boost/property_tree/json_parser.hpp

   1 // ----------------------------------------------------------------------------
   2 // Copyright (C) 2002-2006 Marcin Kalicinski
   3 //
   4 // Distributed under the Boost Software License, Version 1.0.
   5 // (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7 //
   8 // For more information, see www.boost.org
   9 // ----------------------------------------------------------------------------
  10 #ifndef BOOST_PROPERTY_TREE_JSON_PARSER_HPP_INCLUDED
  11 #define BOOST_PROPERTY_TREE_JSON_PARSER_HPP_INCLUDED
  12
  13 #include <boost/property_tree/ptree.hpp>
  14 #include <boost/property_tree/detail/json_parser_read.hpp>
  15 #include <boost/property_tree/detail/json_parser_write.hpp>
  16 #include <boost/property_tree/detail/json_parser_error.hpp>
  17
  18 #include <fstream>
  19 #include <string>
  20 #include <locale>
  21
  22 namespace boost { namespace property_tree { namespace json_parser
  23 {
  24
  25     /**
  26      * Read JSON from a the given stream and translate it to a property tree.
  27      * @note Clears existing contents of property tree.  In case of error the
  28      *       property tree unmodified.
  29      * @note Items of JSON arrays are translated into ptree keys with empty
  30      *       names. Members of objects are translated into named keys.
  31      * @note JSON data can be a string, a numeric value, or one of literals
  32      *       "null", "true" and "false". During parse, any of the above is copied
  33      *       verbatim into ptree data string.
  34      * @throw json_parser_error In case of error deserializing the property tree.
  35      * @param stream Stream from which to read in the property tree.
  36      * @param[out] pt The property tree to populate.
  37      */
  38     template<class Ptree>
  39     void read_json(std::basic_istream<typename Ptree::key_type::value_type> &stream,
  40                    Ptree &pt)
  41     {
  42         read_json_internal(stream, pt, std::string());
  43     }
  44
  45     /**
  46      * Read JSON from a the given file and translate it to a property tree.
  47      * @note Clears existing contents of property tree.  In case of error the
  48      *       property tree unmodified.
  49      * @note Items of JSON arrays are translated into ptree keys with empty
  50      *       names. Members of objects are translated into named keys.
  51      * @note JSON data can be a string, a numeric value, or one of literals
  52      *       "null", "true" and "false". During parse, any of the above is copied
  53      *       verbatim into ptree data string.
  54      * @throw json_parser_error In case of error deserializing the property tree.
  55      * @param filename Name of file from which to read in the property tree.
  56      * @param[out] pt The property tree to populate.
  57      * @param loc The locale to use when reading in the file contents.
  58      */
  59     template<class Ptree>
  60     void read_json(const std::string &filename,
  61                    Ptree &pt,
  62                    const std::locale &loc = std::locale())
  63     {
  64         std::basic_ifstream<typename Ptree::key_type::value_type> stream(filename.c_str());
  65         if (!stream)
  66             BOOST_PROPERTY_TREE_THROW(json_parser_error("cannot open file", filename, 0));
  67         stream.imbue(loc);
  68         read_json_internal(stream, pt, filename);
  69     }
  70
  71     /**
  72      * Translates the property tree to JSON and writes it the given output stream.
  73      * @note Any property tree key containing only unnamed subkeys will be rendered
  74      *       as JSON arrays.
  75      * @pre @e pt cannot contain keys that have both subkeys and non-empty data.
  76      * @throw json_parser_error In case of error translating the property tree to JSON
  77      *                         or writing to the output stream.
  78      * @param stream The stream to which to write the JSON representation of the
  79      *               property tree.
  80      * @param pt The property tree to tranlsate to JSON and output.
  81      */
  82     template<class Ptree>
  83     void write_json(std::basic_ostream<typename Ptree::key_type::value_type> &stream,
  84                     const Ptree &pt)
  85     {
  86         write_json_internal(stream, pt, std::string());
  87     }
  88
  89     /**
  90      * Translates the property tree to JSON and writes it the given file.
  91      * @note Any property tree key containing only unnamed subkeys will be rendered
  92      *       as JSON arrays.
  93      * @pre @e pt cannot contain keys that have both subkeys and non-empty data.
  94      * @throw json_parser_error In case of error translating the property tree to JSON
  95      *                         or writing to the file.
  96      * @param filename The name of the file to which to write the JSON representation
  97      *                 of the property tree.
  98      * @param pt The property tree to tranlsate to JSON and output.
  99      * @param loc The locale to use when writing out to the output file.
 100      */
 101     template<class Ptree>
 102     void write_json(const std::string &filename,
 103                     const Ptree &pt,
 104                     const std::locale &loc = std::locale())
 105     {
 106         std::basic_ofstream<typename Ptree::key_type::value_type> stream(filename.c_str());
 107         if (!stream)
 108             BOOST_PROPERTY_TREE_THROW(json_parser_error("cannot open file", filename, 0));
 109         stream.imbue(loc);
 110         write_json_internal(stream, pt, filename);
 111     }
 112
 113 } } }
 114
 115 namespace boost { namespace property_tree
 116 {
 117     using json_parser::read_json;
 118     using json_parser::write_json;
 119     using json_parser::json_parser_error;
 120 } }
 121
 122 #endif