Roland Conybeare
9c8e23577e
git-subtree-dir: xo-printjson git-subtree-mainline:d49c309f80git-subtree-split:6743b9ef18
99 lines
3.2 KiB
C++
99 lines
3.2 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 "xo/reflect/Reflect.hpp"
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#include "xo/reflect/TypeDrivenMap.hpp"
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#include "xo/reflect/TaggedPtr.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;
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class JsonPrinter {
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public:
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using Reflect = xo::reflect::Reflect;
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using TaggedPtr = xo::reflect::TaggedPtr;
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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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JsonPrinter(PrintJson const * pjson) : pjson_{pjson} {}
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virtual ~JsonPrinter() = default;
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PrintJson const * pjson() const { return pjson_; }
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/* print tagged pointer in json format */
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virtual void print_json(TaggedPtr tp,
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std::ostream * p_os) const = 0;
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void report_internal_type_consistency_error(TypeDescr td1,
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TypeDescr td2,
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std::ostream * p_os) const;
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/* convenience method for derived printers.
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* retrieves contents of tp as a T*, complains to *p_os if that fails.
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*
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* (Failure would occur if printer for type T was instead installed
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* for some unrelated type U)
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*/
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template<typename T>
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T * check_recover_native(TaggedPtr tp, std::ostream * p_os) const {
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T * x = tp.recover_native<T>();
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if (!x) {
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this->report_internal_type_consistency_error(Reflect::require<T>(),
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tp.td(),
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p_os);
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}
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return x;
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} /*check_recover_native*/
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void assign_pjson(PrintJson const * pjson) {
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assert(this->pjson_ == nullptr || this->pjson_ == pjson);
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this->pjson_ = pjson;
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} /*assign_pjson*/
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private:
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/* a json printers is installed into one PrintJson instance;
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* capture address of that instance at install time
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*/
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PrintJson const * pjson_ = nullptr;
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}; /*JsonPrinter*/
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/* AsStringJsonPrinter<T>
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* prints a T-instance by using operator<< and surrounding in quotes.
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*
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* e.g:
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* T & x = ..;
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* std::ostream * p_os = ..;
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*
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* *p_os << "\"" << x << "\""
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*
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*/
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template<typename T>
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class AsStringJsonPrinter : public JsonPrinter {
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public:
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AsStringJsonPrinter(PrintJson const * pjson) : JsonPrinter(pjson) {}
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virtual void print_json(TaggedPtr tp,
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std::ostream * p_os) const override
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{
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T * x = this->check_recover_native<T>(tp, p_os);
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if(x) {
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*p_os << "\"" << *x << "\"";
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}
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} /*print_json*/
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}; /*AsStringJsonPrinter*/
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} /*namespace json*/
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} /*namespace xo*/
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/* end JsonPrinter.hpp */
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