From f1f783877f0f8338a225244faff4e40efe10a4ce Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 21 Jul 2018 18:07:45 +0200
Subject: NBT: rework type system

---
 src/NBT/ByteArrayTag.hpp |   8 +-
 src/NBT/ByteTag.hpp      |   7 +-
 src/NBT/CompoundTag.hpp  |  10 ++-
 src/NBT/DoubleTag.hpp    |   7 +-
 src/NBT/EndTag.hpp       |   9 ++-
 src/NBT/FloatTag.hpp     |   7 +-
 src/NBT/IntArrayTag.hpp  |   7 +-
 src/NBT/IntTag.hpp       |   7 +-
 src/NBT/ListTag.hpp      |  31 ++++----
 src/NBT/LongArrayTag.hpp |   7 +-
 src/NBT/LongTag.hpp      |   7 +-
 src/NBT/ShortTag.hpp     |   7 +-
 src/NBT/StringTag.hpp    |   7 +-
 src/NBT/Tag.cpp          | 194 +++++++++--------------------------------------
 src/NBT/Tag.hpp          |  63 ++++++++++-----
 src/World/Chunk.cpp      |   8 +-
 src/World/Chunk.hpp      |   4 +-
 17 files changed, 162 insertions(+), 228 deletions(-)

diff --git a/src/NBT/ByteArrayTag.hpp b/src/NBT/ByteArrayTag.hpp
index 1e4f2f9..0d58dc8 100644
--- a/src/NBT/ByteArrayTag.hpp
+++ b/src/NBT/ByteArrayTag.hpp
@@ -40,12 +40,16 @@ private:
 	const uint8_t *value;
 
 public:
+	static const MakeType<ByteArrayTag> Type;
+
+
 	ByteArrayTag(Buffer *buffer) {
 		len = buffer->get32();
 		value = buffer->get(len);
 	}
-	virtual Type getType() const {
-		return Type::ByteArray;
+
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &indent) const {
diff --git a/src/NBT/ByteTag.hpp b/src/NBT/ByteTag.hpp
index 28b8b1a..c578b9c 100644
--- a/src/NBT/ByteTag.hpp
+++ b/src/NBT/ByteTag.hpp
@@ -37,12 +37,15 @@ private:
 	uint8_t value;
 
 public:
+	static const MakeType<ByteTag> Type;
+
+
 	ByteTag(Buffer *buffer) {
 		value = buffer->get8();
 	}
 
-	virtual Type getType() const {
-		return Type::Byte;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/CompoundTag.hpp b/src/NBT/CompoundTag.hpp
index 310b995..68e2390 100644
--- a/src/NBT/CompoundTag.hpp
+++ b/src/NBT/CompoundTag.hpp
@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include "EndTag.hpp"
 #include "Tag.hpp"
 
 #include <string>
@@ -37,18 +38,21 @@ namespace NBT {
 
 class CompoundTag : public Tag, public std::unordered_map<std::string, std::shared_ptr<const Tag>> {
 public:
+	static const MakeType<CompoundTag> Type;
+
+
 	CompoundTag(Buffer *buffer) {
 		while (true) {
 			std::pair<std::string, std::shared_ptr<const Tag>> v = Tag::readNamedTag(buffer);
-			if (v.second->getType() == Type::End)
+			if (v.second->getType() == EndTag::Type)
 				break;
 
 			insert(std::move(v));
 		}
 	}
 
-	virtual Type getType() const {
-		return Type::Compound;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &indent) const {
diff --git a/src/NBT/DoubleTag.hpp b/src/NBT/DoubleTag.hpp
index 3dfdb74..b83efe2 100644
--- a/src/NBT/DoubleTag.hpp
+++ b/src/NBT/DoubleTag.hpp
@@ -37,12 +37,15 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<DoubleTag> Type;
+
+
 	DoubleTag(Buffer *buffer) {
 		ptr = buffer->get(8);
 	}
 
-	virtual Type getType() const {
-		return Type::Double;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/EndTag.hpp b/src/NBT/EndTag.hpp
index 5f771fd..167412a 100644
--- a/src/NBT/EndTag.hpp
+++ b/src/NBT/EndTag.hpp
@@ -34,10 +34,13 @@ namespace NBT {
 
 class EndTag : public Tag {
 public:
-	EndTag() {}
+	static const MakeType<EndTag> Type;
 
-	virtual Type getType() const {
-		return Type::End;
+
+	EndTag(Buffer *) {}
+
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream&, const std::string &) const {
diff --git a/src/NBT/FloatTag.hpp b/src/NBT/FloatTag.hpp
index 4442f1a..8748bc6 100644
--- a/src/NBT/FloatTag.hpp
+++ b/src/NBT/FloatTag.hpp
@@ -36,12 +36,15 @@ class FloatTag : public Tag {
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<FloatTag> Type;
+
+
 	FloatTag(Buffer *buffer) {
 		ptr = buffer->get(4);
 	}
 
-	virtual Type getType() const {
-		return Type::Float;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/IntArrayTag.hpp b/src/NBT/IntArrayTag.hpp
index b7a27b4..67c25b1 100644
--- a/src/NBT/IntArrayTag.hpp
+++ b/src/NBT/IntArrayTag.hpp
@@ -40,13 +40,16 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<IntArrayTag> Type;
+
+
 	IntArrayTag(Buffer *buffer) {
 		len = buffer->get32();
 		ptr = buffer->get(4*len);
 	}
 
-	virtual Type getType() const {
-		return Type::IntArray;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &indent) const {
diff --git a/src/NBT/IntTag.hpp b/src/NBT/IntTag.hpp
index 6514546..e6babd0 100644
--- a/src/NBT/IntTag.hpp
+++ b/src/NBT/IntTag.hpp
@@ -37,12 +37,15 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<IntTag> Type;
+
+
 	IntTag(Buffer *buffer) {
 		ptr = buffer->get(4);
 	}
 
-	virtual Type getType() const {
-		return Type::Int;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/ListTag.hpp b/src/NBT/ListTag.hpp
index d86abdb..7276923 100644
--- a/src/NBT/ListTag.hpp
+++ b/src/NBT/ListTag.hpp
@@ -34,34 +34,29 @@
 namespace MinedMap {
 namespace NBT {
 
+class ListTag : public Tag, public std::vector<std::shared_ptr<const Tag>> {
+private:
+	const TagType *subtype;
 
-class ListTagBase : public Tag {
 public:
-	virtual Type getType() const {
-		return Type::List;
-	}
+	static const MakeType<ListTag> Type;
 
-	virtual Type getSubtype() const = 0;
-};
 
+	ListTag(Buffer *buffer) {
+		subtype = &getTypeById(buffer->get8());
 
-template<typename T>
-class ListTag : public ListTagBase, public std::vector<std::shared_ptr<const T>> {
-private:
-	Type type;
-
-public:
-	ListTag(Type type0, Buffer *buffer) : type(type0) {
 		uint32_t len = buffer->get32();
 
-		this->resize(len);
-
 		for (uint32_t i = 0; i < len; i++)
-			(*this)[i] = std::static_pointer_cast<const T>(Tag::readTag(type, buffer));
+			push_back(subtype->read(buffer));
+	}
+
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
-	virtual Type getSubtype() const {
-		return type;
+	virtual const TagType & getSubtype() const {
+		return *subtype;
 	}
 
 	virtual void print(std::ostream& os, const std::string &indent) const {
diff --git a/src/NBT/LongArrayTag.hpp b/src/NBT/LongArrayTag.hpp
index 1ca3ae6..545798f 100644
--- a/src/NBT/LongArrayTag.hpp
+++ b/src/NBT/LongArrayTag.hpp
@@ -40,13 +40,16 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<LongArrayTag> Type;
+
+
 	LongArrayTag(Buffer *buffer) {
 		len = buffer->get32();
 		ptr = buffer->get(8*len);
 	}
 
-	virtual Type getType() const {
-		return Type::LongArray;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &indent) const {
diff --git a/src/NBT/LongTag.hpp b/src/NBT/LongTag.hpp
index f600d8e..05f6bc2 100644
--- a/src/NBT/LongTag.hpp
+++ b/src/NBT/LongTag.hpp
@@ -37,12 +37,15 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<LongTag> Type;
+
+
 	LongTag(Buffer *buffer) {
 		ptr = buffer->get(8);
 	}
 
-	virtual Type getType() const {
-		return Type::Long;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/ShortTag.hpp b/src/NBT/ShortTag.hpp
index c66dc05..593a1ed 100644
--- a/src/NBT/ShortTag.hpp
+++ b/src/NBT/ShortTag.hpp
@@ -37,12 +37,15 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<ShortTag> Type;
+
+
 	ShortTag(Buffer *buffer) {
 		ptr = buffer->get(2);
 	}
 
-	virtual Type getType() const {
-		return Type::Short;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/StringTag.hpp b/src/NBT/StringTag.hpp
index 2fda6d3..8672b73 100644
--- a/src/NBT/StringTag.hpp
+++ b/src/NBT/StringTag.hpp
@@ -38,13 +38,16 @@ private:
 	const uint8_t *ptr;
 
 public:
+	static const MakeType<StringTag> Type;
+
+
 	StringTag(Buffer *buffer) {
 		len = buffer->get16();
 		ptr = buffer->get(len);
 	}
 
-	virtual Type getType() const {
-		return Type::String;
+	virtual const TagType & getType() const {
+		return Type;
 	}
 
 	virtual void print(std::ostream& os, const std::string &) const {
diff --git a/src/NBT/Tag.cpp b/src/NBT/Tag.cpp
index 31f1420..e8c429f 100644
--- a/src/NBT/Tag.cpp
+++ b/src/NBT/Tag.cpp
@@ -41,176 +41,50 @@
 #include "LongArrayTag.hpp"
 
 
-#include <stdexcept>
-
-
 namespace MinedMap {
 namespace NBT {
 
-std::shared_ptr<const Tag> Tag::readTag(Type type, Buffer *buffer) {
-	switch (type) {
-	case Type::End:
-		return std::make_shared<EndTag>();
-
-	case Type::Byte:
-		return std::make_shared<ByteTag>(buffer);
-
-	case Type::Short:
-		return std::make_shared<ShortTag>(buffer);
-
-	case Type::Int:
-		return std::make_shared<IntTag>(buffer);
-
-	case Type::Long:
-		return std::make_shared<LongTag>(buffer);
-
-	case Type::Float:
-		return std::make_shared<FloatTag>(buffer);
-
-	case Type::Double:
-		return std::make_shared<DoubleTag>(buffer);
-
-	case Type::ByteArray:
-		return std::make_shared<ByteArrayTag>(buffer);
-
-	case Type::String:
-		return std::make_shared<StringTag>(buffer);
-
-	case Type::List:
-		return readList(buffer);
-
-	case Type::Compound:
-		return std::make_shared<CompoundTag>(buffer);
-
-	case Type::IntArray:
-		return std::make_shared<IntArrayTag>(buffer);
-
-	case Type::LongArray:
-		return std::make_shared<LongArrayTag>(buffer);
-
-	default:
-		throw std::runtime_error("Tag::readTag: unknown tag type");
-	}
-}
-
-std::shared_ptr<const Tag> Tag::readList(Buffer *buffer) {
-	Type type = static_cast<Type>(buffer->get8());
-
-	switch (type) {
-	case Type::End:
-		return std::make_shared<ListTag<EndTag>>(type, buffer);
-
-	case Type::Byte:
-		return std::make_shared<ListTag<ByteTag>>(type, buffer);
-
-	case Type::Short:
-		return std::make_shared<ListTag<ShortTag>>(type, buffer);
-
-	case Type::Int:
-		return std::make_shared<ListTag<IntTag>>(type, buffer);
-
-	case Type::Long:
-		return std::make_shared<ListTag<LongTag>>(type, buffer);
-
-	case Type::Float:
-		return std::make_shared<ListTag<FloatTag>>(type, buffer);
-
-	case Type::Double:
-		return std::make_shared<ListTag<DoubleTag>>(type, buffer);
+const Tag::MakeType<EndTag> EndTag::Type("End");
+const Tag::MakeType<ByteTag> ByteTag::Type("Byte");
+const Tag::MakeType<ShortTag> ShortTag::Type("Short");
+const Tag::MakeType<IntTag> IntTag::Type("Int");
+const Tag::MakeType<LongTag> LongTag::Type("Long");
+const Tag::MakeType<FloatTag> FloatTag::Type("Float");
+const Tag::MakeType<DoubleTag> DoubleTag::Type("Double");
+const Tag::MakeType<ByteArrayTag> ByteArrayTag::Type("ByteArray");
+const Tag::MakeType<StringTag> StringTag::Type("String");
+const Tag::MakeType<ListTag> ListTag::Type("List");
+const Tag::MakeType<CompoundTag> CompoundTag::Type("Compound");
+const Tag::MakeType<IntArrayTag> IntArrayTag::Type("IntArray");
+const Tag::MakeType<LongArrayTag> LongArrayTag::Type("LongArray");
+
+
+const std::vector<const TagType *> Tag::types = {
+	&EndTag::Type,
+	&ByteTag::Type,
+	&ShortTag::Type,
+	&IntTag::Type,
+	&LongTag::Type,
+	&FloatTag::Type,
+	&DoubleTag::Type,
+	&ByteArrayTag::Type,
+	&StringTag::Type,
+	&ListTag::Type,
+	&CompoundTag::Type,
+	&IntArrayTag::Type,
+	&LongArrayTag::Type,
+};
 
-	case Type::ByteArray:
-		return std::make_shared<ListTag<ByteArrayTag>>(type, buffer);
-
-	case Type::String:
-		return std::make_shared<ListTag<StringTag>>(type, buffer);
-
-	case Type::List:
-		return std::make_shared<ListTag<ListTagBase>>(type, buffer);
-
-	case Type::Compound:
-		return std::make_shared<ListTag<CompoundTag>>(type, buffer);
-
-	case Type::IntArray:
-		return std::make_shared<ListTag<IntArrayTag>>(type, buffer);
-
-	case Type::LongArray:
-		return std::make_shared<ListTag<LongArrayTag>>(type, buffer);
-
-	default:
-		throw std::runtime_error("Tag::readList: unknown tag type");
-	}
-}
 
 std::pair<std::string, std::shared_ptr<const Tag>> Tag::readNamedTag(Buffer *buffer) {
-	Type type = static_cast<Type>(buffer->get8());
-	if (type == Type::End)
-		return std::make_pair("", std::shared_ptr<EndTag>(new EndTag()));
+	const TagType &type = getTypeById(buffer->get8());
+	if (type == EndTag::Type)
+		return std::make_pair("", std::make_shared<EndTag>(buffer));
 
 	uint16_t len = buffer->get16();
 	std::string name(reinterpret_cast<const char*>(buffer->get(len)), len);
 
-	return std::make_pair(name, readTag(type, buffer));
-}
-
-std::ostream& operator<<(std::ostream& os, Tag::Type type) {
-	switch (type) {
-	case Tag::Type::End:
-		os << "End";
-		break;
-
-	case Tag::Type::Byte:
-		os << "Byte";
-		break;
-
-	case Tag::Type::Short:
-		os << "Short";
-		break;
-
-	case Tag::Type::Int:
-		os << "Int";
-		break;
-
-	case Tag::Type::Long:
-		os << "Long";
-		break;
-
-	case Tag::Type::Float:
-		os << "Float";
-		break;
-
-	case Tag::Type::Double:
-		os << "Double";
-		break;
-
-	case Tag::Type::ByteArray:
-		os << "ByteArray";
-		break;
-
-	case Tag::Type::String:
-		os << "String";
-		break;
-
-	case Tag::Type::List:
-		os << "List";
-		break;
-
-	case Tag::Type::Compound:
-		os << "Compound";
-		break;
-
-	case Tag::Type::IntArray:
-		os << "IntArray";
-		break;
-
-	case Tag::Type::LongArray:
-		os << "LongArray";
-		break;
-
-	default:
-		os.setstate(std::ios_base::failbit);
-	}
-
-	return os;
+	return std::make_pair(name, type.read(buffer));
 }
 
 }
diff --git a/src/NBT/Tag.hpp b/src/NBT/Tag.hpp
index b0c20af..3fb824b 100644
--- a/src/NBT/Tag.hpp
+++ b/src/NBT/Tag.hpp
@@ -29,6 +29,7 @@
 #include <cstdint>
 #include <memory>
 #include <ostream>
+#include <vector>
 
 #include "../Buffer.hpp"
 
@@ -36,37 +37,61 @@
 namespace MinedMap {
 namespace NBT {
 
+class Tag;
+
+class TagType {
+public:
+	TagType() = default;
+	TagType(const TagType&) = delete;
+	TagType & operator=(const TagType&) = delete;
+
+	virtual const char * getName() const = 0;
+	virtual std::shared_ptr<const Tag> read(Buffer *buffer) const = 0;
+
+	bool operator==(const TagType &type) const {
+		return this == &type;
+	}
+};
+
 class Tag {
 private:
-	static std::shared_ptr<const Tag> readList(Buffer *buffer);
+	static const std::vector<const TagType *> types;
 
-public:
-	enum class Type {
-		End = 0,
-		Byte = 1,
-		Short = 2,
-		Int = 3,
-		Long = 4,
-		Float = 5,
-		Double = 6,
-		ByteArray = 7,
-		String = 8,
-		List = 9,
-		Compound = 10,
-		IntArray = 11,
-		LongArray = 12,
+protected:
+	template<typename T>
+	class MakeType : public TagType {
+	private:
+		const char *name;
+
+	public:
+		MakeType(const char *name0) : name(name0) {}
+
+		virtual const char * getName() const {
+			return name;
+		}
+
+		virtual std::shared_ptr<const Tag> read(Buffer *buffer) const {
+			return std::make_shared<T>(buffer);
+		}
 	};
 
-	static std::shared_ptr<const Tag> readTag(Type type, Buffer *buffer);
+
+	static const TagType & getTypeById(uint8_t id) {
+		return *types.at(id);
+	}
+
+public:
 	static std::pair<std::string, std::shared_ptr<const Tag>> readNamedTag(Buffer *buffer);
 
-	virtual Type getType() const = 0;
+	virtual const TagType & getType() const = 0;
 	virtual void print(std::ostream& os, const std::string &indent) const = 0;
 
 	virtual ~Tag() {}
 };
 
-std::ostream& operator<<(std::ostream& os, Tag::Type type);
+static inline std::ostream& operator<<(std::ostream& os, const TagType &type) {
+	return os << type.getName();
+}
 
 static inline std::ostream& operator<<(std::ostream& os, const Tag &tag) {
 	os << tag.getType() << " ";
diff --git a/src/World/Chunk.cpp b/src/World/Chunk.cpp
index 07e38a4..38ca496 100644
--- a/src/World/Chunk.cpp
+++ b/src/World/Chunk.cpp
@@ -44,8 +44,9 @@ Chunk::Chunk(const ChunkData *data) {
 	std::shared_ptr<const NBT::ByteTag> lightPopulatedTag = level->get<NBT::ByteTag>("LightPopulated");
 	bool lightPopulated = lightPopulatedTag && lightPopulatedTag->getValue();
 
-	sections = assertValue(level->get<NBT::ListTag<NBT::CompoundTag>>("Sections"));
-	maxY = (assertValue(sections->back()->get<NBT::ByteTag>("Y"))->getValue() + 1) * SIZE;
+	sections = assertValue(level->get<NBT::ListTag>("Sections"));
+	const NBT::CompoundTag *lastSection = assertValue(dynamic_cast<const NBT::CompoundTag *>(sections->back().get()));
+	maxY = (assertValue(lastSection->get<NBT::ByteTag>("Y"))->getValue() + 1) * SIZE;
 
 
 	std::shared_ptr<const NBT::ByteArrayTag> biomeTag = assertValue(level->get<NBT::ByteArrayTag>("Biomes"));
@@ -65,7 +66,8 @@ Chunk::Chunk(const ChunkData *data) {
 	std::memset(blockBlockLight.get(), 0, maxY * SIZE * SIZE / 2);
 
 
-	for (auto &section : *sections) {
+	for (auto &sectionTag : *sections) {
+		const NBT::CompoundTag *section = assertValue(dynamic_cast<const NBT::CompoundTag *>(sectionTag.get()));
 		std::shared_ptr<const NBT::ByteArrayTag> blocks = assertValue(section->get<NBT::ByteArrayTag>("Blocks"));
 		std::shared_ptr<const NBT::ByteArrayTag> data = assertValue(section->get<NBT::ByteArrayTag>("Data"));
 		size_t Y = assertValue(section->get<NBT::ByteTag>("Y"))->getValue();
diff --git a/src/World/Chunk.hpp b/src/World/Chunk.hpp
index d4213b3..4bd301d 100644
--- a/src/World/Chunk.hpp
+++ b/src/World/Chunk.hpp
@@ -52,7 +52,7 @@ public:
 
 private:
 	std::shared_ptr<const NBT::CompoundTag> level;
-	std::shared_ptr<const NBT::ListTag<NBT::CompoundTag>> sections;
+	std::shared_ptr<const NBT::ListTag> sections;
 
 
 	unsigned maxY;
@@ -107,7 +107,7 @@ public:
 		return *level;
 	}
 
-	const NBT::ListTag<NBT::CompoundTag> & getSections() const {
+	const NBT::ListTag & getSections() const {
 		return *sections;
 	}
 
-- 
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