char *p, *pe;
99  double value = 0;
100  double frac = 0;
101  double frac_count = 0;
102  unsigned int exp = 0;
103  bool neg = false, exp_neg = false, exp_overflow = false;
104  const unsigned long long MAX_FRACT = 0xFFFFFFFFFFFFFull; /* 1^52-1 */
105  const unsigned int MAX_EXP = 0x7FFu; /* 1^11-1 */
106  p = buf;
107  pe = p + strlen (p);
108
109  while (p < pe && ISSPACE (*p))
110    p++;
111
112  int cs;
113  %%{
114    write init;
115    write exec;
116  }%%
117
118  *end_ptr = (char *) p;
119
120  if (frac_count) value += frac / _pow10 (frac_count);
121  if (neg) value *= -1.;
122
123  if (unlikely (exp_overflow))
124  {
125    if (value == 0) return value;
126    if (exp_neg)    return neg ? -DBL_MIN : DBL_MIN;
127    else            return neg ? -DBL_MAX : DBL_MAX;
128  }
129
130  if (exp)
131  {
132    if (exp_neg) value /= _pow10 (exp);
133    else         value *= _pow10 (exp);
134  }
135
136  return value;
137}
138
139#endif /* HB_NUMBER_PARSER_HH */
140