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7c673cae | 1 | /*============================================================================= |
92f5a8d4 | 2 | Copyright (c) 2001-2019 Joel de Guzman |
7c673cae FG |
3 | Copyright (c) 2001-2011 Hartmut Kaiser |
4 | http://spirit.sourceforge.net/ | |
5 | ||
6 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
7 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
8 | =============================================================================*/ | |
f67539c2 TL |
9 | #ifndef BOOST_SPIRIT_QI_NUMERIC_DETAIL_REAL_IMPL_HPP |
10 | #define BOOST_SPIRIT_QI_NUMERIC_DETAIL_REAL_IMPL_HPP | |
7c673cae FG |
11 | |
12 | #if defined(_MSC_VER) | |
13 | #pragma once | |
14 | #endif | |
15 | ||
16 | #include <cmath> | |
17 | #include <boost/limits.hpp> | |
18 | #include <boost/type_traits/is_same.hpp> | |
19 | #include <boost/spirit/home/support/unused.hpp> | |
20 | #include <boost/spirit/home/qi/detail/attributes.hpp> | |
21 | #include <boost/spirit/home/support/detail/pow10.hpp> | |
22 | #include <boost/spirit/home/support/detail/sign.hpp> | |
23 | #include <boost/integer.hpp> | |
24 | #include <boost/assert.hpp> | |
25 | ||
26 | #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) | |
27 | # pragma warning(push) | |
28 | # pragma warning(disable: 4100) // 'p': unreferenced formal parameter | |
29 | # pragma warning(disable: 4127) // conditional expression is constant | |
30 | #endif | |
31 | ||
32 | namespace boost { namespace spirit { namespace traits | |
33 | { | |
34 | using spirit::traits::pow10; | |
b32b8144 | 35 | |
7c673cae FG |
36 | namespace detail |
37 | { | |
38 | template <typename T, typename AccT> | |
39 | void compensate_roundoff(T& n, AccT acc_n, mpl::true_) | |
40 | { | |
41 | // at the lowest extremes, we compensate for floating point | |
42 | // roundoff errors by doing imprecise computation using T | |
43 | int const comp = 10; | |
44 | n = T((acc_n / comp) * comp); | |
45 | n += T(acc_n % comp); | |
46 | } | |
b32b8144 | 47 | |
7c673cae FG |
48 | template <typename T, typename AccT> |
49 | void compensate_roundoff(T& n, AccT acc_n, mpl::false_) | |
50 | { | |
51 | // no need to compensate | |
52 | n = acc_n; | |
53 | } | |
b32b8144 | 54 | |
7c673cae FG |
55 | template <typename T, typename AccT> |
56 | void compensate_roundoff(T& n, AccT acc_n) | |
57 | { | |
58 | compensate_roundoff(n, acc_n, is_integral<AccT>()); | |
59 | } | |
60 | } | |
61 | ||
62 | template <typename T, typename AccT> | |
63 | inline bool | |
64 | scale(int exp, T& n, AccT acc_n) | |
65 | { | |
66 | if (exp >= 0) | |
67 | { | |
92f5a8d4 | 68 | int const max_exp = std::numeric_limits<T>::max_exponent10; |
b32b8144 | 69 | |
7c673cae FG |
70 | // return false if exp exceeds the max_exp |
71 | // do this check only for primitive types! | |
92f5a8d4 | 72 | if (is_floating_point<T>() && (exp > max_exp)) |
7c673cae FG |
73 | return false; |
74 | n = acc_n * pow10<T>(exp); | |
75 | } | |
76 | else | |
77 | { | |
78 | if (exp < std::numeric_limits<T>::min_exponent10) | |
79 | { | |
92f5a8d4 | 80 | int const min_exp = std::numeric_limits<T>::min_exponent10; |
7c673cae FG |
81 | detail::compensate_roundoff(n, acc_n); |
82 | n /= pow10<T>(-min_exp); | |
b32b8144 | 83 | |
11fdf7f2 | 84 | // return false if exp still exceeds the min_exp |
7c673cae | 85 | // do this check only for primitive types! |
11fdf7f2 TL |
86 | exp += -min_exp; |
87 | if (is_floating_point<T>() && exp < min_exp) | |
7c673cae FG |
88 | return false; |
89 | ||
11fdf7f2 | 90 | n /= pow10<T>(-exp); |
7c673cae FG |
91 | } |
92 | else | |
93 | { | |
94 | n = T(acc_n) / pow10<T>(-exp); | |
95 | } | |
96 | } | |
97 | return true; | |
98 | } | |
99 | ||
100 | inline bool | |
101 | scale(int /*exp*/, unused_type /*n*/, unused_type /*acc_n*/) | |
102 | { | |
103 | // no-op for unused_type | |
104 | return true; | |
105 | } | |
106 | ||
107 | template <typename T, typename AccT> | |
108 | inline bool | |
109 | scale(int exp, int frac, T& n, AccT acc_n) | |
110 | { | |
111 | return scale(exp - frac, n, acc_n); | |
112 | } | |
113 | ||
114 | inline bool | |
115 | scale(int /*exp*/, int /*frac*/, unused_type /*n*/) | |
116 | { | |
117 | // no-op for unused_type | |
118 | return true; | |
119 | } | |
120 | ||
121 | inline float | |
122 | negate(bool neg, float n) | |
123 | { | |
124 | return neg ? spirit::detail::changesign(n) : n; | |
125 | } | |
126 | ||
127 | inline double | |
128 | negate(bool neg, double n) | |
129 | { | |
130 | return neg ? spirit::detail::changesign(n) : n; | |
131 | } | |
132 | ||
133 | inline long double | |
134 | negate(bool neg, long double n) | |
135 | { | |
136 | return neg ? spirit::detail::changesign(n) : n; | |
137 | } | |
138 | ||
139 | template <typename T> | |
140 | inline T | |
141 | negate(bool neg, T const& n) | |
142 | { | |
143 | return neg ? -n : n; | |
144 | } | |
145 | ||
146 | inline unused_type | |
147 | negate(bool /*neg*/, unused_type n) | |
148 | { | |
149 | // no-op for unused_type | |
150 | return n; | |
151 | } | |
152 | ||
7c673cae FG |
153 | template <typename T> |
154 | struct real_accumulator : mpl::identity<T> {}; | |
155 | ||
156 | template <> | |
157 | struct real_accumulator<float> | |
158 | : mpl::identity<uint_t<(sizeof(float)*CHAR_BIT)>::least> {}; | |
159 | ||
160 | template <> | |
161 | struct real_accumulator<double> | |
162 | : mpl::identity<uint_t<(sizeof(double)*CHAR_BIT)>::least> {}; | |
163 | }}} | |
164 | ||
165 | namespace boost { namespace spirit { namespace qi { namespace detail | |
166 | { | |
92f5a8d4 TL |
167 | BOOST_MPL_HAS_XXX_TRAIT_DEF(version) |
168 | ||
7c673cae FG |
169 | template <typename T, typename RealPolicies> |
170 | struct real_impl | |
171 | { | |
92f5a8d4 TL |
172 | template <typename Iterator> |
173 | static std::size_t | |
f67539c2 | 174 | ignore_excess_digits(Iterator& /* first */, Iterator const& /* last */, mpl::false_) |
92f5a8d4 TL |
175 | { |
176 | return 0; | |
177 | } | |
178 | ||
179 | template <typename Iterator> | |
180 | static std::size_t | |
181 | ignore_excess_digits(Iterator& first, Iterator const& last, mpl::true_) | |
182 | { | |
183 | return RealPolicies::ignore_excess_digits(first, last); | |
184 | } | |
185 | ||
186 | template <typename Iterator> | |
187 | static std::size_t | |
188 | ignore_excess_digits(Iterator& first, Iterator const& last) | |
189 | { | |
190 | typedef mpl::bool_<has_version<RealPolicies>::value> has_version; | |
191 | return ignore_excess_digits(first, last, has_version()); | |
192 | } | |
193 | ||
7c673cae FG |
194 | template <typename Iterator, typename Attribute> |
195 | static bool | |
196 | parse(Iterator& first, Iterator const& last, Attribute& attr, | |
197 | RealPolicies const& p) | |
198 | { | |
199 | if (first == last) | |
200 | return false; | |
201 | Iterator save = first; | |
202 | ||
203 | // Start by parsing the sign. neg will be true if | |
204 | // we got a "-" sign, false otherwise. | |
205 | bool neg = p.parse_sign(first, last); | |
206 | ||
207 | // Now attempt to parse an integer | |
208 | T n; | |
209 | ||
210 | typename traits::real_accumulator<T>::type acc_n = 0; | |
211 | bool got_a_number = p.parse_n(first, last, acc_n); | |
92f5a8d4 | 212 | int excess_n = 0; |
7c673cae FG |
213 | |
214 | // If we did not get a number it might be a NaN, Inf or a leading | |
215 | // dot. | |
216 | if (!got_a_number) | |
217 | { | |
218 | // Check whether the number to parse is a NaN or Inf | |
219 | if (p.parse_nan(first, last, n) || | |
220 | p.parse_inf(first, last, n)) | |
221 | { | |
222 | // If we got a negative sign, negate the number | |
223 | traits::assign_to(traits::negate(neg, n), attr); | |
224 | return true; // got a NaN or Inf, return early | |
225 | } | |
226 | ||
227 | // If we did not get a number and our policies do not | |
228 | // allow a leading dot, fail and return early (no-match) | |
229 | if (!p.allow_leading_dot) | |
230 | { | |
231 | first = save; | |
232 | return false; | |
233 | } | |
234 | } | |
92f5a8d4 TL |
235 | else |
236 | { | |
237 | // We got a number and we still see digits. This happens if acc_n (an integer) | |
238 | // exceeds the integer's capacity. Collect the excess digits. | |
239 | excess_n = static_cast<int>(ignore_excess_digits(first, last)); | |
240 | } | |
7c673cae FG |
241 | |
242 | bool e_hit = false; | |
243 | Iterator e_pos; | |
244 | int frac_digits = 0; | |
245 | ||
246 | // Try to parse the dot ('.' decimal point) | |
247 | if (p.parse_dot(first, last)) | |
248 | { | |
249 | // We got the decimal point. Now we will try to parse | |
250 | // the fraction if it is there. If not, it defaults | |
251 | // to zero (0) only if we already got a number. | |
92f5a8d4 TL |
252 | if (excess_n != 0) |
253 | { | |
254 | // We skip the fractions if we already exceeded our digits capacity | |
255 | ignore_excess_digits(first, last); | |
256 | } | |
257 | else if (p.parse_frac_n(first, last, acc_n, frac_digits)) | |
7c673cae | 258 | { |
11fdf7f2 | 259 | BOOST_ASSERT(frac_digits >= 0); |
7c673cae FG |
260 | } |
261 | else if (!got_a_number || !p.allow_trailing_dot) | |
262 | { | |
263 | // We did not get a fraction. If we still haven't got a | |
264 | // number and our policies do not allow a trailing dot, | |
265 | // return no-match. | |
266 | first = save; | |
267 | return false; | |
268 | } | |
269 | ||
270 | // Now, let's see if we can parse the exponent prefix | |
271 | e_pos = first; | |
272 | e_hit = p.parse_exp(first, last); | |
273 | } | |
274 | else | |
275 | { | |
276 | // No dot and no number! Return no-match. | |
277 | if (!got_a_number) | |
278 | { | |
279 | first = save; | |
280 | return false; | |
281 | } | |
282 | ||
283 | // If we must expect a dot and we didn't see an exponent | |
284 | // prefix, return no-match. | |
285 | e_pos = first; | |
286 | e_hit = p.parse_exp(first, last); | |
287 | if (p.expect_dot && !e_hit) | |
288 | { | |
289 | first = save; | |
290 | return false; | |
291 | } | |
292 | } | |
293 | ||
294 | if (e_hit) | |
295 | { | |
296 | // We got the exponent prefix. Now we will try to parse the | |
297 | // actual exponent. | |
298 | int exp = 0; | |
299 | if (p.parse_exp_n(first, last, exp)) | |
300 | { | |
301 | // Got the exponent value. Scale the number by | |
92f5a8d4 TL |
302 | // exp + excess_n - frac_digits. |
303 | if (!traits::scale(exp + excess_n, frac_digits, n, acc_n)) | |
7c673cae FG |
304 | return false; |
305 | } | |
306 | else | |
307 | { | |
308 | // If there is no number, disregard the exponent altogether. | |
309 | // by resetting 'first' prior to the exponent prefix (e|E) | |
310 | first = e_pos; | |
b32b8144 | 311 | // Scale the number by -frac_digits. |
11fdf7f2 TL |
312 | bool r = traits::scale(-frac_digits, n, acc_n); |
313 | BOOST_VERIFY(r); | |
7c673cae FG |
314 | } |
315 | } | |
316 | else if (frac_digits) | |
317 | { | |
318 | // No exponent found. Scale the number by -frac_digits. | |
11fdf7f2 TL |
319 | bool r = traits::scale(-frac_digits, n, acc_n); |
320 | BOOST_VERIFY(r); | |
7c673cae | 321 | } |
92f5a8d4 | 322 | else |
7c673cae | 323 | { |
92f5a8d4 | 324 | if (excess_n) |
7c673cae | 325 | { |
92f5a8d4 TL |
326 | if (!traits::scale(excess_n, n, acc_n)) |
327 | return false; | |
328 | } | |
329 | else | |
330 | { | |
331 | n = static_cast<T>(acc_n); | |
7c673cae | 332 | } |
7c673cae FG |
333 | } |
334 | ||
335 | // If we got a negative sign, negate the number | |
336 | traits::assign_to(traits::negate(neg, n), attr); | |
337 | ||
338 | // Success!!! | |
339 | return true; | |
340 | } | |
341 | }; | |
342 | ||
343 | #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) | |
344 | # pragma warning(pop) | |
345 | #endif | |
346 | ||
347 | }}}} | |
348 | ||
349 | #endif |