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#ifndef PERSISTANCE_H
#define PERSISTANCE_H
#include <functional>
#include <glm/glm.hpp>
#include <iosfwd>
#include <memory>
#include <special_members.hpp>
#include <stack>
#include <stdexcept>
#include <string>
#include <string_view>
#include <utility>
#include <vector>
namespace glm {
template<glm::length_t L, typename T, glm::qualifier Q> struct vec;
}
namespace Persistanace {
struct Selection;
using SelectionPtr = std::unique_ptr<Selection>;
using Stack = std::stack<SelectionPtr>;
struct Selection {
Selection() = default;
virtual ~Selection() = default;
DEFAULT_MOVE_COPY(Selection);
virtual void setValue(float &);
virtual void setValue(bool &);
virtual void setValue(const std::nullptr_t &);
virtual void setValue(std::string &);
virtual void beginArray(Stack &);
virtual void beginObject(Stack &);
virtual void endObject(Stack &);
virtual void beforeValue(Stack &);
virtual SelectionPtr select(const std::string &);
template<typename T> static SelectionPtr make(T & value);
template<typename S, typename T> static SelectionPtr make_s(T & value);
};
template<typename T> struct SelectionT : public Selection {
explicit SelectionT(T & value) : v {value} { }
void
beforeValue(Stack &) override
{
}
void
setValue(T & evalue) override
{
std::swap(v, evalue);
}
T & v;
};
template<typename T>
SelectionPtr
Selection::make(T & value)
{
return make_s<SelectionT<T>>(value);
}
template<typename S, typename T>
SelectionPtr
Selection::make_s(T & value)
{
return std::make_unique<S>(value);
}
struct PersistanceStore {
// virtual bool persistType(const std::type_info &) = 0;
template<typename T>
inline bool
persistValue(const std::string_view key, T & value)
{
if (key == name) {
sel = Selection::make(value);
return false;
}
return true;
}
const std::string & name;
SelectionPtr sel {};
};
template<glm::length_t L, typename T, glm::qualifier Q> struct SelectionT<glm::vec<L, T, Q>> : public Selection {
using V = glm::vec<L, float, Q>;
struct Members : public Selection {
explicit Members(V & value) : v {value} { }
void
beforeValue(Stack & stk) override
{
stk.push(make(v[idx++]));
}
V & v;
glm::length_t idx {0};
};
explicit SelectionT(V & value) : v {value} { }
void
beginArray(Stack & stk) override
{
stk.push(make_s<Members>(v));
}
void
beforeValue(Stack &) override
{
}
V & v;
};
template<typename T> struct SelectionT<std::vector<T>> : public Selection {
using V = std::vector<T>;
struct Members : public Selection {
explicit Members(V & value) : v {value} { }
void
beforeValue(Stack & stk) override
{
stk.push(make(v.emplace_back()));
}
V & v;
};
explicit SelectionT(V & value) : v {value} { }
void
beginArray(Stack & stk) override
{
stk.push(make_s<Members>(v));
}
void
beforeValue(Stack &) override
{
}
std::vector<T> & v;
};
struct Persistable {
Persistable() = default;
virtual ~Persistable() = default;
DEFAULT_MOVE_COPY(Persistable);
virtual bool persist(PersistanceStore & store) = 0;
static void addFactory(const std::string_view, std::function<std::unique_ptr<Persistable>()>);
static std::unique_ptr<Persistable> callFactory(const std::string_view);
};
template<typename T> struct SelectionT<std::unique_ptr<T>> : public Selection {
using Ptr = std::unique_ptr<T>;
struct SelectionObj : public Selection {
struct MakeObjectByTypeName : public Selection {
explicit MakeObjectByTypeName(Ptr & o) : o {o} { }
void
beforeValue(Stack &) override
{
}
void
setValue(std::string & type) override
{
auto no = Persistable::callFactory(type);
if (dynamic_cast<T *>(no.get())) {
o.reset(static_cast<T *>(no.release()));
}
}
Ptr & o;
};
explicit SelectionObj(Ptr & o) : v {o} { }
SelectionPtr
select(const std::string & mbr) override
{
using namespace std::literals;
if (mbr == "@typeid"sv) {
if (v) {
throw std::runtime_error("cannot set object type after creation");
}
return make_s<MakeObjectByTypeName>(v);
}
else {
if (!v) {
if constexpr (std::is_abstract_v<T>) {
throw std::runtime_error("cannot select member of null object");
}
else {
v = std::make_unique<T>();
}
}
PersistanceStore ps {mbr};
if (v->persist(ps)) {
throw std::runtime_error("cannot find member: " + mbr);
}
return std::move(ps.sel);
}
}
void
endObject(Stack & stk) override
{
if (!v) {
if constexpr (std::is_abstract_v<T>) {
throw std::runtime_error("cannot default create abstract object");
}
else {
v = std::make_unique<T>();
}
}
stk.pop();
}
Ptr & v;
};
explicit SelectionT(Ptr & o) : v {o} { }
void
beforeValue(Stack &) override
{
}
void
setValue(const std::nullptr_t &) override
{
v.reset();
}
void
beginObject(Stack & stk) override
{
stk.push(make_s<SelectionObj>(v));
}
void
endObject(Stack & stk) override
{
stk.pop();
}
Ptr & v;
};
}
#define STORE_TYPE store.persistType(typeid(*this))
#define STORE_MEMBER(mbr) store.persistValue(#mbr, mbr)
#endif
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