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1 | /*============================================================================= |
2 | Copyright (c) 2001-2011 Joel de Guzman | |
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 | =============================================================================*/ | |
9 | #if !defined(SPIRIT_REAL_IMPL_APRIL_18_2006_0901AM) | |
10 | #define SPIRIT_REAL_IMPL_APRIL_18_2006_0901AM | |
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; | |
35 | ||
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 | } | |
47 | ||
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 | } | |
54 | ||
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 | { | |
68 | int max_exp = std::numeric_limits<T>::max_exponent10; | |
69 | ||
70 | // return false if exp exceeds the max_exp | |
71 | // do this check only for primitive types! | |
72 | if (is_floating_point<T>() && exp > max_exp) | |
73 | return false; | |
74 | n = acc_n * pow10<T>(exp); | |
75 | } | |
76 | else | |
77 | { | |
78 | if (exp < std::numeric_limits<T>::min_exponent10) | |
79 | { | |
80 | int min_exp = std::numeric_limits<T>::min_exponent10; | |
81 | detail::compensate_roundoff(n, acc_n); | |
82 | n /= pow10<T>(-min_exp); | |
83 | ||
84 | // return false if (-exp + min_exp) exceeds the -min_exp | |
85 | // do this check only for primitive types! | |
86 | if (is_floating_point<T>() && (-exp + min_exp) > -min_exp) | |
87 | return false; | |
88 | ||
89 | n /= pow10<T>(-exp + min_exp); | |
90 | } | |
91 | else | |
92 | { | |
93 | n = T(acc_n) / pow10<T>(-exp); | |
94 | } | |
95 | } | |
96 | return true; | |
97 | } | |
98 | ||
99 | inline bool | |
100 | scale(int /*exp*/, unused_type /*n*/, unused_type /*acc_n*/) | |
101 | { | |
102 | // no-op for unused_type | |
103 | return true; | |
104 | } | |
105 | ||
106 | template <typename T, typename AccT> | |
107 | inline bool | |
108 | scale(int exp, int frac, T& n, AccT acc_n) | |
109 | { | |
110 | return scale(exp - frac, n, acc_n); | |
111 | } | |
112 | ||
113 | inline bool | |
114 | scale(int /*exp*/, int /*frac*/, unused_type /*n*/) | |
115 | { | |
116 | // no-op for unused_type | |
117 | return true; | |
118 | } | |
119 | ||
120 | inline float | |
121 | negate(bool neg, float n) | |
122 | { | |
123 | return neg ? spirit::detail::changesign(n) : n; | |
124 | } | |
125 | ||
126 | inline double | |
127 | negate(bool neg, double n) | |
128 | { | |
129 | return neg ? spirit::detail::changesign(n) : n; | |
130 | } | |
131 | ||
132 | inline long double | |
133 | negate(bool neg, long double n) | |
134 | { | |
135 | return neg ? spirit::detail::changesign(n) : n; | |
136 | } | |
137 | ||
138 | template <typename T> | |
139 | inline T | |
140 | negate(bool neg, T const& n) | |
141 | { | |
142 | return neg ? -n : n; | |
143 | } | |
144 | ||
145 | inline unused_type | |
146 | negate(bool /*neg*/, unused_type n) | |
147 | { | |
148 | // no-op for unused_type | |
149 | return n; | |
150 | } | |
151 | ||
152 | template <typename T> | |
153 | inline bool | |
154 | is_equal_to_one(T const& value) | |
155 | { | |
156 | return value == 1.0; | |
157 | } | |
158 | ||
159 | inline bool | |
160 | is_equal_to_one(unused_type) | |
161 | { | |
162 | // no-op for unused_type | |
163 | return false; | |
164 | } | |
165 | ||
166 | template <typename T> | |
167 | struct real_accumulator : mpl::identity<T> {}; | |
168 | ||
169 | template <> | |
170 | struct real_accumulator<float> | |
171 | : mpl::identity<uint_t<(sizeof(float)*CHAR_BIT)>::least> {}; | |
172 | ||
173 | template <> | |
174 | struct real_accumulator<double> | |
175 | : mpl::identity<uint_t<(sizeof(double)*CHAR_BIT)>::least> {}; | |
176 | }}} | |
177 | ||
178 | namespace boost { namespace spirit { namespace qi { namespace detail | |
179 | { | |
180 | template <typename T, typename RealPolicies> | |
181 | struct real_impl | |
182 | { | |
183 | template <typename Iterator, typename Attribute> | |
184 | static bool | |
185 | parse(Iterator& first, Iterator const& last, Attribute& attr, | |
186 | RealPolicies const& p) | |
187 | { | |
188 | if (first == last) | |
189 | return false; | |
190 | Iterator save = first; | |
191 | ||
192 | // Start by parsing the sign. neg will be true if | |
193 | // we got a "-" sign, false otherwise. | |
194 | bool neg = p.parse_sign(first, last); | |
195 | ||
196 | // Now attempt to parse an integer | |
197 | T n; | |
198 | ||
199 | typename traits::real_accumulator<T>::type acc_n = 0; | |
200 | bool got_a_number = p.parse_n(first, last, acc_n); | |
201 | ||
202 | // If we did not get a number it might be a NaN, Inf or a leading | |
203 | // dot. | |
204 | if (!got_a_number) | |
205 | { | |
206 | // Check whether the number to parse is a NaN or Inf | |
207 | if (p.parse_nan(first, last, n) || | |
208 | p.parse_inf(first, last, n)) | |
209 | { | |
210 | // If we got a negative sign, negate the number | |
211 | traits::assign_to(traits::negate(neg, n), attr); | |
212 | return true; // got a NaN or Inf, return early | |
213 | } | |
214 | ||
215 | // If we did not get a number and our policies do not | |
216 | // allow a leading dot, fail and return early (no-match) | |
217 | if (!p.allow_leading_dot) | |
218 | { | |
219 | first = save; | |
220 | return false; | |
221 | } | |
222 | } | |
223 | ||
224 | bool e_hit = false; | |
225 | Iterator e_pos; | |
226 | int frac_digits = 0; | |
227 | ||
228 | // Try to parse the dot ('.' decimal point) | |
229 | if (p.parse_dot(first, last)) | |
230 | { | |
231 | // We got the decimal point. Now we will try to parse | |
232 | // the fraction if it is there. If not, it defaults | |
233 | // to zero (0) only if we already got a number. | |
234 | if (p.parse_frac_n(first, last, acc_n, frac_digits)) | |
235 | { | |
236 | } | |
237 | else if (!got_a_number || !p.allow_trailing_dot) | |
238 | { | |
239 | // We did not get a fraction. If we still haven't got a | |
240 | // number and our policies do not allow a trailing dot, | |
241 | // return no-match. | |
242 | first = save; | |
243 | return false; | |
244 | } | |
245 | ||
246 | // Now, let's see if we can parse the exponent prefix | |
247 | e_pos = first; | |
248 | e_hit = p.parse_exp(first, last); | |
249 | } | |
250 | else | |
251 | { | |
252 | // No dot and no number! Return no-match. | |
253 | if (!got_a_number) | |
254 | { | |
255 | first = save; | |
256 | return false; | |
257 | } | |
258 | ||
259 | // If we must expect a dot and we didn't see an exponent | |
260 | // prefix, return no-match. | |
261 | e_pos = first; | |
262 | e_hit = p.parse_exp(first, last); | |
263 | if (p.expect_dot && !e_hit) | |
264 | { | |
265 | first = save; | |
266 | return false; | |
267 | } | |
268 | } | |
269 | ||
270 | if (e_hit) | |
271 | { | |
272 | // We got the exponent prefix. Now we will try to parse the | |
273 | // actual exponent. | |
274 | int exp = 0; | |
275 | if (p.parse_exp_n(first, last, exp)) | |
276 | { | |
277 | // Got the exponent value. Scale the number by | |
278 | // exp-frac_digits. | |
279 | if (!traits::scale(exp, frac_digits, n, acc_n)) | |
280 | return false; | |
281 | } | |
282 | else | |
283 | { | |
284 | // If there is no number, disregard the exponent altogether. | |
285 | // by resetting 'first' prior to the exponent prefix (e|E) | |
286 | first = e_pos; | |
287 | n = static_cast<T>(acc_n); | |
288 | } | |
289 | } | |
290 | else if (frac_digits) | |
291 | { | |
292 | // No exponent found. Scale the number by -frac_digits. | |
293 | traits::scale(-frac_digits, n, acc_n); | |
294 | } | |
295 | else if (traits::is_equal_to_one(acc_n)) | |
296 | { | |
297 | // There is a chance of having to parse one of the 1.0#... | |
298 | // styles some implementations use for representing NaN or Inf. | |
299 | ||
300 | // Check whether the number to parse is a NaN or Inf | |
301 | if (p.parse_nan(first, last, n) || | |
302 | p.parse_inf(first, last, n)) | |
303 | { | |
304 | // If we got a negative sign, negate the number | |
305 | traits::assign_to(traits::negate(neg, n), attr); | |
306 | return true; // got a NaN or Inf, return immediately | |
307 | } | |
308 | ||
309 | n = static_cast<T>(acc_n); | |
310 | } | |
311 | else | |
312 | { | |
313 | n = static_cast<T>(acc_n); | |
314 | } | |
315 | ||
316 | // If we got a negative sign, negate the number | |
317 | traits::assign_to(traits::negate(neg, n), attr); | |
318 | ||
319 | // Success!!! | |
320 | return true; | |
321 | } | |
322 | }; | |
323 | ||
324 | #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400) | |
325 | # pragma warning(pop) | |
326 | #endif | |
327 | ||
328 | }}}} | |
329 | ||
330 | #endif |