boost/format/parsing.hpp

   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
  24 namespace boost {
  25 namespace io {
  26 namespace 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);
  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(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(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 #if !defined(BOOST_NO_STRING_APPEND)
 394         dst.append(src.begin()+beg, src.begin()+end);
 395 #else
 396         dst += src.substr(beg, end-beg);
 397 #endif
 398     }
 399
 400 } // detail namespace
 401 } // io namespace
 402
 403
 404
 405 // -----------------------------------------------
 406 //  format :: parse(..)
 407
 408     template<class Ch, class Tr, class Alloc>
 409     basic_format<Ch, Tr, Alloc>& basic_format<Ch, Tr, Alloc>::
 410     parse (const string_type& buf) {
 411         // parse the format-string
 412         using namespace std;
 413 #if !defined(BOOST_NO_STD_LOCALE)
 414         const std::ctype<Ch> & fac = BOOST_USE_FACET( std::ctype<Ch>, getloc());
 415 #else
 416         io::basic_oaltstringstream<Ch, Tr, Alloc> fac;
 417         //has widen and narrow even on compilers without locale
 418 #endif
 419
 420         const Ch arg_mark = io::detail::const_or_not(fac).widen( '%');
 421         bool ordered_args=true;
 422         int max_argN=-1;
 423
 424         // A: find upper_bound on num_items and allocates arrays
 425         int num_items = io::detail::upper_bound_from_fstring(buf, arg_mark, fac, exceptions());
 426         make_or_reuse_data(num_items);
 427
 428         // B: Now the real parsing of the format string :
 429         num_items=0;
 430         typename string_type::size_type i0=0, i1=0;
 431         typename string_type::const_iterator it;
 432         bool special_things=false;
 433         int cur_item=0;
 434         while( (i1=buf.find(arg_mark,i1)) != string_type::npos ) {
 435             string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
 436             if( buf[i1+1] == buf[i1] ) { // escaped mark, '%%'
 437                 io::detail::append_string(piece, buf, i0, i1+1);
 438                 i1+=2; i0=i1;
 439                 continue;
 440             }
 441             BOOST_ASSERT(  static_cast<unsigned int>(cur_item) < items_.size() || cur_item==0);
 442
 443             if(i1!=i0) {
 444                 io::detail::append_string(piece, buf, i0, i1);
 445                 i0=i1;
 446             }
 447             ++i1;
 448             it = buf.begin()+i1;
 449             bool parse_ok = io::detail::parse_printf_directive(
 450                 it, buf.end(), &items_[cur_item], fac, i1, exceptions());
 451             i1 = it - buf.begin();
 452             if( ! parse_ok ) // the directive will be printed verbatim
 453                 continue;
 454             i0=i1;
 455             items_[cur_item].compute_states(); // process complex options, like zeropad, into params
 456
 457             int argN=items_[cur_item].argN_;
 458             if(argN == format_item_t::argN_ignored)
 459                 continue;
 460             if(argN ==format_item_t::argN_no_posit)
 461                 ordered_args=false;
 462             else if(argN == format_item_t::argN_tabulation) special_things=true;
 463             else if(argN > max_argN) max_argN = argN;
 464             ++num_items;
 465             ++cur_item;
 466         } // loop on %'s
 467         BOOST_ASSERT(cur_item == num_items);
 468
 469         // store the final piece of string
 470         {
 471             string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
 472             io::detail::append_string(piece, buf, i0, buf.size());
 473         }
 474
 475         if( !ordered_args) {
 476             if(max_argN >= 0 ) {  // dont mix positional with non-positionnal directives
 477                 if(exceptions() & io::bad_format_string_bit)
 478                     boost::throw_exception(io::bad_format_string(max_argN, 0));
 479                 // else do nothing. => positionnal arguments are processed as non-positionnal
 480             }
 481             // set things like it would have been with positional directives :
 482             int non_ordered_items = 0;
 483             for(int i=0; i< num_items; ++i)
 484                 if(items_[i].argN_ == format_item_t::argN_no_posit) {
 485                     items_[i].argN_ = non_ordered_items;
 486                     ++non_ordered_items;
 487                 }
 488             max_argN = non_ordered_items-1;
 489         }
 490
 491         // C: set some member data :
 492         items_.resize(num_items, format_item_t(io::detail::const_or_not(fac).widen( ' ')) );
 493
 494         if(special_things) style_ |= special_needs;
 495         num_args_ = max_argN + 1;
 496         if(ordered_args) style_ |=  ordered;
 497         else style_ &= ~ordered;
 498         return *this;
 499     }
 500
 501 } // namespace boost
 502
 503
 504 #endif //  BOOST_FORMAT_PARSING_HPP