json_parser/detail/read.hpp

0001 // ----------------------------------------------------------------------------
0002 // Copyright (C) 2015 Sebastian Redl
0003 //
0004 // Distributed under the Boost Software License, Version 1.0.
0005 // (See accompanying file LICENSE_1_0.txt or copy at
0006 // http://www.boost.org/LICENSE_1_0.txt)
0007 //
0008 // For more information, see www.boost.org
0009 // ----------------------------------------------------------------------------
0010 #ifndef BOOST_PROPERTY_TREE_DETAIL_JSON_PARSER_READ_HPP
0011 #define BOOST_PROPERTY_TREE_DETAIL_JSON_PARSER_READ_HPP
0012
0013 #include <boost/property_tree/json_parser/detail/parser.hpp>
0014 #include <boost/property_tree/json_parser/detail/narrow_encoding.hpp>
0015 #include <boost/property_tree/json_parser/detail/wide_encoding.hpp>
0016 #include <boost/property_tree/json_parser/detail/standard_callbacks.hpp>
0017
0018 #include <boost/static_assert.hpp>
0019 #include <boost/type_traits/is_same.hpp>
0020
0021 #include <istream>
0022 #include <iterator>
0023 #include <string>
0024
0025 namespace boost { namespace property_tree {
0026     namespace json_parser { namespace detail
0027 {
0028
0029     template <typename Iterator, typename Sentinel>
0030     class minirange
0031     {
0032     public:
0033         minirange(Iterator first, Sentinel last) : first(first), last(last) {}
0034         Iterator begin() const { return first; }
0035         Sentinel end() const { return last; }
0036
0037     private:
0038         Iterator first;
0039         Sentinel last;
0040     };
0041     template <typename Iterator, typename Sentinel>
0042     minirange<Iterator, Sentinel> make_minirange(Iterator first, Sentinel last)
0043     {
0044         return minirange<Iterator, Sentinel>(first, last);
0045     }
0046
0047     template <typename Iterator, typename Sentinel,
0048               typename Encoding, typename Callbacks>
0049     void read_json_internal(Iterator first, Sentinel last, Encoding& encoding,
0050         Callbacks& callbacks, const std::string& filename)
0051     {
0052         BOOST_STATIC_ASSERT_MSG((boost::is_same<
0053             typename std::iterator_traits<Iterator>::value_type,
0054             typename Encoding::external_char>::value),
0055             "Encoding is not capable of using the iterator's value type.");
0056         BOOST_STATIC_ASSERT_MSG((boost::is_same<
0057             typename Callbacks::char_type,
0058             typename Encoding::internal_char>::value),
0059             "Encoding is not capable of producing the needed character type.");
0060
0061         detail::parser<Callbacks, Encoding, Iterator, Sentinel>
0062             parser(callbacks, encoding);
0063         parser.set_input(filename, make_minirange(first, last));
0064         parser.parse_value();
0065         parser.finish();
0066     }
0067
0068     template <typename Ch> struct encoding;
0069     template <> struct encoding<char> : utf8_utf8_encoding {};
0070     template <> struct encoding<wchar_t> : wide_wide_encoding {};
0071
0072     template <typename Ptree>
0073     void read_json_internal(
0074         std::basic_istream<typename Ptree::key_type::value_type> &stream,
0075         Ptree &pt, const std::string &filename)
0076     {
0077         typedef typename Ptree::key_type::value_type char_type;
0078         typedef standard_callbacks<Ptree> callbacks_type;
0079         typedef detail::encoding<char_type> encoding_type;
0080         typedef std::istreambuf_iterator<char_type> iterator;
0081         callbacks_type callbacks;
0082         encoding_type encoding;
0083         read_json_internal(iterator(stream), iterator(),
0084             encoding, callbacks, filename);
0085         pt.swap(callbacks.output());
0086     }
0087
0088 }}}}
0089
0090 #endif