Boost read_json和C ++ 11 [英] Boost read_json and C++11

问题描述

我试图使用Boost的property_tree解析器和C ++ 11代码（我的系统是Debian Wheezy与gcc 4.7.2和Boost 1.49）解析JSON。我尝试了以下代码基于使用boost序列化和反序列化json ：

  #include< map& 
 #include< sstream> 
 #include< boost / property_tree / ptree.hpp> 
 #include< boost / property_tree / json_parser.hpp> 
使用boost :: property_tree :: ptree;使用boost :: property_tree :: read_json;使用boost :: property_tree :: write_json; 
 
 void example（）{
 //写入json。 
 ptree pt; 
 pt.put（foo，bar）; 
 std :: ostringstream buf; 
 write_json（buf，pt，false）; 
 std :: string json = buf.str（） // {foo：bar} 
 
 //读取json。 
 ptree pt2; 
 std :: istringstream（json）; 
 read_json（is，pt2）; 
 std :: string foo = pt2.get< std :: string> （foo）; 
} 
  

如果我使用 g ++ -std = c ++ 03 -c'一切都很好。但是，我也想使用C ++ 11的功能（在链接线程中的代码实际上是！）。但是用 g ++ -std = c ++ 11 -c'我得到编译错误：

 文件包括在/usr/include/boost/property_tree/json_parser.hpp:14:0，
从test.cpp：4：
 /usr/include/boost/property_tree/detail/json_parser_read.hpp：在实例化'void boost :: property_tree :: json_parser :: context< Ptree> :: a_literal_val :: operator（）（boost :: property_tree :: json_parser :: context< Ptree> :: It，boost :: property_tree :: json_parser :: context< Ptree> :: It）const [with Ptree = boost :: property_tree :: basic_ptree< std :: basic_string< char>，std :: basic_string< char> > ;; boost :: property_tree :: json_parser :: context< Ptree> :: It = __gnu_cxx :: __ normal_iterator< char *，std :: vector< char，std :: allocator< char> > >]'：
 /usr/include/boost/spirit/home/classic/core/scanner/scanner.hpp:148:13：需要从'static void boost :: spirit :: classic :: attribut_action_policy< boost :: spirit :: classic :: nil_t> :: call（const ActorT& boost :: spirit :: classic :: nil_t，const IteratorT& const IteratorT&）[with ActorT = boost :: property_tree :: json_parser： ：context< boost :: property_tree :: basic_ptree< std :: basic_string< char>，std :: basic_string< char> > > :: a_literal_val; IteratorT = __gnu_cxx :: __ normal_iterator< char *，std :: vector< char，std :: allocator< char> > >]'
 /usr/include/boost/spirit/home/classic/core/scanner/scanner.hpp:163:13：需要从'void boost :: spirit :: classic :: action_policy :: do_action （const ActorT& AttrT& const IteratorT& const IteratorT&）const [with ActorT = boost :: property_tree :: json_parser :: context< boost :: property_tree :: basic_ptree< std :: basic_string< char>，std： ：basic_string< char> > > :: a_literal_val; AttrT = boost :: spirit :: classic :: nil_t; IteratorT = __gnu_cxx :: __ normal_iterator< char *，std :: vector< char，std :: allocator< char> > >]'
 ... 
 test.cpp：20：1：此处需要
 /usr/include/boost/property_tree/detail/json_parser_read.hpp:105:17：error ：没有匹配的函数调用'boost :: property_tree :: basic_ptree< std :: basic_string< char>，std :: basic_string< char> > :: push_back（std :: pair< std :: basic_string< char>，std :: basic_string< char>>）'
 /usr/include/boost/property_tree/detail/json_parser_read.hpp:105 ：17：note：candidate是：
在/usr/include/boost/property_tree/ptree.hpp:516:0包含的文件中，
来自test.cpp：3：
 / usr /include/boost/property_tree/detail/ptree_implementation.hpp:362:9：note：boost :: property_tree :: basic_ptree< Key，Data，KeyCompare> :: iterator boost :: property_tree :: basic_ptree< Key，Data，KeyCompare> :: push_back（const value_type&）[with Key = std :: basic_string< char> ;; Data = std :: basic_string< char> ;; KeyCompare = std :: less< std :: basic_string< char> > ;; boost :: property_tree :: basic_ptree< Key，Data，KeyCompare> :: value_type = std :: pair< const std :: basic_string< char>，boost :: property_tree :: basic_ptree< std :: basic_string< char>，std： ：basic_string< char> > >] 
 /usr/include/boost/property_tree/detail/ptree_implementation.hpp:362:9：note：从std :: pair< std :: basic_string< char>，std的参数1没有已知的转换:: basic_string< char> >'to'const value_type& {aka const std :: pair< const std :: basic_string< char>，boost :: property_tree :: basic_ptree< std :: basic_string< char>，std :: basic_string< char> > &}&}'
  

如何使用Boost的read_json和C ++ 11？我需要一个更新的Boost版本（即从源代码，而不是使用Wheezy的打包）手动安装？我的代码有什么问题吗？

解决方案

这是一个
您可以通过应用以下修补程序来修复它：

pre> --- json_parser_read.hpp 2013-09-01 03：55：57.000000000 +0400
+++ /usr/include/boost/property_tree/detail/json_parser_read.hpp 2013-09-01 03：56：21.000000000 +0400
@@ -102,7 +102,7 @@
void operator（）（It b，It e）const
{
BOOST_ASSERT（c.stack.size（）> = 1）;
- c.stack.back（） - > push_back（std :: make_pair（c.name，Str（b，e）））;
+ c.stack.back（） - > push_back（std :: make_pair（c.name，Ptree（Str（b，e））））;
c.name.clear（）;
c.string.clear（）;
}


或

  sed -i -e's / std :: make_pair（c.name，Str（b，e））/ std :: make_pair（c.name， e）））/'json_parser_read.hpp 
  

I'm trying to parse JSON using Boost's property_tree parser and from C++11 code (my system is Debian Wheezy with gcc 4.7.2 and Boost 1.49). I tried the following code based on Serializing and deserializing json with boost:

#include <map>
#include <sstream>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
using boost::property_tree::ptree; using boost::property_tree::read_json; using    boost::property_tree::write_json;

void example() {
  // Write json.
  ptree pt;
  pt.put ("foo", "bar");
  std::ostringstream buf; 
  write_json (buf, pt, false);
  std::string json = buf.str(); // {"foo":"bar"}

  // Read json.
  ptree pt2;
  std::istringstream is (json);
  read_json (is, pt2);
  std::string foo = pt2.get<std::string> ("foo");
}

If I compile this with g++ -std=c++03 -c' everything is fine. However, I also want to use C++11 features (which the code in the linked thread actually does!). But withg++ -std=c++11 -c' I get compile errors:

In file included from /usr/include/boost/property_tree/json_parser.hpp:14:0,
                 from test.cpp:4:
/usr/include/boost/property_tree/detail/json_parser_read.hpp: In instantiation of ‘void boost::property_tree::json_parser::context<Ptree>::a_literal_val::operator()   (boost::property_tree::json_parser::context<Ptree>::It,       boost::property_tree::json_parser::context<Ptree>::It) const [with Ptree = boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> >; boost::property_tree::json_parser::context<Ptree>::It = __gnu_cxx::__normal_iterator<char*, std::vector<char, std::allocator<char> > >]’:
/usr/include/boost/spirit/home/classic/core/scanner/scanner.hpp:148:13:   required from ‘static void boost::spirit::classic::attributed_action_policy<boost::spirit::classic::nil_t>::call(const ActorT&, boost::spirit::classic::nil_t, const IteratorT&, const IteratorT&) [with ActorT = boost::property_tree::json_parser::context<boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> > >::a_literal_val; IteratorT = __gnu_cxx::__normal_iterator<char*, std::vector<char, std::allocator<char> > >]’
/usr/include/boost/spirit/home/classic/core/scanner/scanner.hpp:163:13:   required from ‘void boost::spirit::classic::action_policy::do_action(const ActorT&, AttrT&, const IteratorT&, const IteratorT&) const [with ActorT = boost::property_tree::json_parser::context<boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> > >::a_literal_val; AttrT = boost::spirit::classic::nil_t; IteratorT = __gnu_cxx::__normal_iterator<char*, std::vector<char, std::allocator<char> > >]’
...
test.cpp:20:1:   required from here
/usr/include/boost/property_tree/detail/json_parser_read.hpp:105:17: error: no matching function for call to ‘boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> >::push_back(std::pair<std::basic_string<char>, std::basic_string<char> >)’
/usr/include/boost/property_tree/detail/json_parser_read.hpp:105:17: note: candidate is:
In file included from /usr/include/boost/property_tree/ptree.hpp:516:0,
             from test.cpp:3:
/usr/include/boost/property_tree/detail/ptree_implementation.hpp:362:9: note: boost::property_tree::basic_ptree<Key, Data, KeyCompare>::iterator boost::property_tree::basic_ptree<Key, Data, KeyCompare>::push_back(const value_type&) [with Key = std::basic_string<char>; Data = std::basic_string<char>; KeyCompare = std::less<std::basic_string<char> >; boost::property_tree::basic_ptree<Key, Data, KeyCompare>::value_type = std::pair<const std::basic_string<char>, boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> > >]
/usr/include/boost/property_tree/detail/ptree_implementation.hpp:362:9: note:   no known conversion for argument 1 from ‘std::pair<std::basic_string<char>, std::basic_string<char> >’ to ‘const value_type& {aka const std::pair<const std::basic_string<char>, boost::property_tree::basic_ptree<std::basic_string<char>, std::basic_string<char> > >&}’

How can I use Boost's read_json with C++11? Do I need a newer Boost version for this (i. e. install manually from source instead of using Wheezy's packaged one)? Is there something wrong in my code? Or is this simply not possible?

解决方案

It is a known bug of older Boost versions.
You can fix it by applying the following patch:

--- json_parser_read.hpp        2013-09-01 03:55:57.000000000 +0400
+++ /usr/include/boost/property_tree/detail/json_parser_read.hpp        2013-09-01 03:56:21.000000000 +0400
@@ -102,7 +102,7 @@
             void operator()(It b, It e) const
             {
                 BOOST_ASSERT(c.stack.size() >= 1);
-                c.stack.back()->push_back(std::make_pair(c.name, Str(b, e)));
+                c.stack.back()->push_back(std::make_pair(c.name, Ptree(Str(b, e))));
                 c.name.clear();
                 c.string.clear();
             }

or with

sed -i -e 's/std::make_pair(c.name, Str(b, e))/std::make_pair(c.name, Ptree(Str(b, e)))/' json_parser_read.hpp

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