1 files changed, 293 insertions, 0 deletions

diff --git a/src/WorldStorage/FastNBT.h b/src/WorldStorage/FastNBT.h
new file mode 100644
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+++ b/src/WorldStorage/FastNBT.h
@@ -0,0 +1,293 @@
+
+// FastNBT.h
+
+// Interfaces to the fast NBT parser and writer
+
+/*
+The fast parser parses the data into a vector of cFastNBTTag structures. These structures describe the NBT tree,
+but themselves are allocated in a vector, thus minimizing reallocation. 
+The structures have a minimal constructor, setting all member "pointers" to "invalid".
+
+The fast writer doesn't need a NBT tree structure built beforehand, it is commanded to open, append and close tags
+(just like XML); it keeps the internal tag stack and reports errors in usage. 
+It directly outputs a string containing the serialized NBT data.
+*/
+
+
+
+
+
+#pragma once
+
+#include "../Endianness.h"
+
+
+
+
+
+enum eTagType
+{
+	TAG_Min       = 0,  // The minimum value for a tag type
+	TAG_End       = 0,
+	TAG_Byte      = 1,
+	TAG_Short     = 2,
+	TAG_Int       = 3,
+	TAG_Long      = 4,
+	TAG_Float     = 5,
+	TAG_Double    = 6,
+	TAG_ByteArray = 7,
+	TAG_String    = 8,
+	TAG_List      = 9,
+	TAG_Compound  = 10,
+	TAG_IntArray  = 11,
+	TAG_Max       = 11,  // The maximum value for a tag type
+} ;
+
+
+
+
+
+/** This structure is used for all NBT tags.
+It contains indices to the parent array of tags, building the NBT tree this way.
+Also contains indices into the data stream being parsed, used for values;
+NO dynamically allocated memory is used!
+Structure (all with the tree structure it describes) supports moving in memory (std::vector reallocation)
+*/
+struct cFastNBTTag
+{
+public:
+	
+	eTagType m_Type;
+	
+	// The following members are indices into the data stream. m_DataLength == 0 if no data available
+	// They must not be pointers, because the datastream may be copied into another AString object in the meantime.
+	int m_NameStart;
+	int m_NameLength;
+	int m_DataStart;
+	int m_DataLength;
+	
+	// The following members are indices into the array returned; -1 if not valid
+	// They must not be pointers, because pointers would not survive std::vector reallocation
+	int m_Parent;
+	int m_PrevSibling;
+	int m_NextSibling;
+	int m_FirstChild;
+	int m_LastChild;
+	
+	cFastNBTTag(eTagType a_Type, int a_Parent) :
+		m_Type(a_Type),
+		m_NameLength(0),
+		m_DataLength(0),
+		m_Parent(a_Parent),
+		m_PrevSibling(-1),
+		m_NextSibling(-1),
+		m_FirstChild(-1),
+		m_LastChild(-1)
+	{
+	}
+
+	cFastNBTTag(eTagType a_Type, int a_Parent, int a_PrevSibling) :
+		m_Type(a_Type),
+		m_NameLength(0),
+		m_DataLength(0),
+		m_Parent(a_Parent),
+		m_PrevSibling(a_PrevSibling),
+		m_NextSibling(-1),
+		m_FirstChild(-1),
+		m_LastChild(-1)
+	{
+	}
+} ;
+
+
+
+
+
+/** Parses and contains the parsed data
+Also implements data accessor functions for tree traversal and value getters
+The data pointer passed in the constructor is assumed to be valid throughout the object's life. Care must be taken not to initialize from a temporary.
+*/
+class cParsedNBT
+{
+public:
+	cParsedNBT(const char * a_Data, int a_Length);
+	
+	bool IsValid(void) const {return m_IsValid; }
+	
+	int GetRoot(void) const {return 0; }
+	int GetFirstChild (int a_Tag) const { return m_Tags[a_Tag].m_FirstChild; }
+	int GetLastChild  (int a_Tag) const { return m_Tags[a_Tag].m_LastChild; }
+	int GetNextSibling(int a_Tag) const { return m_Tags[a_Tag].m_NextSibling; }
+	int GetPrevSibling(int a_Tag) const { return m_Tags[a_Tag].m_PrevSibling; }
+	int GetDataLength (int a_Tag) const { return m_Tags[a_Tag].m_DataLength; }
+
+	const char * GetData(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type != TAG_List);
+		ASSERT(m_Tags[a_Tag].m_Type != TAG_Compound);
+		return m_Data + m_Tags[a_Tag].m_DataStart;
+	}
+	
+	int FindChildByName(int a_Tag, const AString & a_Name) const
+	{
+		return FindChildByName(a_Tag, a_Name.c_str(), a_Name.length());
+	}
+	
+	int FindChildByName(int a_Tag, const char * a_Name, size_t a_NameLength = 0) const;
+	int FindTagByPath  (int a_Tag, const AString & a_Path) const;
+	
+	eTagType GetType(int a_Tag) const { return m_Tags[a_Tag].m_Type; }
+	
+	/// Returns the children type for a list tag; undefined on other tags. If list empty, returns TAG_End
+	eTagType GetChildrenType(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_List);
+		return (m_Tags[a_Tag].m_FirstChild < 0) ? TAG_End : m_Tags[m_Tags[a_Tag].m_FirstChild].m_Type;
+	}
+	
+	inline unsigned char GetByte(int a_Tag) const 
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Byte);
+		return (unsigned char)(m_Data[m_Tags[a_Tag].m_DataStart]);
+	}
+	
+	inline Int16 GetShort(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Short);
+		return ntohs(*((Int16 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
+	}
+
+	inline Int32 GetInt(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Int);
+		return ntohl(*((Int32 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
+	}
+
+	inline Int64 GetLong(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Long);
+		return NetworkToHostLong8(m_Data + m_Tags[a_Tag].m_DataStart);
+	}
+
+	inline float GetFloat(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Float);
+		Int32 tmp = ntohl(*((Int32 *)(m_Data + m_Tags[a_Tag].m_DataStart)));
+		return *((float *)&tmp);
+	}
+	
+	inline double GetDouble(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_Double);
+		return NetworkToHostDouble8(m_Data + m_Tags[a_Tag].m_DataStart);
+	}
+	
+	inline AString GetString(int a_Tag) const
+	{
+		ASSERT(m_Tags[a_Tag].m_Type == TAG_String);
+		AString res;
+		res.assign(m_Data + m_Tags[a_Tag].m_DataStart, m_Tags[a_Tag].m_DataLength);
+		return res;
+	}
+	
+	inline AString GetName(int a_Tag) const
+	{
+		AString res;
+		res.assign(m_Data + m_Tags[a_Tag].m_NameStart, m_Tags[a_Tag].m_NameLength);
+		return res;
+	}
+	
+protected:
+	const char *             m_Data;
+	int                      m_Length;
+	std::vector<cFastNBTTag> m_Tags;
+	bool                     m_IsValid;  // True if parsing succeeded
+
+	// Used while parsing:
+	int m_Pos;
+
+	bool Parse(void);
+	bool ReadString(int & a_StringStart, int & a_StringLen);  // Reads a simple string (2 bytes length + data), sets the string descriptors
+	bool ReadCompound(void);  // Reads the latest tag as a compound
+	bool ReadList(eTagType a_ChildrenType);  // Reads the latest tag as a list of items of type a_ChildrenType
+	bool ReadTag(void);       // Reads the latest tag, depending on its m_Type setting
+} ;
+
+
+
+
+
+class cFastNBTWriter
+{
+public:
+	cFastNBTWriter(const AString & a_RootTagName = "");
+	
+	void BeginCompound(const AString & a_Name);
+	void EndCompound(void);
+	
+	void BeginList(const AString & a_Name, eTagType a_ChildrenType);
+	void EndList(void);
+	
+	void AddByte     (const AString & a_Name, unsigned char a_Value);
+	void AddShort    (const AString & a_Name, Int16 a_Value);
+	void AddInt      (const AString & a_Name, Int32 a_Value);
+	void AddLong     (const AString & a_Name, Int64 a_Value);
+	void AddFloat    (const AString & a_Name, float a_Value);
+	void AddDouble   (const AString & a_Name, double a_Value);
+	void AddString   (const AString & a_Name, const AString & a_Value);
+	void AddByteArray(const AString & a_Name, const char * a_Value, size_t a_NumElements);
+	void AddIntArray (const AString & a_Name, const int *  a_Value, size_t a_NumElements);
+
+	void AddByteArray(const AString & a_Name, const AString & a_Value)
+	{
+		AddByteArray(a_Name, a_Value.data(), a_Value.size());
+	}
+	
+	const AString & GetResult(void) const {return m_Result; }
+	
+	void Finish(void);
+	
+protected:
+
+	struct sParent
+	{
+		int m_Type;   // TAG_Compound or TAG_List
+		int m_Pos;    // for TAG_List, the position of the list count
+		int m_Count;  // for TAG_List, the element count
+		eTagType m_ItemType;  // for TAG_List, the element type
+	} ;
+	
+	static const int MAX_STACK = 50;  // Highliy doubtful that an NBT would be constructed this many levels deep
+	
+	// These two fields emulate a stack. A raw array is used due to speed issues - no reallocations are allowed.
+	sParent m_Stack[MAX_STACK];
+	int     m_CurrentStack;
+	
+	AString m_Result;
+	
+	bool IsStackTopCompound(void) const { return (m_Stack[m_CurrentStack].m_Type == TAG_Compound); }
+	
+	void WriteString(const char * a_Data, short a_Length);
+	
+	inline void TagCommon(const AString & a_Name, eTagType a_Type)
+	{
+		// If we're directly inside a list, check that the list is of the correct type:
+		ASSERT((m_Stack[m_CurrentStack].m_Type != TAG_List) || (m_Stack[m_CurrentStack].m_ItemType == a_Type));
+		
+		if (IsStackTopCompound())
+		{
+			// Compound: add the type and name:
+			m_Result.push_back((char)a_Type);
+			WriteString(a_Name.c_str(), (short)a_Name.length());
+		}
+		else
+		{
+			// List: add to the counter
+			m_Stack[m_CurrentStack].m_Count++;
+		}
+	}
+} ;
+
+
+
+