1// ----------------------------------------------------------------------------
2// parsing.hpp : implementation of the parsing member functions
3// ( parse, parse_printf_directive)
4// ----------------------------------------------------------------------------
5
6// Copyright Samuel Krempp 2003. Use, modification, and distribution are
7// subject to the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9
10// see http://www.boost.org/libs/format for library home page
11
12// ----------------------------------------------------------------------------
13
14#ifndef BOOST_FORMAT_PARSING_HPP
15#define BOOST_FORMAT_PARSING_HPP
16
17
18#include <boost/format/format_class.hpp>
19#include <boost/format/exceptions.hpp>
20#include <boost/throw_exception.hpp>
21#include <boost/assert.hpp>
22
23
24namespace boost {
25namespace io {
26namespace detail {
27
28#if defined(BOOST_NO_STD_LOCALE)
29 // streams will be used for narrow / widen. but these methods are not const
30 template<class T>
31 T& const_or_not(const T& x) {
32 return const_cast<T&> (x);
33 }
34#else
35 template<class T>
36 const T& const_or_not(const T& x) {
37 return x;
38 }
39#endif
40
41 template<class Ch, class Facet> inline
42 char wrap_narrow(const Facet& fac, Ch c, char deflt) {
43 return const_or_not(fac).narrow(c, deflt);
44 }
45
46 template<class Ch, class Facet> inline
47 bool wrap_isdigit(const Facet& fac, Ch c) {
48#if ! defined( BOOST_NO_LOCALE_ISDIGIT )
49 return fac.is(std::ctype<Ch>::digit, c);
50# else
51 (void) fac; // remove "unused parameter" warning
52 using namespace std;
53 return isdigit(c) != 0;
54#endif
55 }
56
57 template<class Iter, class Facet>
58 Iter wrap_scan_notdigit(const Facet & fac, Iter beg, Iter end) {
59 using namespace std;
60 for( ; beg!=end && wrap_isdigit(fac, *beg); ++beg) ;
61 return beg;
62 }
63
64
65 // Input : [start, last) iterators range and a
66 // a Facet to use its widen/narrow member function
67 // Effects : read sequence and convert digits into integral n, of type Res
68 // Returns : n
69 template<class Res, class Iter, class Facet>
70 Iter str2int (const Iter & start, const Iter & last, Res & res,
71 const Facet& fac)
72 {
73 using namespace std;
74 Iter it;
75 res=0;
76 for(it=start; it != last && wrap_isdigit(fac, *it); ++it ) {
77 char cur_ch = wrap_narrow(fac, *it, 0); // cant fail.
78 res *= 10;
79 res += cur_ch - '0'; // 22.2.1.1.2.13 of the C++ standard
80 }
81 return it;
82 }
83
84 // skip printf's "asterisk-fields" directives in the format-string buf
85 // Input : char string, with starting index *pos_p
86 // a Facet merely to use its widen/narrow member function
87 // Effects : advance *pos_p by skipping printf's asterisk fields.
88 // Returns : nothing
89 template<class Iter, class Facet>
90 Iter skip_asterisk(Iter start, Iter last, const Facet& fac)
91 {
92 using namespace std;
93 ++ start;
94 start = wrap_scan_notdigit(fac, start, last);
95 if(start!=last && *start== const_or_not(fac).widen( '$') )
96 ++start;
97 return start;
98 }
99
100
101 // auxiliary func called by parse_printf_directive
102 // for centralising error handling
103 // it either throws if user sets the corresponding flag, or does nothing.
104 inline void maybe_throw_exception(unsigned char exceptions,
105 std::size_t pos, std::size_t size)
106 {
107 if(exceptions & io::bad_format_string_bit)
108 boost::throw_exception(e: io::bad_format_string(pos, size) );
109 }
110
111
112 // Input: the position of a printf-directive in the format-string
113 // a basic_ios& merely to use its widen/narrow member function
114 // a bitset'exceptions' telling whether to throw exceptions on errors.
115 // Returns:
116 // true if parse succeeded (ignore some errors if exceptions disabled)
117 // false if it failed so bad that the directive should be printed verbatim
118 // Effects:
119 // start is incremented so that *start is the first char after
120 // this directive
121 // *fpar is set with the parameters read in the directive
122 template<class Ch, class Tr, class Alloc, class Iter, class Facet>
123 bool parse_printf_directive(Iter & start, const Iter& last,
124 detail::format_item<Ch, Tr, Alloc> * fpar,
125 const Facet& fac,
126 std::size_t offset, unsigned char exceptions)
127 {
128 typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
129
130 fpar->argN_ = format_item_t::argN_no_posit; // if no positional-directive
131 bool precision_set = false;
132 bool in_brackets=false;
133 Iter start0 = start;
134 std::size_t fstring_size = last-start0+offset;
135
136 if(start>= last) { // empty directive : this is a trailing %
137 maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
138 return false;
139 }
140
141 if(*start== const_or_not(fac).widen( '|')) {
142 in_brackets=true;
143 if( ++start >= last ) {
144 maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
145 return false;
146 }
147 }
148
149 // the flag '0' would be picked as a digit for argument order, but here it's a flag :
150 if(*start== const_or_not(fac).widen( '0'))
151 goto parse_flags;
152
153 // handle argument order (%2$d) or possibly width specification: %2d
154 if(wrap_isdigit(fac, *start)) {
155 int n;
156 start = str2int(start, last, n, fac);
157 if( start >= last ) {
158 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
159 return false;
160 }
161
162 // %N% case : this is already the end of the directive
163 if( *start == const_or_not(fac).widen( '%') ) {
164 fpar->argN_ = n-1;
165 ++start;
166 if( in_brackets)
167 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
168 // but don't return. maybe "%" was used in lieu of '$', so we go on.
169 else
170 return true;
171 }
172
173 if ( *start== const_or_not(fac).widen( '$') ) {
174 fpar->argN_ = n-1;
175 ++start;
176 }
177 else {
178 // non-positionnal directive
179 fpar->fmtstate_.width_ = n;
180 fpar->argN_ = format_item_t::argN_no_posit;
181 goto parse_precision;
182 }
183 }
184
185 parse_flags:
186 // handle flags
187 while ( start != last) { // as long as char is one of + - = _ # 0 l h or ' '
188 // misc switches
189 switch ( wrap_narrow(fac, *start, 0)) {
190 case '\'' : break; // no effect yet. (painful to implement)
191 case 'l':
192 case 'h': // short/long modifier : for printf-comaptibility (no action needed)
193 break;
194 case '-':
195 fpar->fmtstate_.flags_ |= std::ios_base::left;
196 break;
197 case '=':
198 fpar->pad_scheme_ |= format_item_t::centered;
199 break;
200 case '_':
201 fpar->fmtstate_.flags_ |= std::ios_base::internal;
202 break;
203 case ' ':
204 fpar->pad_scheme_ |= format_item_t::spacepad;
205 break;
206 case '+':
207 fpar->fmtstate_.flags_ |= std::ios_base::showpos;
208 break;
209 case '0':
210 fpar->pad_scheme_ |= format_item_t::zeropad;
211 // need to know alignment before really setting flags,
212 // so just add 'zeropad' flag for now, it will be processed later.
213 break;
214 case '#':
215 fpar->fmtstate_.flags_ |= std::ios_base::showpoint | std::ios_base::showbase;
216 break;
217 default:
218 goto parse_width;
219 }
220 ++start;
221 } // loop on flag.
222
223 if( start>=last) {
224 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
225 return true;
226 }
227 parse_width:
228 // handle width spec
229 // first skip 'asterisk fields' : *, or *N$
230 if(*start == const_or_not(fac).widen( '*') )
231 start = skip_asterisk(start, last, fac);
232 if(start!=last && wrap_isdigit(fac, *start))
233 start = str2int(start, last, fpar->fmtstate_.width_, fac);
234
235 parse_precision:
236 if( start>= last) {
237 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
238 return true;
239 }
240 // handle precision spec
241 if (*start== const_or_not(fac).widen( '.')) {
242 ++start;
243 if(start != last && *start == const_or_not(fac).widen( '*') )
244 start = skip_asterisk(start, last, fac);
245 if(start != last && wrap_isdigit(fac, *start)) {
246 start = str2int(start, last, fpar->fmtstate_.precision_, fac);
247 precision_set = true;
248 }
249 else
250 fpar->fmtstate_.precision_ =0;
251 }
252
253 // handle formatting-type flags :
254 while( start != last && ( *start== const_or_not(fac).widen( 'l')
255 || *start== const_or_not(fac).widen( 'L')
256 || *start== const_or_not(fac).widen( 'h')) )
257 ++start;
258 if( start>=last) {
259 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
260 return true;
261 }
262
263 if( in_brackets && *start== const_or_not(fac).widen( '|') ) {
264 ++start;
265 return true;
266 }
267 switch ( wrap_narrow(fac, *start, 0) ) {
268 case 'X':
269 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
270 case 'p': // pointer => set hex.
271 case 'x':
272 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
273 fpar->fmtstate_.flags_ |= std::ios_base::hex;
274 break;
275
276 case 'o':
277 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
278 fpar->fmtstate_.flags_ |= std::ios_base::oct;
279 break;
280
281 case 'E':
282 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
283 case 'e':
284 fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
285 fpar->fmtstate_.flags_ |= std::ios_base::scientific;
286
287 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
288 fpar->fmtstate_.flags_ |= std::ios_base::dec;
289 break;
290
291 case 'f':
292 fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
293 fpar->fmtstate_.flags_ |= std::ios_base::fixed;
294 case 'u':
295 case 'd':
296 case 'i':
297 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
298 fpar->fmtstate_.flags_ |= std::ios_base::dec;
299 break;
300
301 case 'T':
302 ++start;
303 if( start >= last)
304 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
305 else
306 fpar->fmtstate_.fill_ = *start;
307 fpar->pad_scheme_ |= format_item_t::tabulation;
308 fpar->argN_ = format_item_t::argN_tabulation;
309 break;
310 case 't':
311 fpar->fmtstate_.fill_ = const_or_not(fac).widen( ' ');
312 fpar->pad_scheme_ |= format_item_t::tabulation;
313 fpar->argN_ = format_item_t::argN_tabulation;
314 break;
315
316 case 'G':
317 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
318 break;
319 case 'g': // 'g' conversion is default for floats.
320 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
321 fpar->fmtstate_.flags_ |= std::ios_base::dec;
322
323 // CLEAR all floatield flags, so stream will CHOOSE
324 fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
325 break;
326
327 case 'C':
328 case 'c':
329 fpar->truncate_ = 1;
330 break;
331 case 'S':
332 case 's':
333 if(precision_set) // handle truncation manually, with own parameter.
334 fpar->truncate_ = fpar->fmtstate_.precision_;
335 fpar->fmtstate_.precision_ = 6; // default stream precision.
336 break;
337 case 'n' :
338 fpar->argN_ = format_item_t::argN_ignored;
339 break;
340 default:
341 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
342 }
343 ++start;
344
345 if( in_brackets ) {
346 if( start != last && *start== const_or_not(fac).widen( '|') ) {
347 ++start;
348 return true;
349 }
350 else maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
351 }
352 return true;
353 }
354 // -end parse_printf_directive()
355
356 template<class String, class Facet>
357 int upper_bound_from_fstring(const String& buf,
358 const typename String::value_type arg_mark,
359 const Facet& fac,
360 unsigned char exceptions)
361 {
362 // quick-parsing of the format-string to count arguments mark (arg_mark, '%')
363 // returns : upper bound on the number of format items in the format strings
364 using namespace boost::io;
365 typename String::size_type i1=0;
366 int num_items=0;
367 while( (i1=buf.find(arg_mark,i1)) != String::npos ) {
368 if( i1+1 >= buf.size() ) {
369 if(exceptions & bad_format_string_bit)
370 boost::throw_exception(e: bad_format_string(i1, buf.size() )); // must not end in ".. %"
371 else {
372 ++num_items;
373 break;
374 }
375 }
376 if(buf[i1+1] == buf[i1] ) {// escaped "%%"
377 i1+=2; continue;
378 }
379
380 ++i1;
381 // in case of %N% directives, dont count it double (wastes allocations..) :
382 i1 = detail::wrap_scan_notdigit(fac, buf.begin()+i1, buf.end()) - buf.begin();
383 if( i1 < buf.size() && buf[i1] == arg_mark )
384 ++i1;
385 ++num_items;
386 }
387 return num_items;
388 }
389 template<class String> inline
390 void append_string(String& dst, const String& src,
391 const typename String::size_type beg,
392 const typename String::size_type end) {
393 dst.append(src.begin()+beg, src.begin()+end);
394 }
395
396} // detail namespace
397} // io namespace
398
399
400
401// -----------------------------------------------
402// format :: parse(..)
403
404 template<class Ch, class Tr, class Alloc>
405 basic_format<Ch, Tr, Alloc>& basic_format<Ch, Tr, Alloc>::
406 parse (const string_type& buf) {
407 // parse the format-string
408 using namespace std;
409#if !defined(BOOST_NO_STD_LOCALE)
410 const std::ctype<Ch> & fac = BOOST_USE_FACET( std::ctype<Ch>, getloc());
411#else
412 io::basic_oaltstringstream<Ch, Tr, Alloc> fac;
413 //has widen and narrow even on compilers without locale
414#endif
415
416 const Ch arg_mark = io::detail::const_or_not(fac).widen( '%');
417 bool ordered_args=true;
418 int max_argN=-1;
419
420 // A: find upper_bound on num_items and allocates arrays
421 int num_items = io::detail::upper_bound_from_fstring(buf, arg_mark, fac, exceptions());
422 make_or_reuse_data(nbitems: num_items);
423
424 // B: Now the real parsing of the format string :
425 num_items=0;
426 typename string_type::size_type i0=0, i1=0;
427 typename string_type::const_iterator it;
428 bool special_things=false;
429 int cur_item=0;
430 while( (i1=buf.find(arg_mark,i1)) != string_type::npos ) {
431 string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
432 if( buf[i1+1] == buf[i1] ) { // escaped mark, '%%'
433 io::detail::append_string(piece, buf, i0, i1+1);
434 i1+=2; i0=i1;
435 continue;
436 }
437 BOOST_ASSERT( static_cast<unsigned int>(cur_item) < items_.size() || cur_item==0);
438
439 if(i1!=i0) {
440 io::detail::append_string(piece, buf, i0, i1);
441 i0=i1;
442 }
443 ++i1;
444 it = buf.begin()+i1;
445 bool parse_ok = io::detail::parse_printf_directive(
446 it, buf.end(), &items_[cur_item], fac, i1, exceptions());
447 i1 = it - buf.begin();
448 if( ! parse_ok ) // the directive will be printed verbatim
449 continue;
450 i0=i1;
451 items_[cur_item].compute_states(); // process complex options, like zeropad, into params
452
453 int argN=items_[cur_item].argN_;
454 if(argN == format_item_t::argN_ignored)
455 continue;
456 if(argN ==format_item_t::argN_no_posit)
457 ordered_args=false;
458 else if(argN == format_item_t::argN_tabulation) special_things=true;
459 else if(argN > max_argN) max_argN = argN;
460 ++num_items;
461 ++cur_item;
462 } // loop on %'s
463 BOOST_ASSERT(cur_item == num_items);
464
465 // store the final piece of string
466 {
467 string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
468 io::detail::append_string(piece, buf, i0, buf.size());
469 }
470
471 if( !ordered_args) {
472 if(max_argN >= 0 ) { // dont mix positional with non-positionnal directives
473 if(exceptions() & io::bad_format_string_bit)
474 boost::throw_exception(
475 e: io::bad_format_string(static_cast<std::size_t>(max_argN), 0));
476 // else do nothing. => positionnal arguments are processed as non-positionnal
477 }
478 // set things like it would have been with positional directives :
479 int non_ordered_items = 0;
480 for(int i=0; i< num_items; ++i)
481 if(items_[i].argN_ == format_item_t::argN_no_posit) {
482 items_[i].argN_ = non_ordered_items;
483 ++non_ordered_items;
484 }
485 max_argN = non_ordered_items-1;
486 }
487
488 // C: set some member data :
489 items_.resize(num_items, format_item_t(io::detail::const_or_not(fac).widen( ' ')) );
490
491 if(special_things) style_ |= special_needs;
492 num_args_ = max_argN + 1;
493 if(ordered_args) style_ |= ordered;
494 else style_ &= ~ordered;
495 return *this;
496 }
497
498} // namespace boost
499
500
501#endif // BOOST_FORMAT_PARSING_HPP
502

source code of boost/boost/format/parsing.hpp