src/util/serialize.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "serialize.h"
  21
  22 #include <sstream>
  23 #include <iomanip>
  24
  25 // Creates a string encoded in JSON format (almost equivalent to a C string literal)
  26 std::string serializeJsonString(const std::string &plain)
  27 {
  28         std::ostringstream os(std::ios::binary);
  29         os<<"\"";
  30         for(size_t i = 0; i < plain.size(); i++)
  31         {
  32                 char c = plain[i];
  33                 switch(c)
  34                 {
  35                         case '"': os<<"\\\""; break;
  36                         case '\\': os<<"\\\\"; break;
  37                         case '/': os<<"\\/"; break;
  38                         case '\b': os<<"\\b"; break;
  39                         case '\f': os<<"\\f"; break;
  40                         case '\n': os<<"\\n"; break;
  41                         case '\r': os<<"\\r"; break;
  42                         case '\t': os<<"\\t"; break;
  43                         default:
  44                         {
  45                                 if(c >= 32 && c <= 126)
  46                                 {
  47                                         os<<c;
  48                                 }
  49                                 else
  50                                 {
  51                                         u32 cnum = (u32) (u8) c;
  52                                         os<<"\\u"<<std::hex<<std::setw(4)<<std::setfill('0')<<cnum;
  53                                 }
  54                                 break;
  55                         }
  56                 }
  57         }
  58         os<<"\"";
  59         return os.str();
  60 }
  61
  62 // Reads a string encoded in JSON format
  63 std::string deSerializeJsonString(std::istream &is)
  64 {
  65         std::ostringstream os(std::ios::binary);
  66         char c, c2;
  67
  68         // Parse initial doublequote
  69         is >> c;
  70         if(c != '"')
  71                 throw SerializationError("JSON string must start with doublequote");
  72
  73         // Parse characters
  74         for(;;)
  75         {
  76                 c = is.get();
  77                 if(is.eof())
  78                         throw SerializationError("JSON string ended prematurely");
  79                 if(c == '"')
  80                 {
  81                         return os.str();
  82                 }
  83                 else if(c == '\\')
  84                 {
  85                         c2 = is.get();
  86                         if(is.eof())
  87                                 throw SerializationError("JSON string ended prematurely");
  88                         switch(c2)
  89                         {
  90                                 default:  os<<c2; break;
  91                                 case 'b': os<<'\b'; break;
  92                                 case 'f': os<<'\f'; break;
  93                                 case 'n': os<<'\n'; break;
  94                                 case 'r': os<<'\r'; break;
  95                                 case 't': os<<'\t'; break;
  96                                 case 'u':
  97                                 {
  98                                         char hexdigits[4+1];
  99                                         is.read(hexdigits, 4);
 100                                         if(is.eof())
 101                                                 throw SerializationError("JSON string ended prematurely");
 102                                         hexdigits[4] = 0;
 103                                         std::istringstream tmp_is(hexdigits, std::ios::binary);
 104                                         int hexnumber;
 105                                         tmp_is >> std::hex >> hexnumber;
 106                                         os<<((char)hexnumber);
 107                                         break;
 108                                 }
 109                         }
 110                 }
 111                 else
 112                 {
 113                         os<<c;
 114                 }
 115         }
 116         return os.str();
 117 }
 118
 119