Initial commit of basis persistence

JSON parser lifted almost verbatim for libjsonpp running into some
custom code for populating ilt objects. Pretty minimal per object code
requirements.

1 files changed, 281 insertions, 0 deletions

diff --git a/test/test-persistance.cpp b/test/test-persistance.cpp
new file mode 100644
index 0000000..7d66675
--- /dev/null
+++ b/test/test-persistance.cpp
@@ -0,0 +1,281 @@
+#define BOOST_TEST_MODULE test_persistance
+
+#include <boost/test/unit_test.hpp>
+
+#include <gfx/models/vertex.hpp>
+#include <glm/glm.hpp>
+#include <jsonParse.h>
+#include <maths.h>
+#include <memory>
+#include <stack>
+#include <stream_support.hpp>
+#include <utility>
+#include <variant>
+#include <vector>
+
+struct PersistanceStore;
+struct Selection;
+using SelectionPtr = std::unique_ptr<Selection>;
+struct Selection {
+	virtual ~Selection() = default;
+	virtual void
+	operator()(float &)
+	{
+		throw std::runtime_error("Unexpected float");
+	}
+	virtual void
+	operator()(bool &)
+	{
+		throw std::runtime_error("Unexpected bool");
+	}
+	virtual void
+	operator()(const std::nullptr_t &)
+	{
+		throw std::runtime_error("Unexpected null");
+	}
+	virtual void
+	operator()(std::string &)
+	{
+		throw std::runtime_error("Unexpected string");
+	}
+	virtual void
+	BeginArray()
+	{
+		throw std::runtime_error("Unexpected array");
+	}
+	virtual SelectionPtr
+	BeginObject()
+	{
+		throw std::runtime_error("Unexpected object");
+	}
+	virtual SelectionPtr select(std::string)
+	{
+		throw std::runtime_error("Unexpected persist");
+	}
+};
+
+template<typename T> struct SelectionT : public Selection {
+	SelectionT(T & value) : v {value} { }
+	void
+	operator()(T & evalue) override
+	{
+		std::swap(v, evalue);
+	}
+	T & v;
+};
+
+template<glm::length_t L, glm::qualifier Q> struct SelectionT<glm::vec<L, float, Q>> : public Selection {
+	SelectionT(glm::vec3 & value) : v {value}
+	{
+		CLOG(__PRETTY_FUNCTION__);
+	}
+	void
+	operator()(float & value) override
+	{
+		v[idx++] = value;
+	}
+	void
+	BeginArray() override
+	{
+	}
+	glm::vec3 & v;
+	glm::vec3::length_type idx {0};
+};
+
+template<typename T> struct SelectionT<std::vector<T>> : public Selection {
+	SelectionT(std::vector<T> & value) : v {value} { }
+	void
+	operator()(T & value) override
+	{
+		v.push_back(value);
+	}
+	void
+	BeginArray()
+	{
+	}
+	std::vector<T> & v;
+};
+
+struct TestObject;
+
+template<typename Ptr> struct MakeObjectByTypeName : public Selection {
+	MakeObjectByTypeName(Ptr & o) : o {o} { }
+	virtual void
+	operator()(std::string &)
+	{
+		o = std::make_unique<TestObject>(); // TODO shared_ptr
+	}
+	Ptr & o;
+};
+
+struct PersistanceStore {
+	// virtual bool persistType(const std::type_info &) = 0;
+	template<typename T>
+	bool
+	persistValue(const std::string_view & key, T & value)
+	{
+		if (key == name) {
+			sel = std::make_unique<SelectionT<T>>(std::ref(value));
+			return false;
+		}
+		return true;
+	}
+	const std::string & name;
+	std::unique_ptr<Selection> sel {};
+};
+
+template<typename Ptr> struct SelectionObj : public Selection {
+	SelectionObj(Ptr & o) : v {o} { }
+
+	SelectionPtr
+	select(std::string mbr) override
+	{
+		if (mbr == "@typeid") {
+			return std::make_unique<MakeObjectByTypeName<Ptr>>(std::ref(v));
+		}
+		else if (v) {
+			CLOG(mbr);
+			PersistanceStore ps {mbr};
+			v->persist(ps);
+			return std::move(ps.sel);
+		}
+		throw std::runtime_error("cannot select member of null object");
+	}
+
+	Ptr & v;
+};
+
+template<typename T> struct SelectionT<std::unique_ptr<T>> : public Selection {
+	SelectionT(std::unique_ptr<T> & o) : v {o} { }
+	SelectionPtr
+	BeginObject() override
+	{
+		CLOG(__PRETTY_FUNCTION__);
+		return std::make_unique<SelectionObj<std::unique_ptr<T>>>(v);
+	}
+	std::unique_ptr<T> & v;
+};
+
+struct Persistable {
+	virtual void persist(PersistanceStore & store) = 0;
+};
+
+struct JsonLoadPersistanceStore : public json::jsonParser {
+	JsonLoadPersistanceStore(std::istream & in) : json::jsonParser {&in} { }
+
+	std::stack<std::unique_ptr<Selection>> stk;
+	std::unique_ptr<Selection> selection;
+
+	template<typename T>
+	void
+	loadState(std::unique_ptr<T> & t)
+	{
+		yy_push_state(0);
+		stk.push(std::make_unique<SelectionT<std::unique_ptr<T>>>(std::ref(t)));
+		yylex();
+	}
+	void
+	BeginObject() override
+	{
+		CLOG(__FUNCTION__);
+		stk.push(stk.top()->BeginObject());
+	}
+	void
+	BeginArray() override
+	{
+		CLOG(__FUNCTION__);
+		selection->BeginArray();
+	}
+	void
+	PushBoolean(bool value) override
+	{
+		CLOG(__FUNCTION__);
+		(*selection)(value);
+	}
+	void
+	PushNumber(float value) override
+	{
+		CLOG(__FUNCTION__);
+		(*selection)(value);
+	}
+	void
+	PushNull() override
+	{
+		CLOG(__FUNCTION__);
+		(*selection)(nullptr);
+	}
+	void
+	PushText(std::string && value) override
+	{
+		CLOG(__FUNCTION__);
+		(*selection)(value);
+	}
+	void
+	PushKey(std::string && k) override
+	{
+		CLOG(__FUNCTION__);
+		selection = stk.top()->select(std::move(k));
+	}
+	void
+	EndArray() override
+	{
+		CLOG(__FUNCTION__);
+	}
+	void
+	EndObject() override
+	{
+		CLOG(__FUNCTION__);
+		stk.pop();
+	}
+};
+
+#define STORE_TYPE store.persistType(typeid(*this))
+#define STORE_MEMBER(mbr) store.persistValue(#mbr##sv, mbr)
+
+struct TestObject : public Persistable {
+	TestObject() = default;
+
+	float flt {};
+	std::string str {};
+	bool bl {};
+	glm::vec3 pos {};
+	std::vector<float> flts;
+
+	void
+	persist(PersistanceStore & store) override
+	{
+		using namespace std::literals;
+		STORE_MEMBER(flt) && STORE_MEMBER(str) && STORE_MEMBER(bl) && STORE_MEMBER(pos) && STORE_MEMBER(flts);
+	}
+};
+
+const std::string input(R"J({
+	"@typeid": "TestObject",
+	"flt": 3.14,
+	"str": "Lovely string",
+	"bl": true,
+	"pos": [3.14, 6.28, 1.57],
+	"flts": [3.14, 6.28, 1.57, 0, -1, -3.14],
+})J");
+
+BOOST_AUTO_TEST_CASE(load_object)
+{
+	std::stringstream ss {input};
+	JsonLoadPersistanceStore jlps {ss};
+	std::unique_ptr<TestObject> to;
+	jlps.loadState(to);
+
+	BOOST_CHECK_CLOSE(to->flt, 3.14, 0.01);
+	BOOST_CHECK_EQUAL(to->str, "Lovely string");
+	BOOST_CHECK_EQUAL(to->bl, true);
+	BOOST_CHECK_CLOSE(to->pos[0], 3.14, 0.01);
+	BOOST_CHECK_CLOSE(to->pos[1], 6.28, 0.01);
+	BOOST_CHECK_CLOSE(to->pos[2], 1.57, 0.01);
+	BOOST_REQUIRE_EQUAL(to->flts.size(), 6);
+	BOOST_CHECK_CLOSE(to->flts[0], 3.14, 0.01);
+	BOOST_CHECK_CLOSE(to->flts[1], 6.28, 0.01);
+	BOOST_CHECK_CLOSE(to->flts[2], 1.57, 0.01);
+	BOOST_CHECK_CLOSE(to->flts[3], 0, 0.01);
+	BOOST_CHECK_CLOSE(to->flts[4], -1, 0.01);
+	BOOST_CHECK_CLOSE(to->flts[5], -3.14, 0.01);
+}