include/libtorrent/xml_parse.hpp

   1 /*
   2
   3 Copyright (c) 2007, Arvid Norberg
   4 All rights reserved.
   5
   6 Redistribution and use in source and binary forms, with or without
   7 modification, are permitted provided that the following conditions
   8 are met:
   9
  10     * Redistributions of source code must retain the above copyright
  11       notice, this list of conditions and the following disclaimer.
  12     * Redistributions in binary form must reproduce the above copyright
  13       notice, this list of conditions and the following disclaimer in
  14       the documentation and/or other materials provided with the distribution.
  15     * Neither the name of the author nor the names of its
  16       contributors may be used to endorse or promote products derived
  17       from this software without specific prior written permission.
  18
  19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  23 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29 POSSIBILITY OF SUCH DAMAGE.
  30
  31 */
  32
  33 #ifndef TORRENT_XML_PARSE_HPP
  34 #define TORRENT_XML_PARSE_HPP
  35
  36 #include <cctype>
  37
  38 namespace libtorrent
  39 {
  40         enum
  41         {
  42                 xml_start_tag,
  43                 xml_end_tag,
  44                 xml_empty_tag,
  45                 xml_declaration_tag,
  46                 xml_string,
  47                 xml_attribute,
  48                 xml_comment,
  49                 xml_parse_error
  50         };
  51
  52         // callback(int type, char const* name, char const* val)
  53         // str2 is only used for attributes. name is element or attribute
  54         // name and val is attribute value
  55
  56         template <class CallbackType>
  57         void xml_parse(char* p, char* end, CallbackType callback)
  58         {
  59                 for(;p != end; ++p)
  60                 {
  61                         char const* start = p;
  62                         char const* val_start = 0;
  63                         int token;
  64                         // look for tag start
  65                         for(; *p != '<' && p != end; ++p);
  66
  67                         if (p != start)
  68                         {
  69                                 if (p != end)
  70                                 {
  71                                         TORRENT_ASSERT(*p == '<');
  72                                         *p = 0;
  73                                 }
  74                                 token = xml_string;
  75                                 callback(token, start, val_start);
  76                                 if (p != end) *p = '<';
  77                         }
  78
  79                         if (p == end) break;
  80
  81                         // skip '<'
  82                         ++p;
  83
  84                         // parse the name of the tag.
  85                         for (start = p; p != end && *p != '>' && !std::isspace(*p); ++p);
  86
  87                         char* tag_name_end = p;
  88
  89                         // skip the attributes for now
  90                         for (; p != end && *p != '>'; ++p);
  91
  92                         // parse error
  93                         if (p == end)
  94                         {
  95                                 token = xml_parse_error;
  96                                 start = "unexpected end of file";
  97                                 callback(token, start, val_start);
  98                                 break;
  99                         }
 100
 101                         TORRENT_ASSERT(*p == '>');
 102                         // save the character that terminated the tag name
 103                         // it could be both '>' and ' '.
 104                         char save = *tag_name_end;
 105                         *tag_name_end = 0;
 106
 107                         char* tag_end = p;
 108                         if (*start == '/')
 109                         {
 110                                 ++start;
 111                                 token = xml_end_tag;
 112                                 callback(token, start, val_start);
 113                         }
 114                         else if (*(p-1) == '/')
 115                         {
 116                                 *(p-1) = 0;
 117                                 token = xml_empty_tag;
 118                                 callback(token, start, val_start);
 119                                 *(p-1) = '/';
 120                                 tag_end = p - 1;
 121                         }
 122                         else if (*start == '?' && *(p-1) == '?')
 123                         {
 124                                 *(p-1) = 0;
 125                                 ++start;
 126                                 token = xml_declaration_tag;
 127                                 callback(token, start, val_start);
 128                                 *(p-1) = '?';
 129                                 tag_end = p - 1;
 130                         }
 131                         else if (start + 5 < p && memcmp(start, "!--", 3) == 0 && memcmp(p-2, "--", 2) == 0)
 132                         {
 133                                 start += 3;
 134                                 *(p-2) = 0;
 135                                 token = xml_comment;
 136                                 callback(token, start, val_start);
 137                                 *(p-2) = '-';
 138                                 tag_end = p - 2;
 139                         }
 140                         else
 141                         {
 142                                 token = xml_start_tag;
 143                                 callback(token, start, val_start);
 144                         }
 145
 146                         *tag_name_end = save;
 147
 148                         // parse attributes
 149                         for (char* i = tag_name_end; i < tag_end; ++i)
 150                         {
 151                                 // find start of attribute name
 152                                 for (; i != tag_end && std::isspace(*i); ++i);
 153                                 if (i == tag_end) break;
 154                                 start = i;
 155                                 // find end of attribute name
 156                                 for (; i != tag_end && *i != '=' && !std::isspace(*i); ++i);
 157                                 char* name_end = i;
 158
 159                                 // look for equality sign
 160                                 for (; i != tag_end && *i != '='; ++i);
 161
 162                                 if (i == tag_end)
 163                                 {
 164                                         token = xml_parse_error;
 165                                         val_start = 0;
 166                                         start = "garbage inside element brackets";
 167                                         callback(token, start, val_start);
 168                                         break;
 169                                 }
 170
 171                                 ++i;
 172                                 for (; i != tag_end && std::isspace(*i); ++i);
 173                                 // check for parse error (values must be quoted)
 174                                 if (i == tag_end || (*i != '\'' && *i != '\"'))
 175                                 {
 176                                         token = xml_parse_error;
 177                                         val_start = 0;
 178                                         start = "unquoted attribute value";
 179                                         callback(token, start, val_start);
 180                                         break;
 181                                 }
 182                                 char quote = *i;
 183                                 ++i;
 184                                 val_start = i;
 185                                 for (; i != tag_end && *i != quote; ++i);
 186                                 // parse error (missing end quote)
 187                                 if (i == tag_end)
 188                                 {
 189                                         token = xml_parse_error;
 190                                         val_start = 0;
 191                                         start = "missing end quote on attribute";
 192                                         callback(token, start, val_start);
 193                                         break;
 194                                 }
 195                                 save = *i;
 196                                 *i = 0;
 197                                 *name_end = 0;
 198                                 token = xml_attribute;
 199                                 callback(token, start, val_start);
 200                                 *name_end = '=';
 201                                 *i = save;
 202                         }
 203                 }
 204
 205         }
 206
 207 }
 208
 209
 210 #endif
 211