JSON to C++
This program will take either a json file or a URL to a web service and build C++ classes to work with that data. By default, it will create the serialization linkage for the JsonLink library that is part of https://github.com/beached/daw_json_link .
- std::optional is used for optional members(those that are not always there or are null in some cases
- std::string is used for strings
- int64_t is used for integral types
- double is used for real types
- bool is used for boolean types
- classes are given the name of their member suffixed with a "_t"
- identifier names are filtered such that C++ keywords, empty id's, or all number id's are prefixed with _json
- Any character in an id that isn't A-Za-z0-9 or _ will be escaped via 0xXXX
- Autogenerated types are their member name suffixed with a _t.
Running
To output the C++ code to the terminal one just needs to type json_to_cpp_bin --in_file jsonfile.json or for a url
something like json_to_cpp_bin --in_file http://ip.jsontest.com/
Command line options
Options:
--help print option descriptions
--in_file arg json source file path or url
--kv_paths arg Specify class members that are key
value pairs
--use_jsonlink arg (=1) Use JsonLink serializaion/deserializati
on
--has_cpp20 arg (=0) Enables use of non-type class template
arguments
--output_file arg output goes to c++ header file.
--allow_overwrite arg (=0) Overwrite existing output files
--hide_null_only arg (=1) Do not output json entries that are
only ever null
--use_string_view arg (=0) Use std::string_view instead of
std::string. Must ensure buffer is
available after parsing when this is
used
--root_object arg (=root_object) Name of the nameless root object
--user_agent arg (=Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.100 Safari/537.36)
User agent to use when downloading via
URL
Example
H2 JSON Data
{
"glossary": {
"title": "example glossary",
"GlossDiv": {
"title": "S",
"GlossList": {
"GlossEntry": {
"ID": "SGML",
"SortAs": "SGML",
"GlossTerm": "Standard Generalized Markup Language",
"Acronym": "SGML",
"Abbrev": "ISO 8879:1986",
"GlossDef": {
"para": "A meta-markup language, used to create markup languages such as DocBook.",
"GlossSeeAlso": ["GML", "XML"]
},
"GlossSee": "markup"
}
}
}
}
}
Generated C++ Code by calling json_to_cpp --in_file name.json
#include <daw/json/daw_json_link.h>
#include <string>
#include <tuple>
#include <vector>
struct GlossDef_t {
std::string para;
std::vector<std::string> GlossSeeAlso;
}; // GlossDef_t
struct GlossEntry_t {
std::string ID;
std::string SortAs;
std::string GlossTerm;
std::string Acronym;
std::string Abbrev;
GlossDef_t GlossDef;
std::string GlossSee;
}; // GlossEntry_t
struct GlossList_t {
GlossEntry_t GlossEntry;
}; // GlossList_t
struct GlossDiv_t {
std::string title;
GlossList_t GlossList;
}; // GlossDiv_t
struct glossary_t {
std::string title;
GlossDiv_t GlossDiv;
}; // glossary_t
struct root_object_t {
glossary_t glossary;
}; // root_object_t
namespace daw::json {
template<>
struct json_data_contract<GlossDef_t> {
static constexpr char const mem_para[] = "para";
static constexpr char const mem_GlossSeeAlso[] = "GlossSeeAlso";
using type = json_member_list<
json_string<mem_para>,
json_array<mem_GlossSeeAlso, std::string, std::vector<std::string>>>;
static inline auto to_json_data( GlossDef_t const &value ) {
return std::forward_as_tuple( value.para, value.GlossSeeAlso );
}
};
}
namespace daw::json {
template<>
struct json_data_contract<GlossEntry_t> {
static constexpr char const mem_ID[] = "ID";
static constexpr char const mem_SortAs[] = "SortAs";
static constexpr char const mem_GlossTerm[] = "GlossTerm";
static constexpr char const mem_Acronym[] = "Acronym";
static constexpr char const mem_Abbrev[] = "Abbrev";
static constexpr char const mem_GlossDef[] = "GlossDef";
static constexpr char const mem_GlossSee[] = "GlossSee";
using type = json_member_list<
json_string<mem_ID>, json_string<mem_SortAs>, json_string<mem_GlossTerm>,
json_string<mem_Acronym>, json_string<mem_Abbrev>,
json_class<mem_GlossDef, GlossDef_t>, json_string<mem_GlossSee>>;
static inline auto to_json_data( GlossEntry_t const &value ) {
return std::forward_as_tuple( value.ID, value.SortAs, value.GlossTerm,
value.Acronym, value.Abbrev, value.GlossDef,
value.GlossSee );
}
};
}
namespace daw::json {
template<>
struct json_data_contract<GlossList_t> {
static constexpr char const mem_GlossEntry[] = "GlossEntry";
using type = json_member_list<json_class<mem_GlossEntry, GlossEntry_t>>;
static inline auto to_json_data( GlossList_t const &value ) {
return std::forward_as_tuple( value.GlossEntry );
}
};
}
namespace daw::json {
template<>
struct json_data_contract<GlossDiv_t> {
static constexpr char const mem_title[] = "title";
static constexpr char const mem_GlossList[] = "GlossList";
using type = json_member_list<json_string<mem_title>,
json_class<mem_GlossList, GlossList_t>>;
static inline auto to_json_data( GlossDiv_t const &value ) {
return std::forward_as_tuple( value.title, value.GlossList );
}
};
}
namespace daw::json {
template<>
struct json_data_contract<glossary_t> {
static constexpr char const mem_title[] = "title";
static constexpr char const mem_GlossDiv[] = "GlossDiv";
using type = json_member_list<json_string<mem_title>,
json_class<mem_GlossDiv, GlossDiv_t>>;
static inline auto to_json_data( glossary_t const &value ) {
return std::forward_as_tuple( value.title, value.GlossDiv );
}
};
}
namespace daw::json {
template<>
struct json_data_contract<root_object_t> {
static constexpr char const mem_glossary[] = "glossary";
using type = json_member_list<json_class<mem_glossary, glossary_t>>;
static inline auto to_json_data( root_object_t const &value ) {
return std::forward_as_tuple( value.glossary );
}
};
}