boost/spirit/home/classic/utility/impl/escape_char.ipp

   1 /*=============================================================================
   2     Copyright (c) 2001-2003 Daniel Nuffer
   3     Copyright (c) 2002-2003 Hartmut Kaiser
   4     http://spirit.sourceforge.net/
   5
   6     Use, modification and distribution is subject to the Boost Software
   7     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   8     http://www.boost.org/LICENSE_1_0.txt)
   9 =============================================================================*/
  10 #ifndef BOOST_SPIRIT_ESCAPE_CHAR_IPP
  11 #define BOOST_SPIRIT_ESCAPE_CHAR_IPP
  12
  13 #include <boost/spirit/home/classic/core/parser.hpp>
  14 #include <boost/spirit/home/classic/core/primitives/numerics.hpp>
  15 #include <boost/spirit/home/classic/core/composite/difference.hpp>
  16 #include <boost/spirit/home/classic/core/composite/sequence.hpp>
  17
  18 ///////////////////////////////////////////////////////////////////////////////
  19 namespace boost { namespace spirit {
  20
  21 BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN
  22
  23 ///////////////////////////////////////////////////////////////////////////////
  24 //
  25 //  escape_char_parser class
  26 //
  27 ///////////////////////////////////////////////////////////////////////////////
  28
  29 const unsigned long c_escapes = 1;
  30 const unsigned long lex_escapes = c_escapes << 1;
  31
  32 //////////////////////////////////
  33 namespace impl {
  34
  35     //////////////////////////////////
  36 #if defined(BOOST_MSVC)
  37 #pragma warning(push)
  38 #pragma warning(disable:4127)
  39 #endif
  40     template <unsigned long Flags, typename CharT>
  41     struct escape_char_action_parse {
  42
  43         template <typename ParserT, typename ScannerT>
  44         static typename parser_result<ParserT, ScannerT>::type
  45         parse(ScannerT const& scan, ParserT const &p)
  46         {
  47             // Actually decode the escape char.
  48             typedef CharT char_t;
  49             typedef typename ScannerT::iterator_t iterator_t;
  50             typedef typename parser_result<ParserT, ScannerT>::type result_t;
  51
  52             if (scan.first != scan.last) {
  53
  54                 iterator_t save = scan.first;
  55                 if (result_t hit = p.subject().parse(scan)) {
  56
  57                     char_t unescaped;
  58
  59                     scan.first = save;
  60                     if (*scan.first == '\\') {
  61
  62                         ++scan.first;
  63                         switch (*scan.first) {
  64                         case 'b':   unescaped = '\b';   ++scan.first; break;
  65                         case 't':   unescaped = '\t';   ++scan.first; break;
  66                         case 'n':   unescaped = '\n';   ++scan.first; break;
  67                         case 'f':   unescaped = '\f';   ++scan.first; break;
  68                         case 'r':   unescaped = '\r';   ++scan.first; break;
  69                         case '"':   unescaped = '"';    ++scan.first; break;
  70                         case '\'':  unescaped = '\'';   ++scan.first; break;
  71                         case '\\':  unescaped = '\\';   ++scan.first; break;
  72
  73                         case 'x': case 'X':
  74                             {
  75                                 char_t hex = 0;
  76                                 char_t const lim =
  77                                     (std::numeric_limits<char_t>::max)() >> 4;
  78
  79                                 ++scan.first;
  80                                 while (scan.first != scan.last)
  81                                 {
  82                                     char_t c = *scan.first;
  83                                     if (hex > lim && impl::isxdigit_(c))
  84                                     {
  85                                         // overflow detected
  86                                         scan.first = save;
  87                                         return scan.no_match();
  88                                     }
  89                                     if (impl::isdigit_(c))
  90                                     {
  91                                         hex <<= 4;
  92                                         hex |= c - '0';
  93                                         ++scan.first;
  94                                     }
  95                                     else if (impl::isxdigit_(c))
  96                                     {
  97                                         hex <<= 4;
  98                                         c = impl::toupper_(c);
  99                                         hex |= c - 'A' + 0xA;
 100                                         ++scan.first;
 101                                     }
 102                                     else
 103                                     {
 104                                         break; // reached the end of the number
 105                                     }
 106                                 }
 107                                 unescaped = hex;
 108                             }
 109                             break;
 110
 111                         case '0': case '1': case '2': case '3':
 112                         case '4': case '5': case '6': case '7':
 113                             {
 114                                 char_t oct = 0;
 115                                 char_t const lim =
 116                                     (std::numeric_limits<char_t>::max)() >> 3;
 117                                 while (scan.first != scan.last)
 118                                 {
 119                                     char_t c = *scan.first;
 120                                     if (oct > lim && (c >= '0' && c <= '7'))
 121                                     {
 122                                         // overflow detected
 123                                         scan.first = save;
 124                                         return scan.no_match();
 125                                     }
 126
 127                                     if (c >= '0' && c <= '7')
 128                                     {
 129                                         oct <<= 3;
 130                                         oct |= c - '0';
 131                                         ++scan.first;
 132                                     }
 133                                     else
 134                                     {
 135                                         break; // reached end of digits
 136                                     }
 137                                 }
 138                                 unescaped = oct;
 139                             }
 140                             break;
 141
 142                         default:
 143                             if (Flags & c_escapes)
 144                             {
 145                                 // illegal C escape sequence
 146                                 scan.first = save;
 147                                 return scan.no_match();
 148                             }
 149                             else
 150                             {
 151                                 unescaped = *scan.first;
 152                                 ++scan.first;
 153                             }
 154                             break;
 155                         }
 156                     }
 157                     else {
 158                         unescaped = *scan.first;
 159                         ++scan.first;
 160                     }
 161
 162                     scan.do_action(p.predicate(), unescaped, save, scan.first);
 163                     return hit;
 164                 }
 165             }
 166             return scan.no_match(); // overflow detected
 167         }
 168     };
 169 #if defined(BOOST_MSVC)
 170 #pragma warning(pop)
 171 #endif
 172
 173     //////////////////////////////////
 174     template <typename CharT>
 175     struct escape_char_parse {
 176
 177         template <typename ScannerT, typename ParserT>
 178         static typename parser_result<ParserT, ScannerT>::type
 179         parse(ScannerT const &scan, ParserT const &/*p*/)
 180         {
 181             typedef
 182                 uint_parser<CharT, 8, 1,
 183                     std::numeric_limits<CharT>::digits / 3 + 1
 184                 >
 185                 oct_parser_t;
 186             typedef
 187                 uint_parser<CharT, 16, 1,
 188                     std::numeric_limits<CharT>::digits / 4 + 1
 189                 >
 190                 hex_parser_t;
 191
 192             typedef alternative<difference<anychar_parser, chlit<CharT> >,
 193                 sequence<chlit<CharT>, alternative<alternative<oct_parser_t,
 194                 sequence<inhibit_case<chlit<CharT> >, hex_parser_t > >,
 195                 difference<difference<anychar_parser,
 196                 inhibit_case<chlit<CharT> > >, oct_parser_t > > > >
 197                 parser_t;
 198
 199             static parser_t p =
 200                 ( (anychar_p - chlit<CharT>(CharT('\\')))
 201                 | (chlit<CharT>(CharT('\\')) >>
 202                     (  oct_parser_t()
 203                      | as_lower_d[chlit<CharT>(CharT('x'))] >> hex_parser_t()
 204                      | (anychar_p - as_lower_d[chlit<CharT>(CharT('x'))] - oct_parser_t())
 205                     )
 206                 ));
 207
 208             BOOST_SPIRIT_DEBUG_TRACE_NODE(p,
 209                 (BOOST_SPIRIT_DEBUG_FLAGS & BOOST_SPIRIT_DEBUG_FLAGS_ESCAPE_CHAR) != 0);
 210
 211             return p.parse(scan);
 212         }
 213     };
 214
 215 ///////////////////////////////////////////////////////////////////////////////
 216 } // namespace impl
 217
 218 ///////////////////////////////////////////////////////////////////////////////
 219 BOOST_SPIRIT_CLASSIC_NAMESPACE_END
 220
 221 }} // namespace boost::spirit
 222
 223 #endif
 224