Roland Conybeare
9c8e23577e
git-subtree-dir: xo-printjson git-subtree-mainline:d49c309f80git-subtree-split:6743b9ef18
143 lines
4.8 KiB
C++
143 lines
4.8 KiB
C++
/* @file JsonPrinter.hpp
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*
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* author: Roland Conybeare, Aug 2022
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*/
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#pragma once
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#include "JsonPrinter.hpp"
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#include "xo/reflect/TypeDrivenMap.hpp"
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#include "xo/reflect/SelfTagging.hpp"
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#include <memory>
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#include <iostream>
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namespace xo {
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namespace json {
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class PrintJson : public reflect::SelfTagging {
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public:
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using Reflect = xo::reflect::Reflect;
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using TypeDrivenMap = xo::reflect::TypeDrivenMap<std::unique_ptr<JsonPrinter>>;
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using SelfTagging = xo::reflect::SelfTagging;
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using TaggedPtr = xo::reflect::TaggedPtr;
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using TaggedRcptr = xo::reflect::TaggedRcptr;
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using TypeDescr = xo::reflect::TypeDescr;
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using TypeId = xo::reflect::TypeId;
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public:
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PrintJson();
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~PrintJson() = default;
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template<typename T>
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void print(T const & x_arg, std::ostream * p_os) const {
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T * x = const_cast<T *>(&x_arg);
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this->print_tp(Reflect::make_tp(x), p_os);
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} /*print*/
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/* print object tp on stream *p_os, in JSON format;
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*/
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void print_tp(TaggedPtr tp, std::ostream * p_os) const;
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/* convenience -- shorthand for
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* .print(obj->self_tp(), p_os)
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*/
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void print_obj(rp<SelfTagging> const & obj, std::ostream * p_os) const;
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void provide_printer(TypeId id, std::unique_ptr<JsonPrinter> p) {
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*(printer_map_.require(id)) = std::move(p);
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}
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void provide_printer(TypeDescr td, std::unique_ptr<JsonPrinter> p) {
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this->provide_printer(td->id(), std::move(p));
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}
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/* write json representation for tp on *p_os */
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void print_aux(TaggedPtr tp, std::ostream * p_os) const;
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// ----- inherited from SelfTagging -----
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virtual TaggedRcptr self_tp();
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private:
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/* provide printers for common basic types */
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void provide_std_printers();
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private:
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/* map contains specialized printers for specific c++ types */
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TypeDrivenMap printer_map_;
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}; /*PrintJson*/
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/* Using singleton here to collect type-specific json printers,
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* collected during program initialization.
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*
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* Could relabel as PrintJsonInitContext if desired
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*/
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class PrintJsonSingleton {
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public:
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static rp<PrintJson> instance();
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private:
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/* we don't need this to be stored as pointer.
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* memory burned if unused will be one empty std::vector<>
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*/
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static rp<PrintJson> s_instance;
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}; /*PrintJsonSingleton*/
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} /*namespace json*/
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#ifdef NOT_USING
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namespace print {
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using PrintJson = xo::json::PrintJson;
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/* stream inserter for printing a T-instance in json format */
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template<typename T>
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class jsonp_impl {
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public:
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jsonp_impl(T const & x, PrintJson const * pjson) : value_(x), pjson_{pjson} {}
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//jsonp_impl(T const & x, PrintJson const * pjson) : value_{x}, pjson_{pjson} {}
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//jsonp_impl(T && x, PrintJson const * pjson) : value_(std::move(x)), pjson_{pjson} {}
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void print(std::ostream & os) const {
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using xo::reflect::Reflect;
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this->pjson_->print_tp(Reflect::make_tp(&value_), &os);
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} /*print*/
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private:
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/* value, to be printed, in json format */
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T value_;
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/* json printer (bc we don't care for singletons) */
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PrintJson const * pjson_ = nullptr;
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}; /*jsonp_impl*/
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template<typename T>
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inline
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std::ostream & operator<<(std::ostream & os, jsonp_impl<T> const & x) {
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x.print(os);
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return os;
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} /*operator<<*/
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/* writing out std::forward<T> behavior for completeness' sake:
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*
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* 1. call jsonp(x) with rvalue std::string x, then:
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* - T will be deduced to [std::string]
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* (in particular: _not_ std::string &, std::string const &, std::string &&)
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* - rvalue std::string passed to jsonp_impl ctor
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*
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* 2a. call jsonp(x) with std::string & x, then:
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* - T deduced to [std::string &]
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* - std::string & passed to jsonp_impl ctor
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*
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* 2b. call jsonp(x) with std::string const & x, then:
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* - T deduced to [std::string const &]
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* - std::string const & passed to jsonp_impl ctor
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*/
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template<typename T>
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auto jsonp(T && x, PrintJson const * pjson) {
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return jsonp_impl<T>(std::forward<T>(x), pjson);
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} /*jsonp*/
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} /*namespace print*/
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#endif
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} /*namespace xo*/
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/* end JsonPrinter.hpp */
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