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%%{
32
33machine double_parser;
34alphtype unsigned char;
35write data;
36
37action see_neg { neg = true; }
38action see_exp_neg { exp_neg = true; }
39
40action add_int  {
41	value = value * 10. + (fc - '0');
42}
43action add_frac {
44	if (likely (frac <= MAX_FRACT / 10))
45	{
46	  frac = frac * 10. + (fc - '0');
47	  ++frac_count;
48	}
49}
50action add_exp  {
51	if (likely (exp * 10 + (fc - '0') <= MAX_EXP))
52	  exp = exp * 10 + (fc - '0');
53	else
54	  exp_overflow = true;
55}
56
57num = [0-9]+;
58
59main := (
60	(
61		(('+'|'-'@see_neg)? num @add_int) ('.' num @add_frac)?
62		|
63		(('+'|'-'@see_neg)? '.' num @add_frac)
64	)
65	(('e'|'E') (('+'|'-'@see_exp_neg)? num @add_exp))?
66);
67
68}%%
69
70/* Works only for n < 512 */
71static inline double
72_pow10 (unsigned exponent)
73{
74  static const double _powers_of_10[] =
75  {
76    1.0e+256,
77    1.0e+128,
78    1.0e+64,
79    1.0e+32,
80    1.0e+16,
81    1.0e+8,
82    10000.,
83    100.,
84    10.
85  };
86  unsigned mask = 1 << (ARRAY_LENGTH (_powers_of_10) - 1);
87  double result = 1;
88  for (const double *power = _powers_of_10; mask; ++power, mask >>= 1)
89    if (exponent & mask) result *= *power;
90  return result;
91}
92
93/* a variant of strtod that also gets end of buffer in its second argument */
94static inline double
95strtod_rl (const char *p, const char **end_ptr /* IN/OUT */)
96{
97  double value = 0;
98  double frac = 0;
99  double frac_count = 0;
100  unsigned exp = 0;
101  bool neg = false, exp_neg = false, exp_overflow = false;
102  const unsigned long long MAX_FRACT = 0xFFFFFFFFFFFFFull; /* 2^52-1 */
103  const unsigned MAX_EXP = 0x7FFu; /* 2^11-1 */
104
105  const char *pe = *end_ptr;
106  while (p < pe && ISSPACE (*p))
107    p++;
108
109  int cs;
110  %%{
111    write init;
112    write exec;
113  }%%
114
115  *end_ptr = p;
116
117  if (frac_count) value += frac / _pow10 (frac_count);
118  if (neg) value *= -1.;
119
120  if (unlikely (exp_overflow))
121  {
122    if (value == 0) return value;
123    if (exp_neg)    return neg ? -DBL_MIN : DBL_MIN;
124    else            return neg ? -DBL_MAX : DBL_MAX;
125  }
126
127  if (exp)
128  {
129    if (exp_neg) value /= _pow10 (exp);
130    else         value *= _pow10 (exp);
131  }
132
133  return value;
134}
135
136#endif /* HB_NUMBER_PARSER_HH */
137